Force latest version of pongo2

v3 has a bug with sorted keyword

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.gitignore

@@ -1 +1,2 @@
 certcheck
+promcertcheck

Gopkg.lock

@@ -14,10 +14,10 @@
   revision = "4c0e84591b9aa9e6dcfdf3e020114cd81f89d5f9"
 
 [[projects]]
+  branch = "master"
   name = "github.com/flosch/pongo2"
   packages = ["."]
-  revision = "5e81b817a0c48c1c57cdf1a9056cf76bdee02ca9"
+  revision = "1f4be1efe3b3529b7e58861f75d70120a9567dc4"
-  version = "v3.0"
 
 [[projects]]
   branch = "master"
@@ -37,6 +37,12 @@
   revision = "24fca303ac6da784b9e8269f724ddeb0b2eea5e7"
   version = "v1.5.0"
 
+[[projects]]
+  branch = "master"
+  name = "github.com/juju/errors"
+  packages = ["."]
+  revision = "c7d06af17c68cd34c835053720b21f6549d9b0ee"
+
 [[projects]]
   name = "github.com/matttproud/golang_protobuf_extensions"
   packages = ["pbutil"]
@@ -112,6 +118,6 @@
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "d0a90698569f49d4e7ef58586b857a1c7c60e48eaca07f1585d02e7ce91ca092"
+  inputs-digest = "f88f786b9ff5e99b5589aea171923fd8d9dcef123a4d6be68d7659b923e8dc1e"
   solver-name = "gps-cdcl"
   solver-version = 1

Gopkg.toml

@@ -27,6 +27,7 @@
 
 [[constraint]]
   name = "github.com/flosch/pongo2"
+  branch = "master"
 
 [[constraint]]
   name = "github.com/gorilla/mux"

vendor/github.com/flosch/pongo2/.gitignore

@@ -7,6 +7,7 @@
 _obj
 _test
 .idea
+.vscode
 
 # Architecture specific extensions/prefixes
 *.[568vq]

vendor/github.com/flosch/pongo2/.travis.yml

@@ -1,12 +1,13 @@
 language: go
 
 go:
-  - 1.3
+  - 1.7
   - tip
 install:
-  - go get code.google.com/p/go.tools/cmd/cover
+  - go get golang.org/x/tools/cmd/cover
   - go get github.com/mattn/goveralls
   - go get gopkg.in/check.v1
+  - go get github.com/juju/errors
 script:
   - go test -v -covermode=count -coverprofile=coverage.out -bench . -cpu 1,4
   - '[ "${TRAVIS_PULL_REQUEST}" = "false" ] && $HOME/gopath/bin/goveralls -coverprofile=coverage.out -service=travis-ci -repotoken $COVERALLS_TOKEN || true'

vendor/github.com/flosch/pongo2/README.md

@@ -1,8 +1,9 @@
 # [pongo](https://en.wikipedia.org/wiki/Pongo_%28genus%29)2
 
-[![GoDoc](https://godoc.org/github.com/flosch/pongo2?status.png)](https://godoc.org/github.com/flosch/pongo2)
+[![Join the chat at https://gitter.im/flosch/pongo2](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/flosch/pongo2)
+[![GoDoc](https://godoc.org/github.com/flosch/pongo2?status.svg)](https://godoc.org/github.com/flosch/pongo2)
 [![Build Status](https://travis-ci.org/flosch/pongo2.svg?branch=master)](https://travis-ci.org/flosch/pongo2)
-[![Coverage Status](https://coveralls.io/repos/flosch/pongo2/badge.png?branch=master)](https://coveralls.io/r/flosch/pongo2?branch=master)
+[![Coverage Status](https://coveralls.io/repos/flosch/pongo2/badge.svg?branch=master)](https://coveralls.io/r/flosch/pongo2?branch=master)
 [![gratipay](http://img.shields.io/badge/gratipay-support%20pongo-brightgreen.svg)](https://gratipay.com/flosch/)
 [![Bountysource](https://www.bountysource.com/badge/tracker?tracker_id=3654947)](https://www.bountysource.com/trackers/3654947-pongo2?utm_source=3654947&utm_medium=shield&utm_campaign=TRACKER_BADGE)
 
@@ -95,6 +96,7 @@ Please also have a look on the [caveats](https://github.com/flosch/pongo2#caveat
 
 If you're using the `master`-branch of pongo2, you might be interested in this section. Since pongo2 is still in development (even though there is a first stable release!), there could be (backwards-incompatible) API changes over time. To keep track of these and therefore make it painless for you to adapt your codebase, I'll list them here.
 
+ * Function signature for tag execution changed: not taking a `bytes.Buffer` anymore; instead `Execute()`-functions are now taking a `TemplateWriter` interface.
  * Function signature for tag and filter parsing/execution changed (`error` return type changed to `*Error`).
  * `INodeEvaluator` has been removed and got replaced by `IEvaluator`. You can change your existing tags/filters by simply replacing the interface.
  * Two new helper functions: [`RenderTemplateFile()`](https://godoc.org/github.com/flosch/pongo2#RenderTemplateFile) and [`RenderTemplateString()`](https://godoc.org/github.com/flosch/pongo2#RenderTemplateString).
@@ -104,7 +106,7 @@ If you're using the `master`-branch of pongo2, you might be interested in this s
 ## How you can help
 
  * Write [filters](https://github.com/flosch/pongo2/blob/master/filters_builtin.go#L3) / [tags](https://github.com/flosch/pongo2/blob/master/tags.go#L4) (see [tutorial](https://www.florian-schlachter.de/post/pongo2/)) by forking pongo2 and sending pull requests
- * Write/improve code tests (use the following command to see what tests are missing: `go test -v -cover -covermode=count -coverprofile=cover.out && go tool cover -html=cover.out`)
+ * Write/improve code tests (use the following command to see what tests are missing: `go test -v -cover -covermode=count -coverprofile=cover.out && go tool cover -html=cover.out` or have a look on [gocover.io/github.com/flosch/pongo2](http://gocover.io/github.com/flosch/pongo2))
  * Write/improve template tests (see the `template_tests/` directory)
  * Write middleware, libraries and websites using pongo2. :-)
 
@@ -116,6 +118,7 @@ You can access pongo2's API documentation on [godoc](https://godoc.org/github.co
 
 ## Blog post series
  
+ * [pongo2 v3 released](https://www.florian-schlachter.de/post/pongo2-v3/)
  * [pongo2 v2 released](https://www.florian-schlachter.de/post/pongo2-v2/)
  * [pongo2 1.0 released](https://www.florian-schlachter.de/post/pongo2-10/) [August 8th 2014]
  * [pongo2 playground](https://www.florian-schlachter.de/post/pongo2-playground/) [August 1st 2014]
@@ -154,7 +157,11 @@ You can access pongo2's API documentation on [godoc](https://godoc.org/github.co
  * [beego-pongo2.v2](https://github.com/ipfans/beego-pongo2.v2) - Same as `beego-pongo2`, but for pongo2 v2.
  * [macaron-pongo2](https://github.com/macaron-contrib/pongo2) - pongo2 support for [Macaron](https://github.com/Unknwon/macaron), a modular web framework.
  * [ginpongo2](https://github.com/ngerakines/ginpongo2) - middleware for [gin](github.com/gin-gonic/gin) to use pongo2 templates
- * [pongo2-trans](https://github.com/fromYukki/pongo2trans) - `trans`-tag implementation for internationalization
+ * [Build'n support for Iris' template engine](https://github.com/kataras/iris) 
+ * [pongo2gin](https://github.com/robvdl/pongo2gin) - alternative renderer for [gin](github.com/gin-gonic/gin) to use pongo2 templates
+ * [pongo2-trans](https://github.com/digitalcrab/pongo2trans) - `trans`-tag implementation for internationalization
+ * [tpongo2](https://github.com/tango-contrib/tpongo2) - pongo2 support for [Tango](https://github.com/lunny/tango), a micro-kernel & pluggable web framework.
+ * [p2cli](https://github.com/wrouesnel/p2cli) - command line templating utility based on pongo2
  
 Please add your project to this list and send me a pull request when you've developed something nice for pongo2.
 

vendor/github.com/flosch/pongo2/context.go

@@ -1,13 +1,14 @@
 package pongo2
 
 import (
-	"fmt"
 	"regexp"
+
+	"github.com/juju/errors"
 )
 
 var reIdentifiers = regexp.MustCompile("^[a-zA-Z0-9_]+$")
 
-// Use this Context type to provide constants, variables, instances or functions to your template.
+// A Context type provides constants, variables, instances or functions to a template.
 //
 // pongo2 automatically provides meta-information or functions through the "pongo2"-key.
 // Currently, context["pongo2"] contains the following keys:
@@ -24,14 +25,15 @@ func (c Context) checkForValidIdentifiers() *Error {
 	for k, v := range c {
 		if !reIdentifiers.MatchString(k) {
 			return &Error{
-				Sender:   "checkForValidIdentifiers",
+				Sender:    "checkForValidIdentifiers",
-				ErrorMsg: fmt.Sprintf("Context-key '%s' (value: '%+v') is not a valid identifier.", k, v),
+				OrigError: errors.Errorf("context-key '%s' (value: '%+v') is not a valid identifier", k, v),
 			}
 		}
 	}
 	return nil
 }
 
+// Update updates this context with the key/value-pairs from another context.
 func (c Context) Update(other Context) Context {
 	for k, v := range other {
 		c[k] = v
@@ -39,6 +41,8 @@ func (c Context) Update(other Context) Context {
 	return c
 }
 
+// ExecutionContext contains all data important for the current rendering state.
+//
 // If you're writing a custom tag, your tag's Execute()-function will
 // have access to the ExecutionContext. This struct stores anything
 // about the current rendering process's Context including
@@ -97,6 +101,10 @@ func NewChildExecutionContext(parent *ExecutionContext) *ExecutionContext {
 }
 
 func (ctx *ExecutionContext) Error(msg string, token *Token) *Error {
+	return ctx.OrigError(errors.New(msg), token)
+}
+
+func (ctx *ExecutionContext) OrigError(err error, token *Token) *Error {
 	filename := ctx.template.name
 	var line, col int
 	if token != nil {
@@ -107,13 +115,13 @@ func (ctx *ExecutionContext) Error(msg string, token *Token) *Error {
 		col = token.Col
 	}
 	return &Error{
-		Template: ctx.template,
+		Template:  ctx.template,
-		Filename: filename,
+		Filename:  filename,
-		Line:     line,
+		Line:      line,
-		Column:   col,
+		Column:    col,
-		Token:    token,
+		Token:     token,
-		Sender:   "execution",
+		Sender:    "execution",
-		ErrorMsg: msg,
+		OrigError: err,
 	}
 }
 

vendor/github.com/flosch/pongo2/error.go

@@ -6,20 +6,20 @@ import (
 	"os"
 )
 
-// This Error type is being used to address an error during lexing, parsing or
+// The Error type is being used to address an error during lexing, parsing or
 // execution. If you want to return an error object (for example in your own
 // tag or filter) fill this object with as much information as you have.
 // Make sure "Sender" is always given (if you're returning an error within
 // a filter, make Sender equals 'filter:yourfilter'; same goes for tags: 'tag:mytag').
 // It's okay if you only fill in ErrorMsg if you don't have any other details at hand.
 type Error struct {
-	Template *Template
+	Template  *Template
-	Filename string
+	Filename  string
-	Line     int
+	Line      int
-	Column   int
+	Column    int
-	Token    *Token
+	Token     *Token
-	Sender   string
+	Sender    string
-	ErrorMsg string
+	OrigError error
 }
 
 func (e *Error) updateFromTokenIfNeeded(template *Template, t *Token) *Error {
@@ -54,14 +54,14 @@ func (e *Error) Error() string {
 		}
 	}
 	s += "] "
-	s += e.ErrorMsg
+	s += e.OrigError.Error()
 	return s
 }
 
-// Returns the affected line from the original template, if available.
+// RawLine returns the affected line from the original template, if available.
-func (e *Error) RawLine() (line string, available bool) {
+func (e *Error) RawLine() (line string, available bool, outErr error) {
 	if e.Line <= 0 || e.Filename == "<string>" {
-		return "", false
+		return "", false, nil
 	}
 
 	filename := e.Filename
@@ -70,17 +70,22 @@ func (e *Error) RawLine() (line string, available bool) {
 	}
 	file, err := os.Open(filename)
 	if err != nil {
-		panic(err)
+		return "", false, err
 	}
-	defer file.Close()
+	defer func() {
+		err := file.Close()
+		if err != nil && outErr == nil {
+			outErr = err
+		}
+	}()
 
 	scanner := bufio.NewScanner(file)
 	l := 0
 	for scanner.Scan() {
 		l++
 		if l == e.Line {
-			return scanner.Text(), true
+			return scanner.Text(), true, nil
 		}
 	}
-	return "", false
+	return "", false, nil
 }

vendor/github.com/flosch/pongo2/filters.go

@@ -2,8 +2,11 @@ package pongo2
 
 import (
 	"fmt"
+
+	"github.com/juju/errors"
 )
 
+// FilterFunction is the type filter functions must fulfil
 type FilterFunction func(in *Value, param *Value) (out *Value, err *Error)
 
 var filters map[string]FilterFunction
@@ -12,32 +15,38 @@ func init() {
 	filters = make(map[string]FilterFunction)
 }
 
-// Registers a new filter. If there's already a filter with the same
+// FilterExists returns true if the given filter is already registered
+func FilterExists(name string) bool {
+	_, existing := filters[name]
+	return existing
+}
+
+// RegisterFilter registers a new filter. If there's already a filter with the same
 // name, RegisterFilter will panic. You usually want to call this
 // function in the filter's init() function:
 // http://golang.org/doc/effective_go.html#init
 //
 // See http://www.florian-schlachter.de/post/pongo2/ for more about
 // writing filters and tags.
-func RegisterFilter(name string, fn FilterFunction) {
+func RegisterFilter(name string, fn FilterFunction) error {
-	_, existing := filters[name]
+	if FilterExists(name) {
-	if existing {
+		return errors.Errorf("filter with name '%s' is already registered", name)
-		panic(fmt.Sprintf("Filter with name '%s' is already registered.", name))
 	}
 	filters[name] = fn
+	return nil
 }
 
-// Replaces an already registered filter with a new implementation. Use this
+// ReplaceFilter replaces an already registered filter with a new implementation. Use this
 // function with caution since it allows you to change existing filter behaviour.
-func ReplaceFilter(name string, fn FilterFunction) {
+func ReplaceFilter(name string, fn FilterFunction) error {
-	_, existing := filters[name]
+	if !FilterExists(name) {
-	if !existing {
+		return errors.Errorf("filter with name '%s' does not exist (therefore cannot be overridden)", name)
-		panic(fmt.Sprintf("Filter with name '%s' does not exist (therefore cannot be overridden).", name))
 	}
 	filters[name] = fn
+	return nil
 }
 
-// Like ApplyFilter, but panics on an error
+// MustApplyFilter behaves like ApplyFilter, but panics on an error.
 func MustApplyFilter(name string, value *Value, param *Value) *Value {
 	val, err := ApplyFilter(name, value, param)
 	if err != nil {
@@ -46,13 +55,14 @@ func MustApplyFilter(name string, value *Value, param *Value) *Value {
 	return val
 }
 
-// Applies a filter to a given value using the given parameters. Returns a *pongo2.Value or an error.
+// ApplyFilter applies a filter to a given value using the given parameters.
+// Returns a *pongo2.Value or an error.
 func ApplyFilter(name string, value *Value, param *Value) (*Value, *Error) {
 	fn, existing := filters[name]
 	if !existing {
 		return nil, &Error{
-			Sender:   "applyfilter",
+			Sender:    "applyfilter",
-			ErrorMsg: fmt.Sprintf("Filter with name '%s' not found.", name),
+			OrigError: errors.Errorf("Filter with name '%s' not found.", name),
 		}
 	}
 
@@ -86,31 +96,31 @@ func (fc *filterCall) Execute(v *Value, ctx *ExecutionContext) (*Value, *Error)
 		param = AsValue(nil)
 	}
 
-	filtered_value, err := fc.filterFunc(v, param)
+	filteredValue, err := fc.filterFunc(v, param)
 	if err != nil {
 		return nil, err.updateFromTokenIfNeeded(ctx.template, fc.token)
 	}
-	return filtered_value, nil
+	return filteredValue, nil
 }
 
 // Filter = IDENT | IDENT ":" FilterArg | IDENT "|" Filter
 func (p *Parser) parseFilter() (*filterCall, *Error) {
-	ident_token := p.MatchType(TokenIdentifier)
+	identToken := p.MatchType(TokenIdentifier)
 
 	// Check filter ident
-	if ident_token == nil {
+	if identToken == nil {
 		return nil, p.Error("Filter name must be an identifier.", nil)
 	}
 
 	filter := &filterCall{
-		token: ident_token,
+		token: identToken,
-		name:  ident_token.Val,
+		name:  identToken.Val,
 	}
 
 	// Get the appropriate filter function and bind it
-	filterFn, exists := filters[ident_token.Val]
+	filterFn, exists := filters[identToken.Val]
 	if !exists {
-		return nil, p.Error(fmt.Sprintf("Filter '%s' does not exist.", ident_token.Val), ident_token)
+		return nil, p.Error(fmt.Sprintf("Filter '%s' does not exist.", identToken.Val), identToken)
 	}
 
 	filter.filterFunc = filterFn

vendor/github.com/flosch/pongo2/filters_builtin.go

@@ -35,6 +35,8 @@ import (
 	"strings"
 	"time"
 	"unicode/utf8"
+
+	"github.com/juju/errors"
 )
 
 func init() {
@@ -73,14 +75,15 @@ func init() {
 	RegisterFilter("removetags", filterRemovetags)
 	RegisterFilter("rjust", filterRjust)
 	RegisterFilter("slice", filterSlice)
+	RegisterFilter("split", filterSplit)
 	RegisterFilter("stringformat", filterStringformat)
 	RegisterFilter("striptags", filterStriptags)
 	RegisterFilter("time", filterDate) // time uses filterDate (same golang-format)
 	RegisterFilter("title", filterTitle)
 	RegisterFilter("truncatechars", filterTruncatechars)
-	RegisterFilter("truncatechars_html", filterTruncatecharsHtml)
+	RegisterFilter("truncatechars_html", filterTruncatecharsHTML)
 	RegisterFilter("truncatewords", filterTruncatewords)
-	RegisterFilter("truncatewords_html", filterTruncatewordsHtml)
+	RegisterFilter("truncatewords_html", filterTruncatewordsHTML)
 	RegisterFilter("upper", filterUpper)
 	RegisterFilter("urlencode", filterUrlencode)
 	RegisterFilter("urlize", filterUrlize)
@@ -105,9 +108,9 @@ func filterTruncatecharsHelper(s string, newLen int) string {
 	return string(runes)
 }
 
-func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func() bool, fn func(c rune, s int, idx int) int, finalize func()) {
+func filterTruncateHTMLHelper(value string, newOutput *bytes.Buffer, cond func() bool, fn func(c rune, s int, idx int) int, finalize func()) {
 	vLen := len(value)
-	tag_stack := make([]string, 0)
+	var tagStack []string
 	idx := 0
 
 	for idx < vLen && !cond() {
@@ -118,17 +121,17 @@ func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func(
 		}
 
 		if c == '<' {
-			new_output.WriteRune(c)
+			newOutput.WriteRune(c)
 			idx += s // consume "<"
 
 			if idx+1 < vLen {
 				if value[idx] == '/' {
 					// Close tag
 
-					new_output.WriteString("/")
+					newOutput.WriteString("/")
 
 					tag := ""
-					idx += 1 // consume "/"
+					idx++ // consume "/"
 
 					for idx < vLen {
 						c2, size2 := utf8.DecodeRuneInString(value[idx:])
@@ -146,21 +149,21 @@ func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func(
 						idx += size2
 					}
 
-					if len(tag_stack) > 0 {
+					if len(tagStack) > 0 {
 						// Ideally, the close tag is TOP of tag stack
 						// In malformed HTML, it must not be, so iterate through the stack and remove the tag
-						for i := len(tag_stack) - 1; i >= 0; i-- {
+						for i := len(tagStack) - 1; i >= 0; i-- {
-							if tag_stack[i] == tag {
+							if tagStack[i] == tag {
 								// Found the tag
-								tag_stack[i] = tag_stack[len(tag_stack)-1]
+								tagStack[i] = tagStack[len(tagStack)-1]
-								tag_stack = tag_stack[:len(tag_stack)-1]
+								tagStack = tagStack[:len(tagStack)-1]
 								break
 							}
 						}
 					}
 
-					new_output.WriteString(tag)
+					newOutput.WriteString(tag)
-					new_output.WriteString(">")
+					newOutput.WriteString(">")
 				} else {
 					// Open tag
 
@@ -174,7 +177,7 @@ func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func(
 							continue
 						}
 
-						new_output.WriteRune(c2)
+						newOutput.WriteRune(c2)
 
 						// End of tag found
 						if c2 == '>' {
@@ -194,7 +197,7 @@ func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func(
 					}
 
 					// Add tag to stack
-					tag_stack = append(tag_stack, tag)
+					tagStack = append(tagStack, tag)
 				}
 			}
 		} else {
@@ -204,10 +207,10 @@ func filterTruncateHtmlHelper(value string, new_output *bytes.Buffer, cond func(
 
 	finalize()
 
-	for i := len(tag_stack) - 1; i >= 0; i-- {
+	for i := len(tagStack) - 1; i >= 0; i-- {
-		tag := tag_stack[i]
+		tag := tagStack[i]
 		// Close everything from the regular tag stack
-		new_output.WriteString(fmt.Sprintf("</%s>", tag))
+		newOutput.WriteString(fmt.Sprintf("</%s>", tag))
 	}
 }
 
@@ -217,28 +220,28 @@ func filterTruncatechars(in *Value, param *Value) (*Value, *Error) {
 	return AsValue(filterTruncatecharsHelper(s, newLen)), nil
 }
 
-func filterTruncatecharsHtml(in *Value, param *Value) (*Value, *Error) {
+func filterTruncatecharsHTML(in *Value, param *Value) (*Value, *Error) {
 	value := in.String()
 	newLen := max(param.Integer()-3, 0)
 
-	new_output := bytes.NewBuffer(nil)
+	newOutput := bytes.NewBuffer(nil)
 
 	textcounter := 0
 
-	filterTruncateHtmlHelper(value, new_output, func() bool {
+	filterTruncateHTMLHelper(value, newOutput, func() bool {
 		return textcounter >= newLen
 	}, func(c rune, s int, idx int) int {
 		textcounter++
-		new_output.WriteRune(c)
+		newOutput.WriteRune(c)
 
 		return idx + s
 	}, func() {
 		if textcounter >= newLen && textcounter < len(value) {
-			new_output.WriteString("...")
+			newOutput.WriteString("...")
 		}
 	})
 
-	return AsSafeValue(new_output.String()), nil
+	return AsSafeValue(newOutput.String()), nil
 }
 
 func filterTruncatewords(in *Value, param *Value) (*Value, *Error) {
@@ -260,19 +263,19 @@ func filterTruncatewords(in *Value, param *Value) (*Value, *Error) {
 	return AsValue(strings.Join(out, " ")), nil
 }
 
-func filterTruncatewordsHtml(in *Value, param *Value) (*Value, *Error) {
+func filterTruncatewordsHTML(in *Value, param *Value) (*Value, *Error) {
 	value := in.String()
 	newLen := max(param.Integer(), 0)
 
-	new_output := bytes.NewBuffer(nil)
+	newOutput := bytes.NewBuffer(nil)
 
 	wordcounter := 0
 
-	filterTruncateHtmlHelper(value, new_output, func() bool {
+	filterTruncateHTMLHelper(value, newOutput, func() bool {
 		return wordcounter >= newLen
 	}, func(_ rune, _ int, idx int) int {
 		// Get next word
-		word_found := false
+		wordFound := false
 
 		for idx < len(value) {
 			c2, size2 := utf8.DecodeRuneInString(value[idx:])
@@ -286,29 +289,29 @@ func filterTruncatewordsHtml(in *Value, param *Value) (*Value, *Error) {
 				return idx
 			}
 
-			new_output.WriteRune(c2)
+			newOutput.WriteRune(c2)
 			idx += size2
 
 			if c2 == ' ' || c2 == '.' || c2 == ',' || c2 == ';' {
 				// Word ends here, stop capturing it now
 				break
 			} else {
-				word_found = true
+				wordFound = true
 			}
 		}
 
-		if word_found {
+		if wordFound {
 			wordcounter++
 		}
 
 		return idx
 	}, func() {
 		if wordcounter >= newLen {
-			new_output.WriteString("...")
+			newOutput.WriteString("...")
 		}
 	})
 
-	return AsSafeValue(new_output.String()), nil
+	return AsSafeValue(newOutput.String()), nil
 }
 
 func filterEscape(in *Value, param *Value) (*Value, *Error) {
@@ -377,12 +380,11 @@ func filterAdd(in *Value, param *Value) (*Value, *Error) {
 	if in.IsNumber() && param.IsNumber() {
 		if in.IsFloat() || param.IsFloat() {
 			return AsValue(in.Float() + param.Float()), nil
-		} else {
-			return AsValue(in.Integer() + param.Integer()), nil
 		}
+		return AsValue(in.Integer() + param.Integer()), nil
 	}
 	// If in/param is not a number, we're relying on the
-	// Value's String() convertion and just add them both together
+	// Value's String() conversion and just add them both together
 	return AsValue(in.String() + param.String()), nil
 }
 
@@ -550,11 +552,11 @@ func filterCenter(in *Value, param *Value) (*Value, *Error) {
 }
 
 func filterDate(in *Value, param *Value) (*Value, *Error) {
-	t, is_time := in.Interface().(time.Time)
+	t, isTime := in.Interface().(time.Time)
-	if !is_time {
+	if !isTime {
 		return nil, &Error{
-			Sender:   "filter:date",
+			Sender:    "filter:date",
-			ErrorMsg: "Filter input argument must be of type 'time.Time'.",
+			OrigError: errors.New("filter input argument must be of type 'time.Time'"),
 		}
 	}
 	return AsValue(t.Format(param.String())), nil
@@ -612,6 +614,12 @@ func filterLinebreaks(in *Value, param *Value) (*Value, *Error) {
 	return AsValue(b.String()), nil
 }
 
+func filterSplit(in *Value, param *Value) (*Value, *Error) {
+	chunks := strings.Split(in.String(), param.String())
+
+	return AsValue(chunks), nil
+}
+
 func filterLinebreaksbr(in *Value, param *Value) (*Value, *Error) {
 	return AsValue(strings.Replace(in.String(), "\n", "<br />", -1)), nil
 }
@@ -641,7 +649,8 @@ func filterUrlencode(in *Value, param *Value) (*Value, *Error) {
 var filterUrlizeURLRegexp = regexp.MustCompile(`((((http|https)://)|www\.|((^|[ ])[0-9A-Za-z_\-]+(\.com|\.net|\.org|\.info|\.biz|\.de))))(?U:.*)([ ]+|$)`)
 var filterUrlizeEmailRegexp = regexp.MustCompile(`(\w+@\w+\.\w{2,4})`)
 
-func filterUrlizeHelper(input string, autoescape bool, trunc int) string {
+func filterUrlizeHelper(input string, autoescape bool, trunc int) (string, error) {
+	var soutErr error
 	sout := filterUrlizeURLRegexp.ReplaceAllStringFunc(input, func(raw_url string) string {
 		var prefix string
 		var suffix string
@@ -656,7 +665,8 @@ func filterUrlizeHelper(input string, autoescape bool, trunc int) string {
 
 		t, err := ApplyFilter("iriencode", AsValue(raw_url), nil)
 		if err != nil {
-			panic(err)
+			soutErr = err
+			return ""
 		}
 		url := t.String()
 
@@ -673,16 +683,19 @@ func filterUrlizeHelper(input string, autoescape bool, trunc int) string {
 		if autoescape {
 			t, err := ApplyFilter("escape", AsValue(title), nil)
 			if err != nil {
-				panic(err)
+				soutErr = err
+				return ""
 			}
 			title = t.String()
 		}
 
 		return fmt.Sprintf(`%s<a href="%s" rel="nofollow">%s</a>%s`, prefix, url, title, suffix)
 	})
+	if soutErr != nil {
+		return "", soutErr
+	}
 
 	sout = filterUrlizeEmailRegexp.ReplaceAllStringFunc(sout, func(mail string) string {
-
 		title := mail
 
 		if trunc > 3 && len(title) > trunc {
@@ -692,7 +705,7 @@ func filterUrlizeHelper(input string, autoescape bool, trunc int) string {
 		return fmt.Sprintf(`<a href="mailto:%s">%s</a>`, mail, title)
 	})
 
-	return sout
+	return sout, nil
 }
 
 func filterUrlize(in *Value, param *Value) (*Value, *Error) {
@@ -701,24 +714,36 @@ func filterUrlize(in *Value, param *Value) (*Value, *Error) {
 		autoescape = param.Bool()
 	}
 
-	return AsValue(filterUrlizeHelper(in.String(), autoescape, -1)), nil
+	s, err := filterUrlizeHelper(in.String(), autoescape, -1)
+	if err != nil {
+
+	}
+
+	return AsValue(s), nil
 }
 
 func filterUrlizetrunc(in *Value, param *Value) (*Value, *Error) {
-	return AsValue(filterUrlizeHelper(in.String(), true, param.Integer())), nil
+	s, err := filterUrlizeHelper(in.String(), true, param.Integer())
+	if err != nil {
+		return nil, &Error{
+			Sender:    "filter:urlizetrunc",
+			OrigError: errors.New("you cannot pass more than 2 arguments to filter 'pluralize'"),
+		}
+	}
+	return AsValue(s), nil
 }
 
 func filterStringformat(in *Value, param *Value) (*Value, *Error) {
 	return AsValue(fmt.Sprintf(param.String(), in.Interface())), nil
 }
 
-var re_striptags = regexp.MustCompile("<[^>]*?>")
+var reStriptags = regexp.MustCompile("<[^>]*?>")
 
 func filterStriptags(in *Value, param *Value) (*Value, *Error) {
 	s := in.String()
 
 	// Strip all tags
-	s = re_striptags.ReplaceAllString(s, "")
+	s = reStriptags.ReplaceAllString(s, "")
 
 	return AsValue(strings.TrimSpace(s)), nil
 }
@@ -746,8 +771,8 @@ func filterPluralize(in *Value, param *Value) (*Value, *Error) {
 			endings := strings.Split(param.String(), ",")
 			if len(endings) > 2 {
 				return nil, &Error{
-					Sender:   "filter:pluralize",
+					Sender:    "filter:pluralize",
-					ErrorMsg: "You cannot pass more than 2 arguments to filter 'pluralize'.",
+					OrigError: errors.New("you cannot pass more than 2 arguments to filter 'pluralize'"),
 				}
 			}
 			if len(endings) == 1 {
@@ -770,11 +795,10 @@ func filterPluralize(in *Value, param *Value) (*Value, *Error) {
 		}
 
 		return AsValue(""), nil
-	} else {
+	}
-		return nil, &Error{
+	return nil, &Error{
-			Sender:   "filter:pluralize",
+		Sender:    "filter:pluralize",
-			ErrorMsg: "Filter 'pluralize' does only work on numbers.",
+		OrigError: errors.New("filter 'pluralize' does only work on numbers"),
-		}
 	}
 }
 
@@ -807,8 +831,8 @@ func filterSlice(in *Value, param *Value) (*Value, *Error) {
 	comp := strings.Split(param.String(), ":")
 	if len(comp) != 2 {
 		return nil, &Error{
-			Sender:   "filter:slice",
+			Sender:    "filter:slice",
-			ErrorMsg: "Slice string must have the format 'from:to' [from/to can be omitted, but the ':' is required]",
+			OrigError: errors.New("Slice string must have the format 'from:to' [from/to can be omitted, but the ':' is required]"),
 		}
 	}
 
@@ -844,16 +868,16 @@ func filterWordcount(in *Value, param *Value) (*Value, *Error) {
 
 func filterWordwrap(in *Value, param *Value) (*Value, *Error) {
 	words := strings.Fields(in.String())
-	words_len := len(words)
+	wordsLen := len(words)
-	wrap_at := param.Integer()
+	wrapAt := param.Integer()
-	if wrap_at <= 0 {
+	if wrapAt <= 0 {
 		return in, nil
 	}
 
-	linecount := words_len/wrap_at + words_len%wrap_at
+	linecount := wordsLen/wrapAt + wordsLen%wrapAt
 	lines := make([]string, 0, linecount)
 	for i := 0; i < linecount; i++ {
-		lines = append(lines, strings.Join(words[wrap_at*i:min(wrap_at*(i+1), words_len)], " "))
+		lines = append(lines, strings.Join(words[wrapAt*i:min(wrapAt*(i+1), wordsLen)], " "))
 	}
 	return AsValue(strings.Join(lines, "\n")), nil
 }
@@ -864,27 +888,27 @@ func filterYesno(in *Value, param *Value) (*Value, *Error) {
 		1: "no",
 		2: "maybe",
 	}
-	param_string := param.String()
+	paramString := param.String()
-	custom_choices := strings.Split(param_string, ",")
+	customChoices := strings.Split(paramString, ",")
-	if len(param_string) > 0 {
+	if len(paramString) > 0 {
-		if len(custom_choices) > 3 {
+		if len(customChoices) > 3 {
 			return nil, &Error{
-				Sender:   "filter:yesno",
+				Sender:    "filter:yesno",
-				ErrorMsg: fmt.Sprintf("You cannot pass more than 3 options to the 'yesno'-filter (got: '%s').", param_string),
+				OrigError: errors.Errorf("You cannot pass more than 3 options to the 'yesno'-filter (got: '%s').", paramString),
 			}
 		}
-		if len(custom_choices) < 2 {
+		if len(customChoices) < 2 {
 			return nil, &Error{
-				Sender:   "filter:yesno",
+				Sender:    "filter:yesno",
-				ErrorMsg: fmt.Sprintf("You must pass either no or at least 2 arguments to the 'yesno'-filter (got: '%s').", param_string),
+				OrigError: errors.Errorf("You must pass either no or at least 2 arguments to the 'yesno'-filter (got: '%s').", paramString),
 			}
 		}
 
 		// Map to the options now
-		choices[0] = custom_choices[0]
+		choices[0] = customChoices[0]
-		choices[1] = custom_choices[1]
+		choices[1] = customChoices[1]
-		if len(custom_choices) == 3 {
+		if len(customChoices) == 3 {
-			choices[2] = custom_choices[2]
+			choices[2] = customChoices[2]
 		}
 	}
 

vendor/github.com/flosch/pongo2/lexer.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"strings"
 	"unicode/utf8"
+
+	"github.com/juju/errors"
 )
 
 const (
@@ -63,8 +65,8 @@ type lexer struct {
 	line      int
 	col       int
 
-	in_verbatim   bool
+	inVerbatim   bool
-	verbatim_name string
+	verbatimName string
 }
 
 func (t *Token) String() string {
@@ -111,11 +113,11 @@ func lex(name string, input string) ([]*Token, *Error) {
 	if l.errored {
 		errtoken := l.tokens[len(l.tokens)-1]
 		return nil, &Error{
-			Filename: name,
+			Filename:  name,
-			Line:     errtoken.Line,
+			Line:      errtoken.Line,
-			Column:   errtoken.Col,
+			Column:    errtoken.Col,
-			Sender:   "lexer",
+			Sender:    "lexer",
-			ErrorMsg: errtoken.Val,
+			OrigError: errors.New(errtoken.Val),
 		}
 	}
 	return l.tokens, nil
@@ -216,8 +218,8 @@ func (l *lexer) run() {
 	for {
 		// TODO: Support verbatim tag names
 		// https://docs.djangoproject.com/en/dev/ref/templates/builtins/#verbatim
-		if l.in_verbatim {
+		if l.inVerbatim {
-			name := l.verbatim_name
+			name := l.verbatimName
 			if name != "" {
 				name += " "
 			}
@@ -229,20 +231,20 @@ func (l *lexer) run() {
 				l.pos += w
 				l.col += w
 				l.ignore()
-				l.in_verbatim = false
+				l.inVerbatim = false
 			}
 		} else if strings.HasPrefix(l.input[l.pos:], "{% verbatim %}") { // tag
 			if l.pos > l.start {
 				l.emit(TokenHTML)
 			}
-			l.in_verbatim = true
+			l.inVerbatim = true
 			w := len("{% verbatim %}")
 			l.pos += w
 			l.col += w
 			l.ignore()
 		}
 
-		if !l.in_verbatim {
+		if !l.inVerbatim {
 			// Ignore single-line comments {# ... #}
 			if strings.HasPrefix(l.input[l.pos:], "{#") {
 				if l.pos > l.start {
@@ -303,7 +305,7 @@ func (l *lexer) run() {
 		l.emit(TokenHTML)
 	}
 
-	if l.in_verbatim {
+	if l.inVerbatim {
 		l.errorf("verbatim-tag not closed, got EOF.")
 	}
 }
@@ -328,7 +330,7 @@ outer_loop:
 			return l.stateIdentifier
 		case l.accept(tokenDigits):
 			return l.stateNumber
-		case l.accept(`"`):
+		case l.accept(`"'`):
 			return l.stateString
 		}
 
@@ -348,10 +350,6 @@ outer_loop:
 			}
 		}
 
-		if l.pos < len(l.input) {
-			return l.errorf("Unknown character: %q (%d)", l.peek(), l.peek())
-		}
-
 		break
 	}
 
@@ -374,6 +372,11 @@ func (l *lexer) stateIdentifier() lexerStateFn {
 
 func (l *lexer) stateNumber() lexerStateFn {
 	l.acceptRun(tokenDigits)
+	if l.accept(tokenIdentifierCharsWithDigits) {
+		// This seems to be an identifier starting with a number.
+		// See https://github.com/flosch/pongo2/issues/151
+		return l.stateIdentifier()
+	}
 	/*
 		Maybe context-sensitive number lexing?
 		* comments.0.Text // first comment
@@ -393,9 +396,10 @@ func (l *lexer) stateNumber() lexerStateFn {
 }
 
 func (l *lexer) stateString() lexerStateFn {
+	quotationMark := l.value()
 	l.ignore()
-	l.startcol -= 1 // we're starting the position at the first "
+	l.startcol-- // we're starting the position at the first "
-	for !l.accept(`"`) {
+	for !l.accept(quotationMark) {
 		switch l.next() {
 		case '\\':
 			// escape sequence

vendor/github.com/flosch/pongo2/nodes.go

@@ -1,17 +1,13 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 // The root document
 type nodeDocument struct {
 	Nodes []INode
 }
 
-func (doc *nodeDocument) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (doc *nodeDocument) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	for _, n := range doc.Nodes {
-		err := n.Execute(ctx, buffer)
+		err := n.Execute(ctx, writer)
 		if err != nil {
 			return err
 		}

vendor/github.com/flosch/pongo2/nodes_html.go

@@ -1,14 +1,10 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type nodeHTML struct {
 	token *Token
 }
 
-func (n *nodeHTML) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (n *nodeHTML) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	buffer.WriteString(n.token.Val)
+	writer.WriteString(n.token.Val)
 	return nil
 }

vendor/github.com/flosch/pongo2/nodes_wrapper.go

@@ -1,17 +1,13 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type NodeWrapper struct {
 	Endtag string
 	nodes  []INode
 }
 
-func (wrapper *NodeWrapper) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (wrapper *NodeWrapper) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	for _, n := range wrapper.nodes {
-		err := n.Execute(ctx, buffer)
+		err := n.Execute(ctx, writer)
 		if err != nil {
 			return err
 		}

vendor/github.com/flosch/pongo2/parser.go

@@ -1,13 +1,14 @@
 package pongo2
 
 import (
-	"bytes"
 	"fmt"
 	"strings"
+
+	"github.com/juju/errors"
 )
 
 type INode interface {
-	Execute(*ExecutionContext, *bytes.Buffer) *Error
+	Execute(*ExecutionContext, TemplateWriter) *Error
 }
 
 type IEvaluator interface {
@@ -27,10 +28,10 @@ type IEvaluator interface {
 //
 // (See Token's documentation for more about tokens)
 type Parser struct {
-	name       string
+	name      string
-	idx        int
+	idx       int
-	tokens     []*Token
+	tokens    []*Token
-	last_token *Token
+	lastToken *Token
 
 	// if the parser parses a template document, here will be
 	// a reference to it (needed to access the template through Tags)
@@ -47,7 +48,7 @@ func newParser(name string, tokens []*Token, template *Template) *Parser {
 		template: template,
 	}
 	if len(tokens) > 0 {
-		p.last_token = tokens[len(tokens)-1]
+		p.lastToken = tokens[len(tokens)-1]
 	}
 	return p
 }
@@ -175,7 +176,7 @@ func (p *Parser) GetR(shift int) *Token {
 	return p.Get(i)
 }
 
-// Produces a nice error message and returns an error-object.
+// Error produces a nice error message and returns an error-object.
 // The 'token'-argument is optional. If provided, it will take
 // the token's position information. If not provided, it will
 // automatically use the CURRENT token's position information.
@@ -196,13 +197,13 @@ func (p *Parser) Error(msg string, token *Token) *Error {
 		col = token.Col
 	}
 	return &Error{
-		Template: p.template,
+		Template:  p.template,
-		Filename: p.name,
+		Filename:  p.name,
-		Sender:   "parser",
+		Sender:    "parser",
-		Line:     line,
+		Line:      line,
-		Column:   col,
+		Column:    col,
-		Token:    token,
+		Token:     token,
-		ErrorMsg: msg,
+		OrigError: errors.New(msg),
 	}
 }
 
@@ -212,19 +213,19 @@ func (p *Parser) Error(msg string, token *Token) *Error {
 func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
 	wrapper := &NodeWrapper{}
 
-	tagArgs := make([]*Token, 0)
+	var tagArgs []*Token
 
 	for p.Remaining() > 0 {
 		// New tag, check whether we have to stop wrapping here
 		if p.Peek(TokenSymbol, "{%") != nil {
-			tag_ident := p.PeekTypeN(1, TokenIdentifier)
+			tagIdent := p.PeekTypeN(1, TokenIdentifier)
 
-			if tag_ident != nil {
+			if tagIdent != nil {
 				// We've found a (!) end-tag
 
 				found := false
 				for _, n := range names {
-					if tag_ident.Val == n {
+					if tagIdent.Val == n {
 						found = true
 						break
 					}
@@ -238,16 +239,15 @@ func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
 					for {
 						if p.Match(TokenSymbol, "%}") != nil {
 							// Okay, end the wrapping here
-							wrapper.Endtag = tag_ident.Val
+							wrapper.Endtag = tagIdent.Val
 							return wrapper, newParser(p.template.name, tagArgs, p.template), nil
-						} else {
-							t := p.Current()
-							p.Consume()
-							if t == nil {
-								return nil, nil, p.Error("Unexpected EOF.", p.last_token)
-							}
-							tagArgs = append(tagArgs, t)
 						}
+						t := p.Current()
+						p.Consume()
+						if t == nil {
+							return nil, nil, p.Error("Unexpected EOF.", p.lastToken)
+						}
+						tagArgs = append(tagArgs, t)
 					}
 				}
 			}
@@ -263,5 +263,47 @@ func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
 	}
 
 	return nil, nil, p.Error(fmt.Sprintf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")),
-		p.last_token)
+		p.lastToken)
+}
+
+// Skips all nodes between starting tag and "{% endtag %}"
+func (p *Parser) SkipUntilTag(names ...string) *Error {
+	for p.Remaining() > 0 {
+		// New tag, check whether we have to stop wrapping here
+		if p.Peek(TokenSymbol, "{%") != nil {
+			tagIdent := p.PeekTypeN(1, TokenIdentifier)
+
+			if tagIdent != nil {
+				// We've found a (!) end-tag
+
+				found := false
+				for _, n := range names {
+					if tagIdent.Val == n {
+						found = true
+						break
+					}
+				}
+
+				// We only process the tag if we've found an end tag
+				if found {
+					// Okay, endtag found.
+					p.ConsumeN(2) // '{%' tagname
+
+					for {
+						if p.Match(TokenSymbol, "%}") != nil {
+							// Done skipping, exit.
+							return nil
+						}
+					}
+				}
+			}
+		}
+		t := p.Current()
+		p.Consume()
+		if t == nil {
+			return p.Error("Unexpected EOF.", p.lastToken)
+		}
+	}
+
+	return p.Error(fmt.Sprintf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")), p.lastToken)
 }

vendor/github.com/flosch/pongo2/parser_expression.go

@@ -1,38 +1,37 @@
 package pongo2
 
 import (
-	"bytes"
 	"fmt"
 	"math"
 )
 
 type Expression struct {
 	// TODO: Add location token?
-	expr1    IEvaluator
+	expr1   IEvaluator
-	expr2    IEvaluator
+	expr2   IEvaluator
-	op_token *Token
+	opToken *Token
 }
 
 type relationalExpression struct {
 	// TODO: Add location token?
-	expr1    IEvaluator
+	expr1   IEvaluator
-	expr2    IEvaluator
+	expr2   IEvaluator
-	op_token *Token
+	opToken *Token
 }
 
 type simpleExpression struct {
-	negate        bool
+	negate       bool
-	negative_sign bool
+	negativeSign bool
-	term1         IEvaluator
+	term1        IEvaluator
-	term2         IEvaluator
+	term2        IEvaluator
-	op_token      *Token
+	opToken      *Token
 }
 
 type term struct {
 	// TODO: Add location token?
-	factor1  IEvaluator
+	factor1 IEvaluator
-	factor2  IEvaluator
+	factor2 IEvaluator
-	op_token *Token
+	opToken *Token
 }
 
 type power struct {
@@ -56,14 +55,14 @@ func (expr *simpleExpression) FilterApplied(name string) bool {
 		(expr.term2 != nil && expr.term2.FilterApplied(name)))
 }
 
-func (t *term) FilterApplied(name string) bool {
+func (expr *term) FilterApplied(name string) bool {
-	return t.factor1.FilterApplied(name) && (t.factor2 == nil ||
+	return expr.factor1.FilterApplied(name) && (expr.factor2 == nil ||
-		(t.factor2 != nil && t.factor2.FilterApplied(name)))
+		(expr.factor2 != nil && expr.factor2.FilterApplied(name)))
 }
 
-func (p *power) FilterApplied(name string) bool {
+func (expr *power) FilterApplied(name string) bool {
-	return p.power1.FilterApplied(name) && (p.power2 == nil ||
+	return expr.power1.FilterApplied(name) && (expr.power2 == nil ||
-		(p.power2 != nil && p.power2.FilterApplied(name)))
+		(expr.power2 != nil && expr.power2.FilterApplied(name)))
 }
 
 func (expr *Expression) GetPositionToken() *Token {
@@ -86,48 +85,48 @@ func (expr *power) GetPositionToken() *Token {
 	return expr.power1.GetPositionToken()
 }
 
-func (expr *Expression) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (expr *Expression) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := expr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *relationalExpression) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (expr *relationalExpression) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := expr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *simpleExpression) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (expr *simpleExpression) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := expr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *term) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (expr *term) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := expr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *power) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (expr *power) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := expr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
@@ -141,13 +140,13 @@ func (expr *Expression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 		if err != nil {
 			return nil, err
 		}
-		switch expr.op_token.Val {
+		switch expr.opToken.Val {
 		case "and", "&&":
 			return AsValue(v1.IsTrue() && v2.IsTrue()), nil
 		case "or", "||":
 			return AsValue(v1.IsTrue() || v2.IsTrue()), nil
 		default:
-			panic(fmt.Sprintf("unimplemented: %s", expr.op_token.Val))
+			return nil, ctx.Error(fmt.Sprintf("unimplemented: %s", expr.opToken.Val), expr.opToken)
 		}
 	} else {
 		return v1, nil
@@ -164,39 +163,35 @@ func (expr *relationalExpression) Evaluate(ctx *ExecutionContext) (*Value, *Erro
 		if err != nil {
 			return nil, err
 		}
-		switch expr.op_token.Val {
+		switch expr.opToken.Val {
 		case "<=":
 			if v1.IsFloat() || v2.IsFloat() {
 				return AsValue(v1.Float() <= v2.Float()), nil
-			} else {
-				return AsValue(v1.Integer() <= v2.Integer()), nil
 			}
+			return AsValue(v1.Integer() <= v2.Integer()), nil
 		case ">=":
 			if v1.IsFloat() || v2.IsFloat() {
 				return AsValue(v1.Float() >= v2.Float()), nil
-			} else {
-				return AsValue(v1.Integer() >= v2.Integer()), nil
 			}
+			return AsValue(v1.Integer() >= v2.Integer()), nil
 		case "==":
 			return AsValue(v1.EqualValueTo(v2)), nil
 		case ">":
 			if v1.IsFloat() || v2.IsFloat() {
 				return AsValue(v1.Float() > v2.Float()), nil
-			} else {
-				return AsValue(v1.Integer() > v2.Integer()), nil
 			}
+			return AsValue(v1.Integer() > v2.Integer()), nil
 		case "<":
 			if v1.IsFloat() || v2.IsFloat() {
 				return AsValue(v1.Float() < v2.Float()), nil
-			} else {
-				return AsValue(v1.Integer() < v2.Integer()), nil
 			}
+			return AsValue(v1.Integer() < v2.Integer()), nil
 		case "!=", "<>":
 			return AsValue(!v1.EqualValueTo(v2)), nil
 		case "in":
 			return AsValue(v2.Contains(v1)), nil
 		default:
-			panic(fmt.Sprintf("unimplemented: %s", expr.op_token.Val))
+			return nil, ctx.Error(fmt.Sprintf("unimplemented: %s", expr.opToken.Val), expr.opToken)
 		}
 	} else {
 		return v1, nil
@@ -214,7 +209,7 @@ func (expr *simpleExpression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 		result = result.Negate()
 	}
 
-	if expr.negative_sign {
+	if expr.negativeSign {
 		if result.IsNumber() {
 			switch {
 			case result.IsFloat():
@@ -222,7 +217,7 @@ func (expr *simpleExpression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 			case result.IsInteger():
 				result = AsValue(-1 * result.Integer())
 			default:
-				panic("not possible")
+				return nil, ctx.Error("Operation between a number and a non-(float/integer) is not possible", nil)
 			}
 		} else {
 			return nil, ctx.Error("Negative sign on a non-number expression", expr.GetPositionToken())
@@ -234,42 +229,40 @@ func (expr *simpleExpression) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 		if err != nil {
 			return nil, err
 		}
-		switch expr.op_token.Val {
+		switch expr.opToken.Val {
 		case "+":
 			if result.IsFloat() || t2.IsFloat() {
 				// Result will be a float
 				return AsValue(result.Float() + t2.Float()), nil
-			} else {
-				// Result will be an integer
-				return AsValue(result.Integer() + t2.Integer()), nil
 			}
+			// Result will be an integer
+			return AsValue(result.Integer() + t2.Integer()), nil
 		case "-":
 			if result.IsFloat() || t2.IsFloat() {
 				// Result will be a float
 				return AsValue(result.Float() - t2.Float()), nil
-			} else {
-				// Result will be an integer
-				return AsValue(result.Integer() - t2.Integer()), nil
 			}
+			// Result will be an integer
+			return AsValue(result.Integer() - t2.Integer()), nil
 		default:
-			panic("unimplemented")
+			return nil, ctx.Error("Unimplemented", expr.GetPositionToken())
 		}
 	}
 
 	return result, nil
 }
 
-func (t *term) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
+func (expr *term) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
-	f1, err := t.factor1.Evaluate(ctx)
+	f1, err := expr.factor1.Evaluate(ctx)
 	if err != nil {
 		return nil, err
 	}
-	if t.factor2 != nil {
+	if expr.factor2 != nil {
-		f2, err := t.factor2.Evaluate(ctx)
+		f2, err := expr.factor2.Evaluate(ctx)
 		if err != nil {
 			return nil, err
 		}
-		switch t.op_token.Val {
+		switch expr.opToken.Val {
 		case "*":
 			if f1.IsFloat() || f2.IsFloat() {
 				// Result will be float
@@ -288,27 +281,26 @@ func (t *term) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 			// Result will be int
 			return AsValue(f1.Integer() % f2.Integer()), nil
 		default:
-			panic("unimplemented")
+			return nil, ctx.Error("unimplemented", expr.opToken)
 		}
 	} else {
 		return f1, nil
 	}
 }
 
-func (pw *power) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
+func (expr *power) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
-	p1, err := pw.power1.Evaluate(ctx)
+	p1, err := expr.power1.Evaluate(ctx)
 	if err != nil {
 		return nil, err
 	}
-	if pw.power2 != nil {
+	if expr.power2 != nil {
-		p2, err := pw.power2.Evaluate(ctx)
+		p2, err := expr.power2.Evaluate(ctx)
 		if err != nil {
 			return nil, err
 		}
 		return AsValue(math.Pow(p1.Float(), p2.Float())), nil
-	} else {
-		return p1, nil
 	}
+	return p1, nil
 }
 
 func (p *Parser) parseFactor() (IEvaluator, *Error) {
@@ -352,19 +344,19 @@ func (p *Parser) parsePower() (IEvaluator, *Error) {
 }
 
 func (p *Parser) parseTerm() (IEvaluator, *Error) {
-	return_term := new(term)
+	returnTerm := new(term)
 
 	factor1, err := p.parsePower()
 	if err != nil {
 		return nil, err
 	}
-	return_term.factor1 = factor1
+	returnTerm.factor1 = factor1
 
 	for p.PeekOne(TokenSymbol, "*", "/", "%") != nil {
-		if return_term.op_token != nil {
+		if returnTerm.opToken != nil {
 			// Create new sub-term
-			return_term = &term{
+			returnTerm = &term{
-				factor1: return_term,
+				factor1: returnTerm,
 			}
 		}
 
@@ -376,16 +368,16 @@ func (p *Parser) parseTerm() (IEvaluator, *Error) {
 			return nil, err
 		}
 
-		return_term.op_token = op
+		returnTerm.opToken = op
-		return_term.factor2 = factor2
+		returnTerm.factor2 = factor2
 	}
 
-	if return_term.op_token == nil {
+	if returnTerm.opToken == nil {
 		// Shortcut for faster evaluation
-		return return_term.factor1, nil
+		return returnTerm.factor1, nil
 	}
 
-	return return_term, nil
+	return returnTerm, nil
 }
 
 func (p *Parser) parseSimpleExpression() (IEvaluator, *Error) {
@@ -393,7 +385,7 @@ func (p *Parser) parseSimpleExpression() (IEvaluator, *Error) {
 
 	if sign := p.MatchOne(TokenSymbol, "+", "-"); sign != nil {
 		if sign.Val == "-" {
-			expr.negative_sign = true
+			expr.negativeSign = true
 		}
 	}
 
@@ -408,7 +400,7 @@ func (p *Parser) parseSimpleExpression() (IEvaluator, *Error) {
 	expr.term1 = term1
 
 	for p.PeekOne(TokenSymbol, "+", "-") != nil {
-		if expr.op_token != nil {
+		if expr.opToken != nil {
 			// New sub expr
 			expr = &simpleExpression{
 				term1: expr,
@@ -424,10 +416,10 @@ func (p *Parser) parseSimpleExpression() (IEvaluator, *Error) {
 		}
 
 		expr.term2 = term2
-		expr.op_token = op
+		expr.opToken = op
 	}
 
-	if expr.negate == false && expr.negative_sign == false && expr.term2 == nil {
+	if expr.negate == false && expr.negativeSign == false && expr.term2 == nil {
 		// Shortcut for faster evaluation
 		return expr.term1, nil
 	}
@@ -450,14 +442,14 @@ func (p *Parser) parseRelationalExpression() (IEvaluator, *Error) {
 		if err != nil {
 			return nil, err
 		}
-		expr.op_token = t
+		expr.opToken = t
 		expr.expr2 = expr2
 	} else if t := p.MatchOne(TokenKeyword, "in"); t != nil {
 		expr2, err := p.parseSimpleExpression()
 		if err != nil {
 			return nil, err
 		}
-		expr.op_token = t
+		expr.opToken = t
 		expr.expr2 = expr2
 	}
 
@@ -487,7 +479,7 @@ func (p *Parser) ParseExpression() (IEvaluator, *Error) {
 			return nil, err
 		}
 		exp.expr2 = expr2
-		exp.op_token = op
+		exp.opToken = op
 	}
 
 	if exp.expr2 == nil {

vendor/github.com/flosch/pongo2/pongo2.go

@@ -1,10 +1,10 @@
 package pongo2
 
 // Version string
-const Version = "v3"
+const Version = "dev"
 
-// Helper function which panics, if a Template couldn't
+// Must panics, if a Template couldn't successfully parsed. This is how you
-// successfully parsed. This is how you would use it:
+// would use it:
 //     var baseTemplate = pongo2.Must(pongo2.FromFile("templates/base.html"))
 func Must(tpl *Template, err error) *Template {
 	if err != nil {

vendor/github.com/flosch/pongo2/pongo2_issues_test.go

@@ -1,20 +1,29 @@
-package pongo2
+package pongo2_test
 
 import (
 	"testing"
 
-	. "gopkg.in/check.v1"
+	"github.com/flosch/pongo2"
 )
 
-// Hook up gocheck into the "go test" runner.
+func TestIssue151(t *testing.T) {
+	tpl, err := pongo2.FromString("{{ mydict.51232_3 }}{{ 12345_123}}{{ 995189baz }}")
+	if err != nil {
+		t.Fatal(err)
+	}
 
-func TestIssues(t *testing.T) { TestingT(t) }
+	str, err := tpl.Execute(pongo2.Context{
+		"mydict": map[string]string{
+			"51232_3": "foo",
+		},
+		"12345_123": "bar",
+		"995189baz": "baz",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
 
-type IssueTestSuite struct{}
+	if str != "foobarbaz" {
-
+		t.Fatalf("Expected output 'foobarbaz', but got '%s'.", str)
-var _ = Suite(&IssueTestSuite{})
+	}
-
-func (s *TestSuite) TestIssues(c *C) {
-	// Add a test for any issue
-	c.Check(42, Equals, 42)
 }

vendor/github.com/flosch/pongo2/pongo2_template_test.go

@@ -1,4 +1,4 @@
-package pongo2
+package pongo2_test
 
 import (
 	"bytes"
@@ -9,9 +9,11 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/flosch/pongo2"
 )
 
-var admin_list = []string{"user2"}
+var adminList = []string{"user2"}
 
 var time1 = time.Date(2014, 06, 10, 15, 30, 15, 0, time.UTC)
 var time2 = time.Date(2011, 03, 21, 8, 37, 56, 12, time.UTC)
@@ -32,8 +34,8 @@ type comment struct {
 	Text   string
 }
 
-func is_admin(u *user) bool {
+func isAdmin(u *user) bool {
-	for _, a := range admin_list {
+	for _, a := range adminList {
 		if a == u.Name {
 			return true
 		}
@@ -41,12 +43,12 @@ func is_admin(u *user) bool {
 	return false
 }
 
-func (u *user) Is_admin() *Value {
+func (u *user) Is_admin() *pongo2.Value {
-	return AsValue(is_admin(u))
+	return pongo2.AsValue(isAdmin(u))
 }
 
 func (u *user) Is_admin2() bool {
-	return is_admin(u)
+	return isAdmin(u)
 }
 
 func (p *post) String() string {
@@ -60,74 +62,53 @@ func (p *post) String() string {
 type tagSandboxDemoTag struct {
 }
 
-func (node *tagSandboxDemoTag) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagSandboxDemoTag) Execute(ctx *pongo2.ExecutionContext, writer pongo2.TemplateWriter) *pongo2.Error {
-	buffer.WriteString("hello")
+	writer.WriteString("hello")
 	return nil
 }
 
-func tagSandboxDemoTagParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
+func tagSandboxDemoTagParser(doc *pongo2.Parser, start *pongo2.Token, arguments *pongo2.Parser) (pongo2.INodeTag, *pongo2.Error) {
 	return &tagSandboxDemoTag{}, nil
 }
 
-func BannedFilterFn(in *Value, params *Value) (*Value, *Error) {
+func BannedFilterFn(in *pongo2.Value, params *pongo2.Value) (*pongo2.Value, *pongo2.Error) {
 	return in, nil
 }
 
 func init() {
-	DefaultSet.Debug = true
+	pongo2.DefaultSet.Debug = true
 
-	RegisterFilter("banned_filter", BannedFilterFn)
+	pongo2.RegisterFilter("banned_filter", BannedFilterFn)
-	RegisterFilter("unbanned_filter", BannedFilterFn)
+	pongo2.RegisterFilter("unbanned_filter", BannedFilterFn)
-	RegisterTag("banned_tag", tagSandboxDemoTagParser)
+	pongo2.RegisterTag("banned_tag", tagSandboxDemoTagParser)
-	RegisterTag("unbanned_tag", tagSandboxDemoTagParser)
+	pongo2.RegisterTag("unbanned_tag", tagSandboxDemoTagParser)
 
-	DefaultSet.BanFilter("banned_filter")
+	pongo2.DefaultSet.BanFilter("banned_filter")
-	DefaultSet.BanTag("banned_tag")
+	pongo2.DefaultSet.BanTag("banned_tag")
-
-	// Allow different kind of levels inside template_tests/
-	abs_path, err := filepath.Abs("./template_tests/*")
-	if err != nil {
-		panic(err)
-	}
-	DefaultSet.SandboxDirectories = append(DefaultSet.SandboxDirectories, abs_path)
-
-	abs_path, err = filepath.Abs("./template_tests/*/*")
-	if err != nil {
-		panic(err)
-	}
-	DefaultSet.SandboxDirectories = append(DefaultSet.SandboxDirectories, abs_path)
-
-	abs_path, err = filepath.Abs("./template_tests/*/*/*")
-	if err != nil {
-		panic(err)
-	}
-	DefaultSet.SandboxDirectories = append(DefaultSet.SandboxDirectories, abs_path)
-
-	// Allow pongo2 temp files
-	DefaultSet.SandboxDirectories = append(DefaultSet.SandboxDirectories, "/tmp/pongo2_*")
 
 	f, err := ioutil.TempFile("/tmp/", "pongo2_")
 	if err != nil {
 		panic("cannot write to /tmp/")
 	}
 	f.Write([]byte("Hello from pongo2"))
-	DefaultSet.Globals["temp_file"] = f.Name()
+	pongo2.DefaultSet.Globals["temp_file"] = f.Name()
 }
 
 /*
  * End setup sandbox
  */
 
-var tplContext = Context{
+var tplContext = pongo2.Context{
 	"number": 11,
 	"simple": map[string]interface{}{
-		"number":        42,
+		"number":                   42,
-		"name":          "john doe",
+		"name":                     "john doe",
-		"included_file": "INCLUDES.helper",
+		"included_file":            "INCLUDES.helper",
-		"nil":           nil,
+		"included_file_not_exists": "INCLUDES.helper.not_exists",
-		"uint":          uint(8),
+		"nil":   nil,
-		"float":         float64(3.1415),
+		"uint":  uint(8),
-		"str":           "string",
+		"float": float64(3.1415),
+		"str":   "string",
 		"chinese_hello_world": "你好世界",
 		"bool_true":           true,
 		"bool_false":          false,
@@ -142,13 +123,23 @@ Yep!`,
 		"escape_js_test":     `escape sequences \r\n\'\" special chars "?!=$<>`,
 		"one_item_list":      []int{99},
 		"multiple_item_list": []int{1, 1, 2, 3, 5, 8, 13, 21, 34, 55},
+		"unsorted_int_list":  []int{192, 581, 22, 1, 249, 9999, 1828591, 8271},
+		"fixed_item_list":    [...]int{1, 2, 3, 4},
 		"misc_list":          []interface{}{"Hello", 99, 3.14, "good"},
 		"escape_text":        "This is \\a Test. \"Yep\". 'Yep'.",
 		"xss":                "<script>alert(\"uh oh\");</script>",
 		"intmap": map[int]string{
 			1: "one",
-			2: "two",
 			5: "five",
+			2: "two",
+		},
+		"strmap": map[string]string{
+			"abc": "def",
+			"bcd": "efg",
+			"zab": "cde",
+			"gh":  "kqm",
+			"ukq": "qqa",
+			"aab": "aba",
 		},
 		"func_add": func(a, b int) int {
 			return a + b
@@ -167,17 +158,17 @@ Yep!`,
 			}
 			return s
 		},
-		"func_variadic_sum_int2": func(args ...*Value) *Value {
+		"func_variadic_sum_int2": func(args ...*pongo2.Value) *pongo2.Value {
 			// Create a sum
 			s := 0
 			for _, i := range args {
 				s += i.Integer()
 			}
-			return AsValue(s)
+			return pongo2.AsValue(s)
 		},
 	},
 	"complex": map[string]interface{}{
-		"is_admin": is_admin,
+		"is_admin": isAdmin,
 		"post": post{
 			Text:    "<h2>Hello!</h2><p>Welcome to my new blog page. I'm using pongo2 which supports {{ variables }} and {% tags %}.</p>",
 			Created: time2,
@@ -238,10 +229,8 @@ Yep!`,
 }
 
 func TestTemplates(t *testing.T) {
-	debug = true
-
 	// Add a global to the default set
-	Globals["this_is_a_global_variable"] = "this is a global text"
+	pongo2.Globals["this_is_a_global_variable"] = "this is a global text"
 
 	matches, err := filepath.Glob("./template_tests/*.tpl")
 	if err != nil {
@@ -249,34 +238,34 @@ func TestTemplates(t *testing.T) {
 	}
 	for idx, match := range matches {
 		t.Logf("[Template %3d] Testing '%s'", idx+1, match)
-		tpl, err := FromFile(match)
+		tpl, err := pongo2.FromFile(match)
 		if err != nil {
 			t.Fatalf("Error on FromFile('%s'): %s", match, err.Error())
 		}
-		test_filename := fmt.Sprintf("%s.out", match)
+		testFilename := fmt.Sprintf("%s.out", match)
-		test_out, rerr := ioutil.ReadFile(test_filename)
+		testOut, rerr := ioutil.ReadFile(testFilename)
 		if rerr != nil {
-			t.Fatalf("Error on ReadFile('%s'): %s", test_filename, rerr.Error())
+			t.Fatalf("Error on ReadFile('%s'): %s", testFilename, rerr.Error())
 		}
-		tpl_out, err := tpl.ExecuteBytes(tplContext)
+		tplOut, err := tpl.ExecuteBytes(tplContext)
 		if err != nil {
 			t.Fatalf("Error on Execute('%s'): %s", match, err.Error())
 		}
-		if bytes.Compare(test_out, tpl_out) != 0 {
+		if bytes.Compare(testOut, tplOut) != 0 {
-			t.Logf("Template (rendered) '%s': '%s'", match, tpl_out)
+			t.Logf("Template (rendered) '%s': '%s'", match, tplOut)
-			err_filename := filepath.Base(fmt.Sprintf("%s.error", match))
+			errFilename := filepath.Base(fmt.Sprintf("%s.error", match))
-			err := ioutil.WriteFile(err_filename, []byte(tpl_out), 0600)
+			err := ioutil.WriteFile(errFilename, []byte(tplOut), 0600)
 			if err != nil {
 				t.Fatalf(err.Error())
 			}
-			t.Logf("get a complete diff with command: 'diff -ya %s %s'", test_filename, err_filename)
+			t.Logf("get a complete diff with command: 'diff -ya %s %s'", testFilename, errFilename)
 			t.Errorf("Failed: test_out != tpl_out for %s", match)
 		}
 	}
 }
 
 func TestExecutionErrors(t *testing.T) {
-	debug = true
+	//debug = true
 
 	matches, err := filepath.Glob("./template_tests/*-execution.err")
 	if err != nil {
@@ -285,15 +274,15 @@ func TestExecutionErrors(t *testing.T) {
 	for idx, match := range matches {
 		t.Logf("[Errors %3d] Testing '%s'", idx+1, match)
 
-		test_data, err := ioutil.ReadFile(match)
+		testData, err := ioutil.ReadFile(match)
-		tests := strings.Split(string(test_data), "\n")
+		tests := strings.Split(string(testData), "\n")
 
-		check_filename := fmt.Sprintf("%s.out", match)
+		checkFilename := fmt.Sprintf("%s.out", match)
-		check_data, err := ioutil.ReadFile(check_filename)
+		checkData, err := ioutil.ReadFile(checkFilename)
 		if err != nil {
-			t.Fatalf("Error on ReadFile('%s'): %s", check_filename, err.Error())
+			t.Fatalf("Error on ReadFile('%s'): %s", checkFilename, err.Error())
 		}
-		checks := strings.Split(string(check_data), "\n")
+		checks := strings.Split(string(checkData), "\n")
 
 		if len(checks) != len(tests) {
 			t.Fatal("Template lines != Checks lines")
@@ -308,11 +297,16 @@ func TestExecutionErrors(t *testing.T) {
 					match, idx+1)
 			}
 
-			tpl, err := FromString(test)
+			tpl, err := pongo2.FromString(test)
 			if err != nil {
 				t.Fatalf("Error on FromString('%s'): %s", test, err.Error())
 			}
 
+			tpl, err = pongo2.FromBytes([]byte(test))
+			if err != nil {
+				t.Fatalf("Error on FromBytes('%s'): %s", test, err.Error())
+			}
+
 			_, err = tpl.ExecuteBytes(tplContext)
 			if err == nil {
 				t.Fatalf("[%s Line %d] Expected error for (got none): %s",
@@ -329,7 +323,7 @@ func TestExecutionErrors(t *testing.T) {
 }
 
 func TestCompilationErrors(t *testing.T) {
-	debug = true
+	//debug = true
 
 	matches, err := filepath.Glob("./template_tests/*-compilation.err")
 	if err != nil {
@@ -338,15 +332,15 @@ func TestCompilationErrors(t *testing.T) {
 	for idx, match := range matches {
 		t.Logf("[Errors %3d] Testing '%s'", idx+1, match)
 
-		test_data, err := ioutil.ReadFile(match)
+		testData, err := ioutil.ReadFile(match)
-		tests := strings.Split(string(test_data), "\n")
+		tests := strings.Split(string(testData), "\n")
 
-		check_filename := fmt.Sprintf("%s.out", match)
+		checkFilename := fmt.Sprintf("%s.out", match)
-		check_data, err := ioutil.ReadFile(check_filename)
+		checkData, err := ioutil.ReadFile(checkFilename)
 		if err != nil {
-			t.Fatalf("Error on ReadFile('%s'): %s", check_filename, err.Error())
+			t.Fatalf("Error on ReadFile('%s'): %s", checkFilename, err.Error())
 		}
-		checks := strings.Split(string(check_data), "\n")
+		checks := strings.Split(string(checkData), "\n")
 
 		if len(checks) != len(tests) {
 			t.Fatal("Template lines != Checks lines")
@@ -361,7 +355,7 @@ func TestCompilationErrors(t *testing.T) {
 					match, idx+1)
 			}
 
-			_, err = FromString(test)
+			_, err = pongo2.FromString(test)
 			if err == nil {
 				t.Fatalf("[%s | Line %d] Expected error for (got none): %s", match, idx+1, tests[idx])
 			}
@@ -377,9 +371,10 @@ func TestCompilationErrors(t *testing.T) {
 func TestBaseDirectory(t *testing.T) {
 	mustStr := "Hello from template_tests/base_dir_test/"
 
-	s := NewSet("test set with base directory")
+	fs := pongo2.MustNewLocalFileSystemLoader("")
+	s := pongo2.NewSet("test set with base directory", fs)
 	s.Globals["base_directory"] = "template_tests/base_dir_test/"
-	if err := s.SetBaseDirectory(s.Globals["base_directory"].(string)); err != nil {
+	if err := fs.SetBaseDir(s.Globals["base_directory"].(string)); err != nil {
 		t.Fatal(err)
 	}
 
@@ -405,13 +400,13 @@ func TestBaseDirectory(t *testing.T) {
 }
 
 func BenchmarkCache(b *testing.B) {
-	cache_set := NewSet("cache set")
+	cacheSet := pongo2.NewSet("cache set", pongo2.MustNewLocalFileSystemLoader(""))
 	for i := 0; i < b.N; i++ {
-		tpl, err := cache_set.FromCache("template_tests/complex.tpl")
+		tpl, err := cacheSet.FromCache("template_tests/complex.tpl")
 		if err != nil {
 			b.Fatal(err)
 		}
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -419,14 +414,14 @@ func BenchmarkCache(b *testing.B) {
 }
 
 func BenchmarkCacheDebugOn(b *testing.B) {
-	cache_debug_set := NewSet("cache set")
+	cacheDebugSet := pongo2.NewSet("cache set", pongo2.MustNewLocalFileSystemLoader(""))
-	cache_debug_set.Debug = true
+	cacheDebugSet.Debug = true
 	for i := 0; i < b.N; i++ {
-		tpl, err := cache_debug_set.FromFile("template_tests/complex.tpl")
+		tpl, err := cacheDebugSet.FromFile("template_tests/complex.tpl")
 		if err != nil {
 			b.Fatal(err)
 		}
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -434,13 +429,13 @@ func BenchmarkCacheDebugOn(b *testing.B) {
 }
 
 func BenchmarkExecuteComplexWithSandboxActive(b *testing.B) {
-	tpl, err := FromFile("template_tests/complex.tpl")
+	tpl, err := pongo2.FromFile("template_tests/complex.tpl")
 	if err != nil {
 		b.Fatal(err)
 	}
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -455,12 +450,12 @@ func BenchmarkCompileAndExecuteComplexWithSandboxActive(b *testing.B) {
 	preloadedTpl := string(buf)
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		tpl, err := FromString(preloadedTpl)
+		tpl, err := pongo2.FromString(preloadedTpl)
 		if err != nil {
 			b.Fatal(err)
 		}
 
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -468,14 +463,14 @@ func BenchmarkCompileAndExecuteComplexWithSandboxActive(b *testing.B) {
 }
 
 func BenchmarkParallelExecuteComplexWithSandboxActive(b *testing.B) {
-	tpl, err := FromFile("template_tests/complex.tpl")
+	tpl, err := pongo2.FromFile("template_tests/complex.tpl")
 	if err != nil {
 		b.Fatal(err)
 	}
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			_, err := tpl.ExecuteBytes(tplContext)
+			err := tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 			if err != nil {
 				b.Fatal(err)
 			}
@@ -484,14 +479,14 @@ func BenchmarkParallelExecuteComplexWithSandboxActive(b *testing.B) {
 }
 
 func BenchmarkExecuteComplexWithoutSandbox(b *testing.B) {
-	s := NewSet("set without sandbox")
+	s := pongo2.NewSet("set without sandbox", pongo2.MustNewLocalFileSystemLoader(""))
 	tpl, err := s.FromFile("template_tests/complex.tpl")
 	if err != nil {
 		b.Fatal(err)
 	}
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -505,7 +500,7 @@ func BenchmarkCompileAndExecuteComplexWithoutSandbox(b *testing.B) {
 	}
 	preloadedTpl := string(buf)
 
-	s := NewSet("set without sandbox")
+	s := pongo2.NewSet("set without sandbox", pongo2.MustNewLocalFileSystemLoader(""))
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
@@ -514,7 +509,7 @@ func BenchmarkCompileAndExecuteComplexWithoutSandbox(b *testing.B) {
 			b.Fatal(err)
 		}
 
-		_, err = tpl.ExecuteBytes(tplContext)
+		err = tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -522,7 +517,7 @@ func BenchmarkCompileAndExecuteComplexWithoutSandbox(b *testing.B) {
 }
 
 func BenchmarkParallelExecuteComplexWithoutSandbox(b *testing.B) {
-	s := NewSet("set without sandbox")
+	s := pongo2.NewSet("set without sandbox", pongo2.MustNewLocalFileSystemLoader(""))
 	tpl, err := s.FromFile("template_tests/complex.tpl")
 	if err != nil {
 		b.Fatal(err)
@@ -530,7 +525,7 @@ func BenchmarkParallelExecuteComplexWithoutSandbox(b *testing.B) {
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			_, err := tpl.ExecuteBytes(tplContext)
+			err := tpl.ExecuteWriterUnbuffered(tplContext, ioutil.Discard)
 			if err != nil {
 				b.Fatal(err)
 			}

vendor/github.com/flosch/pongo2/pongo2_test.go

@@ -1,26 +1,26 @@
-package pongo2
+package pongo2_test
 
 import (
 	"testing"
 
+	"github.com/flosch/pongo2"
 	. "gopkg.in/check.v1"
 )
 
 // Hook up gocheck into the "go test" runner.
-
 func Test(t *testing.T) { TestingT(t) }
 
 type TestSuite struct {
-	tpl *Template
+	tpl *pongo2.Template
 }
 
 var (
-	_           = Suite(&TestSuite{})
+	_          = Suite(&TestSuite{})
-	test_suite2 = NewSet("test suite 2")
+	testSuite2 = pongo2.NewSet("test suite 2", pongo2.MustNewLocalFileSystemLoader(""))
 )
 
-func parseTemplate(s string, c Context) string {
+func parseTemplate(s string, c pongo2.Context) string {
-	t, err := test_suite2.FromString(s)
+	t, err := testSuite2.FromString(s)
 	if err != nil {
 		panic(err)
 	}
@@ -31,7 +31,7 @@ func parseTemplate(s string, c Context) string {
 	return out
 }
 
-func parseTemplateFn(s string, c Context) func() {
+func parseTemplateFn(s string, c pongo2.Context) func() {
 	return func() {
 		parseTemplate(s, c)
 	}
@@ -40,27 +40,64 @@ func parseTemplateFn(s string, c Context) func() {
 func (s *TestSuite) TestMisc(c *C) {
 	// Must
 	// TODO: Add better error message (see issue #18)
-	c.Check(func() { Must(test_suite2.FromFile("template_tests/inheritance/base2.tpl")) },
+	c.Check(
+		func() { pongo2.Must(testSuite2.FromFile("template_tests/inheritance/base2.tpl")) },
 		PanicMatches,
-		`\[Error \(where: fromfile\) in template_tests/inheritance/doesnotexist.tpl | Line 1 Col 12 near 'doesnotexist.tpl'\] open template_tests/inheritance/doesnotexist.tpl: no such file or directory`)
+		`\[Error \(where: fromfile\) in .*template_tests/inheritance/doesnotexist.tpl | Line 1 Col 12 near 'doesnotexist.tpl'\] open .*template_tests/inheritance/doesnotexist.tpl: no such file or directory`,
+	)
 
 	// Context
-	c.Check(parseTemplateFn("", Context{"'illegal": nil}), PanicMatches, ".*not a valid identifier.*")
+	c.Check(parseTemplateFn("", pongo2.Context{"'illegal": nil}), PanicMatches, ".*not a valid identifier.*")
 
 	// Registers
-	c.Check(func() { RegisterFilter("escape", nil) }, PanicMatches, ".*is already registered.*")
+	c.Check(pongo2.RegisterFilter("escape", nil).Error(), Matches, ".*is already registered")
-	c.Check(func() { RegisterTag("for", nil) }, PanicMatches, ".*is already registered.*")
+	c.Check(pongo2.RegisterTag("for", nil).Error(), Matches, ".*is already registered")
 
 	// ApplyFilter
-	v, err := ApplyFilter("title", AsValue("this is a title"), nil)
+	v, err := pongo2.ApplyFilter("title", pongo2.AsValue("this is a title"), nil)
 	if err != nil {
 		c.Fatal(err)
 	}
 	c.Check(v.String(), Equals, "This Is A Title")
 	c.Check(func() {
-		_, err := ApplyFilter("doesnotexist", nil, nil)
+		_, err := pongo2.ApplyFilter("doesnotexist", nil, nil)
 		if err != nil {
 			panic(err)
 		}
 	}, PanicMatches, `\[Error \(where: applyfilter\)\] Filter with name 'doesnotexist' not found.`)
 }
+
+func (s *TestSuite) TestImplicitExecCtx(c *C) {
+	tpl, err := pongo2.FromString("{{ ImplicitExec }}")
+	if err != nil {
+		c.Fatalf("Error in FromString: %v", err)
+	}
+
+	val := "a stringy thing"
+
+	res, err := tpl.Execute(pongo2.Context{
+		"Value": val,
+		"ImplicitExec": func(ctx *pongo2.ExecutionContext) string {
+			return ctx.Public["Value"].(string)
+		},
+	})
+
+	if err != nil {
+		c.Fatalf("Error executing template: %v", err)
+	}
+
+	c.Check(res, Equals, val)
+
+	// The implicit ctx should not be persisted from call-to-call
+	res, err = tpl.Execute(pongo2.Context{
+		"ImplicitExec": func() string {
+			return val
+		},
+	})
+
+	if err != nil {
+		c.Fatalf("Error executing template: %v", err)
+	}
+
+	c.Check(res, Equals, val)
+}

vendor/github.com/flosch/pongo2/tags.go

@@ -21,6 +21,8 @@ package pongo2
 
 import (
 	"fmt"
+
+	"github.com/juju/errors"
 )
 
 type INodeTag interface {
@@ -53,80 +55,81 @@ func init() {
 	tags = make(map[string]*tag)
 }
 
-// Registers a new tag. If there's already a tag with the same
+// Registers a new tag. You usually want to call this
-// name, RegisterTag will panic. You usually want to call this
 // function in the tag's init() function:
 // http://golang.org/doc/effective_go.html#init
 //
 // See http://www.florian-schlachter.de/post/pongo2/ for more about
 // writing filters and tags.
-func RegisterTag(name string, parserFn TagParser) {
+func RegisterTag(name string, parserFn TagParser) error {
 	_, existing := tags[name]
 	if existing {
-		panic(fmt.Sprintf("Tag with name '%s' is already registered.", name))
+		return errors.Errorf("tag with name '%s' is already registered", name)
 	}
 	tags[name] = &tag{
 		name:   name,
 		parser: parserFn,
 	}
+	return nil
 }
 
 // Replaces an already registered tag with a new implementation. Use this
 // function with caution since it allows you to change existing tag behaviour.
-func ReplaceTag(name string, parserFn TagParser) {
+func ReplaceTag(name string, parserFn TagParser) error {
 	_, existing := tags[name]
 	if !existing {
-		panic(fmt.Sprintf("Tag with name '%s' does not exist (therefore cannot be overridden).", name))
+		return errors.Errorf("tag with name '%s' does not exist (therefore cannot be overridden)", name)
 	}
 	tags[name] = &tag{
 		name:   name,
 		parser: parserFn,
 	}
+	return nil
 }
 
 // Tag = "{%" IDENT ARGS "%}"
 func (p *Parser) parseTagElement() (INodeTag, *Error) {
 	p.Consume() // consume "{%"
-	token_name := p.MatchType(TokenIdentifier)
+	tokenName := p.MatchType(TokenIdentifier)
 
 	// Check for identifier
-	if token_name == nil {
+	if tokenName == nil {
 		return nil, p.Error("Tag name must be an identifier.", nil)
 	}
 
 	// Check for the existing tag
-	tag, exists := tags[token_name.Val]
+	tag, exists := tags[tokenName.Val]
 	if !exists {
 		// Does not exists
-		return nil, p.Error(fmt.Sprintf("Tag '%s' not found (or beginning tag not provided)", token_name.Val), token_name)
+		return nil, p.Error(fmt.Sprintf("Tag '%s' not found (or beginning tag not provided)", tokenName.Val), tokenName)
 	}
 
 	// Check sandbox tag restriction
-	if _, is_banned := p.template.set.bannedTags[token_name.Val]; is_banned {
+	if _, isBanned := p.template.set.bannedTags[tokenName.Val]; isBanned {
-		return nil, p.Error(fmt.Sprintf("Usage of tag '%s' is not allowed (sandbox restriction active).", token_name.Val), token_name)
+		return nil, p.Error(fmt.Sprintf("Usage of tag '%s' is not allowed (sandbox restriction active).", tokenName.Val), tokenName)
 	}
 
-	args_token := make([]*Token, 0)
+	var argsToken []*Token
 	for p.Peek(TokenSymbol, "%}") == nil && p.Remaining() > 0 {
 		// Add token to args
-		args_token = append(args_token, p.Current())
+		argsToken = append(argsToken, p.Current())
 		p.Consume() // next token
 	}
 
 	// EOF?
 	if p.Remaining() == 0 {
-		return nil, p.Error("Unexpectedly reached EOF, no tag end found.", p.last_token)
+		return nil, p.Error("Unexpectedly reached EOF, no tag end found.", p.lastToken)
 	}
 
 	p.Match(TokenSymbol, "%}")
 
-	arg_parser := newParser(p.name, args_token, p.template)
+	argParser := newParser(p.name, argsToken, p.template)
-	if len(args_token) == 0 {
+	if len(argsToken) == 0 {
 		// This is done to have nice EOF error messages
-		arg_parser.last_token = token_name
+		argParser.lastToken = tokenName
 	}
 
 	p.template.level++
 	defer func() { p.template.level-- }()
-	return tag.parser(p, token_name, arg_parser)
+	return tag.parser(p, tokenName, argParser)
 }

vendor/github.com/flosch/pongo2/tags_autoescape.go

@@ -1,19 +1,15 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagAutoescapeNode struct {
 	wrapper    *NodeWrapper
 	autoescape bool
 }
 
-func (node *tagAutoescapeNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagAutoescapeNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	old := ctx.Autoescape
 	ctx.Autoescape = node.autoescape
 
-	err := node.wrapper.Execute(ctx, buffer)
+	err := node.wrapper.Execute(ctx, writer)
 	if err != nil {
 		return err
 	}
@@ -24,22 +20,22 @@ func (node *tagAutoescapeNode) Execute(ctx *ExecutionContext, buffer *bytes.Buff
 }
 
 func tagAutoescapeParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	autoescape_node := &tagAutoescapeNode{}
+	autoescapeNode := &tagAutoescapeNode{}
 
 	wrapper, _, err := doc.WrapUntilTag("endautoescape")
 	if err != nil {
 		return nil, err
 	}
-	autoescape_node.wrapper = wrapper
+	autoescapeNode.wrapper = wrapper
 
-	mode_token := arguments.MatchType(TokenIdentifier)
+	modeToken := arguments.MatchType(TokenIdentifier)
-	if mode_token == nil {
+	if modeToken == nil {
 		return nil, arguments.Error("A mode is required for autoescape-tag.", nil)
 	}
-	if mode_token.Val == "on" {
+	if modeToken.Val == "on" {
-		autoescape_node.autoescape = true
+		autoescapeNode.autoescape = true
-	} else if mode_token.Val == "off" {
+	} else if modeToken.Val == "off" {
-		autoescape_node.autoescape = false
+		autoescapeNode.autoescape = false
 	} else {
 		return nil, arguments.Error("Only 'on' or 'off' is valid as an autoescape-mode.", nil)
 	}
@@ -48,7 +44,7 @@ func tagAutoescapeParser(doc *Parser, start *Token, arguments *Parser) (INodeTag
 		return nil, arguments.Error("Malformed autoescape-tag arguments.", nil)
 	}
 
-	return autoescape_node, nil
+	return autoescapeNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_block.go

@@ -9,47 +9,82 @@ type tagBlockNode struct {
 	name string
 }
 
-func (node *tagBlockNode) getBlockWrapperByName(tpl *Template) *NodeWrapper {
+func (node *tagBlockNode) getBlockWrappers(tpl *Template) []*NodeWrapper {
+	nodeWrappers := make([]*NodeWrapper, 0)
 	var t *NodeWrapper
-	if tpl.child != nil {
+
-		// First ask the child for the block
+	for tpl != nil {
-		t = node.getBlockWrapperByName(tpl.child)
-	}
-	if t == nil {
-		// Child has no block, lets look up here at parent
 		t = tpl.blocks[node.name]
+		if t != nil {
+			nodeWrappers = append(nodeWrappers, t)
+		}
+		tpl = tpl.child
 	}
-	return t
+
+	return nodeWrappers
 }
 
-func (node *tagBlockNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagBlockNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	tpl := ctx.template
 	if tpl == nil {
 		panic("internal error: tpl == nil")
 	}
+
 	// Determine the block to execute
-	block_wrapper := node.getBlockWrapperByName(tpl)
+	blockWrappers := node.getBlockWrappers(tpl)
-	if block_wrapper == nil {
+	lenBlockWrappers := len(blockWrappers)
-		// fmt.Printf("could not find: %s\n", node.name)
+
-		return ctx.Error("internal error: block_wrapper == nil in tagBlockNode.Execute()", nil)
+	if lenBlockWrappers == 0 {
+		return ctx.Error("internal error: len(block_wrappers) == 0 in tagBlockNode.Execute()", nil)
 	}
-	err := block_wrapper.Execute(ctx, buffer)
+
+	blockWrapper := blockWrappers[lenBlockWrappers-1]
+	ctx.Private["block"] = tagBlockInformation{
+		ctx:      ctx,
+		wrappers: blockWrappers[0 : lenBlockWrappers-1],
+	}
+	err := blockWrapper.Execute(ctx, writer)
 	if err != nil {
 		return err
 	}
 
-	// TODO: Add support for {{ block.super }}
-
 	return nil
 }
 
+type tagBlockInformation struct {
+	ctx      *ExecutionContext
+	wrappers []*NodeWrapper
+}
+
+func (t tagBlockInformation) Super() string {
+	lenWrappers := len(t.wrappers)
+
+	if lenWrappers == 0 {
+		return ""
+	}
+
+	superCtx := NewChildExecutionContext(t.ctx)
+	superCtx.Private["block"] = tagBlockInformation{
+		ctx:      t.ctx,
+		wrappers: t.wrappers[0 : lenWrappers-1],
+	}
+
+	blockWrapper := t.wrappers[lenWrappers-1]
+	buf := bytes.NewBufferString("")
+	err := blockWrapper.Execute(superCtx, &templateWriter{buf})
+	if err != nil {
+		return ""
+	}
+	return buf.String()
+}
+
 func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
 	if arguments.Count() == 0 {
 		return nil, arguments.Error("Tag 'block' requires an identifier.", nil)
 	}
 
-	name_token := arguments.MatchType(TokenIdentifier)
+	nameToken := arguments.MatchType(TokenIdentifier)
-	if name_token == nil {
+	if nameToken == nil {
 		return nil, arguments.Error("First argument for tag 'block' must be an identifier.", nil)
 	}
 
@@ -62,15 +97,15 @@ func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 		return nil, err
 	}
 	if endtagargs.Remaining() > 0 {
-		endtagname_token := endtagargs.MatchType(TokenIdentifier)
+		endtagnameToken := endtagargs.MatchType(TokenIdentifier)
-		if endtagname_token != nil {
+		if endtagnameToken != nil {
-			if endtagname_token.Val != name_token.Val {
+			if endtagnameToken.Val != nameToken.Val {
 				return nil, endtagargs.Error(fmt.Sprintf("Name for 'endblock' must equal to 'block'-tag's name ('%s' != '%s').",
-					name_token.Val, endtagname_token.Val), nil)
+					nameToken.Val, endtagnameToken.Val), nil)
 			}
 		}
 
-		if endtagname_token == nil || endtagargs.Remaining() > 0 {
+		if endtagnameToken == nil || endtagargs.Remaining() > 0 {
 			return nil, endtagargs.Error("Either no or only one argument (identifier) allowed for 'endblock'.", nil)
 		}
 	}
@@ -79,14 +114,14 @@ func tagBlockParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 	if tpl == nil {
 		panic("internal error: tpl == nil")
 	}
-	_, has_block := tpl.blocks[name_token.Val]
+	_, hasBlock := tpl.blocks[nameToken.Val]
-	if !has_block {
+	if !hasBlock {
-		tpl.blocks[name_token.Val] = wrapper
+		tpl.blocks[nameToken.Val] = wrapper
 	} else {
-		return nil, arguments.Error(fmt.Sprintf("Block named '%s' already defined", name_token.Val), nil)
+		return nil, arguments.Error(fmt.Sprintf("Block named '%s' already defined", nameToken.Val), nil)
 	}
 
-	return &tagBlockNode{name: name_token.Val}, nil
+	return &tagBlockNode{name: nameToken.Val}, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_comment.go

@@ -1,20 +1,16 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagCommentNode struct{}
 
-func (node *tagCommentNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagCommentNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	return nil
 }
 
 func tagCommentParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	comment_node := &tagCommentNode{}
+	commentNode := &tagCommentNode{}
 
 	// TODO: Process the endtag's arguments (see django 'comment'-tag documentation)
-	_, _, err := doc.WrapUntilTag("endcomment")
+	err := doc.SkipUntilTag("endcomment")
 	if err != nil {
 		return nil, err
 	}
@@ -23,7 +19,7 @@ func tagCommentParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		return nil, arguments.Error("Tag 'comment' does not take any argument.", nil)
 	}
 
-	return comment_node, nil
+	return commentNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_cycle.go

@@ -1,9 +1,5 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagCycleValue struct {
 	node  *tagCycleNode
 	value *Value
@@ -13,7 +9,7 @@ type tagCycleNode struct {
 	position *Token
 	args     []IEvaluator
 	idx      int
-	as_name  string
+	asName   string
 	silent   bool
 }
 
@@ -21,7 +17,7 @@ func (cv *tagCycleValue) String() string {
 	return cv.value.String()
 }
 
-func (node *tagCycleNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagCycleNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	item := node.args[node.idx%len(node.args)]
 	node.idx++
 
@@ -46,30 +42,30 @@ func (node *tagCycleNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *
 		t.value = val
 
 		if !t.node.silent {
-			buffer.WriteString(val.String())
+			writer.WriteString(val.String())
 		}
 	} else {
 		// Regular call
 
-		cycle_value := &tagCycleValue{
+		cycleValue := &tagCycleValue{
 			node:  node,
 			value: val,
 		}
 
-		if node.as_name != "" {
+		if node.asName != "" {
-			ctx.Private[node.as_name] = cycle_value
+			ctx.Private[node.asName] = cycleValue
 		}
 		if !node.silent {
-			buffer.WriteString(val.String())
+			writer.WriteString(val.String())
 		}
 	}
 
 	return nil
 }
 
-// HINT: We're not supporting the old comma-seperated list of expresions argument-style
+// HINT: We're not supporting the old comma-separated list of expressions argument-style
 func tagCycleParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	cycle_node := &tagCycleNode{
+	cycleNode := &tagCycleNode{
 		position: start,
 	}
 
@@ -78,19 +74,19 @@ func tagCycleParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 		if err != nil {
 			return nil, err
 		}
-		cycle_node.args = append(cycle_node.args, node)
+		cycleNode.args = append(cycleNode.args, node)
 
 		if arguments.MatchOne(TokenKeyword, "as") != nil {
 			// as
 
-			name_token := arguments.MatchType(TokenIdentifier)
+			nameToken := arguments.MatchType(TokenIdentifier)
-			if name_token == nil {
+			if nameToken == nil {
 				return nil, arguments.Error("Name (identifier) expected after 'as'.", nil)
 			}
-			cycle_node.as_name = name_token.Val
+			cycleNode.asName = nameToken.Val
 
 			if arguments.MatchOne(TokenIdentifier, "silent") != nil {
-				cycle_node.silent = true
+				cycleNode.silent = true
 			}
 
 			// Now we're finished
@@ -102,7 +98,7 @@ func tagCycleParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 		return nil, arguments.Error("Malformed cycle-tag.", nil)
 	}
 
-	return cycle_node, nil
+	return cycleNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_extends.go

@@ -1,19 +1,15 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagExtendsNode struct {
 	filename string
 }
 
-func (node *tagExtendsNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagExtendsNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	return nil
 }
 
 func tagExtendsParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	extends_node := &tagExtendsNode{}
+	extendsNode := &tagExtendsNode{}
 
 	if doc.template.level > 1 {
 		return nil, arguments.Error("The 'extends' tag can only defined on root level.", start)
@@ -24,22 +20,22 @@ func tagExtendsParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		return nil, arguments.Error("This template has already one parent.", start)
 	}
 
-	if filename_token := arguments.MatchType(TokenString); filename_token != nil {
+	if filenameToken := arguments.MatchType(TokenString); filenameToken != nil {
 		// prepared, static template
 
 		// Get parent's filename
-		parent_filename := doc.template.set.resolveFilename(doc.template, filename_token.Val)
+		parentFilename := doc.template.set.resolveFilename(doc.template, filenameToken.Val)
 
 		// Parse the parent
-		parent_template, err := doc.template.set.FromFile(parent_filename)
+		parentTemplate, err := doc.template.set.FromFile(parentFilename)
 		if err != nil {
 			return nil, err.(*Error)
 		}
 
 		// Keep track of things
-		parent_template.child = doc.template
+		parentTemplate.child = doc.template
-		doc.template.parent = parent_template
+		doc.template.parent = parentTemplate
-		extends_node.filename = parent_filename
+		extendsNode.filename = parentFilename
 	} else {
 		return nil, arguments.Error("Tag 'extends' requires a template filename as string.", nil)
 	}
@@ -48,7 +44,7 @@ func tagExtendsParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		return nil, arguments.Error("Tag 'extends' does only take 1 argument.", nil)
 	}
 
-	return extends_node, nil
+	return extendsNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_filter.go

@@ -5,8 +5,8 @@ import (
 )
 
 type nodeFilterCall struct {
-	name       string
+	name      string
-	param_expr IEvaluator
+	paramExpr IEvaluator
 }
 
 type tagFilterNode struct {
@@ -15,7 +15,7 @@ type tagFilterNode struct {
 	filterChain []*nodeFilterCall
 }
 
-func (node *tagFilterNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagFilterNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	temp := bytes.NewBuffer(make([]byte, 0, 1024)) // 1 KiB size
 
 	err := node.bodyWrapper.Execute(ctx, temp)
@@ -27,8 +27,8 @@ func (node *tagFilterNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 
 	for _, call := range node.filterChain {
 		var param *Value
-		if call.param_expr != nil {
+		if call.paramExpr != nil {
-			param, err = call.param_expr.Evaluate(ctx)
+			param, err = call.paramExpr.Evaluate(ctx)
 			if err != nil {
 				return err
 			}
@@ -41,13 +41,13 @@ func (node *tagFilterNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 		}
 	}
 
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 
 	return nil
 }
 
 func tagFilterParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	filter_node := &tagFilterNode{
+	filterNode := &tagFilterNode{
 		position: start,
 	}
 
@@ -55,16 +55,16 @@ func tagFilterParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *E
 	if err != nil {
 		return nil, err
 	}
-	filter_node.bodyWrapper = wrapper
+	filterNode.bodyWrapper = wrapper
 
 	for arguments.Remaining() > 0 {
 		filterCall := &nodeFilterCall{}
 
-		name_token := arguments.MatchType(TokenIdentifier)
+		nameToken := arguments.MatchType(TokenIdentifier)
-		if name_token == nil {
+		if nameToken == nil {
 			return nil, arguments.Error("Expected a filter name (identifier).", nil)
 		}
-		filterCall.name = name_token.Val
+		filterCall.name = nameToken.Val
 
 		if arguments.MatchOne(TokenSymbol, ":") != nil {
 			// Filter parameter
@@ -73,10 +73,10 @@ func tagFilterParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *E
 			if err != nil {
 				return nil, err
 			}
-			filterCall.param_expr = expr
+			filterCall.paramExpr = expr
 		}
 
-		filter_node.filterChain = append(filter_node.filterChain, filterCall)
+		filterNode.filterChain = append(filterNode.filterChain, filterCall)
 
 		if arguments.MatchOne(TokenSymbol, "|") == nil {
 			break
@@ -87,7 +87,7 @@ func tagFilterParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *E
 		return nil, arguments.Error("Malformed filter-tag arguments.", nil)
 	}
 
-	return filter_node, nil
+	return filterNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_firstof.go

@@ -1,15 +1,11 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagFirstofNode struct {
 	position *Token
 	args     []IEvaluator
 }
 
-func (node *tagFirstofNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagFirstofNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	for _, arg := range node.args {
 		val, err := arg.Evaluate(ctx)
 		if err != nil {
@@ -24,7 +20,7 @@ func (node *tagFirstofNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 				}
 			}
 
-			buffer.WriteString(val.String())
+			writer.WriteString(val.String())
 			return nil
 		}
 	}
@@ -33,7 +29,7 @@ func (node *tagFirstofNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 }
 
 func tagFirstofParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	firstof_node := &tagFirstofNode{
+	firstofNode := &tagFirstofNode{
 		position: start,
 	}
 
@@ -42,10 +38,10 @@ func tagFirstofParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		if err != nil {
 			return nil, err
 		}
-		firstof_node.args = append(firstof_node.args, node)
+		firstofNode.args = append(firstofNode.args, node)
 	}
 
-	return firstof_node, nil
+	return firstofNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_for.go

@@ -1,14 +1,11 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagForNode struct {
-	key              string
+	key             string
-	value            string // only for maps: for key, value in map
+	value           string // only for maps: for key, value in map
-	object_evaluator IEvaluator
+	objectEvaluator IEvaluator
-	reversed         bool
+	reversed        bool
+	sorted          bool
 
 	bodyWrapper  *NodeWrapper
 	emptyWrapper *NodeWrapper
@@ -24,7 +21,7 @@ type tagForLoopInformation struct {
 	Parentloop  *tagForLoopInformation
 }
 
-func (node *tagForNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) (forError *Error) {
+func (node *tagForNode) Execute(ctx *ExecutionContext, writer TemplateWriter) (forError *Error) {
 	// Backup forloop (as parentloop in public context), key-name and value-name
 	forCtx := NewChildExecutionContext(ctx)
 	parentloop := forCtx.Private["forloop"]
@@ -42,7 +39,7 @@ func (node *tagForNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) (fo
 	// Register loopInfo in public context
 	forCtx.Private["forloop"] = loopInfo
 
-	obj, err := node.object_evaluator.Evaluate(forCtx)
+	obj, err := node.objectEvaluator.Evaluate(forCtx)
 	if err != nil {
 		return err
 	}
@@ -67,7 +64,7 @@ func (node *tagForNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) (fo
 		loopInfo.Revcounter0 = count - (idx + 1) // TODO: Not sure about this, have to look it up
 
 		// Render elements with updated context
-		err := node.bodyWrapper.Execute(forCtx, buffer)
+		err := node.bodyWrapper.Execute(forCtx, writer)
 		if err != nil {
 			forError = err
 			return false
@@ -76,30 +73,30 @@ func (node *tagForNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) (fo
 	}, func() {
 		// Nothing to iterate over (maybe wrong type or no items)
 		if node.emptyWrapper != nil {
-			err := node.emptyWrapper.Execute(forCtx, buffer)
+			err := node.emptyWrapper.Execute(forCtx, writer)
 			if err != nil {
 				forError = err
 			}
 		}
-	}, node.reversed)
+	}, node.reversed, node.sorted)
 
-	return nil
+	return forError
 }
 
 func tagForParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	for_node := &tagForNode{}
+	forNode := &tagForNode{}
 
 	// Arguments parsing
-	var value_token *Token
+	var valueToken *Token
-	key_token := arguments.MatchType(TokenIdentifier)
+	keyToken := arguments.MatchType(TokenIdentifier)
-	if key_token == nil {
+	if keyToken == nil {
 		return nil, arguments.Error("Expected an key identifier as first argument for 'for'-tag", nil)
 	}
 
 	if arguments.Match(TokenSymbol, ",") != nil {
 		// Value name is provided
-		value_token = arguments.MatchType(TokenIdentifier)
+		valueToken = arguments.MatchType(TokenIdentifier)
-		if value_token == nil {
+		if valueToken == nil {
 			return nil, arguments.Error("Value name must be an identifier.", nil)
 		}
 	}
@@ -108,18 +105,22 @@ func tagForParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Erro
 		return nil, arguments.Error("Expected keyword 'in'.", nil)
 	}
 
-	object_evaluator, err := arguments.ParseExpression()
+	objectEvaluator, err := arguments.ParseExpression()
 	if err != nil {
 		return nil, err
 	}
-	for_node.object_evaluator = object_evaluator
+	forNode.objectEvaluator = objectEvaluator
-	for_node.key = key_token.Val
+	forNode.key = keyToken.Val
-	if value_token != nil {
+	if valueToken != nil {
-		for_node.value = value_token.Val
+		forNode.value = valueToken.Val
 	}
 
 	if arguments.MatchOne(TokenIdentifier, "reversed") != nil {
-		for_node.reversed = true
+		forNode.reversed = true
+	}
+
+	if arguments.MatchOne(TokenIdentifier, "sorted") != nil {
+		forNode.sorted = true
 	}
 
 	if arguments.Remaining() > 0 {
@@ -131,7 +132,7 @@ func tagForParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Erro
 	if err != nil {
 		return nil, err
 	}
-	for_node.bodyWrapper = wrapper
+	forNode.bodyWrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
@@ -143,14 +144,14 @@ func tagForParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Erro
 		if err != nil {
 			return nil, err
 		}
-		for_node.emptyWrapper = wrapper
+		forNode.emptyWrapper = wrapper
 
 		if endargs.Count() > 0 {
 			return nil, endargs.Error("Arguments not allowed here.", nil)
 		}
 	}
 
-	return for_node, nil
+	return forNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_if.go

@@ -1,15 +1,11 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagIfNode struct {
 	conditions []IEvaluator
 	wrappers   []*NodeWrapper
 }
 
-func (node *tagIfNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagIfNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	for i, condition := range node.conditions {
 		result, err := condition.Evaluate(ctx)
 		if err != nil {
@@ -17,26 +13,25 @@ func (node *tagIfNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Err
 		}
 
 		if result.IsTrue() {
-			return node.wrappers[i].Execute(ctx, buffer)
+			return node.wrappers[i].Execute(ctx, writer)
-		} else {
+		}
-			// Last condition?
+		// Last condition?
-			if len(node.conditions) == i+1 && len(node.wrappers) > i+1 {
+		if len(node.conditions) == i+1 && len(node.wrappers) > i+1 {
-				return node.wrappers[i+1].Execute(ctx, buffer)
+			return node.wrappers[i+1].Execute(ctx, writer)
-			}
 		}
 	}
 	return nil
 }
 
 func tagIfParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	if_node := &tagIfNode{}
+	ifNode := &tagIfNode{}
 
 	// Parse first and main IF condition
 	condition, err := arguments.ParseExpression()
 	if err != nil {
 		return nil, err
 	}
-	if_node.conditions = append(if_node.conditions, condition)
+	ifNode.conditions = append(ifNode.conditions, condition)
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("If-condition is malformed.", nil)
@@ -44,27 +39,27 @@ func tagIfParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error
 
 	// Check the rest
 	for {
-		wrapper, tag_args, err := doc.WrapUntilTag("elif", "else", "endif")
+		wrapper, tagArgs, err := doc.WrapUntilTag("elif", "else", "endif")
 		if err != nil {
 			return nil, err
 		}
-		if_node.wrappers = append(if_node.wrappers, wrapper)
+		ifNode.wrappers = append(ifNode.wrappers, wrapper)
 
 		if wrapper.Endtag == "elif" {
 			// elif can take a condition
-			condition, err := tag_args.ParseExpression()
+			condition, err = tagArgs.ParseExpression()
 			if err != nil {
 				return nil, err
 			}
-			if_node.conditions = append(if_node.conditions, condition)
+			ifNode.conditions = append(ifNode.conditions, condition)
 
-			if tag_args.Remaining() > 0 {
+			if tagArgs.Remaining() > 0 {
-				return nil, tag_args.Error("Elif-condition is malformed.", nil)
+				return nil, tagArgs.Error("Elif-condition is malformed.", nil)
 			}
 		} else {
-			if tag_args.Count() > 0 {
+			if tagArgs.Count() > 0 {
 				// else/endif can't take any conditions
-				return nil, tag_args.Error("Arguments not allowed here.", nil)
+				return nil, tagArgs.Error("Arguments not allowed here.", nil)
 			}
 		}
 
@@ -73,7 +68,7 @@ func tagIfParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error
 		}
 	}
 
-	return if_node, nil
+	return ifNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_ifchanged.go

@@ -5,16 +5,15 @@ import (
 )
 
 type tagIfchangedNode struct {
-	watched_expr []IEvaluator
+	watchedExpr []IEvaluator
-	last_values  []*Value
+	lastValues  []*Value
-	last_content []byte
+	lastContent []byte
-	thenWrapper  *NodeWrapper
+	thenWrapper *NodeWrapper
-	elseWrapper  *NodeWrapper
+	elseWrapper *NodeWrapper
 }
 
-func (node *tagIfchangedNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagIfchangedNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-
+	if len(node.watchedExpr) == 0 {
-	if len(node.watched_expr) == 0 {
 		// Check against own rendered body
 
 		buf := bytes.NewBuffer(make([]byte, 0, 1024)) // 1 KiB
@@ -23,43 +22,43 @@ func (node *tagIfchangedNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffe
 			return err
 		}
 
-		buf_bytes := buf.Bytes()
+		bufBytes := buf.Bytes()
-		if !bytes.Equal(node.last_content, buf_bytes) {
+		if !bytes.Equal(node.lastContent, bufBytes) {
 			// Rendered content changed, output it
-			buffer.Write(buf_bytes)
+			writer.Write(bufBytes)
-			node.last_content = buf_bytes
+			node.lastContent = bufBytes
 		}
 	} else {
-		now_values := make([]*Value, 0, len(node.watched_expr))
+		nowValues := make([]*Value, 0, len(node.watchedExpr))
-		for _, expr := range node.watched_expr {
+		for _, expr := range node.watchedExpr {
 			val, err := expr.Evaluate(ctx)
 			if err != nil {
 				return err
 			}
-			now_values = append(now_values, val)
+			nowValues = append(nowValues, val)
 		}
 
 		// Compare old to new values now
-		changed := len(node.last_values) == 0
+		changed := len(node.lastValues) == 0
 
-		for idx, old_val := range node.last_values {
+		for idx, oldVal := range node.lastValues {
-			if !old_val.EqualValueTo(now_values[idx]) {
+			if !oldVal.EqualValueTo(nowValues[idx]) {
 				changed = true
 				break // we can stop here because ONE value changed
 			}
 		}
 
-		node.last_values = now_values
+		node.lastValues = nowValues
 
 		if changed {
 			// Render thenWrapper
-			err := node.thenWrapper.Execute(ctx, buffer)
+			err := node.thenWrapper.Execute(ctx, writer)
 			if err != nil {
 				return err
 			}
 		} else {
 			// Render elseWrapper
-			err := node.elseWrapper.Execute(ctx, buffer)
+			err := node.elseWrapper.Execute(ctx, writer)
 			if err != nil {
 				return err
 			}
@@ -70,7 +69,7 @@ func (node *tagIfchangedNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffe
 }
 
 func tagIfchangedParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	ifchanged_node := &tagIfchangedNode{}
+	ifchangedNode := &tagIfchangedNode{}
 
 	for arguments.Remaining() > 0 {
 		// Parse condition
@@ -78,7 +77,7 @@ func tagIfchangedParser(doc *Parser, start *Token, arguments *Parser) (INodeTag,
 		if err != nil {
 			return nil, err
 		}
-		ifchanged_node.watched_expr = append(ifchanged_node.watched_expr, expr)
+		ifchangedNode.watchedExpr = append(ifchangedNode.watchedExpr, expr)
 	}
 
 	if arguments.Remaining() > 0 {
@@ -90,7 +89,7 @@ func tagIfchangedParser(doc *Parser, start *Token, arguments *Parser) (INodeTag,
 	if err != nil {
 		return nil, err
 	}
-	ifchanged_node.thenWrapper = wrapper
+	ifchangedNode.thenWrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
@@ -102,14 +101,14 @@ func tagIfchangedParser(doc *Parser, start *Token, arguments *Parser) (INodeTag,
 		if err != nil {
 			return nil, err
 		}
-		ifchanged_node.elseWrapper = wrapper
+		ifchangedNode.elseWrapper = wrapper
 
 		if endargs.Count() > 0 {
 			return nil, endargs.Error("Arguments not allowed here.", nil)
 		}
 	}
 
-	return ifchanged_node, nil
+	return ifchangedNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_ifequal.go

@@ -1,16 +1,12 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagIfEqualNode struct {
 	var1, var2  IEvaluator
 	thenWrapper *NodeWrapper
 	elseWrapper *NodeWrapper
 }
 
-func (node *tagIfEqualNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagIfEqualNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	r1, err := node.var1.Evaluate(ctx)
 	if err != nil {
 		return err
@@ -23,17 +19,16 @@ func (node *tagIfEqualNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 	result := r1.EqualValueTo(r2)
 
 	if result {
-		return node.thenWrapper.Execute(ctx, buffer)
+		return node.thenWrapper.Execute(ctx, writer)
-	} else {
+	}
-		if node.elseWrapper != nil {
+	if node.elseWrapper != nil {
-			return node.elseWrapper.Execute(ctx, buffer)
+		return node.elseWrapper.Execute(ctx, writer)
-		}
 	}
 	return nil
 }
 
 func tagIfEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	ifequal_node := &tagIfEqualNode{}
+	ifequalNode := &tagIfEqualNode{}
 
 	// Parse two expressions
 	var1, err := arguments.ParseExpression()
@@ -44,8 +39,8 @@ func tagIfEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 	if err != nil {
 		return nil, err
 	}
-	ifequal_node.var1 = var1
+	ifequalNode.var1 = var1
-	ifequal_node.var2 = var2
+	ifequalNode.var2 = var2
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("ifequal only takes 2 arguments.", nil)
@@ -56,7 +51,7 @@ func tagIfEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 	if err != nil {
 		return nil, err
 	}
-	ifequal_node.thenWrapper = wrapper
+	ifequalNode.thenWrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
@@ -68,14 +63,14 @@ func tagIfEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		if err != nil {
 			return nil, err
 		}
-		ifequal_node.elseWrapper = wrapper
+		ifequalNode.elseWrapper = wrapper
 
 		if endargs.Count() > 0 {
 			return nil, endargs.Error("Arguments not allowed here.", nil)
 		}
 	}
 
-	return ifequal_node, nil
+	return ifequalNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_ifnotequal.go

@@ -1,16 +1,12 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagIfNotEqualNode struct {
 	var1, var2  IEvaluator
 	thenWrapper *NodeWrapper
 	elseWrapper *NodeWrapper
 }
 
-func (node *tagIfNotEqualNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagIfNotEqualNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	r1, err := node.var1.Evaluate(ctx)
 	if err != nil {
 		return err
@@ -23,17 +19,16 @@ func (node *tagIfNotEqualNode) Execute(ctx *ExecutionContext, buffer *bytes.Buff
 	result := !r1.EqualValueTo(r2)
 
 	if result {
-		return node.thenWrapper.Execute(ctx, buffer)
+		return node.thenWrapper.Execute(ctx, writer)
-	} else {
+	}
-		if node.elseWrapper != nil {
+	if node.elseWrapper != nil {
-			return node.elseWrapper.Execute(ctx, buffer)
+		return node.elseWrapper.Execute(ctx, writer)
-		}
 	}
 	return nil
 }
 
 func tagIfNotEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	ifnotequal_node := &tagIfNotEqualNode{}
+	ifnotequalNode := &tagIfNotEqualNode{}
 
 	// Parse two expressions
 	var1, err := arguments.ParseExpression()
@@ -44,19 +39,19 @@ func tagIfNotEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag
 	if err != nil {
 		return nil, err
 	}
-	ifnotequal_node.var1 = var1
+	ifnotequalNode.var1 = var1
-	ifnotequal_node.var2 = var2
+	ifnotequalNode.var2 = var2
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("ifequal only takes 2 arguments.", nil)
 	}
 
 	// Wrap then/else-blocks
-	wrapper, endargs, err := doc.WrapUntilTag("else", "endifequal")
+	wrapper, endargs, err := doc.WrapUntilTag("else", "endifnotequal")
 	if err != nil {
 		return nil, err
 	}
-	ifnotequal_node.thenWrapper = wrapper
+	ifnotequalNode.thenWrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
@@ -64,18 +59,18 @@ func tagIfNotEqualParser(doc *Parser, start *Token, arguments *Parser) (INodeTag
 
 	if wrapper.Endtag == "else" {
 		// if there's an else in the if-statement, we need the else-Block as well
-		wrapper, endargs, err = doc.WrapUntilTag("endifequal")
+		wrapper, endargs, err = doc.WrapUntilTag("endifnotequal")
 		if err != nil {
 			return nil, err
 		}
-		ifnotequal_node.elseWrapper = wrapper
+		ifnotequalNode.elseWrapper = wrapper
 
 		if endargs.Count() > 0 {
 			return nil, endargs.Error("Arguments not allowed here.", nil)
 		}
 	}
 
-	return ifnotequal_node, nil
+	return ifnotequalNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_import.go

@@ -1,18 +1,16 @@
 package pongo2
 
 import (
-	"bytes"
 	"fmt"
 )
 
 type tagImportNode struct {
 	position *Token
 	filename string
-	template *Template
 	macros   map[string]*tagMacroNode // alias/name -> macro instance
 }
 
-func (node *tagImportNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagImportNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	for name, macro := range node.macros {
 		func(name string, macro *tagMacroNode) {
 			ctx.Private[name] = func(args ...*Value) *Value {
@@ -24,50 +22,50 @@ func (node *tagImportNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 }
 
 func tagImportParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	import_node := &tagImportNode{
+	importNode := &tagImportNode{
 		position: start,
 		macros:   make(map[string]*tagMacroNode),
 	}
 
-	filename_token := arguments.MatchType(TokenString)
+	filenameToken := arguments.MatchType(TokenString)
-	if filename_token == nil {
+	if filenameToken == nil {
 		return nil, arguments.Error("Import-tag needs a filename as string.", nil)
 	}
 
-	import_node.filename = doc.template.set.resolveFilename(doc.template, filename_token.Val)
+	importNode.filename = doc.template.set.resolveFilename(doc.template, filenameToken.Val)
 
 	if arguments.Remaining() == 0 {
 		return nil, arguments.Error("You must at least specify one macro to import.", nil)
 	}
 
 	// Compile the given template
-	tpl, err := doc.template.set.FromFile(import_node.filename)
+	tpl, err := doc.template.set.FromFile(importNode.filename)
 	if err != nil {
 		return nil, err.(*Error).updateFromTokenIfNeeded(doc.template, start)
 	}
 
 	for arguments.Remaining() > 0 {
-		macro_name_token := arguments.MatchType(TokenIdentifier)
+		macroNameToken := arguments.MatchType(TokenIdentifier)
-		if macro_name_token == nil {
+		if macroNameToken == nil {
 			return nil, arguments.Error("Expected macro name (identifier).", nil)
 		}
 
-		as_name := macro_name_token.Val
+		asName := macroNameToken.Val
 		if arguments.Match(TokenKeyword, "as") != nil {
-			alias_token := arguments.MatchType(TokenIdentifier)
+			aliasToken := arguments.MatchType(TokenIdentifier)
-			if alias_token == nil {
+			if aliasToken == nil {
 				return nil, arguments.Error("Expected macro alias name (identifier).", nil)
 			}
-			as_name = alias_token.Val
+			asName = aliasToken.Val
 		}
 
-		macro_instance, has := tpl.exported_macros[macro_name_token.Val]
+		macroInstance, has := tpl.exportedMacros[macroNameToken.Val]
 		if !has {
-			return nil, arguments.Error(fmt.Sprintf("Macro '%s' not found (or not exported) in '%s'.", macro_name_token.Val,
+			return nil, arguments.Error(fmt.Sprintf("Macro '%s' not found (or not exported) in '%s'.", macroNameToken.Val,
-				import_node.filename), macro_name_token)
+				importNode.filename), macroNameToken)
 		}
 
-		import_node.macros[as_name] = macro_instance
+		importNode.macros[asName] = macroInstance
 
 		if arguments.Remaining() == 0 {
 			break
@@ -78,7 +76,7 @@ func tagImportParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *E
 		}
 	}
 
-	return import_node, nil
+	return importNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_include.go

@@ -1,41 +1,38 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagIncludeNode struct {
-	tpl                *Template
+	tpl               *Template
-	filename_evaluator IEvaluator
+	filenameEvaluator IEvaluator
-	lazy               bool
+	lazy              bool
-	only               bool
+	only              bool
-	filename           string
+	filename          string
-	with_pairs         map[string]IEvaluator
+	withPairs         map[string]IEvaluator
+	ifExists          bool
 }
 
-func (node *tagIncludeNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagIncludeNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	// Building the context for the template
-	include_ctx := make(Context)
+	includeCtx := make(Context)
 
 	// Fill the context with all data from the parent
 	if !node.only {
-		include_ctx.Update(ctx.Public)
+		includeCtx.Update(ctx.Public)
-		include_ctx.Update(ctx.Private)
+		includeCtx.Update(ctx.Private)
 	}
 
 	// Put all custom with-pairs into the context
-	for key, value := range node.with_pairs {
+	for key, value := range node.withPairs {
 		val, err := value.Evaluate(ctx)
 		if err != nil {
 			return err
 		}
-		include_ctx[key] = val
+		includeCtx[key] = val
 	}
 
 	// Execute the template
 	if node.lazy {
 		// Evaluate the filename
-		filename, err := node.filename_evaluator.Evaluate(ctx)
+		filename, err := node.filenameEvaluator.Evaluate(ctx)
 		if err != nil {
 			return err
 		}
@@ -45,76 +42,93 @@ func (node *tagIncludeNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer)
 		}
 
 		// Get include-filename
-		included_filename := ctx.template.set.resolveFilename(ctx.template, filename.String())
+		includedFilename := ctx.template.set.resolveFilename(ctx.template, filename.String())
 
-		included_tpl, err2 := ctx.template.set.FromFile(included_filename)
+		includedTpl, err2 := ctx.template.set.FromFile(includedFilename)
 		if err2 != nil {
+			// if this is ReadFile error, and "if_exists" flag is enabled
+			if node.ifExists && err2.(*Error).Sender == "fromfile" {
+				return nil
+			}
 			return err2.(*Error)
 		}
-		err2 = included_tpl.ExecuteWriter(include_ctx, buffer)
+		err2 = includedTpl.ExecuteWriter(includeCtx, writer)
 		if err2 != nil {
 			return err2.(*Error)
 		}
 		return nil
-	} else {
-		// Template is already parsed with static filename
-		err := node.tpl.ExecuteWriter(include_ctx, buffer)
-		if err != nil {
-			return err.(*Error)
-		}
-		return nil
 	}
+	// Template is already parsed with static filename
+	err := node.tpl.ExecuteWriter(includeCtx, writer)
+	if err != nil {
+		return err.(*Error)
+	}
+	return nil
+}
+
+type tagIncludeEmptyNode struct{}
+
+func (node *tagIncludeEmptyNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
+	return nil
 }
 
 func tagIncludeParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	include_node := &tagIncludeNode{
+	includeNode := &tagIncludeNode{
-		with_pairs: make(map[string]IEvaluator),
+		withPairs: make(map[string]IEvaluator),
 	}
 
-	if filename_token := arguments.MatchType(TokenString); filename_token != nil {
+	if filenameToken := arguments.MatchType(TokenString); filenameToken != nil {
 		// prepared, static template
 
+		// "if_exists" flag
+		ifExists := arguments.Match(TokenIdentifier, "if_exists") != nil
+
 		// Get include-filename
-		included_filename := doc.template.set.resolveFilename(doc.template, filename_token.Val)
+		includedFilename := doc.template.set.resolveFilename(doc.template, filenameToken.Val)
 
 		// Parse the parent
-		include_node.filename = included_filename
+		includeNode.filename = includedFilename
-		included_tpl, err := doc.template.set.FromFile(included_filename)
+		includedTpl, err := doc.template.set.FromFile(includedFilename)
 		if err != nil {
-			return nil, err.(*Error).updateFromTokenIfNeeded(doc.template, filename_token)
+			// if this is ReadFile error, and "if_exists" token presents we should create and empty node
+			if err.(*Error).Sender == "fromfile" && ifExists {
+				return &tagIncludeEmptyNode{}, nil
+			}
+			return nil, err.(*Error).updateFromTokenIfNeeded(doc.template, filenameToken)
 		}
-		include_node.tpl = included_tpl
+		includeNode.tpl = includedTpl
 	} else {
 		// No String, then the user wants to use lazy-evaluation (slower, but possible)
-		filename_evaluator, err := arguments.ParseExpression()
+		filenameEvaluator, err := arguments.ParseExpression()
 		if err != nil {
-			return nil, err.updateFromTokenIfNeeded(doc.template, filename_token)
+			return nil, err.updateFromTokenIfNeeded(doc.template, filenameToken)
 		}
-		include_node.filename_evaluator = filename_evaluator
+		includeNode.filenameEvaluator = filenameEvaluator
-		include_node.lazy = true
+		includeNode.lazy = true
+		includeNode.ifExists = arguments.Match(TokenIdentifier, "if_exists") != nil // "if_exists" flag
 	}
 
 	// After having parsed the filename we're gonna parse the with+only options
 	if arguments.Match(TokenIdentifier, "with") != nil {
 		for arguments.Remaining() > 0 {
 			// We have at least one key=expr pair (because of starting "with")
-			key_token := arguments.MatchType(TokenIdentifier)
+			keyToken := arguments.MatchType(TokenIdentifier)
-			if key_token == nil {
+			if keyToken == nil {
 				return nil, arguments.Error("Expected an identifier", nil)
 			}
 			if arguments.Match(TokenSymbol, "=") == nil {
 				return nil, arguments.Error("Expected '='.", nil)
 			}
-			value_expr, err := arguments.ParseExpression()
+			valueExpr, err := arguments.ParseExpression()
 			if err != nil {
-				return nil, err.updateFromTokenIfNeeded(doc.template, key_token)
+				return nil, err.updateFromTokenIfNeeded(doc.template, keyToken)
 			}
 
-			include_node.with_pairs[key_token.Val] = value_expr
+			includeNode.withPairs[keyToken.Val] = valueExpr
 
 			// Only?
 			if arguments.Match(TokenIdentifier, "only") != nil {
-				include_node.only = true
+				includeNode.only = true
 				break // stop parsing arguments because it's the last option
 			}
 		}
@@ -124,7 +138,7 @@ func tagIncludeParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *
 		return nil, arguments.Error("Malformed 'include'-tag arguments.", nil)
 	}
 
-	return include_node, nil
+	return includeNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_lorem.go

@@ -1,10 +1,11 @@
 package pongo2
 
 import (
-	"bytes"
 	"math/rand"
 	"strings"
 	"time"
+
+	"github.com/juju/errors"
 )
 
 var (
@@ -19,102 +20,102 @@ type tagLoremNode struct {
 	random   bool   // does not use the default paragraph "Lorem ipsum dolor sit amet, ..."
 }
 
-func (node *tagLoremNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagLoremNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	switch node.method {
 	case "b":
 		if node.random {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString("\n")
+					writer.WriteString("\n")
 				}
 				par := tagLoremParagraphs[rand.Intn(len(tagLoremParagraphs))]
-				buffer.WriteString(par)
+				writer.WriteString(par)
 			}
 		} else {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString("\n")
+					writer.WriteString("\n")
 				}
 				par := tagLoremParagraphs[i%len(tagLoremParagraphs)]
-				buffer.WriteString(par)
+				writer.WriteString(par)
 			}
 		}
 	case "w":
 		if node.random {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString(" ")
+					writer.WriteString(" ")
 				}
 				word := tagLoremWords[rand.Intn(len(tagLoremWords))]
-				buffer.WriteString(word)
+				writer.WriteString(word)
 			}
 		} else {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString(" ")
+					writer.WriteString(" ")
 				}
 				word := tagLoremWords[i%len(tagLoremWords)]
-				buffer.WriteString(word)
+				writer.WriteString(word)
 			}
 		}
 	case "p":
 		if node.random {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString("\n")
+					writer.WriteString("\n")
 				}
-				buffer.WriteString("<p>")
+				writer.WriteString("<p>")
 				par := tagLoremParagraphs[rand.Intn(len(tagLoremParagraphs))]
-				buffer.WriteString(par)
+				writer.WriteString(par)
-				buffer.WriteString("</p>")
+				writer.WriteString("</p>")
 			}
 		} else {
 			for i := 0; i < node.count; i++ {
 				if i > 0 {
-					buffer.WriteString("\n")
+					writer.WriteString("\n")
 				}
-				buffer.WriteString("<p>")
+				writer.WriteString("<p>")
 				par := tagLoremParagraphs[i%len(tagLoremParagraphs)]
-				buffer.WriteString(par)
+				writer.WriteString(par)
-				buffer.WriteString("</p>")
+				writer.WriteString("</p>")
 
 			}
 		}
 	default:
-		panic("unsupported method")
+		return ctx.OrigError(errors.Errorf("unsupported method: %s", node.method), nil)
 	}
 
 	return nil
 }
 
 func tagLoremParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	lorem_node := &tagLoremNode{
+	loremNode := &tagLoremNode{
 		position: start,
 		count:    1,
 		method:   "b",
 	}
 
-	if count_token := arguments.MatchType(TokenNumber); count_token != nil {
+	if countToken := arguments.MatchType(TokenNumber); countToken != nil {
-		lorem_node.count = AsValue(count_token.Val).Integer()
+		loremNode.count = AsValue(countToken.Val).Integer()
 	}
 
-	if method_token := arguments.MatchType(TokenIdentifier); method_token != nil {
+	if methodToken := arguments.MatchType(TokenIdentifier); methodToken != nil {
-		if method_token.Val != "w" && method_token.Val != "p" && method_token.Val != "b" {
+		if methodToken.Val != "w" && methodToken.Val != "p" && methodToken.Val != "b" {
 			return nil, arguments.Error("lorem-method must be either 'w', 'p' or 'b'.", nil)
 		}
 
-		lorem_node.method = method_token.Val
+		loremNode.method = methodToken.Val
 	}
 
 	if arguments.MatchOne(TokenIdentifier, "random") != nil {
-		lorem_node.random = true
+		loremNode.random = true
 	}
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("Malformed lorem-tag arguments.", nil)
 	}
 
-	return lorem_node, nil
+	return loremNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_macro.go

@@ -6,16 +6,16 @@ import (
 )
 
 type tagMacroNode struct {
-	position   *Token
+	position  *Token
-	name       string
+	name      string
-	args_order []string
+	argsOrder []string
-	args       map[string]IEvaluator
+	args      map[string]IEvaluator
-	exported   bool
+	exported  bool
 
 	wrapper *NodeWrapper
 }
 
-func (node *tagMacroNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagMacroNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	ctx.Private[node.name] = func(args ...*Value) *Value {
 		return node.call(ctx, args...)
 	}
@@ -24,28 +24,28 @@ func (node *tagMacroNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *
 }
 
 func (node *tagMacroNode) call(ctx *ExecutionContext, args ...*Value) *Value {
-	args_ctx := make(Context)
+	argsCtx := make(Context)
 
 	for k, v := range node.args {
 		if v == nil {
 			// User did not provided a default value
-			args_ctx[k] = nil
+			argsCtx[k] = nil
 		} else {
 			// Evaluate the default value
-			value_expr, err := v.Evaluate(ctx)
+			valueExpr, err := v.Evaluate(ctx)
 			if err != nil {
 				ctx.Logf(err.Error())
 				return AsSafeValue(err.Error())
 			}
 
-			args_ctx[k] = value_expr
+			argsCtx[k] = valueExpr
 		}
 	}
 
-	if len(args) > len(node.args_order) {
+	if len(args) > len(node.argsOrder) {
 		// Too many arguments, we're ignoring them and just logging into debug mode.
 		err := ctx.Error(fmt.Sprintf("Macro '%s' called with too many arguments (%d instead of %d).",
-			node.name, len(args), len(node.args_order)), nil).updateFromTokenIfNeeded(ctx.template, node.position)
+			node.name, len(args), len(node.argsOrder)), nil).updateFromTokenIfNeeded(ctx.template, node.position)
 
 		ctx.Logf(err.Error()) // TODO: This is a workaround, because the error is not returned yet to the Execution()-methods
 		return AsSafeValue(err.Error())
@@ -55,10 +55,10 @@ func (node *tagMacroNode) call(ctx *ExecutionContext, args ...*Value) *Value {
 	macroCtx := NewChildExecutionContext(ctx)
 
 	// Register all arguments in the private context
-	macroCtx.Private.Update(args_ctx)
+	macroCtx.Private.Update(argsCtx)
 
-	for idx, arg_value := range args {
+	for idx, argValue := range args {
-		macroCtx.Private[node.args_order[idx]] = arg_value.Interface()
+		macroCtx.Private[node.argsOrder[idx]] = argValue.Interface()
 	}
 
 	var b bytes.Buffer
@@ -71,38 +71,38 @@ func (node *tagMacroNode) call(ctx *ExecutionContext, args ...*Value) *Value {
 }
 
 func tagMacroParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	macro_node := &tagMacroNode{
+	macroNode := &tagMacroNode{
 		position: start,
 		args:     make(map[string]IEvaluator),
 	}
 
-	name_token := arguments.MatchType(TokenIdentifier)
+	nameToken := arguments.MatchType(TokenIdentifier)
-	if name_token == nil {
+	if nameToken == nil {
 		return nil, arguments.Error("Macro-tag needs at least an identifier as name.", nil)
 	}
-	macro_node.name = name_token.Val
+	macroNode.name = nameToken.Val
 
 	if arguments.MatchOne(TokenSymbol, "(") == nil {
 		return nil, arguments.Error("Expected '('.", nil)
 	}
 
 	for arguments.Match(TokenSymbol, ")") == nil {
-		arg_name_token := arguments.MatchType(TokenIdentifier)
+		argNameToken := arguments.MatchType(TokenIdentifier)
-		if arg_name_token == nil {
+		if argNameToken == nil {
 			return nil, arguments.Error("Expected argument name as identifier.", nil)
 		}
-		macro_node.args_order = append(macro_node.args_order, arg_name_token.Val)
+		macroNode.argsOrder = append(macroNode.argsOrder, argNameToken.Val)
 
 		if arguments.Match(TokenSymbol, "=") != nil {
 			// Default expression follows
-			arg_default_expr, err := arguments.ParseExpression()
+			argDefaultExpr, err := arguments.ParseExpression()
 			if err != nil {
 				return nil, err
 			}
-			macro_node.args[arg_name_token.Val] = arg_default_expr
+			macroNode.args[argNameToken.Val] = argDefaultExpr
 		} else {
 			// No default expression
-			macro_node.args[arg_name_token.Val] = nil
+			macroNode.args[argNameToken.Val] = nil
 		}
 
 		if arguments.Match(TokenSymbol, ")") != nil {
@@ -114,7 +114,7 @@ func tagMacroParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 	}
 
 	if arguments.Match(TokenKeyword, "export") != nil {
-		macro_node.exported = true
+		macroNode.exported = true
 	}
 
 	if arguments.Remaining() > 0 {
@@ -126,22 +126,22 @@ func tagMacroParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Er
 	if err != nil {
 		return nil, err
 	}
-	macro_node.wrapper = wrapper
+	macroNode.wrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
 	}
 
-	if macro_node.exported {
+	if macroNode.exported {
 		// Now register the macro if it wants to be exported
-		_, has := doc.template.exported_macros[macro_node.name]
+		_, has := doc.template.exportedMacros[macroNode.name]
 		if has {
-			return nil, doc.Error(fmt.Sprintf("Another macro with name '%s' already exported.", macro_node.name), start)
+			return nil, doc.Error(fmt.Sprintf("another macro with name '%s' already exported", macroNode.name), start)
 		}
-		doc.template.exported_macros[macro_node.name] = macro_node
+		doc.template.exportedMacros[macroNode.name] = macroNode
 	}
 
-	return macro_node, nil
+	return macroNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_now.go

@@ -1,7 +1,6 @@
 package pongo2
 
 import (
-	"bytes"
 	"time"
 )
 
@@ -11,7 +10,7 @@ type tagNowNode struct {
 	fake     bool
 }
 
-func (node *tagNowNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagNowNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	var t time.Time
 	if node.fake {
 		t = time.Date(2014, time.February, 05, 18, 31, 45, 00, time.UTC)
@@ -19,31 +18,31 @@ func (node *tagNowNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Er
 		t = time.Now()
 	}
 
-	buffer.WriteString(t.Format(node.format))
+	writer.WriteString(t.Format(node.format))
 
 	return nil
 }
 
 func tagNowParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	now_node := &tagNowNode{
+	nowNode := &tagNowNode{
 		position: start,
 	}
 
-	format_token := arguments.MatchType(TokenString)
+	formatToken := arguments.MatchType(TokenString)
-	if format_token == nil {
+	if formatToken == nil {
 		return nil, arguments.Error("Expected a format string.", nil)
 	}
-	now_node.format = format_token.Val
+	nowNode.format = formatToken.Val
 
 	if arguments.MatchOne(TokenIdentifier, "fake") != nil {
-		now_node.fake = true
+		nowNode.fake = true
 	}
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("Malformed now-tag arguments.", nil)
 	}
 
-	return now_node, nil
+	return nowNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_set.go

@@ -1,13 +1,11 @@
 package pongo2
 
-import "bytes"
-
 type tagSetNode struct {
 	name       string
 	expression IEvaluator
 }
 
-func (node *tagSetNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagSetNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	// Evaluate expression
 	value, err := node.expression.Evaluate(ctx)
 	if err != nil {

vendor/github.com/flosch/pongo2/tags_spaceless.go

@@ -11,7 +11,7 @@ type tagSpacelessNode struct {
 
 var tagSpacelessRegexp = regexp.MustCompile(`(?U:(<.*>))([\t\n\v\f\r ]+)(?U:(<.*>))`)
 
-func (node *tagSpacelessNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagSpacelessNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	b := bytes.NewBuffer(make([]byte, 0, 1024)) // 1 KiB
 
 	err := node.wrapper.Execute(ctx, b)
@@ -28,25 +28,25 @@ func (node *tagSpacelessNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffe
 		s = s2
 	}
 
-	buffer.WriteString(s)
+	writer.WriteString(s)
 
 	return nil
 }
 
 func tagSpacelessParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	spaceless_node := &tagSpacelessNode{}
+	spacelessNode := &tagSpacelessNode{}
 
 	wrapper, _, err := doc.WrapUntilTag("endspaceless")
 	if err != nil {
 		return nil, err
 	}
-	spaceless_node.wrapper = wrapper
+	spacelessNode.wrapper = wrapper
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("Malformed spaceless-tag arguments.", nil)
 	}
 
-	return spaceless_node, nil
+	return spacelessNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_ssi.go

@@ -1,7 +1,6 @@
 package pongo2
 
 import (
-	"bytes"
 	"io/ioutil"
 )
 
@@ -11,47 +10,47 @@ type tagSSINode struct {
 	template *Template
 }
 
-func (node *tagSSINode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagSSINode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	if node.template != nil {
 		// Execute the template within the current context
 		includeCtx := make(Context)
 		includeCtx.Update(ctx.Public)
 		includeCtx.Update(ctx.Private)
 
-		err := node.template.ExecuteWriter(includeCtx, buffer)
+		err := node.template.execute(includeCtx, writer)
 		if err != nil {
 			return err.(*Error)
 		}
 	} else {
 		// Just print out the content
-		buffer.WriteString(node.content)
+		writer.WriteString(node.content)
 	}
 	return nil
 }
 
 func tagSSIParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	ssi_node := &tagSSINode{}
+	SSINode := &tagSSINode{}
 
-	if file_token := arguments.MatchType(TokenString); file_token != nil {
+	if fileToken := arguments.MatchType(TokenString); fileToken != nil {
-		ssi_node.filename = file_token.Val
+		SSINode.filename = fileToken.Val
 
 		if arguments.Match(TokenIdentifier, "parsed") != nil {
 			// parsed
-			temporary_tpl, err := doc.template.set.FromFile(doc.template.set.resolveFilename(doc.template, file_token.Val))
+			temporaryTpl, err := doc.template.set.FromFile(doc.template.set.resolveFilename(doc.template, fileToken.Val))
 			if err != nil {
-				return nil, err.(*Error).updateFromTokenIfNeeded(doc.template, file_token)
+				return nil, err.(*Error).updateFromTokenIfNeeded(doc.template, fileToken)
 			}
-			ssi_node.template = temporary_tpl
+			SSINode.template = temporaryTpl
 		} else {
 			// plaintext
-			buf, err := ioutil.ReadFile(doc.template.set.resolveFilename(doc.template, file_token.Val))
+			buf, err := ioutil.ReadFile(doc.template.set.resolveFilename(doc.template, fileToken.Val))
 			if err != nil {
 				return nil, (&Error{
-					Sender:   "tag:ssi",
+					Sender:    "tag:ssi",
-					ErrorMsg: err.Error(),
+					OrigError: err,
-				}).updateFromTokenIfNeeded(doc.template, file_token)
+				}).updateFromTokenIfNeeded(doc.template, fileToken)
 			}
-			ssi_node.content = string(buf)
+			SSINode.content = string(buf)
 		}
 	} else {
 		return nil, arguments.Error("First argument must be a string.", nil)
@@ -61,7 +60,7 @@ func tagSSIParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Erro
 		return nil, arguments.Error("Malformed SSI-tag argument.", nil)
 	}
 
-	return ssi_node, nil
+	return SSINode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_templatetag.go

@@ -1,9 +1,5 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagTemplateTagNode struct {
 	content string
 }
@@ -19,20 +15,20 @@ var templateTagMapping = map[string]string{
 	"closecomment":  "#}",
 }
 
-func (node *tagTemplateTagNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagTemplateTagNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	buffer.WriteString(node.content)
+	writer.WriteString(node.content)
 	return nil
 }
 
 func tagTemplateTagParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	tt_node := &tagTemplateTagNode{}
+	ttNode := &tagTemplateTagNode{}
 
-	if arg_token := arguments.MatchType(TokenIdentifier); arg_token != nil {
+	if argToken := arguments.MatchType(TokenIdentifier); argToken != nil {
-		output, found := templateTagMapping[arg_token.Val]
+		output, found := templateTagMapping[argToken.Val]
 		if !found {
-			return nil, arguments.Error("Argument not found", arg_token)
+			return nil, arguments.Error("Argument not found", argToken)
 		}
-		tt_node.content = output
+		ttNode.content = output
 	} else {
 		return nil, arguments.Error("Identifier expected.", nil)
 	}
@@ -41,7 +37,7 @@ func tagTemplateTagParser(doc *Parser, start *Token, arguments *Parser) (INodeTa
 		return nil, arguments.Error("Malformed templatetag-tag argument.", nil)
 	}
 
-	return tt_node, nil
+	return ttNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_widthratio.go

@@ -1,7 +1,6 @@
 package pongo2
 
 import (
-	"bytes"
 	"fmt"
 	"math"
 )
@@ -10,10 +9,10 @@ type tagWidthratioNode struct {
 	position     *Token
 	current, max IEvaluator
 	width        IEvaluator
-	ctx_name     string
+	ctxName      string
 }
 
-func (node *tagWidthratioNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagWidthratioNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	current, err := node.current.Evaluate(ctx)
 	if err != nil {
 		return err
@@ -31,17 +30,17 @@ func (node *tagWidthratioNode) Execute(ctx *ExecutionContext, buffer *bytes.Buff
 
 	value := int(math.Ceil(current.Float()/max.Float()*width.Float() + 0.5))
 
-	if node.ctx_name == "" {
+	if node.ctxName == "" {
-		buffer.WriteString(fmt.Sprintf("%d", value))
+		writer.WriteString(fmt.Sprintf("%d", value))
 	} else {
-		ctx.Private[node.ctx_name] = value
+		ctx.Private[node.ctxName] = value
 	}
 
 	return nil
 }
 
 func tagWidthratioParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	widthratio_node := &tagWidthratioNode{
+	widthratioNode := &tagWidthratioNode{
 		position: start,
 	}
 
@@ -49,34 +48,34 @@ func tagWidthratioParser(doc *Parser, start *Token, arguments *Parser) (INodeTag
 	if err != nil {
 		return nil, err
 	}
-	widthratio_node.current = current
+	widthratioNode.current = current
 
 	max, err := arguments.ParseExpression()
 	if err != nil {
 		return nil, err
 	}
-	widthratio_node.max = max
+	widthratioNode.max = max
 
 	width, err := arguments.ParseExpression()
 	if err != nil {
 		return nil, err
 	}
-	widthratio_node.width = width
+	widthratioNode.width = width
 
 	if arguments.MatchOne(TokenKeyword, "as") != nil {
 		// Name follows
-		name_token := arguments.MatchType(TokenIdentifier)
+		nameToken := arguments.MatchType(TokenIdentifier)
-		if name_token == nil {
+		if nameToken == nil {
 			return nil, arguments.Error("Expected name (identifier).", nil)
 		}
-		widthratio_node.ctx_name = name_token.Val
+		widthratioNode.ctxName = nameToken.Val
 	}
 
 	if arguments.Remaining() > 0 {
 		return nil, arguments.Error("Malformed widthratio-tag arguments.", nil)
 	}
 
-	return widthratio_node, nil
+	return widthratioNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/tags_with.go

@@ -1,20 +1,16 @@
 package pongo2
 
-import (
-	"bytes"
-)
-
 type tagWithNode struct {
-	with_pairs map[string]IEvaluator
+	withPairs map[string]IEvaluator
-	wrapper    *NodeWrapper
+	wrapper   *NodeWrapper
 }
 
-func (node *tagWithNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (node *tagWithNode) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	//new context for block
 	withctx := NewChildExecutionContext(ctx)
 
 	// Put all custom with-pairs into the context
-	for key, value := range node.with_pairs {
+	for key, value := range node.withPairs {
 		val, err := value.Evaluate(ctx)
 		if err != nil {
 			return err
@@ -22,12 +18,12 @@ func (node *tagWithNode) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *E
 		withctx.Private[key] = val
 	}
 
-	return node.wrapper.Execute(withctx, buffer)
+	return node.wrapper.Execute(withctx, writer)
 }
 
 func tagWithParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error) {
-	with_node := &tagWithNode{
+	withNode := &tagWithNode{
-		with_pairs: make(map[string]IEvaluator),
+		withPairs: make(map[string]IEvaluator),
 	}
 
 	if arguments.Count() == 0 {
@@ -38,7 +34,7 @@ func tagWithParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Err
 	if err != nil {
 		return nil, err
 	}
-	with_node.wrapper = wrapper
+	withNode.wrapper = wrapper
 
 	if endargs.Count() > 0 {
 		return nil, endargs.Error("Arguments not allowed here.", nil)
@@ -46,45 +42,45 @@ func tagWithParser(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Err
 
 	// Scan through all arguments to see which style the user uses (old or new style).
 	// If we find any "as" keyword we will enforce old style; otherwise we will use new style.
-	old_style := false // by default we're using the new_style
+	oldStyle := false // by default we're using the new_style
 	for i := 0; i < arguments.Count(); i++ {
 		if arguments.PeekN(i, TokenKeyword, "as") != nil {
-			old_style = true
+			oldStyle = true
 			break
 		}
 	}
 
 	for arguments.Remaining() > 0 {
-		if old_style {
+		if oldStyle {
-			value_expr, err := arguments.ParseExpression()
+			valueExpr, err := arguments.ParseExpression()
 			if err != nil {
 				return nil, err
 			}
 			if arguments.Match(TokenKeyword, "as") == nil {
 				return nil, arguments.Error("Expected 'as' keyword.", nil)
 			}
-			key_token := arguments.MatchType(TokenIdentifier)
+			keyToken := arguments.MatchType(TokenIdentifier)
-			if key_token == nil {
+			if keyToken == nil {
 				return nil, arguments.Error("Expected an identifier", nil)
 			}
-			with_node.with_pairs[key_token.Val] = value_expr
+			withNode.withPairs[keyToken.Val] = valueExpr
 		} else {
-			key_token := arguments.MatchType(TokenIdentifier)
+			keyToken := arguments.MatchType(TokenIdentifier)
-			if key_token == nil {
+			if keyToken == nil {
 				return nil, arguments.Error("Expected an identifier", nil)
 			}
 			if arguments.Match(TokenSymbol, "=") == nil {
 				return nil, arguments.Error("Expected '='.", nil)
 			}
-			value_expr, err := arguments.ParseExpression()
+			valueExpr, err := arguments.ParseExpression()
 			if err != nil {
 				return nil, err
 			}
-			with_node.with_pairs[key_token.Val] = value_expr
+			withNode.withPairs[keyToken.Val] = valueExpr
 		}
 	}
 
-	return with_node, nil
+	return withNode, nil
 }
 
 func init() {

vendor/github.com/flosch/pongo2/template.go

@@ -2,52 +2,72 @@ package pongo2
 
 import (
 	"bytes"
-	"fmt"
 	"io"
+
+	"github.com/juju/errors"
 )
 
+type TemplateWriter interface {
+	io.Writer
+	WriteString(string) (int, error)
+}
+
+type templateWriter struct {
+	w io.Writer
+}
+
+func (tw *templateWriter) WriteString(s string) (int, error) {
+	return tw.w.Write([]byte(s))
+}
+
+func (tw *templateWriter) Write(b []byte) (int, error) {
+	return tw.w.Write(b)
+}
+
 type Template struct {
 	set *TemplateSet
 
 	// Input
-	is_tpl_string bool
+	isTplString bool
-	name          string
+	name        string
-	tpl           string
+	tpl         string
-	size          int
+	size        int
 
 	// Calculation
 	tokens []*Token
 	parser *Parser
 
 	// first come, first serve (it's important to not override existing entries in here)
-	level           int
+	level          int
-	parent          *Template
+	parent         *Template
-	child           *Template
+	child          *Template
-	blocks          map[string]*NodeWrapper
+	blocks         map[string]*NodeWrapper
-	exported_macros map[string]*tagMacroNode
+	exportedMacros map[string]*tagMacroNode
 
 	// Output
 	root *nodeDocument
 }
 
-func newTemplateString(set *TemplateSet, tpl string) (*Template, error) {
+func newTemplateString(set *TemplateSet, tpl []byte) (*Template, error) {
 	return newTemplate(set, "<string>", true, tpl)
 }
 
-func newTemplate(set *TemplateSet, name string, is_tpl_string bool, tpl string) (*Template, error) {
+func newTemplate(set *TemplateSet, name string, isTplString bool, tpl []byte) (*Template, error) {
+	strTpl := string(tpl)
+
 	// Create the template
 	t := &Template{
-		set:             set,
+		set:            set,
-		is_tpl_string:   is_tpl_string,
+		isTplString:    isTplString,
-		name:            name,
+		name:           name,
-		tpl:             tpl,
+		tpl:            strTpl,
-		size:            len(tpl),
+		size:           len(strTpl),
-		blocks:          make(map[string]*NodeWrapper),
+		blocks:         make(map[string]*NodeWrapper),
-		exported_macros: make(map[string]*tagMacroNode),
+		exportedMacros: make(map[string]*tagMacroNode),
 	}
 
 	// Tokenize it
-	tokens, err := lex(name, tpl)
+	tokens, err := lex(name, strTpl)
 	if err != nil {
 		return nil, err
 	}
@@ -67,11 +87,7 @@ func newTemplate(set *TemplateSet, name string, is_tpl_string bool, tpl string)
 	return t, nil
 }
 
-func (tpl *Template) execute(context Context) (*bytes.Buffer, error) {
+func (tpl *Template) execute(context Context, writer TemplateWriter) error {
-	// Create output buffer
-	// We assume that the rendered template will be 30% larger
-	buffer := bytes.NewBuffer(make([]byte, 0, int(float64(tpl.size)*1.3)))
-
 	// Determine the parent to be executed (for template inheritance)
 	parent := tpl
 	for parent.parent != nil {
@@ -89,17 +105,17 @@ func (tpl *Template) execute(context Context) (*bytes.Buffer, error) {
 			// Check for context name syntax
 			err := newContext.checkForValidIdentifiers()
 			if err != nil {
-				return nil, err
+				return err
 			}
 
 			// Check for clashes with macro names
-			for k, _ := range newContext {
+			for k := range newContext {
-				_, has := tpl.exported_macros[k]
+				_, has := tpl.exportedMacros[k]
 				if has {
-					return nil, &Error{
+					return &Error{
-						Filename: tpl.name,
+						Filename:  tpl.name,
-						Sender:   "execution",
+						Sender:    "execution",
-						ErrorMsg: fmt.Sprintf("Context key name '%s' clashes with macro '%s'.", k, k),
+						OrigError: errors.Errorf("context key name '%s' clashes with macro '%s'", k, k),
 					}
 				}
 			}
@@ -110,8 +126,22 @@ func (tpl *Template) execute(context Context) (*bytes.Buffer, error) {
 	ctx := newExecutionContext(parent, newContext)
 
 	// Run the selected document
-	err := parent.root.Execute(ctx, buffer)
+	if err := parent.root.Execute(ctx, writer); err != nil {
-	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (tpl *Template) newTemplateWriterAndExecute(context Context, writer io.Writer) error {
+	return tpl.execute(context, &templateWriter{w: writer})
+}
+
+func (tpl *Template) newBufferAndExecute(context Context) (*bytes.Buffer, error) {
+	// Create output buffer
+	// We assume that the rendered template will be 30% larger
+	buffer := bytes.NewBuffer(make([]byte, 0, int(float64(tpl.size)*1.3)))
+	if err := tpl.execute(context, buffer); err != nil {
 		return nil, err
 	}
 	return buffer, nil
@@ -121,30 +151,30 @@ func (tpl *Template) execute(context Context) (*bytes.Buffer, error) {
 // on success. Context can be nil. Nothing is written on error; instead the error
 // is being returned.
 func (tpl *Template) ExecuteWriter(context Context, writer io.Writer) error {
-	buffer, err := tpl.execute(context)
+	buf, err := tpl.newBufferAndExecute(context)
 	if err != nil {
 		return err
 	}
-
+	_, err = buf.WriteTo(writer)
-	l := buffer.Len()
+	if err != nil {
-	n, werr := buffer.WriteTo(writer)
+		return err
-	if int(n) != l {
-		panic(fmt.Sprintf("error on writing template: n(%d) != buffer.Len(%d)", n, l))
-	}
-	if werr != nil {
-		return &Error{
-			Filename: tpl.name,
-			Sender:   "execution",
-			ErrorMsg: werr.Error(),
-		}
 	}
 	return nil
 }
 
+// Same as ExecuteWriter. The only difference between both functions is that
+// this function might already have written parts of the generated template in the
+// case of an execution error because there's no intermediate buffer involved for
+// performance reasons. This is handy if you need high performance template
+// generation or if you want to manage your own pool of buffers.
+func (tpl *Template) ExecuteWriterUnbuffered(context Context, writer io.Writer) error {
+	return tpl.newTemplateWriterAndExecute(context, writer)
+}
+
 // Executes the template and returns the rendered template as a []byte
 func (tpl *Template) ExecuteBytes(context Context) ([]byte, error) {
 	// Execute template
-	buffer, err := tpl.execute(context)
+	buffer, err := tpl.newBufferAndExecute(context)
 	if err != nil {
 		return nil, err
 	}
@@ -154,7 +184,7 @@ func (tpl *Template) ExecuteBytes(context Context) ([]byte, error) {
 // Executes the template and returns the rendered template as a string
 func (tpl *Template) Execute(context Context) (string, error) {
 	// Execute template
-	buffer, err := tpl.execute(context)
+	buffer, err := tpl.newBufferAndExecute(context)
 	if err != nil {
 		return "", err
 	}

vendor/github.com/flosch/pongo2/template_loader.go

@@ -0,0 +1,157 @@
+package pongo2
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/juju/errors"
+)
+
+// LocalFilesystemLoader represents a local filesystem loader with basic
+// BaseDirectory capabilities. The access to the local filesystem is unrestricted.
+type LocalFilesystemLoader struct {
+	baseDir string
+}
+
+// MustNewLocalFileSystemLoader creates a new LocalFilesystemLoader instance
+// and panics if there's any error during instantiation. The parameters
+// are the same like NewLocalFileSystemLoader.
+func MustNewLocalFileSystemLoader(baseDir string) *LocalFilesystemLoader {
+	fs, err := NewLocalFileSystemLoader(baseDir)
+	if err != nil {
+		log.Panic(err)
+	}
+	return fs
+}
+
+// NewLocalFileSystemLoader creates a new LocalFilesystemLoader and allows
+// templatesto be loaded from disk (unrestricted). If any base directory
+// is given (or being set using SetBaseDir), this base directory is being used
+// for path calculation in template inclusions/imports. Otherwise the path
+// is calculated based relatively to the including template's path.
+func NewLocalFileSystemLoader(baseDir string) (*LocalFilesystemLoader, error) {
+	fs := &LocalFilesystemLoader{}
+	if baseDir != "" {
+		if err := fs.SetBaseDir(baseDir); err != nil {
+			return nil, err
+		}
+	}
+	return fs, nil
+}
+
+// SetBaseDir sets the template's base directory. This directory will
+// be used for any relative path in filters, tags and From*-functions to determine
+// your template. See the comment for NewLocalFileSystemLoader as well.
+func (fs *LocalFilesystemLoader) SetBaseDir(path string) error {
+	// Make the path absolute
+	if !filepath.IsAbs(path) {
+		abs, err := filepath.Abs(path)
+		if err != nil {
+			return err
+		}
+		path = abs
+	}
+
+	// Check for existence
+	fi, err := os.Stat(path)
+	if err != nil {
+		return err
+	}
+	if !fi.IsDir() {
+		return errors.Errorf("The given path '%s' is not a directory.", path)
+	}
+
+	fs.baseDir = path
+	return nil
+}
+
+// Get reads the path's content from your local filesystem.
+func (fs *LocalFilesystemLoader) Get(path string) (io.Reader, error) {
+	buf, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return bytes.NewReader(buf), nil
+}
+
+// Abs resolves a filename relative to the base directory. Absolute paths are allowed.
+// When there's no base dir set, the absolute path to the filename
+// will be calculated based on either the provided base directory (which
+// might be a path of a template which includes another template) or
+// the current working directory.
+func (fs *LocalFilesystemLoader) Abs(base, name string) string {
+	if filepath.IsAbs(name) {
+		return name
+	}
+
+	// Our own base dir has always priority; if there's none
+	// we use the path provided in base.
+	var err error
+	if fs.baseDir == "" {
+		if base == "" {
+			base, err = os.Getwd()
+			if err != nil {
+				panic(err)
+			}
+			return filepath.Join(base, name)
+		}
+
+		return filepath.Join(filepath.Dir(base), name)
+	}
+
+	return filepath.Join(fs.baseDir, name)
+}
+
+// SandboxedFilesystemLoader is still WIP.
+type SandboxedFilesystemLoader struct {
+	*LocalFilesystemLoader
+}
+
+// NewSandboxedFilesystemLoader creates a new sandboxed local file system instance.
+func NewSandboxedFilesystemLoader(baseDir string) (*SandboxedFilesystemLoader, error) {
+	fs, err := NewLocalFileSystemLoader(baseDir)
+	if err != nil {
+		return nil, err
+	}
+	return &SandboxedFilesystemLoader{
+		LocalFilesystemLoader: fs,
+	}, nil
+}
+
+// Move sandbox to a virtual fs
+
+/*
+if len(set.SandboxDirectories) > 0 {
+    defer func() {
+        // Remove any ".." or other crap
+        resolvedPath = filepath.Clean(resolvedPath)
+
+        // Make the path absolute
+        absPath, err := filepath.Abs(resolvedPath)
+        if err != nil {
+            panic(err)
+        }
+        resolvedPath = absPath
+
+        // Check against the sandbox directories (once one pattern matches, we're done and can allow it)
+        for _, pattern := range set.SandboxDirectories {
+            matched, err := filepath.Match(pattern, resolvedPath)
+            if err != nil {
+                panic("Wrong sandbox directory match pattern (see http://golang.org/pkg/path/filepath/#Match).")
+            }
+            if matched {
+                // OK!
+                return
+            }
+        }
+
+        // No pattern matched, we have to log+deny the request
+        set.logf("Access attempt outside of the sandbox directories (blocked): '%s'", resolvedPath)
+        resolvedPath = ""
+    }()
+}
+*/

vendor/github.com/flosch/pongo2/template_sets.go

@@ -2,48 +2,49 @@ package pongo2
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
-	"path/filepath"
 	"sync"
+
+	"github.com/juju/errors"
 )
 
-// A template set allows you to create your own group of templates with their own global context (which is shared
+// TemplateLoader allows to implement a virtual file system.
-// among all members of the set), their own configuration (like a specific base directory) and their own sandbox.
+type TemplateLoader interface {
-// It's useful for a separation of different kind of templates (e. g. web templates vs. mail templates).
+	// Abs calculates the path to a given template. Whenever a path must be resolved
+	// due to an import from another template, the base equals the parent template's path.
+	Abs(base, name string) string
+
+	// Get returns an io.Reader where the template's content can be read from.
+	Get(path string) (io.Reader, error)
+}
+
+// TemplateSet allows you to create your own group of templates with their own
+// global context (which is shared among all members of the set) and their own
+// configuration.
+// It's useful for a separation of different kind of templates
+// (e. g. web templates vs. mail templates).
 type TemplateSet struct {
-	name string
+	name   string
+	loader TemplateLoader
 
 	// Globals will be provided to all templates created within this template set
 	Globals Context
 
-	// If debug is true (default false), ExecutionContext.Logf() will work and output to STDOUT. Furthermore,
+	// If debug is true (default false), ExecutionContext.Logf() will work and output
-	// FromCache() won't cache the templates. Make sure to synchronize the access to it in case you're changing this
+	// to STDOUT. Furthermore, FromCache() won't cache the templates.
+	// Make sure to synchronize the access to it in case you're changing this
 	// variable during program execution (and template compilation/execution).
 	Debug bool
 
-	// Base directory: If you set the base directory (string is non-empty), all filename lookups in tags/filters are
-	// relative to this directory. If it's empty, all lookups are relative to the current filename which is importing.
-	baseDirectory string
-
 	// Sandbox features
-	// - Limit access to directories (using SandboxDirectories)
 	// - Disallow access to specific tags and/or filters (using BanTag() and BanFilter())
 	//
-	// You can limit file accesses (for all tags/filters which are using pongo2's file resolver technique)
+	// For efficiency reasons you can ban tags/filters only *before* you have
-	// to these sandbox directories. All default pongo2 filters/tags are respecting these restrictions.
+	// added your first template to the set (restrictions are statically checked).
-	// For example, if you only have your base directory in the list, a {% ssi "/etc/passwd" %} will not work.
+	// After you added one, it's not possible anymore (for your personal security).
-	// No items in SandboxDirectories means no restrictions at all.
-	//
-	// For efficiency reasons you can ban tags/filters only *before* you have added your first
-	// template to the set (restrictions are statically checked). After you added one, it's not possible anymore
-	// (for your personal security).
-	//
-	// SandboxDirectories can be changed at runtime. Please synchronize the access to it if you need to change it
-	// after you've added your first template to the set. You *must* use this match pattern for your directories:
-	// http://golang.org/pkg/path/filepath/#Match
-	SandboxDirectories   []string
 	firstTemplateCreated bool
 	bannedTags           map[string]bool
 	bannedFilters        map[string]bool
@@ -53,11 +54,13 @@ type TemplateSet struct {
 	templateCacheMutex sync.Mutex
 }
 
-// Create your own template sets to separate different kind of templates (e. g. web from mail templates) with
+// NewSet can be used to create sets with different kind of templates
-// different globals or other configurations (like base directories).
+// (e. g. web from mail templates), with different globals or
-func NewSet(name string) *TemplateSet {
+// other configurations.
+func NewSet(name string, loader TemplateLoader) *TemplateSet {
 	return &TemplateSet{
 		name:          name,
+		loader:        loader,
 		Globals:       make(Context),
 		bannedTags:    make(map[string]bool),
 		bannedFilters: make(map[string]bool),
@@ -65,151 +68,157 @@ func NewSet(name string) *TemplateSet {
 	}
 }
 
-// Use this function to set your template set's base directory. This directory will be used for any relative
+func (set *TemplateSet) resolveFilename(tpl *Template, path string) string {
-// path in filters, tags and From*-functions to determine your template.
+	name := ""
-func (set *TemplateSet) SetBaseDirectory(name string) error {
+	if tpl != nil && tpl.isTplString {
-	// Make the path absolute
+		return path
-	if !filepath.IsAbs(name) {
-		abs, err := filepath.Abs(name)
-		if err != nil {
-			return err
-		}
-		name = abs
 	}
-
+	if tpl != nil {
-	// Check for existence
+		name = tpl.name
-	fi, err := os.Stat(name)
-	if err != nil {
-		return err
 	}
-	if !fi.IsDir() {
+	return set.loader.Abs(name, path)
-		return fmt.Errorf("The given path '%s' is not a directory.")
-	}
-
-	set.baseDirectory = name
-	return nil
 }
 
-func (set *TemplateSet) BaseDirectory() string {
+// BanTag bans a specific tag for this template set. See more in the documentation for TemplateSet.
-	return set.baseDirectory
+func (set *TemplateSet) BanTag(name string) error {
-}
-
-// Ban a specific tag for this template set. See more in the documentation for TemplateSet.
-func (set *TemplateSet) BanTag(name string) {
 	_, has := tags[name]
 	if !has {
-		panic(fmt.Sprintf("Tag '%s' not found.", name))
+		return errors.Errorf("tag '%s' not found", name)
 	}
 	if set.firstTemplateCreated {
-		panic("You cannot ban any tags after you've added your first template to your template set.")
+		return errors.New("you cannot ban any tags after you've added your first template to your template set")
 	}
 	_, has = set.bannedTags[name]
 	if has {
-		panic(fmt.Sprintf("Tag '%s' is already banned.", name))
+		return errors.Errorf("tag '%s' is already banned", name)
 	}
 	set.bannedTags[name] = true
+
+	return nil
 }
 
-// Ban a specific filter for this template set. See more in the documentation for TemplateSet.
+// BanFilter bans a specific filter for this template set. See more in the documentation for TemplateSet.
-func (set *TemplateSet) BanFilter(name string) {
+func (set *TemplateSet) BanFilter(name string) error {
 	_, has := filters[name]
 	if !has {
-		panic(fmt.Sprintf("Filter '%s' not found.", name))
+		return errors.Errorf("filter '%s' not found", name)
 	}
 	if set.firstTemplateCreated {
-		panic("You cannot ban any filters after you've added your first template to your template set.")
+		return errors.New("you cannot ban any filters after you've added your first template to your template set")
 	}
 	_, has = set.bannedFilters[name]
 	if has {
-		panic(fmt.Sprintf("Filter '%s' is already banned.", name))
+		return errors.Errorf("filter '%s' is already banned", name)
 	}
 	set.bannedFilters[name] = true
+
+	return nil
 }
 
-// FromCache() is a convenient method to cache templates. It is thread-safe
+// FromCache is a convenient method to cache templates. It is thread-safe
 // and will only compile the template associated with a filename once.
 // If TemplateSet.Debug is true (for example during development phase),
 // FromCache() will not cache the template and instead recompile it on any
 // call (to make changes to a template live instantaneously).
-// Like FromFile(), FromCache() takes a relative path to a set base directory.
-// Sandbox restrictions apply (if given).
 func (set *TemplateSet) FromCache(filename string) (*Template, error) {
 	if set.Debug {
 		// Recompile on any request
 		return set.FromFile(filename)
-	} else {
+	}
-		// Cache the template
+	// Cache the template
-		cleaned_filename := set.resolveFilename(nil, filename)
+	cleanedFilename := set.resolveFilename(nil, filename)
 
-		set.templateCacheMutex.Lock()
+	set.templateCacheMutex.Lock()
-		defer set.templateCacheMutex.Unlock()
+	defer set.templateCacheMutex.Unlock()
 
-		tpl, has := set.templateCache[cleaned_filename]
+	tpl, has := set.templateCache[cleanedFilename]
 
-		// Cache miss
+	// Cache miss
-		if !has {
+	if !has {
-			tpl, err := set.FromFile(cleaned_filename)
+		tpl, err := set.FromFile(cleanedFilename)
-			if err != nil {
+		if err != nil {
-				return nil, err
+			return nil, err
-			}
-			set.templateCache[cleaned_filename] = tpl
-			return tpl, nil
 		}
-
+		set.templateCache[cleanedFilename] = tpl
-		// Cache hit
 		return tpl, nil
 	}
+
+	// Cache hit
+	return tpl, nil
 }
 
-// Loads  a template from string and returns a Template instance.
+// FromString loads a template from string and returns a Template instance.
 func (set *TemplateSet) FromString(tpl string) (*Template, error) {
 	set.firstTemplateCreated = true
 
+	return newTemplateString(set, []byte(tpl))
+}
+
+// FromBytes loads a template from bytes and returns a Template instance.
+func (set *TemplateSet) FromBytes(tpl []byte) (*Template, error) {
+	set.firstTemplateCreated = true
+
 	return newTemplateString(set, tpl)
 }
 
-// Loads a template from a filename and returns a Template instance.
+// FromFile loads a template from a filename and returns a Template instance.
-// If a base directory is set, the filename must be either relative to it
-// or be an absolute path. Sandbox restrictions (SandboxDirectories) apply
-// if given.
 func (set *TemplateSet) FromFile(filename string) (*Template, error) {
 	set.firstTemplateCreated = true
 
-	buf, err := ioutil.ReadFile(set.resolveFilename(nil, filename))
+	fd, err := set.loader.Get(set.resolveFilename(nil, filename))
 	if err != nil {
 		return nil, &Error{
-			Filename: filename,
+			Filename:  filename,
-			Sender:   "fromfile",
+			Sender:    "fromfile",
-			ErrorMsg: err.Error(),
+			OrigError: err,
 		}
 	}
-	return newTemplate(set, filename, false, string(buf))
+	buf, err := ioutil.ReadAll(fd)
+	if err != nil {
+		return nil, &Error{
+			Filename:  filename,
+			Sender:    "fromfile",
+			OrigError: err,
+		}
+	}
+
+	return newTemplate(set, filename, false, buf)
 }
 
-// Shortcut; renders a template string directly. Panics when providing a
+// RenderTemplateString is a shortcut and renders a template string directly.
-// malformed template or an error occurs during execution.
+func (set *TemplateSet) RenderTemplateString(s string, ctx Context) (string, error) {
-func (set *TemplateSet) RenderTemplateString(s string, ctx Context) string {
 	set.firstTemplateCreated = true
 
 	tpl := Must(set.FromString(s))
 	result, err := tpl.Execute(ctx)
 	if err != nil {
-		panic(err)
+		return "", err
 	}
-	return result
+	return result, nil
 }
 
-// Shortcut; renders a template file directly. Panics when providing a
+// RenderTemplateBytes is a shortcut and renders template bytes directly.
-// malformed template or an error occurs during execution.
+func (set *TemplateSet) RenderTemplateBytes(b []byte, ctx Context) (string, error) {
-func (set *TemplateSet) RenderTemplateFile(fn string, ctx Context) string {
+	set.firstTemplateCreated = true
+
+	tpl := Must(set.FromBytes(b))
+	result, err := tpl.Execute(ctx)
+	if err != nil {
+		return "", err
+	}
+	return result, nil
+}
+
+// RenderTemplateFile is a shortcut and renders a template file directly.
+func (set *TemplateSet) RenderTemplateFile(fn string, ctx Context) (string, error) {
 	set.firstTemplateCreated = true
 
 	tpl := Must(set.FromFile(fn))
 	result, err := tpl.Execute(ctx)
 	if err != nil {
-		panic(err)
+		return "", err
 	}
-	return result
+	return result, nil
 }
 
 func (set *TemplateSet) logf(format string, args ...interface{}) {
@@ -218,58 +227,6 @@ func (set *TemplateSet) logf(format string, args ...interface{}) {
 	}
 }
 
-// Resolves a filename relative to the base directory. Absolute paths are allowed.
-// If sandbox restrictions are given (SandboxDirectories), they will be respected and checked.
-// On sandbox restriction violation, resolveFilename() panics.
-func (set *TemplateSet) resolveFilename(tpl *Template, filename string) (resolved_path string) {
-	if len(set.SandboxDirectories) > 0 {
-		defer func() {
-			// Remove any ".." or other crap
-			resolved_path = filepath.Clean(resolved_path)
-
-			// Make the path absolute
-			abs_path, err := filepath.Abs(resolved_path)
-			if err != nil {
-				panic(err)
-			}
-			resolved_path = abs_path
-
-			// Check against the sandbox directories (once one pattern matches, we're done and can allow it)
-			for _, pattern := range set.SandboxDirectories {
-				matched, err := filepath.Match(pattern, resolved_path)
-				if err != nil {
-					panic("Wrong sandbox directory match pattern (see http://golang.org/pkg/path/filepath/#Match).")
-				}
-				if matched {
-					// OK!
-					return
-				}
-			}
-
-			// No pattern matched, we have to log+deny the request
-			set.logf("Access attempt outside of the sandbox directories (blocked): '%s'", resolved_path)
-			resolved_path = ""
-		}()
-	}
-
-	if filepath.IsAbs(filename) {
-		return filename
-	}
-
-	if set.baseDirectory == "" {
-		if tpl != nil {
-			if tpl.is_tpl_string {
-				return filename
-			}
-			base := filepath.Dir(tpl.name)
-			return filepath.Join(base, filename)
-		}
-		return filename
-	} else {
-		return filepath.Join(set.baseDirectory, filename)
-	}
-}
-
 // Logging function (internally used)
 func logf(format string, items ...interface{}) {
 	if debug {
@@ -279,13 +236,18 @@ func logf(format string, items ...interface{}) {
 
 var (
 	debug  bool // internal debugging
-	logger = log.New(os.Stdout, "[pongo2] ", log.LstdFlags)
+	logger = log.New(os.Stdout, "[pongo2] ", log.LstdFlags|log.Lshortfile)
 
-	// Creating a default set
+	// DefaultLoader allows the default un-sandboxed access to the local file
-	DefaultSet = NewSet("default")
+	// system and is being used by the DefaultSet.
+	DefaultLoader = MustNewLocalFileSystemLoader("")
+
+	// DefaultSet is a set created for you for convinience reasons.
+	DefaultSet = NewSet("default", DefaultLoader)
 
 	// Methods on the default set
 	FromString           = DefaultSet.FromString
+	FromBytes            = DefaultSet.FromBytes
 	FromFile             = DefaultSet.FromFile
 	FromCache            = DefaultSet.FromCache
 	RenderTemplateString = DefaultSet.RenderTemplateString

vendor/github.com/flosch/pongo2/template_tests/comment.tpl

@@ -0,0 +1,50 @@
+empty single line comment
+{# #}
+
+filled single line comment
+{# testing single line comment #}
+
+filled single line comment with valid tags
+{# testing single line comment {% if thing %}{% endif %} #}
+
+filled single line comment with invalid tags
+{# testing single line comment {% if thing %} #}
+
+filled single line comment with invalid syntax
+{# testing single line comment {% if thing('') %}wow{% endif %} #}
+
+empty block comment
+{% comment %}{% endcomment %}
+
+filled text single line block comment
+{% comment %}filled block comment {% endcomment %}
+
+empty multi line block comment
+{% comment %}
+
+
+{% endcomment %}
+
+block comment with other tags inside of it
+{% comment %}
+  {{ thing_goes_here }}
+  {% if stuff %}do stuff{% endif %}
+{% endcomment %}
+
+block comment with invalid tags inside of it
+{% comment %}
+  {% if thing %}
+{% endcomment %}
+
+block comment with invalid syntax inside of it
+{% comment %}
+  {% thing('') %}
+{% endcomment %}
+
+Regular tags between comments to verify it doesn't break in the lexer
+{% if hello %}
+{% endif %}
+after if
+{% comment %}All done{% endcomment %}
+
+end of file

vendor/github.com/flosch/pongo2/template_tests/comment.tpl.out

@@ -0,0 +1,39 @@
+empty single line comment
+
+
+filled single line comment
+
+
+filled single line comment with valid tags
+
+
+filled single line comment with invalid tags
+
+
+filled single line comment with invalid syntax
+
+
+empty block comment
+
+
+filled text single line block comment
+
+
+empty multi line block comment
+
+
+block comment with other tags inside of it
+
+
+block comment with invalid tags inside of it
+
+
+block comment with invalid syntax inside of it
+
+
+Regular tags between comments to verify it doesn't break in the lexer
+
+after if
+
+
+end of file

vendor/github.com/flosch/pongo2/template_tests/expressions.tpl

@@ -46,8 +46,24 @@ in/not in
 {{ 7 in simple.intmap }}
 {{ !(5 in simple.intmap) }}
 {{ not(7 in simple.intmap) }}
+{{ 1 in simple.multiple_item_list }}
+{{ 4 in simple.multiple_item_list }}
+{{ !(4 in simple.multiple_item_list) }}
+{{ "Hello" in simple.misc_list }}
+{{ "Hello2" in simple.misc_list }}
+{{ 99 in simple.misc_list }}
+{{ False in simple.misc_list }}
 
 issue #48 (associativity for infix operators)
 {{ 34/3*3 }}
 {{ 10 + 24 / 6 / 2 }}
 {{ 6 - 4 - 2 }}
+
+issue #64 (uint comparison with int const)
+{{ simple.uint }}
+{{ simple.uint == 8 }}
+{{ simple.uint == 9 }}
+{{ simple.uint >= 8 }}
+{{ simple.uint <= 8 }}
+{{ simple.uint < 8 }}
+{{ simple.uint > 8 }}

vendor/github.com/flosch/pongo2/template_tests/expressions.tpl.out

@@ -46,8 +46,24 @@ True
 False
 False
 True
+True
+False
+True
+True
+False
+True
+False
 
 issue #48 (associativity for infix operators)
 33
 12
 0
+
+issue #64 (uint comparison with int const)
+8
+True
+False
+True
+True
+False
+False

vendor/github.com/flosch/pongo2/template_tests/extends_super.tpl

@@ -0,0 +1,3 @@
+{% extends "inheritance/base.tpl" %}
+
+{% block content %}{{ block.Super }}extends-level-1{% endblock %}

vendor/github.com/flosch/pongo2/template_tests/extends_super.tpl.out

@@ -0,0 +1 @@
+Start#This is base's bodyDefault contentextends-level-1#End

vendor/github.com/flosch/pongo2/template_tests/extends_super2.tpl

@@ -0,0 +1,3 @@
+{% extends "extends_super.tpl" %}
+
+{% block content %}{{ block.Super }}extends-level-2{% endblock %}

vendor/github.com/flosch/pongo2/template_tests/extends_super2.tpl.out

@@ -0,0 +1 @@
+Start#This is base's bodyDefault contentextends-level-1extends-level-2#End

vendor/github.com/flosch/pongo2/template_tests/filters-execution.err

@@ -1,3 +1,4 @@
 {{ -(true || false) }}
 {{ simple.func_add("test", 5) }}
+{% for item in simple.multiple_item_list %} {{ simple.func_add("test", 5) }} {% endfor %}
 {{ simple.func_variadic_sum_int("foo") }}

vendor/github.com/flosch/pongo2/template_tests/filters-execution.err.out

@@ -1,3 +1,4 @@
 .*where: execution.*Negative sign on a non\-number expression
 .*Function input argument 0 of 'simple.func_add' must be of type int or \*pongo2.Value \(not string\).
+.*Function input argument 0 of 'simple.func_add' must be of type int or \*pongo2.Value \(not string\).
 .*Function variadic input argument of 'simple.func_variadic_sum_int' must be of type int or \*pongo2.Value \(not string\).

vendor/github.com/flosch/pongo2/template_tests/filters.tpl

@@ -176,6 +176,9 @@ floatformat
 join
 {{ simple.misc_list|join:", " }}
 
+split
+{{ "Hello, 99, 3.140000, good"|split:", "|join:", " }}
+
 stringformat
 {{ simple.float|stringformat:"%.2f" }}
 {{ simple.uint|stringformat:"Test: %d" }}

vendor/github.com/flosch/pongo2/template_tests/filters.tpl.out

@@ -105,7 +105,7 @@ h
 
 first
 T
-<pongo2.comment Value>
+<pongo2_test.comment Value>
 
 
 
@@ -113,7 +113,7 @@ T
 
 last
 t
-<pongo2.comment Value>
+<pongo2_test.comment Value>
 
 
 
@@ -176,6 +176,9 @@ floatformat
 join
 Hello, 99, 3.140000, good
 
+split
+Hello, 99, 3.140000, good
+
 stringformat
 3.14
 Test: 8

vendor/github.com/flosch/pongo2/template_tests/for.tpl

@@ -7,3 +7,21 @@
 
 reversed
 '{% for item in simple.multiple_item_list reversed %}{{ item }} {% endfor %}'
+
+sorted string map
+'{% for key in simple.strmap sorted %}{{ key }} {% endfor %}'
+
+sorted int map
+'{% for key in simple.intmap sorted %}{{ key }} {% endfor %}'
+
+sorted int list
+'{% for key in simple.unsorted_int_list sorted %}{{ key }} {% endfor %}'
+
+reversed sorted int list
+'{% for key in simple.unsorted_int_list reversed sorted %}{{ key }} {% endfor %}'
+
+reversed sorted string map
+'{% for key in simple.strmap reversed sorted %}{{ key }} {% endfor %}'
+
+reversed sorted int map
+'{% for key in simple.intmap reversed sorted %}{{ key }} {% endfor %}'

vendor/github.com/flosch/pongo2/template_tests/for.tpl.out

@@ -17,3 +17,21 @@
 
 reversed
 '55 34 21 13 8 5 3 2 1 1 '
+
+sorted string map
+'aab abc bcd gh ukq zab '
+
+sorted int map
+'1 2 5 '
+
+sorted int list
+'1 22 192 249 581 8271 9999 1828591 '
+
+reversed sorted int list
+'1828591 9999 8271 581 249 192 22 1 '
+
+reversed sorted string map
+'zab ukq gh bcd abc aab '
+
+reversed sorted int map
+'5 2 1 '

vendor/github.com/flosch/pongo2/template_tests/if.tpl

@@ -9,6 +9,7 @@
 {% if 5 in simple.intmap %}5 in simple.intmap{% endif %}
 {% if !0.0 %}!0.0{% endif %}
 {% if !0 %}!0{% endif %}
+{% if not complex.post %}true{% else %}false{% endif %}
 {% if simple.number == 43 %}no{% else %}42{% endif %}
 {% if simple.number < 42 %}false{% elif simple.number > 42 %}no{% elif simple.number >= 42 %}yes{% else %}no{% endif %}
 {% if simple.number < 42 %}false{% elif simple.number > 42 %}no{% elif simple.number != 42 %}no{% else %}yes{% endif %}

vendor/github.com/flosch/pongo2/template_tests/if.tpl.out

@@ -9,6 +9,7 @@ text field in complex.post
 5 in simple.intmap
 !0.0
 !0
+false
 42
 yes
 yes

vendor/github.com/flosch/pongo2/template_tests/includes.tpl

@@ -1,4 +1,7 @@
 Start '{% include "includes.helper" %}' End
+Start '{% include "includes.helper" if_exists %}' End
 Start '{% include "includes.helper" with what_am_i=simple.name only %}' End
 Start '{% include "includes.helper" with what_am_i=simple.name %}' End
 Start '{% include simple.included_file|lower with number=7 what_am_i="guest" %}' End
+Start '{% include "includes.helper.not_exists" if_exists %}' End
+Start '{% include simple.included_file_not_exists if_exists with number=7 what_am_i="guest" %}' End

vendor/github.com/flosch/pongo2/template_tests/includes.tpl.out

@@ -1,4 +1,7 @@
 Start 'I'm 11' End
+Start 'I'm 11' End
 Start 'I'm john doe' End
 Start 'I'm john doe11' End
 Start 'I'm guest7' End
+Start '' End
+Start '' End

vendor/github.com/flosch/pongo2/template_tests/macro-compilation.err.out

@@ -1 +1 @@
-.*Another macro with name 'test_override' already exported.
+.*another macro with name 'test_override' already exported

vendor/github.com/flosch/pongo2/template_tests/macro-execution.err.out

@@ -1 +1 @@
-.*Context key name 'number' clashes with macro 'number'.
+.*context key name 'number' clashes with macro 'number'

vendor/github.com/flosch/pongo2/template_tests/pongo2ctx.tpl.out

@@ -1 +1 @@
-v3
+dev

vendor/github.com/flosch/pongo2/template_tests/quotes.tpl

@@ -0,0 +1,15 @@
+Variables
+{{ "hello" }}
+{{ 'hello' }}
+{{ "hell'o" }}
+
+Filters
+{{ 'Test'|slice:'1:3' }}
+{{ '<div class=\"foo\"><ul class=\"foo\"><li class=\"foo\"><p class=\"foo\">This is a long test which will be cutted after some chars.</p></li></ul></div>'|truncatechars_html:25 }}
+{{ '<a name="link"><p>This </a>is a long test which will be cutted after some chars.</p>'|truncatechars_html:25 }}
+
+Tags
+{% if 'Text' in complex.post %}text field in complex.post{% endif %}
+
+Functions
+{{ simple.func_variadic('hello') }}

vendor/github.com/flosch/pongo2/template_tests/quotes.tpl.out

@@ -0,0 +1,15 @@
+Variables
+hello
+hello
+hell'o
+
+Filters
+es
+<div class="foo"><ul class="foo"><li class="foo"><p class="foo">This is a long test wh...</p></li></ul></div>
+<a name="link"><p>This </a>is a long test wh...</p>
+
+Tags
+text field in complex.post
+
+Functions
+hello

vendor/github.com/flosch/pongo2/template_tests/set.tpl

@@ -3,3 +3,4 @@
 {{ new_var }}{% for item in simple.misc_list %}
 {% set new_var = item %}{{ new_var }}{% endfor %}
 {{ new_var }}
+{% set car=someUndefinedVar %}{{ car.Drive }}No Panic

vendor/github.com/flosch/pongo2/template_tests/set.tpl.out

@@ -6,3 +6,4 @@ Hello
 3.140000
 good
 world
+No Panic

vendor/github.com/flosch/pongo2/template_tests/variables.tpl

@@ -11,3 +11,5 @@
 {{ simple.uint }}
 {{ simple.uint|integer }}
 {{ simple.uint|float }}
+{{ simple.multiple_item_list.10 }}
+{{ simple.multiple_item_list.4 }}

vendor/github.com/flosch/pongo2/template_tests/variables.tpl.out

@@ -11,3 +11,5 @@ True
 8
 8
 8.000000
+
+5

vendor/github.com/flosch/pongo2/template_tests/with.tpl.out

@@ -11,6 +11,6 @@ Start 'I'm guest7' End
 Start 'Hi number 10! Will not be overridden inside the block. I'm john doe, 50 years old.I have 10 children.' End
 
 more with tests
-<pongo2.user Value>
+<pongo2_test.user Value>
 user1
 user3

vendor/github.com/flosch/pongo2/value.go

@@ -3,6 +3,7 @@ package pongo2
 import (
 	"fmt"
 	"reflect"
+	"sort"
 	"strconv"
 	"strings"
 )
@@ -12,7 +13,7 @@ type Value struct {
 	safe bool // used to indicate whether a Value needs explicit escaping in the template
 }
 
-// Converts any given value to a pongo2.Value
+// AsValue converts any given value to a pongo2.Value
 // Usually being used within own functions passed to a template
 // through a Context or within filter functions.
 //
@@ -24,7 +25,7 @@ func AsValue(i interface{}) *Value {
 	}
 }
 
-// Like AsValue, but does not apply the 'escape' filter.
+// AsSafeValue works like AsValue, but does not apply the 'escape' filter.
 func AsSafeValue(i interface{}) *Value {
 	return &Value{
 		val:  reflect.ValueOf(i),
@@ -39,23 +40,23 @@ func (v *Value) getResolvedValue() reflect.Value {
 	return v.val
 }
 
-// Checks whether the underlying value is a string
+// IsString checks whether the underlying value is a string
 func (v *Value) IsString() bool {
 	return v.getResolvedValue().Kind() == reflect.String
 }
 
-// Checks whether the underlying value is a bool
+// IsBool checks whether the underlying value is a bool
 func (v *Value) IsBool() bool {
 	return v.getResolvedValue().Kind() == reflect.Bool
 }
 
-// Checks whether the underlying value is a float
+// IsFloat checks whether the underlying value is a float
 func (v *Value) IsFloat() bool {
 	return v.getResolvedValue().Kind() == reflect.Float32 ||
 		v.getResolvedValue().Kind() == reflect.Float64
 }
 
-// Checks whether the underlying value is an integer
+// IsInteger checks whether the underlying value is an integer
 func (v *Value) IsInteger() bool {
 	return v.getResolvedValue().Kind() == reflect.Int ||
 		v.getResolvedValue().Kind() == reflect.Int8 ||
@@ -69,19 +70,19 @@ func (v *Value) IsInteger() bool {
 		v.getResolvedValue().Kind() == reflect.Uint64
 }
 
-// Checks whether the underlying value is either an integer
+// IsNumber checks whether the underlying value is either an integer
 // or a float.
 func (v *Value) IsNumber() bool {
 	return v.IsInteger() || v.IsFloat()
 }
 
-// Checks whether the underlying value is NIL
+// IsNil checks whether the underlying value is NIL
 func (v *Value) IsNil() bool {
 	//fmt.Printf("%+v\n", v.getResolvedValue().Type().String())
 	return !v.getResolvedValue().IsValid()
 }
 
-// Returns a string for the underlying value. If this value is not
+// String returns a string for the underlying value. If this value is not
 // of type string, pongo2 tries to convert it. Currently the following
 // types for underlying values are supported:
 //
@@ -111,9 +112,8 @@ func (v *Value) String() string {
 	case reflect.Bool:
 		if v.Bool() {
 			return "True"
-		} else {
-			return "False"
 		}
+		return "False"
 	case reflect.Struct:
 		if t, ok := v.Interface().(fmt.Stringer); ok {
 			return t.String()
@@ -124,7 +124,7 @@ func (v *Value) String() string {
 	return v.getResolvedValue().String()
 }
 
-// Returns the underlying value as an integer (converts the underlying
+// Integer returns the underlying value as an integer (converts the underlying
 // value, if necessary). If it's not possible to convert the underlying value,
 // it will return 0.
 func (v *Value) Integer() int {
@@ -148,7 +148,7 @@ func (v *Value) Integer() int {
 	}
 }
 
-// Returns the underlying value as a float (converts the underlying
+// Float returns the underlying value as a float (converts the underlying
 // value, if necessary). If it's not possible to convert the underlying value,
 // it will return 0.0.
 func (v *Value) Float() float64 {
@@ -172,7 +172,7 @@ func (v *Value) Float() float64 {
 	}
 }
 
-// Returns the underlying value as bool. If the value is not bool, false
+// Bool returns the underlying value as bool. If the value is not bool, false
 // will always be returned. If you're looking for true/false-evaluation of the
 // underlying value, have a look on the IsTrue()-function.
 func (v *Value) Bool() bool {
@@ -185,7 +185,7 @@ func (v *Value) Bool() bool {
 	}
 }
 
-// Tries to evaluate the underlying value the Pythonic-way:
+// IsTrue tries to evaluate the underlying value the Pythonic-way:
 //
 // Returns TRUE in one the following cases:
 //
@@ -217,7 +217,7 @@ func (v *Value) IsTrue() bool {
 	}
 }
 
-// Tries to negate the underlying value. It's mainly used for
+// Negate tries to negate the underlying value. It's mainly used for
 // the NOT-operator and in conjunction with a call to
 // return_value.IsTrue() afterwards.
 //
@@ -229,26 +229,26 @@ func (v *Value) Negate() *Value {
 		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		if v.Integer() != 0 {
 			return AsValue(0)
-		} else {
-			return AsValue(1)
 		}
+		return AsValue(1)
 	case reflect.Float32, reflect.Float64:
 		if v.Float() != 0.0 {
 			return AsValue(float64(0.0))
-		} else {
-			return AsValue(float64(1.1))
 		}
+		return AsValue(float64(1.1))
 	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
 		return AsValue(v.getResolvedValue().Len() == 0)
 	case reflect.Bool:
 		return AsValue(!v.getResolvedValue().Bool())
+	case reflect.Struct:
+		return AsValue(false)
 	default:
 		logf("Value.IsTrue() not available for type: %s\n", v.getResolvedValue().Kind().String())
 		return AsValue(true)
 	}
 }
 
-// Returns the length for an array, chan, map, slice or string.
+// Len returns the length for an array, chan, map, slice or string.
 // Otherwise it will return 0.
 func (v *Value) Len() int {
 	switch v.getResolvedValue().Kind() {
@@ -263,7 +263,7 @@ func (v *Value) Len() int {
 	}
 }
 
-// Slices an array, slice or string. Otherwise it will
+// Slice slices an array, slice or string. Otherwise it will
 // return an empty []int.
 func (v *Value) Slice(i, j int) *Value {
 	switch v.getResolvedValue().Kind() {
@@ -278,7 +278,7 @@ func (v *Value) Slice(i, j int) *Value {
 	}
 }
 
-// Get the i-th item of an array, slice or string. Otherwise
+// Index gets the i-th item of an array, slice or string. Otherwise
 // it will return NIL.
 func (v *Value) Index(i int) *Value {
 	switch v.getResolvedValue().Kind() {
@@ -301,7 +301,7 @@ func (v *Value) Index(i int) *Value {
 	}
 }
 
-// Checks whether the underlying value (which must be of type struct, map,
+// Contains checks whether the underlying value (which must be of type struct, map,
 // string, array or slice) contains of another Value (e. g. used to check
 // whether a struct contains of a specific field or a map contains a specific key).
 //
@@ -310,25 +310,32 @@ func (v *Value) Index(i int) *Value {
 func (v *Value) Contains(other *Value) bool {
 	switch v.getResolvedValue().Kind() {
 	case reflect.Struct:
-		field_value := v.getResolvedValue().FieldByName(other.String())
+		fieldValue := v.getResolvedValue().FieldByName(other.String())
-		return field_value.IsValid()
+		return fieldValue.IsValid()
 	case reflect.Map:
-		var map_value reflect.Value
+		var mapValue reflect.Value
 		switch other.Interface().(type) {
 		case int:
-			map_value = v.getResolvedValue().MapIndex(other.getResolvedValue())
+			mapValue = v.getResolvedValue().MapIndex(other.getResolvedValue())
 		case string:
-			map_value = v.getResolvedValue().MapIndex(other.getResolvedValue())
+			mapValue = v.getResolvedValue().MapIndex(other.getResolvedValue())
 		default:
 			logf("Value.Contains() does not support lookup type '%s'\n", other.getResolvedValue().Kind().String())
 			return false
 		}
 
-		return map_value.IsValid()
+		return mapValue.IsValid()
 	case reflect.String:
 		return strings.Contains(v.getResolvedValue().String(), other.String())
 
-	// TODO: reflect.Array, reflect.Slice
+	case reflect.Slice, reflect.Array:
+		for i := 0; i < v.getResolvedValue().Len(); i++ {
+			item := v.getResolvedValue().Index(i)
+			if other.Interface() == item.Interface() {
+				return true
+			}
+		}
+		return false
 
 	default:
 		logf("Value.Contains() not available for type: %s\n", v.getResolvedValue().Kind().String())
@@ -336,7 +343,7 @@ func (v *Value) Contains(other *Value) bool {
 	}
 }
 
-// Checks whether the underlying value is of type array, slice or string.
+// CanSlice checks whether the underlying value is of type array, slice or string.
 // You normally would use CanSlice() before using the Slice() operation.
 func (v *Value) CanSlice() bool {
 	switch v.getResolvedValue().Kind() {
@@ -346,7 +353,7 @@ func (v *Value) CanSlice() bool {
 	return false
 }
 
-// Iterates over a map, array, slice or a string. It calls the
+// Iterate iterates over a map, array, slice or a string. It calls the
 // function's first argument for every value with the following arguments:
 //
 //     idx      current 0-index
@@ -357,16 +364,23 @@ func (v *Value) CanSlice() bool {
 // If the underlying value has no items or is not one of the types above,
 // the empty function (function's second argument) will be called.
 func (v *Value) Iterate(fn func(idx, count int, key, value *Value) bool, empty func()) {
-	v.IterateOrder(fn, empty, false)
+	v.IterateOrder(fn, empty, false, false)
 }
 
-// Like Value.Iterate, but can iterate through an array/slice/string in reverse. Does
+// IterateOrder behaves like Value.Iterate, but can iterate through an array/slice/string in reverse. Does
 // not affect the iteration through a map because maps don't have any particular order.
-func (v *Value) IterateOrder(fn func(idx, count int, key, value *Value) bool, empty func(), reverse bool) {
+// However, you can force an order using the `sorted` keyword (and even use `reversed sorted`).
+func (v *Value) IterateOrder(fn func(idx, count int, key, value *Value) bool, empty func(), reverse bool, sorted bool) {
 	switch v.getResolvedValue().Kind() {
 	case reflect.Map:
-		// Reverse not needed for maps, since they are not ordered
+		keys := sortedKeys(v.getResolvedValue().MapKeys())
-		keys := v.getResolvedValue().MapKeys()
+		if sorted {
+			if reverse {
+				sort.Sort(sort.Reverse(keys))
+			} else {
+				sort.Sort(keys)
+			}
+		}
 		keyLen := len(keys)
 		for idx, key := range keys {
 			value := v.getResolvedValue().MapIndex(key)
@@ -379,19 +393,31 @@ func (v *Value) IterateOrder(fn func(idx, count int, key, value *Value) bool, em
 		}
 		return // done
 	case reflect.Array, reflect.Slice:
+		var items valuesList
+
 		itemCount := v.getResolvedValue().Len()
-		if itemCount > 0 {
+		for i := 0; i < itemCount; i++ {
+			items = append(items, &Value{val: v.getResolvedValue().Index(i)})
+		}
+
+		if sorted {
 			if reverse {
-				for i := itemCount - 1; i >= 0; i-- {
+				sort.Sort(sort.Reverse(items))
-					if !fn(i, itemCount, &Value{val: v.getResolvedValue().Index(i)}, nil) {
-						return
-					}
-				}
 			} else {
-				for i := 0; i < itemCount; i++ {
+				sort.Sort(items)
-					if !fn(i, itemCount, &Value{val: v.getResolvedValue().Index(i)}, nil) {
+			}
-						return
+		} else {
-					}
+			if reverse {
+				for i := 0; i < itemCount/2; i++ {
+					items[i], items[itemCount-1-i] = items[itemCount-1-i], items[i]
+				}
+			}
+		}
+
+		if len(items) > 0 {
+			for idx, item := range items {
+				if !fn(idx, itemCount, item, nil) {
+					return
 				}
 			}
 		} else {
@@ -399,7 +425,12 @@ func (v *Value) IterateOrder(fn func(idx, count int, key, value *Value) bool, em
 		}
 		return // done
 	case reflect.String:
-		// TODO: Not utf8-compatible (utf8-decoding neccessary)
+		if sorted {
+			// TODO(flosch): Handle sorted
+			panic("TODO: handle sort for type string")
+		}
+
+		// TODO(flosch): Not utf8-compatible (utf8-decoding necessary)
 		charCount := v.getResolvedValue().Len()
 		if charCount > 0 {
 			if reverse {
@@ -425,7 +456,7 @@ func (v *Value) IterateOrder(fn func(idx, count int, key, value *Value) bool, em
 	empty()
 }
 
-// Gives you access to the underlying value.
+// Interface gives you access to the underlying value.
 func (v *Value) Interface() interface{} {
 	if v.val.IsValid() {
 		return v.val.Interface()
@@ -433,7 +464,57 @@ func (v *Value) Interface() interface{} {
 	return nil
 }
 
-// Checks whether two values are containing the same value or object.
+// EqualValueTo checks whether two values are containing the same value or object.
 func (v *Value) EqualValueTo(other *Value) bool {
+	// comparison of uint with int fails using .Interface()-comparison (see issue #64)
+	if v.IsInteger() && other.IsInteger() {
+		return v.Integer() == other.Integer()
+	}
 	return v.Interface() == other.Interface()
 }
+
+type sortedKeys []reflect.Value
+
+func (sk sortedKeys) Len() int {
+	return len(sk)
+}
+
+func (sk sortedKeys) Less(i, j int) bool {
+	vi := &Value{val: sk[i]}
+	vj := &Value{val: sk[j]}
+	switch {
+	case vi.IsInteger() && vj.IsInteger():
+		return vi.Integer() < vj.Integer()
+	case vi.IsFloat() && vj.IsFloat():
+		return vi.Float() < vj.Float()
+	default:
+		return vi.String() < vj.String()
+	}
+}
+
+func (sk sortedKeys) Swap(i, j int) {
+	sk[i], sk[j] = sk[j], sk[i]
+}
+
+type valuesList []*Value
+
+func (vl valuesList) Len() int {
+	return len(vl)
+}
+
+func (vl valuesList) Less(i, j int) bool {
+	vi := vl[i]
+	vj := vl[j]
+	switch {
+	case vi.IsInteger() && vj.IsInteger():
+		return vi.Integer() < vj.Integer()
+	case vi.IsFloat() && vj.IsFloat():
+		return vi.Float() < vj.Float()
+	default:
+		return vi.String() < vj.String()
+	}
+}
+
+func (vl valuesList) Swap(i, j int) {
+	vl[i], vl[j] = vl[j], vl[i]
+}

vendor/github.com/flosch/pongo2/variable.go

@@ -1,11 +1,12 @@
 package pongo2
 
 import (
-	"bytes"
 	"fmt"
 	"reflect"
 	"strconv"
 	"strings"
+
+	"github.com/juju/errors"
 )
 
 const (
@@ -13,13 +14,18 @@ const (
 	varTypeIdent
 )
 
+var (
+	typeOfValuePtr   = reflect.TypeOf(new(Value))
+	typeOfExecCtxPtr = reflect.TypeOf(new(ExecutionContext))
+)
+
 type variablePart struct {
 	typ int
 	s   string
 	i   int
 
-	is_function_call bool
+	isFunctionCall bool
-	calling_args     []functionCallArgument // needed for a function call, represents all argument nodes (INode supports nested function calls)
+	callingArgs    []functionCallArgument // needed for a function call, represents all argument nodes (INode supports nested function calls)
 }
 
 type functionCallArgument interface {
@@ -28,119 +34,121 @@ type functionCallArgument interface {
 
 // TODO: Add location tokens
 type stringResolver struct {
-	location_token *Token
+	locationToken *Token
-	val            string
+	val           string
 }
 
 type intResolver struct {
-	location_token *Token
+	locationToken *Token
-	val            int
+	val           int
 }
 
 type floatResolver struct {
-	location_token *Token
+	locationToken *Token
-	val            float64
+	val           float64
 }
 
 type boolResolver struct {
-	location_token *Token
+	locationToken *Token
-	val            bool
+	val           bool
 }
 
 type variableResolver struct {
-	location_token *Token
+	locationToken *Token
 
 	parts []*variablePart
 }
 
 type nodeFilteredVariable struct {
-	location_token *Token
+	locationToken *Token
 
 	resolver    IEvaluator
 	filterChain []*filterCall
 }
 
 type nodeVariable struct {
-	location_token *Token
+	locationToken *Token
-	expr           IEvaluator
+	expr          IEvaluator
 }
 
-func (expr *nodeFilteredVariable) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+type executionCtxEval struct{}
-	value, err := expr.Evaluate(ctx)
+
+func (v *nodeFilteredVariable) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
+	value, err := v.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *variableResolver) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (vr *variableResolver) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	value, err := expr.Evaluate(ctx)
+	value, err := vr.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *stringResolver) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (s *stringResolver) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	value, err := expr.Evaluate(ctx)
+	value, err := s.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *intResolver) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (i *intResolver) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	value, err := expr.Evaluate(ctx)
+	value, err := i.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *floatResolver) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (f *floatResolver) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	value, err := expr.Evaluate(ctx)
+	value, err := f.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
-func (expr *boolResolver) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (b *boolResolver) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
-	value, err := expr.Evaluate(ctx)
+	value, err := b.Evaluate(ctx)
 	if err != nil {
 		return err
 	}
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
 func (v *nodeFilteredVariable) GetPositionToken() *Token {
-	return v.location_token
+	return v.locationToken
 }
 
-func (v *variableResolver) GetPositionToken() *Token {
+func (vr *variableResolver) GetPositionToken() *Token {
-	return v.location_token
+	return vr.locationToken
 }
 
-func (v *stringResolver) GetPositionToken() *Token {
+func (s *stringResolver) GetPositionToken() *Token {
-	return v.location_token
+	return s.locationToken
 }
 
-func (v *intResolver) GetPositionToken() *Token {
+func (i *intResolver) GetPositionToken() *Token {
-	return v.location_token
+	return i.locationToken
 }
 
-func (v *floatResolver) GetPositionToken() *Token {
+func (f *floatResolver) GetPositionToken() *Token {
-	return v.location_token
+	return f.locationToken
 }
 
-func (v *boolResolver) GetPositionToken() *Token {
+func (b *boolResolver) GetPositionToken() *Token {
-	return v.location_token
+	return b.locationToken
 }
 
 func (s *stringResolver) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
@@ -179,7 +187,7 @@ func (nv *nodeVariable) FilterApplied(name string) bool {
 	return nv.expr.FilterApplied(name)
 }
 
-func (nv *nodeVariable) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Error {
+func (nv *nodeVariable) Execute(ctx *ExecutionContext, writer TemplateWriter) *Error {
 	value, err := nv.expr.Evaluate(ctx)
 	if err != nil {
 		return err
@@ -193,10 +201,14 @@ func (nv *nodeVariable) Execute(ctx *ExecutionContext, buffer *bytes.Buffer) *Er
 		}
 	}
 
-	buffer.WriteString(value.String())
+	writer.WriteString(value.String())
 	return nil
 }
 
+func (executionCtxEval) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
+	return AsValue(ctx), nil
+}
+
 func (vr *variableResolver) FilterApplied(name string) bool {
 	return false
 }
@@ -218,15 +230,15 @@ func (vr *variableResolver) String() string {
 
 func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 	var current reflect.Value
-	var is_safe bool
+	var isSafe bool
 
 	for idx, part := range vr.parts {
 		if idx == 0 {
 			// We're looking up the first part of the variable.
 			// First we're having a look in our private
 			// context (e. g. information provided by tags, like the forloop)
-			val, in_private := ctx.Private[vr.parts[0].s]
+			val, inPrivate := ctx.Private[vr.parts[0].s]
-			if !in_private {
+			if !inPrivate {
 				// Nothing found? Then have a final lookup in the public context
 				val = ctx.Public[vr.parts[0].s]
 			}
@@ -236,16 +248,16 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 
 			// Before resolving the pointer, let's see if we have a method to call
 			// Problem with resolving the pointer is we're changing the receiver
-			is_func := false
+			isFunc := false
 			if part.typ == varTypeIdent {
-				func_value := current.MethodByName(part.s)
+				funcValue := current.MethodByName(part.s)
-				if func_value.IsValid() {
+				if funcValue.IsValid() {
-					current = func_value
+					current = funcValue
-					is_func = true
+					isFunc = true
 				}
 			}
 
-			if !is_func {
+			if !isFunc {
 				// If current a pointer, resolve it
 				if current.Kind() == reflect.Ptr {
 					current = current.Elem()
@@ -262,9 +274,14 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 					// * slices/arrays/strings
 					switch current.Kind() {
 					case reflect.String, reflect.Array, reflect.Slice:
-						current = current.Index(part.i)
+						if part.i >= 0 && current.Len() > part.i {
+							current = current.Index(part.i)
+						} else {
+							// In Django, exceeding the length of a list is just empty.
+							return AsValue(nil), nil
+						}
 					default:
-						return nil, fmt.Errorf("Can't access an index on type %s (variable %s)",
+						return nil, errors.Errorf("Can't access an index on type %s (variable %s)",
 							current.Kind().String(), vr.String())
 					}
 				case varTypeIdent:
@@ -278,7 +295,7 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 					case reflect.Map:
 						current = current.MapIndex(reflect.ValueOf(part.s))
 					default:
-						return nil, fmt.Errorf("Can't access a field by name on type %s (variable %s)",
+						return nil, errors.Errorf("Can't access a field by name on type %s (variable %s)",
 							current.Kind().String(), vr.String())
 					}
 				default:
@@ -295,10 +312,10 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 		// If current is a reflect.ValueOf(pongo2.Value), then unpack it
 		// Happens in function calls (as a return value) or by injecting
 		// into the execution context (e.g. in a for-loop)
-		if current.Type() == reflect.TypeOf(&Value{}) {
+		if current.Type() == typeOfValuePtr {
-			tmp_value := current.Interface().(*Value)
+			tmpValue := current.Interface().(*Value)
-			current = tmp_value.val
+			current = tmpValue.val
-			is_safe = tmp_value.safe
+			isSafe = tmpValue.safe
 		}
 
 		// Check whether this is an interface and resolve it where required
@@ -307,69 +324,73 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 		}
 
 		// Check if the part is a function call
-		if part.is_function_call || current.Kind() == reflect.Func {
+		if part.isFunctionCall || current.Kind() == reflect.Func {
 			// Check for callable
 			if current.Kind() != reflect.Func {
-				return nil, fmt.Errorf("'%s' is not a function (it is %s).", vr.String(), current.Kind().String())
+				return nil, errors.Errorf("'%s' is not a function (it is %s)", vr.String(), current.Kind().String())
 			}
 
 			// Check for correct function syntax and types
 			// func(*Value, ...) *Value
 			t := current.Type()
+			currArgs := part.callingArgs
+
+			// If an implicit ExecCtx is needed
+			if t.NumIn() > 0 && t.In(0) == typeOfExecCtxPtr {
+				currArgs = append([]functionCallArgument{executionCtxEval{}}, currArgs...)
+			}
 
 			// Input arguments
-			if len(part.calling_args) != t.NumIn() && !(len(part.calling_args) >= t.NumIn()-1 && t.IsVariadic()) {
+			if len(currArgs) != t.NumIn() && !(len(currArgs) >= t.NumIn()-1 && t.IsVariadic()) {
 				return nil,
-					fmt.Errorf("Function input argument count (%d) of '%s' must be equal to the calling argument count (%d).",
+					errors.Errorf("Function input argument count (%d) of '%s' must be equal to the calling argument count (%d).",
-						t.NumIn(), vr.String(), len(part.calling_args))
+						t.NumIn(), vr.String(), len(currArgs))
 			}
 
 			// Output arguments
 			if t.NumOut() != 1 {
-				return nil, fmt.Errorf("'%s' must have exactly 1 output argument.", vr.String())
+				return nil, errors.Errorf("'%s' must have exactly 1 output argument", vr.String())
 			}
 
 			// Evaluate all parameters
-			parameters := make([]reflect.Value, 0)
+			var parameters []reflect.Value
 
-			num_args := t.NumIn()
+			numArgs := t.NumIn()
-			is_variadic := t.IsVariadic()
+			isVariadic := t.IsVariadic()
-			var fn_arg reflect.Type
+			var fnArg reflect.Type
 
-			for idx, arg := range part.calling_args {
+			for idx, arg := range currArgs {
 				pv, err := arg.Evaluate(ctx)
 				if err != nil {
 					return nil, err
 				}
 
-				if is_variadic {
+				if isVariadic {
 					if idx >= t.NumIn()-1 {
-						fn_arg = t.In(num_args - 1).Elem()
+						fnArg = t.In(numArgs - 1).Elem()
 					} else {
-						fn_arg = t.In(idx)
+						fnArg = t.In(idx)
 					}
 				} else {
-					fn_arg = t.In(idx)
+					fnArg = t.In(idx)
 				}
 
-				if fn_arg != reflect.TypeOf(new(Value)) {
+				if fnArg != typeOfValuePtr {
 					// Function's argument is not a *pongo2.Value, then we have to check whether input argument is of the same type as the function's argument
-					if !is_variadic {
+					if !isVariadic {
-						if fn_arg != reflect.TypeOf(pv.Interface()) && fn_arg.Kind() != reflect.Interface {
+						if fnArg != reflect.TypeOf(pv.Interface()) && fnArg.Kind() != reflect.Interface {
-							return nil, fmt.Errorf("Function input argument %d of '%s' must be of type %s or *pongo2.Value (not %T).",
+							return nil, errors.Errorf("Function input argument %d of '%s' must be of type %s or *pongo2.Value (not %T).",
-								idx, vr.String(), fn_arg.String(), pv.Interface())
+								idx, vr.String(), fnArg.String(), pv.Interface())
-						} else {
-							// Function's argument has another type, using the interface-value
-							parameters = append(parameters, reflect.ValueOf(pv.Interface()))
 						}
+						// Function's argument has another type, using the interface-value
+						parameters = append(parameters, reflect.ValueOf(pv.Interface()))
 					} else {
-						if fn_arg != reflect.TypeOf(pv.Interface()) && fn_arg.Kind() != reflect.Interface {
+						if fnArg != reflect.TypeOf(pv.Interface()) && fnArg.Kind() != reflect.Interface {
-							return nil, fmt.Errorf("Function variadic input argument of '%s' must be of type %s or *pongo2.Value (not %T).",
+							return nil, errors.Errorf("Function variadic input argument of '%s' must be of type %s or *pongo2.Value (not %T).",
-								vr.String(), fn_arg.String(), pv.Interface())
+								vr.String(), fnArg.String(), pv.Interface())
-						} else {
-							// Function's argument has another type, using the interface-value
-							parameters = append(parameters, reflect.ValueOf(pv.Interface()))
 						}
+						// Function's argument has another type, using the interface-value
+						parameters = append(parameters, reflect.ValueOf(pv.Interface()))
 					}
 				} else {
 					// Function's argument is a *pongo2.Value
@@ -377,31 +398,38 @@ func (vr *variableResolver) resolve(ctx *ExecutionContext) (*Value, error) {
 				}
 			}
 
+			// Check if any of the values are invalid
+			for _, p := range parameters {
+				if p.Kind() == reflect.Invalid {
+					return nil, errors.Errorf("Calling a function using an invalid parameter")
+				}
+			}
+
 			// Call it and get first return parameter back
 			rv := current.Call(parameters)[0]
 
-			if rv.Type() != reflect.TypeOf(new(Value)) {
+			if rv.Type() != typeOfValuePtr {
 				current = reflect.ValueOf(rv.Interface())
 			} else {
 				// Return the function call value
 				current = rv.Interface().(*Value).val
-				is_safe = rv.Interface().(*Value).safe
+				isSafe = rv.Interface().(*Value).safe
 			}
 		}
+
+		if !current.IsValid() {
+			// Value is not valid (e. g. NIL value)
+			return AsValue(nil), nil
+		}
 	}
 
-	if !current.IsValid() {
+	return &Value{val: current, safe: isSafe}, nil
-		// Value is not valid (e. g. NIL value)
-		return AsValue(nil), nil
-	}
-
-	return &Value{val: current, safe: is_safe}, nil
 }
 
 func (vr *variableResolver) Evaluate(ctx *ExecutionContext) (*Value, *Error) {
 	value, err := vr.resolve(ctx)
 	if err != nil {
-		return AsValue(nil), ctx.Error(err.Error(), vr.location_token)
+		return AsValue(nil), ctx.Error(err.Error(), vr.locationToken)
 	}
 	return value, nil
 }
@@ -436,7 +464,7 @@ func (p *Parser) parseVariableOrLiteral() (IEvaluator, *Error) {
 	t := p.Current()
 
 	if t == nil {
-		return nil, p.Error("Unexpected EOF, expected a number, string, keyword or identifier.", p.last_token)
+		return nil, p.Error("Unexpected EOF, expected a number, string, keyword or identifier.", p.lastToken)
 	}
 
 	// Is first part a number or a string, there's nothing to resolve (because there's only to return the value then)
@@ -460,26 +488,26 @@ func (p *Parser) parseVariableOrLiteral() (IEvaluator, *Error) {
 				return nil, p.Error(err.Error(), t)
 			}
 			fr := &floatResolver{
-				location_token: t,
+				locationToken: t,
-				val:            f,
+				val:           f,
 			}
 			return fr, nil
-		} else {
-			i, err := strconv.Atoi(t.Val)
-			if err != nil {
-				return nil, p.Error(err.Error(), t)
-			}
-			nr := &intResolver{
-				location_token: t,
-				val:            i,
-			}
-			return nr, nil
 		}
+		i, err := strconv.Atoi(t.Val)
+		if err != nil {
+			return nil, p.Error(err.Error(), t)
+		}
+		nr := &intResolver{
+			locationToken: t,
+			val:           i,
+		}
+		return nr, nil
+
 	case TokenString:
 		p.Consume()
 		sr := &stringResolver{
-			location_token: t,
+			locationToken: t,
-			val:            t.Val,
+			val:           t.Val,
 		}
 		return sr, nil
 	case TokenKeyword:
@@ -487,14 +515,14 @@ func (p *Parser) parseVariableOrLiteral() (IEvaluator, *Error) {
 		switch t.Val {
 		case "true":
 			br := &boolResolver{
-				location_token: t,
+				locationToken: t,
-				val:            true,
+				val:           true,
 			}
 			return br, nil
 		case "false":
 			br := &boolResolver{
-				location_token: t,
+				locationToken: t,
-				val:            false,
+				val:           false,
 			}
 			return br, nil
 		default:
@@ -503,7 +531,7 @@ func (p *Parser) parseVariableOrLiteral() (IEvaluator, *Error) {
 	}
 
 	resolver := &variableResolver{
-		location_token: t,
+		locationToken: t,
 	}
 
 	// First part of a variable MUST be an identifier
@@ -551,26 +579,26 @@ variableLoop:
 			} else {
 				// EOF
 				return nil, p.Error("Unexpected EOF, expected either IDENTIFIER or NUMBER after DOT.",
-					p.last_token)
+					p.lastToken)
 			}
 		} else if p.Match(TokenSymbol, "(") != nil {
 			// Function call
 			// FunctionName '(' Comma-separated list of expressions ')'
 			part := resolver.parts[len(resolver.parts)-1]
-			part.is_function_call = true
+			part.isFunctionCall = true
 		argumentLoop:
 			for {
 				if p.Remaining() == 0 {
-					return nil, p.Error("Unexpected EOF, expected function call argument list.", p.last_token)
+					return nil, p.Error("Unexpected EOF, expected function call argument list.", p.lastToken)
 				}
 
 				if p.Peek(TokenSymbol, ")") == nil {
 					// No closing bracket, so we're parsing an expression
-					expr_arg, err := p.ParseExpression()
+					exprArg, err := p.ParseExpression()
 					if err != nil {
 						return nil, err
 					}
-					part.calling_args = append(part.calling_args, expr_arg)
+					part.callingArgs = append(part.callingArgs, exprArg)
 
 					if p.Match(TokenSymbol, ")") != nil {
 						// If there's a closing bracket after an expression, we will stop parsing the arguments
@@ -601,7 +629,7 @@ variableLoop:
 
 func (p *Parser) parseVariableOrLiteralWithFilter() (*nodeFilteredVariable, *Error) {
 	v := &nodeFilteredVariable{
-		location_token: p.Current(),
+		locationToken: p.Current(),
 	}
 
 	// Parse the variable name
@@ -621,15 +649,13 @@ filterLoop:
 		}
 
 		// Check sandbox filter restriction
-		if _, is_banned := p.template.set.bannedFilters[filter.name]; is_banned {
+		if _, isBanned := p.template.set.bannedFilters[filter.name]; isBanned {
 			return nil, p.Error(fmt.Sprintf("Usage of filter '%s' is not allowed (sandbox restriction active).", filter.name), nil)
 		}
 
 		v.filterChain = append(v.filterChain, filter)
 
 		continue filterLoop
-
-		return nil, p.Error("This token is not allowed within a variable.", nil)
 	}
 
 	return v, nil
@@ -637,7 +663,7 @@ filterLoop:
 
 func (p *Parser) parseVariableElement() (INode, *Error) {
 	node := &nodeVariable{
-		location_token: p.Current(),
+		locationToken: p.Current(),
 	}
 
 	p.Consume() // consume '{{'

vendor/github.com/juju/errors/.gitignore

@@ -0,0 +1,23 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test

vendor/github.com/juju/errors/LICENSE

@@ -0,0 +1,191 @@
+All files in this repository are licensed as follows. If you contribute
+to this repository, it is assumed that you license your contribution
+under the same license unless you state otherwise.
+
+All files Copyright (C) 2015 Canonical Ltd. unless otherwise specified in the file.
+
+This software is licensed under the LGPLv3, included below.
+
+As a special exception to the GNU Lesser General Public License version 3
+("LGPL3"), the copyright holders of this Library give you permission to
+convey to a third party a Combined Work that links statically or dynamically
+to this Library without providing any Minimal Corresponding Source or
+Minimal Application Code as set out in 4d or providing the installation
+information set out in section 4e, provided that you comply with the other
+provisions of LGPL3 and provided that you meet, for the Application the
+terms and conditions of the license(s) which apply to the Application.
+
+Except as stated in this special exception, the provisions of LGPL3 will
+continue to comply in full to this Library. If you modify this Library, you
+may apply this exception to your version of this Library, but you are not
+obliged to do so. If you do not wish to do so, delete this exception
+statement from your version. This exception does not (and cannot) modify any
+license terms which apply to the Application, with which you must still
+comply.
+
+
+                   GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+
+  This version of the GNU Lesser General Public License incorporates
+the terms and conditions of version 3 of the GNU General Public
+License, supplemented by the additional permissions listed below.
+
+  0. Additional Definitions.
+
+  As used herein, "this License" refers to version 3 of the GNU Lesser
+General Public License, and the "GNU GPL" refers to version 3 of the GNU
+General Public License.
+
+  "The Library" refers to a covered work governed by this License,
+other than an Application or a Combined Work as defined below.
+
+  An "Application" is any work that makes use of an interface provided
+by the Library, but which is not otherwise based on the Library.
+Defining a subclass of a class defined by the Library is deemed a mode
+of using an interface provided by the Library.
+
+  A "Combined Work" is a work produced by combining or linking an
+Application with the Library.  The particular version of the Library
+with which the Combined Work was made is also called the "Linked
+Version".
+
+  The "Minimal Corresponding Source" for a Combined Work means the
+Corresponding Source for the Combined Work, excluding any source code
+for portions of the Combined Work that, considered in isolation, are
+based on the Application, and not on the Linked Version.
+
+  The "Corresponding Application Code" for a Combined Work means the
+object code and/or source code for the Application, including any data
+and utility programs needed for reproducing the Combined Work from the
+Application, but excluding the System Libraries of the Combined Work.
+
+  1. Exception to Section 3 of the GNU GPL.
+
+  You may convey a covered work under sections 3 and 4 of this License
+without being bound by section 3 of the GNU GPL.
+
+  2. Conveying Modified Versions.
+
+  If you modify a copy of the Library, and, in your modifications, a
+facility refers to a function or data to be supplied by an Application
+that uses the facility (other than as an argument passed when the
+facility is invoked), then you may convey a copy of the modified
+version:
+
+   a) under this License, provided that you make a good faith effort to
+   ensure that, in the event an Application does not supply the
+   function or data, the facility still operates, and performs
+   whatever part of its purpose remains meaningful, or
+
+   b) under the GNU GPL, with none of the additional permissions of
+   this License applicable to that copy.
+
+  3. Object Code Incorporating Material from Library Header Files.
+
+  The object code form of an Application may incorporate material from
+a header file that is part of the Library.  You may convey such object
+code under terms of your choice, provided that, if the incorporated
+material is not limited to numerical parameters, data structure
+layouts and accessors, or small macros, inline functions and templates
+(ten or fewer lines in length), you do both of the following:
+
+   a) Give prominent notice with each copy of the object code that the
+   Library is used in it and that the Library and its use are
+   covered by this License.
+
+   b) Accompany the object code with a copy of the GNU GPL and this license
+   document.
+
+  4. Combined Works.
+
+  You may convey a Combined Work under terms of your choice that,
+taken together, effectively do not restrict modification of the
+portions of the Library contained in the Combined Work and reverse
+engineering for debugging such modifications, if you also do each of
+the following:
+
+   a) Give prominent notice with each copy of the Combined Work that
+   the Library is used in it and that the Library and its use are
+   covered by this License.
+
+   b) Accompany the Combined Work with a copy of the GNU GPL and this license
+   document.
+
+   c) For a Combined Work that displays copyright notices during
+   execution, include the copyright notice for the Library among
+   these notices, as well as a reference directing the user to the
+   copies of the GNU GPL and this license document.
+
+   d) Do one of the following:
+
+       0) Convey the Minimal Corresponding Source under the terms of this
+       License, and the Corresponding Application Code in a form
+       suitable for, and under terms that permit, the user to
+       recombine or relink the Application with a modified version of
+       the Linked Version to produce a modified Combined Work, in the
+       manner specified by section 6 of the GNU GPL for conveying
+       Corresponding Source.
+
+       1) Use a suitable shared library mechanism for linking with the
+       Library.  A suitable mechanism is one that (a) uses at run time
+       a copy of the Library already present on the user's computer
+       system, and (b) will operate properly with a modified version
+       of the Library that is interface-compatible with the Linked
+       Version.
+
+   e) Provide Installation Information, but only if you would otherwise
+   be required to provide such information under section 6 of the
+   GNU GPL, and only to the extent that such information is
+   necessary to install and execute a modified version of the
+   Combined Work produced by recombining or relinking the
+   Application with a modified version of the Linked Version. (If
+   you use option 4d0, the Installation Information must accompany
+   the Minimal Corresponding Source and Corresponding Application
+   Code. If you use option 4d1, you must provide the Installation
+   Information in the manner specified by section 6 of the GNU GPL
+   for conveying Corresponding Source.)
+
+  5. Combined Libraries.
+
+  You may place library facilities that are a work based on the
+Library side by side in a single library together with other library
+facilities that are not Applications and are not covered by this
+License, and convey such a combined library under terms of your
+choice, if you do both of the following:
+
+   a) Accompany the combined library with a copy of the same work based
+   on the Library, uncombined with any other library facilities,
+   conveyed under the terms of this License.
+
+   b) Give prominent notice with the combined library that part of it
+   is a work based on the Library, and explaining where to find the
+   accompanying uncombined form of the same work.
+
+  6. Revised Versions of the GNU Lesser General Public License.
+
+  The Free Software Foundation may publish revised and/or new versions
+of the GNU Lesser General Public License from time to time. Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns.
+
+  Each version is given a distinguishing version number. If the
+Library as you received it specifies that a certain numbered version
+of the GNU Lesser General Public License "or any later version"
+applies to it, you have the option of following the terms and
+conditions either of that published version or of any later version
+published by the Free Software Foundation. If the Library as you
+received it does not specify a version number of the GNU Lesser
+General Public License, you may choose any version of the GNU Lesser
+General Public License ever published by the Free Software Foundation.
+
+  If the Library as you received it specifies that a proxy can decide
+whether future versions of the GNU Lesser General Public License shall
+apply, that proxy's public statement of acceptance of any version is
+permanent authorization for you to choose that version for the
+Library.

vendor/github.com/juju/errors/Makefile

@@ -0,0 +1,11 @@
+default: check
+
+check:
+	go test && go test -compiler gccgo
+
+docs:
+	godoc2md github.com/juju/errors > README.md
+	sed -i 's|\[godoc-link-here\]|[![GoDoc](https://godoc.org/github.com/juju/errors?status.svg)](https://godoc.org/github.com/juju/errors)|' README.md 
+
+
+.PHONY: default check docs

vendor/github.com/juju/errors/README.md

@@ -0,0 +1,543 @@
+
+# errors
+    import "github.com/juju/errors"
+
+[![GoDoc](https://godoc.org/github.com/juju/errors?status.svg)](https://godoc.org/github.com/juju/errors)
+
+The juju/errors provides an easy way to annotate errors without losing the
+orginal error context.
+
+The exported `New` and `Errorf` functions are designed to replace the
+`errors.New` and `fmt.Errorf` functions respectively. The same underlying
+error is there, but the package also records the location at which the error
+was created.
+
+A primary use case for this library is to add extra context any time an
+error is returned from a function.
+
+
+	    if err := SomeFunc(); err != nil {
+		    return err
+		}
+
+This instead becomes:
+
+
+	    if err := SomeFunc(); err != nil {
+		    return errors.Trace(err)
+		}
+
+which just records the file and line number of the Trace call, or
+
+
+	    if err := SomeFunc(); err != nil {
+		    return errors.Annotate(err, "more context")
+		}
+
+which also adds an annotation to the error.
+
+When you want to check to see if an error is of a particular type, a helper
+function is normally exported by the package that returned the error, like the
+`os` package does.  The underlying cause of the error is available using the
+`Cause` function.
+
+
+	os.IsNotExist(errors.Cause(err))
+
+The result of the `Error()` call on an annotated error is the annotations joined
+with colons, then the result of the `Error()` method for the underlying error
+that was the cause.
+
+
+	err := errors.Errorf("original")
+	err = errors.Annotatef(err, "context")
+	err = errors.Annotatef(err, "more context")
+	err.Error() -> "more context: context: original"
+
+Obviously recording the file, line and functions is not very useful if you
+cannot get them back out again.
+
+
+	errors.ErrorStack(err)
+
+will return something like:
+
+
+	first error
+	github.com/juju/errors/annotation_test.go:193:
+	github.com/juju/errors/annotation_test.go:194: annotation
+	github.com/juju/errors/annotation_test.go:195:
+	github.com/juju/errors/annotation_test.go:196: more context
+	github.com/juju/errors/annotation_test.go:197:
+
+The first error was generated by an external system, so there was no location
+associated. The second, fourth, and last lines were generated with Trace calls,
+and the other two through Annotate.
+
+Sometimes when responding to an error you want to return a more specific error
+for the situation.
+
+
+	    if err := FindField(field); err != nil {
+		    return errors.Wrap(err, errors.NotFoundf(field))
+		}
+
+This returns an error where the complete error stack is still available, and
+`errors.Cause()` will return the `NotFound` error.
+
+
+
+
+
+
+## func AlreadyExistsf
+``` go
+func AlreadyExistsf(format string, args ...interface{}) error
+```
+AlreadyExistsf returns an error which satisfies IsAlreadyExists().
+
+
+## func Annotate
+``` go
+func Annotate(other error, message string) error
+```
+Annotate is used to add extra context to an existing error. The location of
+the Annotate call is recorded with the annotations. The file, line and
+function are also recorded.
+
+For example:
+
+
+	if err := SomeFunc(); err != nil {
+	    return errors.Annotate(err, "failed to frombulate")
+	}
+
+
+## func Annotatef
+``` go
+func Annotatef(other error, format string, args ...interface{}) error
+```
+Annotatef is used to add extra context to an existing error. The location of
+the Annotate call is recorded with the annotations. The file, line and
+function are also recorded.
+
+For example:
+
+
+	if err := SomeFunc(); err != nil {
+	    return errors.Annotatef(err, "failed to frombulate the %s", arg)
+	}
+
+
+## func Cause
+``` go
+func Cause(err error) error
+```
+Cause returns the cause of the given error.  This will be either the
+original error, or the result of a Wrap or Mask call.
+
+Cause is the usual way to diagnose errors that may have been wrapped by
+the other errors functions.
+
+
+## func DeferredAnnotatef
+``` go
+func DeferredAnnotatef(err *error, format string, args ...interface{})
+```
+DeferredAnnotatef annotates the given error (when it is not nil) with the given
+format string and arguments (like fmt.Sprintf). If *err is nil, DeferredAnnotatef
+does nothing. This method is used in a defer statement in order to annotate any
+resulting error with the same message.
+
+For example:
+
+
+	defer DeferredAnnotatef(&err, "failed to frombulate the %s", arg)
+
+
+## func Details
+``` go
+func Details(err error) string
+```
+Details returns information about the stack of errors wrapped by err, in
+the format:
+
+
+	[{filename:99: error one} {otherfile:55: cause of error one}]
+
+This is a terse alternative to ErrorStack as it returns a single line.
+
+
+## func ErrorStack
+``` go
+func ErrorStack(err error) string
+```
+ErrorStack returns a string representation of the annotated error. If the
+error passed as the parameter is not an annotated error, the result is
+simply the result of the Error() method on that error.
+
+If the error is an annotated error, a multi-line string is returned where
+each line represents one entry in the annotation stack. The full filename
+from the call stack is used in the output.
+
+
+	first error
+	github.com/juju/errors/annotation_test.go:193:
+	github.com/juju/errors/annotation_test.go:194: annotation
+	github.com/juju/errors/annotation_test.go:195:
+	github.com/juju/errors/annotation_test.go:196: more context
+	github.com/juju/errors/annotation_test.go:197:
+
+
+## func Errorf
+``` go
+func Errorf(format string, args ...interface{}) error
+```
+Errorf creates a new annotated error and records the location that the
+error is created.  This should be a drop in replacement for fmt.Errorf.
+
+For example:
+
+
+	return errors.Errorf("validation failed: %s", message)
+
+
+## func IsAlreadyExists
+``` go
+func IsAlreadyExists(err error) bool
+```
+IsAlreadyExists reports whether the error was created with
+AlreadyExistsf() or NewAlreadyExists().
+
+
+## func IsNotFound
+``` go
+func IsNotFound(err error) bool
+```
+IsNotFound reports whether err was created with NotFoundf() or
+NewNotFound().
+
+
+## func IsNotImplemented
+``` go
+func IsNotImplemented(err error) bool
+```
+IsNotImplemented reports whether err was created with
+NotImplementedf() or NewNotImplemented().
+
+
+## func IsNotSupported
+``` go
+func IsNotSupported(err error) bool
+```
+IsNotSupported reports whether the error was created with
+NotSupportedf() or NewNotSupported().
+
+
+## func IsNotValid
+``` go
+func IsNotValid(err error) bool
+```
+IsNotValid reports whether the error was created with NotValidf() or
+NewNotValid().
+
+
+## func IsUnauthorized
+``` go
+func IsUnauthorized(err error) bool
+```
+IsUnauthorized reports whether err was created with Unauthorizedf() or
+NewUnauthorized().
+
+
+## func Mask
+``` go
+func Mask(other error) error
+```
+Mask hides the underlying error type, and records the location of the masking.
+
+
+## func Maskf
+``` go
+func Maskf(other error, format string, args ...interface{}) error
+```
+Mask masks the given error with the given format string and arguments (like
+fmt.Sprintf), returning a new error that maintains the error stack, but
+hides the underlying error type.  The error string still contains the full
+annotations. If you want to hide the annotations, call Wrap.
+
+
+## func New
+``` go
+func New(message string) error
+```
+New is a drop in replacement for the standard libary errors module that records
+the location that the error is created.
+
+For example:
+
+
+	return errors.New("validation failed")
+
+
+## func NewAlreadyExists
+``` go
+func NewAlreadyExists(err error, msg string) error
+```
+NewAlreadyExists returns an error which wraps err and satisfies
+IsAlreadyExists().
+
+
+## func NewNotFound
+``` go
+func NewNotFound(err error, msg string) error
+```
+NewNotFound returns an error which wraps err that satisfies
+IsNotFound().
+
+
+## func NewNotImplemented
+``` go
+func NewNotImplemented(err error, msg string) error
+```
+NewNotImplemented returns an error which wraps err and satisfies
+IsNotImplemented().
+
+
+## func NewNotSupported
+``` go
+func NewNotSupported(err error, msg string) error
+```
+NewNotSupported returns an error which wraps err and satisfies
+IsNotSupported().
+
+
+## func NewNotValid
+``` go
+func NewNotValid(err error, msg string) error
+```
+NewNotValid returns an error which wraps err and satisfies IsNotValid().
+
+
+## func NewUnauthorized
+``` go
+func NewUnauthorized(err error, msg string) error
+```
+NewUnauthorized returns an error which wraps err and satisfies
+IsUnauthorized().
+
+
+## func NotFoundf
+``` go
+func NotFoundf(format string, args ...interface{}) error
+```
+NotFoundf returns an error which satisfies IsNotFound().
+
+
+## func NotImplementedf
+``` go
+func NotImplementedf(format string, args ...interface{}) error
+```
+NotImplementedf returns an error which satisfies IsNotImplemented().
+
+
+## func NotSupportedf
+``` go
+func NotSupportedf(format string, args ...interface{}) error
+```
+NotSupportedf returns an error which satisfies IsNotSupported().
+
+
+## func NotValidf
+``` go
+func NotValidf(format string, args ...interface{}) error
+```
+NotValidf returns an error which satisfies IsNotValid().
+
+
+## func Trace
+``` go
+func Trace(other error) error
+```
+Trace adds the location of the Trace call to the stack.  The Cause of the
+resulting error is the same as the error parameter.  If the other error is
+nil, the result will be nil.
+
+For example:
+
+
+	if err := SomeFunc(); err != nil {
+	    return errors.Trace(err)
+	}
+
+
+## func Unauthorizedf
+``` go
+func Unauthorizedf(format string, args ...interface{}) error
+```
+Unauthorizedf returns an error which satisfies IsUnauthorized().
+
+
+## func Forbiddenf
+``` go
+func Forbiddenf(format string, args ...interface{}) error
+```
+Forbiddenf returns an error which satisfies IsForbidden().
+
+
+## func Wrap
+``` go
+func Wrap(other, newDescriptive error) error
+```
+Wrap changes the Cause of the error. The location of the Wrap call is also
+stored in the error stack.
+
+For example:
+
+
+	if err := SomeFunc(); err != nil {
+	    newErr := &packageError{"more context", private_value}
+	    return errors.Wrap(err, newErr)
+	}
+
+
+## func Wrapf
+``` go
+func Wrapf(other, newDescriptive error, format string, args ...interface{}) error
+```
+Wrapf changes the Cause of the error, and adds an annotation. The location
+of the Wrap call is also stored in the error stack.
+
+For example:
+
+
+	if err := SomeFunc(); err != nil {
+	    return errors.Wrapf(err, simpleErrorType, "invalid value %q", value)
+	}
+
+
+
+## type Err
+``` go
+type Err struct {
+    // contains filtered or unexported fields
+}
+```
+Err holds a description of an error along with information about
+where the error was created.
+
+It may be embedded in custom error types to add extra information that
+this errors package can understand.
+
+
+
+
+
+
+
+
+
+### func NewErr
+``` go
+func NewErr(format string, args ...interface{}) Err
+```
+NewErr is used to return an Err for the purpose of embedding in other
+structures.  The location is not specified, and needs to be set with a call
+to SetLocation.
+
+For example:
+
+
+	type FooError struct {
+	    errors.Err
+	    code int
+	}
+	
+	func NewFooError(code int) error {
+	    err := &FooError{errors.NewErr("foo"), code}
+	    err.SetLocation(1)
+	    return err
+	}
+
+
+
+
+### func (\*Err) Cause
+``` go
+func (e *Err) Cause() error
+```
+The Cause of an error is the most recent error in the error stack that
+meets one of these criteria: the original error that was raised; the new
+error that was passed into the Wrap function; the most recently masked
+error; or nil if the error itself is considered the Cause.  Normally this
+method is not invoked directly, but instead through the Cause stand alone
+function.
+
+
+
+### func (\*Err) Error
+``` go
+func (e *Err) Error() string
+```
+Error implements error.Error.
+
+
+
+### func (\*Err) Location
+``` go
+func (e *Err) Location() (filename string, line int)
+```
+Location is the file and line of where the error was most recently
+created or annotated.
+
+
+
+### func (\*Err) Message
+``` go
+func (e *Err) Message() string
+```
+Message returns the message stored with the most recent location. This is
+the empty string if the most recent call was Trace, or the message stored
+with Annotate or Mask.
+
+
+
+### func (\*Err) SetLocation
+``` go
+func (e *Err) SetLocation(callDepth int)
+```
+SetLocation records the source location of the error at callDepth stack
+frames above the call.
+
+
+
+### func (\*Err) StackTrace
+``` go
+func (e *Err) StackTrace() []string
+```
+StackTrace returns one string for each location recorded in the stack of
+errors. The first value is the originating error, with a line for each
+other annotation or tracing of the error.
+
+
+
+### func (\*Err) Underlying
+``` go
+func (e *Err) Underlying() error
+```
+Underlying returns the previous error in the error stack, if any. A client
+should not ever really call this method.  It is used to build the error
+stack and should not be introspected by client calls.  Or more
+specifically, clients should not depend on anything but the `Cause` of an
+error.
+
+
+
+
+
+
+
+
+
+- - -
+Generated by [godoc2md](http://godoc.org/github.com/davecheney/godoc2md)

vendor/github.com/juju/errors/doc.go

@@ -0,0 +1,81 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+/*
+[godoc-link-here]
+
+The juju/errors provides an easy way to annotate errors without losing the
+orginal error context.
+
+The exported `New` and `Errorf` functions are designed to replace the
+`errors.New` and `fmt.Errorf` functions respectively. The same underlying
+error is there, but the package also records the location at which the error
+was created.
+
+A primary use case for this library is to add extra context any time an
+error is returned from a function.
+
+    if err := SomeFunc(); err != nil {
+	    return err
+	}
+
+This instead becomes:
+
+    if err := SomeFunc(); err != nil {
+	    return errors.Trace(err)
+	}
+
+which just records the file and line number of the Trace call, or
+
+    if err := SomeFunc(); err != nil {
+	    return errors.Annotate(err, "more context")
+	}
+
+which also adds an annotation to the error.
+
+When you want to check to see if an error is of a particular type, a helper
+function is normally exported by the package that returned the error, like the
+`os` package does.  The underlying cause of the error is available using the
+`Cause` function.
+
+	os.IsNotExist(errors.Cause(err))
+
+The result of the `Error()` call on an annotated error is the annotations joined
+with colons, then the result of the `Error()` method for the underlying error
+that was the cause.
+
+	err := errors.Errorf("original")
+	err = errors.Annotatef(err, "context")
+	err = errors.Annotatef(err, "more context")
+	err.Error() -> "more context: context: original"
+
+Obviously recording the file, line and functions is not very useful if you
+cannot get them back out again.
+
+	errors.ErrorStack(err)
+
+will return something like:
+
+	first error
+	github.com/juju/errors/annotation_test.go:193:
+	github.com/juju/errors/annotation_test.go:194: annotation
+	github.com/juju/errors/annotation_test.go:195:
+	github.com/juju/errors/annotation_test.go:196: more context
+	github.com/juju/errors/annotation_test.go:197:
+
+The first error was generated by an external system, so there was no location
+associated. The second, fourth, and last lines were generated with Trace calls,
+and the other two through Annotate.
+
+Sometimes when responding to an error you want to return a more specific error
+for the situation.
+
+    if err := FindField(field); err != nil {
+	    return errors.Wrap(err, errors.NotFoundf(field))
+	}
+
+This returns an error where the complete error stack is still available, and
+`errors.Cause()` will return the `NotFound` error.
+
+*/
+package errors

vendor/github.com/juju/errors/error.go

@@ -0,0 +1,172 @@
+// Copyright 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors
+
+import (
+	"fmt"
+	"reflect"
+	"runtime"
+)
+
+// Err holds a description of an error along with information about
+// where the error was created.
+//
+// It may be embedded in custom error types to add extra information that
+// this errors package can understand.
+type Err struct {
+	// message holds an annotation of the error.
+	message string
+
+	// cause holds the cause of the error as returned
+	// by the Cause method.
+	cause error
+
+	// previous holds the previous error in the error stack, if any.
+	previous error
+
+	// file and line hold the source code location where the error was
+	// created.
+	file string
+	line int
+}
+
+// NewErr is used to return an Err for the purpose of embedding in other
+// structures.  The location is not specified, and needs to be set with a call
+// to SetLocation.
+//
+// For example:
+//     type FooError struct {
+//         errors.Err
+//         code int
+//     }
+//
+//     func NewFooError(code int) error {
+//         err := &FooError{errors.NewErr("foo"), code}
+//         err.SetLocation(1)
+//         return err
+//     }
+func NewErr(format string, args ...interface{}) Err {
+	return Err{
+		message: fmt.Sprintf(format, args...),
+	}
+}
+
+// NewErrWithCause is used to return an Err with case by other error for the purpose of embedding in other
+// structures. The location is not specified, and needs to be set with a call
+// to SetLocation.
+//
+// For example:
+//     type FooError struct {
+//         errors.Err
+//         code int
+//     }
+//
+//     func (e *FooError) Annotate(format string, args ...interface{}) error {
+//         err := &FooError{errors.NewErrWithCause(e.Err, format, args...), e.code}
+//         err.SetLocation(1)
+//         return err
+//     })
+func NewErrWithCause(other error, format string, args ...interface{}) Err {
+	return Err{
+		message:  fmt.Sprintf(format, args...),
+		cause:    Cause(other),
+		previous: other,
+	}
+}
+
+// Location is the file and line of where the error was most recently
+// created or annotated.
+func (e *Err) Location() (filename string, line int) {
+	return e.file, e.line
+}
+
+// Underlying returns the previous error in the error stack, if any. A client
+// should not ever really call this method.  It is used to build the error
+// stack and should not be introspected by client calls.  Or more
+// specifically, clients should not depend on anything but the `Cause` of an
+// error.
+func (e *Err) Underlying() error {
+	return e.previous
+}
+
+// The Cause of an error is the most recent error in the error stack that
+// meets one of these criteria: the original error that was raised; the new
+// error that was passed into the Wrap function; the most recently masked
+// error; or nil if the error itself is considered the Cause.  Normally this
+// method is not invoked directly, but instead through the Cause stand alone
+// function.
+func (e *Err) Cause() error {
+	return e.cause
+}
+
+// Message returns the message stored with the most recent location. This is
+// the empty string if the most recent call was Trace, or the message stored
+// with Annotate or Mask.
+func (e *Err) Message() string {
+	return e.message
+}
+
+// Error implements error.Error.
+func (e *Err) Error() string {
+	// We want to walk up the stack of errors showing the annotations
+	// as long as the cause is the same.
+	err := e.previous
+	if !sameError(Cause(err), e.cause) && e.cause != nil {
+		err = e.cause
+	}
+	switch {
+	case err == nil:
+		return e.message
+	case e.message == "":
+		return err.Error()
+	}
+	return fmt.Sprintf("%s: %v", e.message, err)
+}
+
+// Format implements fmt.Formatter
+// When printing errors with %+v it also prints the stack trace.
+// %#v unsurprisingly will print the real underlying type.
+func (e *Err) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		switch {
+		case s.Flag('+'):
+			fmt.Fprintf(s, "%s", ErrorStack(e))
+			return
+		case s.Flag('#'):
+			// avoid infinite recursion by wrapping e into a type
+			// that doesn't implement Formatter.
+			fmt.Fprintf(s, "%#v", (*unformatter)(e))
+			return
+		}
+		fallthrough
+	case 's':
+		fmt.Fprintf(s, "%s", e.Error())
+	}
+}
+
+// helper for Format
+type unformatter Err
+
+func (unformatter) Format() { /* break the fmt.Formatter interface */ }
+
+// SetLocation records the source location of the error at callDepth stack
+// frames above the call.
+func (e *Err) SetLocation(callDepth int) {
+	_, file, line, _ := runtime.Caller(callDepth + 1)
+	e.file = trimGoPath(file)
+	e.line = line
+}
+
+// StackTrace returns one string for each location recorded in the stack of
+// errors. The first value is the originating error, with a line for each
+// other annotation or tracing of the error.
+func (e *Err) StackTrace() []string {
+	return errorStack(e)
+}
+
+// Ideally we'd have a way to check identity, but deep equals will do.
+func sameError(e1, e2 error) bool {
+	return reflect.DeepEqual(e1, e2)
+}

vendor/github.com/juju/errors/error_test.go

@@ -0,0 +1,178 @@
+// Copyright 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	"fmt"
+	"runtime"
+
+	jc "github.com/juju/testing/checkers"
+	gc "gopkg.in/check.v1"
+
+	"github.com/juju/errors"
+)
+
+type errorsSuite struct{}
+
+var _ = gc.Suite(&errorsSuite{})
+
+var someErr = errors.New("some error") //err varSomeErr
+
+func (*errorsSuite) TestErrorString(c *gc.C) {
+	for i, test := range []struct {
+		message   string
+		generator func() error
+		expected  string
+	}{
+		{
+			message: "uncomparable errors",
+			generator: func() error {
+				err := errors.Annotatef(newNonComparableError("uncomparable"), "annotation")
+				return errors.Annotatef(err, "another")
+			},
+			expected: "another: annotation: uncomparable",
+		}, {
+			message: "Errorf",
+			generator: func() error {
+				return errors.Errorf("first error")
+			},
+			expected: "first error",
+		}, {
+			message: "annotated error",
+			generator: func() error {
+				err := errors.Errorf("first error")
+				return errors.Annotatef(err, "annotation")
+			},
+			expected: "annotation: first error",
+		}, {
+			message: "test annotation format",
+			generator: func() error {
+				err := errors.Errorf("first %s", "error")
+				return errors.Annotatef(err, "%s", "annotation")
+			},
+			expected: "annotation: first error",
+		}, {
+			message: "wrapped error",
+			generator: func() error {
+				err := newError("first error")
+				return errors.Wrap(err, newError("detailed error"))
+			},
+			expected: "detailed error",
+		}, {
+			message: "wrapped annotated error",
+			generator: func() error {
+				err := errors.Errorf("first error")
+				err = errors.Annotatef(err, "annotated")
+				return errors.Wrap(err, fmt.Errorf("detailed error"))
+			},
+			expected: "detailed error",
+		}, {
+			message: "annotated wrapped error",
+			generator: func() error {
+				err := errors.Errorf("first error")
+				err = errors.Wrap(err, fmt.Errorf("detailed error"))
+				return errors.Annotatef(err, "annotated")
+			},
+			expected: "annotated: detailed error",
+		}, {
+			message: "traced, and annotated",
+			generator: func() error {
+				err := errors.New("first error")
+				err = errors.Trace(err)
+				err = errors.Annotate(err, "some context")
+				err = errors.Trace(err)
+				err = errors.Annotate(err, "more context")
+				return errors.Trace(err)
+			},
+			expected: "more context: some context: first error",
+		}, {
+			message: "traced, and annotated, masked and annotated",
+			generator: func() error {
+				err := errors.New("first error")
+				err = errors.Trace(err)
+				err = errors.Annotate(err, "some context")
+				err = errors.Maskf(err, "masked")
+				err = errors.Annotate(err, "more context")
+				return errors.Trace(err)
+			},
+			expected: "more context: masked: some context: first error",
+		},
+	} {
+		c.Logf("%v: %s", i, test.message)
+		err := test.generator()
+		ok := c.Check(err.Error(), gc.Equals, test.expected)
+		if !ok {
+			c.Logf("%#v", test.generator())
+		}
+	}
+}
+
+type embed struct {
+	errors.Err
+}
+
+func newEmbed(format string, args ...interface{}) *embed {
+	err := &embed{errors.NewErr(format, args...)}
+	err.SetLocation(1)
+	return err
+}
+
+func (*errorsSuite) TestNewErr(c *gc.C) {
+	if runtime.Compiler == "gccgo" {
+		c.Skip("gccgo can't determine the location")
+	}
+	err := newEmbed("testing %d", 42) //err embedErr
+	c.Assert(err.Error(), gc.Equals, "testing 42")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["embedErr"].String())
+}
+
+func newEmbedWithCause(other error, format string, args ...interface{}) *embed {
+	err := &embed{errors.NewErrWithCause(other, format, args...)}
+	err.SetLocation(1)
+	return err
+}
+
+func (*errorsSuite) TestNewErrWithCause(c *gc.C) {
+	if runtime.Compiler == "gccgo" {
+		c.Skip("gccgo can't determine the location")
+	}
+	causeErr := fmt.Errorf("external error")
+	err := newEmbedWithCause(causeErr, "testing %d", 43) //err embedCause
+	c.Assert(err.Error(), gc.Equals, "testing 43: external error")
+	c.Assert(errors.Cause(err), gc.Equals, causeErr)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["embedCause"].String())
+}
+
+var _ error = (*embed)(nil)
+
+// This is an uncomparable error type, as it is a struct that supports the
+// error interface (as opposed to a pointer type).
+type error_ struct {
+	info  string
+	slice []string
+}
+
+// Create a non-comparable error
+func newNonComparableError(message string) error {
+	return error_{info: message}
+}
+
+func (e error_) Error() string {
+	return e.info
+}
+
+func newError(message string) error {
+	return testError{message}
+}
+
+// The testError is a value type error for ease of seeing results
+// when the test fails.
+type testError struct {
+	message string
+}
+
+func (e testError) Error() string {
+	return e.message
+}

vendor/github.com/juju/errors/errortypes.go

@@ -0,0 +1,309 @@
+// Copyright 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors
+
+import (
+	"fmt"
+)
+
+// wrap is a helper to construct an *wrapper.
+func wrap(err error, format, suffix string, args ...interface{}) Err {
+	newErr := Err{
+		message:  fmt.Sprintf(format+suffix, args...),
+		previous: err,
+	}
+	newErr.SetLocation(2)
+	return newErr
+}
+
+// notFound represents an error when something has not been found.
+type notFound struct {
+	Err
+}
+
+// NotFoundf returns an error which satisfies IsNotFound().
+func NotFoundf(format string, args ...interface{}) error {
+	return &notFound{wrap(nil, format, " not found", args...)}
+}
+
+// NewNotFound returns an error which wraps err that satisfies
+// IsNotFound().
+func NewNotFound(err error, msg string) error {
+	return &notFound{wrap(err, msg, "")}
+}
+
+// IsNotFound reports whether err was created with NotFoundf() or
+// NewNotFound().
+func IsNotFound(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notFound)
+	return ok
+}
+
+// userNotFound represents an error when an inexistent user is looked up.
+type userNotFound struct {
+	Err
+}
+
+// UserNotFoundf returns an error which satisfies IsUserNotFound().
+func UserNotFoundf(format string, args ...interface{}) error {
+	return &userNotFound{wrap(nil, format, " user not found", args...)}
+}
+
+// NewUserNotFound returns an error which wraps err and satisfies
+// IsUserNotFound().
+func NewUserNotFound(err error, msg string) error {
+	return &userNotFound{wrap(err, msg, "")}
+}
+
+// IsUserNotFound reports whether err was created with UserNotFoundf() or
+// NewUserNotFound().
+func IsUserNotFound(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*userNotFound)
+	return ok
+}
+
+// unauthorized represents an error when an operation is unauthorized.
+type unauthorized struct {
+	Err
+}
+
+// Unauthorizedf returns an error which satisfies IsUnauthorized().
+func Unauthorizedf(format string, args ...interface{}) error {
+	return &unauthorized{wrap(nil, format, "", args...)}
+}
+
+// NewUnauthorized returns an error which wraps err and satisfies
+// IsUnauthorized().
+func NewUnauthorized(err error, msg string) error {
+	return &unauthorized{wrap(err, msg, "")}
+}
+
+// IsUnauthorized reports whether err was created with Unauthorizedf() or
+// NewUnauthorized().
+func IsUnauthorized(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*unauthorized)
+	return ok
+}
+
+// notImplemented represents an error when something is not
+// implemented.
+type notImplemented struct {
+	Err
+}
+
+// NotImplementedf returns an error which satisfies IsNotImplemented().
+func NotImplementedf(format string, args ...interface{}) error {
+	return &notImplemented{wrap(nil, format, " not implemented", args...)}
+}
+
+// NewNotImplemented returns an error which wraps err and satisfies
+// IsNotImplemented().
+func NewNotImplemented(err error, msg string) error {
+	return &notImplemented{wrap(err, msg, "")}
+}
+
+// IsNotImplemented reports whether err was created with
+// NotImplementedf() or NewNotImplemented().
+func IsNotImplemented(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notImplemented)
+	return ok
+}
+
+// alreadyExists represents and error when something already exists.
+type alreadyExists struct {
+	Err
+}
+
+// AlreadyExistsf returns an error which satisfies IsAlreadyExists().
+func AlreadyExistsf(format string, args ...interface{}) error {
+	return &alreadyExists{wrap(nil, format, " already exists", args...)}
+}
+
+// NewAlreadyExists returns an error which wraps err and satisfies
+// IsAlreadyExists().
+func NewAlreadyExists(err error, msg string) error {
+	return &alreadyExists{wrap(err, msg, "")}
+}
+
+// IsAlreadyExists reports whether the error was created with
+// AlreadyExistsf() or NewAlreadyExists().
+func IsAlreadyExists(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*alreadyExists)
+	return ok
+}
+
+// notSupported represents an error when something is not supported.
+type notSupported struct {
+	Err
+}
+
+// NotSupportedf returns an error which satisfies IsNotSupported().
+func NotSupportedf(format string, args ...interface{}) error {
+	return &notSupported{wrap(nil, format, " not supported", args...)}
+}
+
+// NewNotSupported returns an error which wraps err and satisfies
+// IsNotSupported().
+func NewNotSupported(err error, msg string) error {
+	return &notSupported{wrap(err, msg, "")}
+}
+
+// IsNotSupported reports whether the error was created with
+// NotSupportedf() or NewNotSupported().
+func IsNotSupported(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notSupported)
+	return ok
+}
+
+// notValid represents an error when something is not valid.
+type notValid struct {
+	Err
+}
+
+// NotValidf returns an error which satisfies IsNotValid().
+func NotValidf(format string, args ...interface{}) error {
+	return &notValid{wrap(nil, format, " not valid", args...)}
+}
+
+// NewNotValid returns an error which wraps err and satisfies IsNotValid().
+func NewNotValid(err error, msg string) error {
+	return &notValid{wrap(err, msg, "")}
+}
+
+// IsNotValid reports whether the error was created with NotValidf() or
+// NewNotValid().
+func IsNotValid(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notValid)
+	return ok
+}
+
+// notProvisioned represents an error when something is not yet provisioned.
+type notProvisioned struct {
+	Err
+}
+
+// NotProvisionedf returns an error which satisfies IsNotProvisioned().
+func NotProvisionedf(format string, args ...interface{}) error {
+	return &notProvisioned{wrap(nil, format, " not provisioned", args...)}
+}
+
+// NewNotProvisioned returns an error which wraps err that satisfies
+// IsNotProvisioned().
+func NewNotProvisioned(err error, msg string) error {
+	return &notProvisioned{wrap(err, msg, "")}
+}
+
+// IsNotProvisioned reports whether err was created with NotProvisionedf() or
+// NewNotProvisioned().
+func IsNotProvisioned(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notProvisioned)
+	return ok
+}
+
+// notAssigned represents an error when something is not yet assigned to
+// something else.
+type notAssigned struct {
+	Err
+}
+
+// NotAssignedf returns an error which satisfies IsNotAssigned().
+func NotAssignedf(format string, args ...interface{}) error {
+	return &notAssigned{wrap(nil, format, " not assigned", args...)}
+}
+
+// NewNotAssigned returns an error which wraps err that satisfies
+// IsNotAssigned().
+func NewNotAssigned(err error, msg string) error {
+	return &notAssigned{wrap(err, msg, "")}
+}
+
+// IsNotAssigned reports whether err was created with NotAssignedf() or
+// NewNotAssigned().
+func IsNotAssigned(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*notAssigned)
+	return ok
+}
+
+// badRequest represents an error when a request has bad parameters.
+type badRequest struct {
+	Err
+}
+
+// BadRequestf returns an error which satisfies IsBadRequest().
+func BadRequestf(format string, args ...interface{}) error {
+	return &badRequest{wrap(nil, format, "", args...)}
+}
+
+// NewBadRequest returns an error which wraps err that satisfies
+// IsBadRequest().
+func NewBadRequest(err error, msg string) error {
+	return &badRequest{wrap(err, msg, "")}
+}
+
+// IsBadRequest reports whether err was created with BadRequestf() or
+// NewBadRequest().
+func IsBadRequest(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*badRequest)
+	return ok
+}
+
+// methodNotAllowed represents an error when an HTTP request
+// is made with an inappropriate method.
+type methodNotAllowed struct {
+	Err
+}
+
+// MethodNotAllowedf returns an error which satisfies IsMethodNotAllowed().
+func MethodNotAllowedf(format string, args ...interface{}) error {
+	return &methodNotAllowed{wrap(nil, format, "", args...)}
+}
+
+// NewMethodNotAllowed returns an error which wraps err that satisfies
+// IsMethodNotAllowed().
+func NewMethodNotAllowed(err error, msg string) error {
+	return &methodNotAllowed{wrap(err, msg, "")}
+}
+
+// IsMethodNotAllowed reports whether err was created with MethodNotAllowedf() or
+// NewMethodNotAllowed().
+func IsMethodNotAllowed(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*methodNotAllowed)
+	return ok
+}
+
+// forbidden represents an error when a request cannot be completed because of
+// missing privileges
+type forbidden struct {
+	Err
+}
+
+// Forbiddenf returns an error which satistifes IsForbidden()
+func Forbiddenf(format string, args ...interface{}) error {
+	return &forbidden{wrap(nil, format, "", args...)}
+}
+
+// NewForbidden returns an error which wraps err that satisfies
+// IsForbidden().
+func NewForbidden(err error, msg string) error {
+	return &forbidden{wrap(err, msg, "")}
+}
+
+// IsForbidden reports whether err was created with Forbiddenf() or
+// NewForbidden().
+func IsForbidden(err error) bool {
+	err = Cause(err)
+	_, ok := err.(*forbidden)
+	return ok
+}

vendor/github.com/juju/errors/errortypes_test.go

@@ -0,0 +1,174 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	stderrors "errors"
+	"fmt"
+	"reflect"
+	"runtime"
+
+	"github.com/juju/errors"
+	jc "github.com/juju/testing/checkers"
+	gc "gopkg.in/check.v1"
+)
+
+// errorInfo holds information about a single error type: a satisfier
+// function, wrapping and variable arguments constructors and message
+// suffix.
+type errorInfo struct {
+	satisfier       func(error) bool
+	argsConstructor func(string, ...interface{}) error
+	wrapConstructor func(error, string) error
+	suffix          string
+}
+
+// allErrors holds information for all defined errors. When adding new
+// errors, add them here as well to include them in tests.
+var allErrors = []*errorInfo{
+	{errors.IsNotFound, errors.NotFoundf, errors.NewNotFound, " not found"},
+	{errors.IsUserNotFound, errors.UserNotFoundf, errors.NewUserNotFound, " user not found"},
+	{errors.IsUnauthorized, errors.Unauthorizedf, errors.NewUnauthorized, ""},
+	{errors.IsNotImplemented, errors.NotImplementedf, errors.NewNotImplemented, " not implemented"},
+	{errors.IsAlreadyExists, errors.AlreadyExistsf, errors.NewAlreadyExists, " already exists"},
+	{errors.IsNotSupported, errors.NotSupportedf, errors.NewNotSupported, " not supported"},
+	{errors.IsNotValid, errors.NotValidf, errors.NewNotValid, " not valid"},
+	{errors.IsNotProvisioned, errors.NotProvisionedf, errors.NewNotProvisioned, " not provisioned"},
+	{errors.IsNotAssigned, errors.NotAssignedf, errors.NewNotAssigned, " not assigned"},
+	{errors.IsMethodNotAllowed, errors.MethodNotAllowedf, errors.NewMethodNotAllowed, ""},
+	{errors.IsBadRequest, errors.BadRequestf, errors.NewBadRequest, ""},
+	{errors.IsForbidden, errors.Forbiddenf, errors.NewForbidden, ""},
+}
+
+type errorTypeSuite struct{}
+
+var _ = gc.Suite(&errorTypeSuite{})
+
+func (t *errorInfo) satisfierName() string {
+	value := reflect.ValueOf(t.satisfier)
+	f := runtime.FuncForPC(value.Pointer())
+	return f.Name()
+}
+
+func (t *errorInfo) equal(t0 *errorInfo) bool {
+	if t0 == nil {
+		return false
+	}
+	return t.satisfierName() == t0.satisfierName()
+}
+
+type errorTest struct {
+	err     error
+	message string
+	errInfo *errorInfo
+}
+
+func deferredAnnotatef(err error, format string, args ...interface{}) error {
+	errors.DeferredAnnotatef(&err, format, args...)
+	return err
+}
+
+func mustSatisfy(c *gc.C, err error, errInfo *errorInfo) {
+	if errInfo != nil {
+		msg := fmt.Sprintf("%#v must satisfy %v", err, errInfo.satisfierName())
+		c.Check(err, jc.Satisfies, errInfo.satisfier, gc.Commentf(msg))
+	}
+}
+
+func mustNotSatisfy(c *gc.C, err error, errInfo *errorInfo) {
+	if errInfo != nil {
+		msg := fmt.Sprintf("%#v must not satisfy %v", err, errInfo.satisfierName())
+		c.Check(err, gc.Not(jc.Satisfies), errInfo.satisfier, gc.Commentf(msg))
+	}
+}
+
+func checkErrorMatches(c *gc.C, err error, message string, errInfo *errorInfo) {
+	if message == "<nil>" {
+		c.Check(err, gc.IsNil)
+		c.Check(errInfo, gc.IsNil)
+	} else {
+		c.Check(err, gc.ErrorMatches, message)
+	}
+}
+
+func runErrorTests(c *gc.C, errorTests []errorTest, checkMustSatisfy bool) {
+	for i, t := range errorTests {
+		c.Logf("test %d: %T: %v", i, t.err, t.err)
+		checkErrorMatches(c, t.err, t.message, t.errInfo)
+		if checkMustSatisfy {
+			mustSatisfy(c, t.err, t.errInfo)
+		}
+
+		// Check all other satisfiers to make sure none match.
+		for _, otherErrInfo := range allErrors {
+			if checkMustSatisfy && otherErrInfo.equal(t.errInfo) {
+				continue
+			}
+			mustNotSatisfy(c, t.err, otherErrInfo)
+		}
+	}
+}
+
+func (*errorTypeSuite) TestDeferredAnnotatef(c *gc.C) {
+	// Ensure DeferredAnnotatef annotates the errors.
+	errorTests := []errorTest{}
+	for _, errInfo := range allErrors {
+		errorTests = append(errorTests, []errorTest{{
+			deferredAnnotatef(nil, "comment"),
+			"<nil>",
+			nil,
+		}, {
+			deferredAnnotatef(stderrors.New("blast"), "comment"),
+			"comment: blast",
+			nil,
+		}, {
+			deferredAnnotatef(errInfo.argsConstructor("foo %d", 42), "comment %d", 69),
+			"comment 69: foo 42" + errInfo.suffix,
+			errInfo,
+		}, {
+			deferredAnnotatef(errInfo.argsConstructor(""), "comment"),
+			"comment: " + errInfo.suffix,
+			errInfo,
+		}, {
+			deferredAnnotatef(errInfo.wrapConstructor(stderrors.New("pow!"), "woo"), "comment"),
+			"comment: woo: pow!",
+			errInfo,
+		}}...)
+	}
+
+	runErrorTests(c, errorTests, true)
+}
+
+func (*errorTypeSuite) TestAllErrors(c *gc.C) {
+	errorTests := []errorTest{}
+	for _, errInfo := range allErrors {
+		errorTests = append(errorTests, []errorTest{{
+			nil,
+			"<nil>",
+			nil,
+		}, {
+			errInfo.argsConstructor("foo %d", 42),
+			"foo 42" + errInfo.suffix,
+			errInfo,
+		}, {
+			errInfo.argsConstructor(""),
+			errInfo.suffix,
+			errInfo,
+		}, {
+			errInfo.wrapConstructor(stderrors.New("pow!"), "prefix"),
+			"prefix: pow!",
+			errInfo,
+		}, {
+			errInfo.wrapConstructor(stderrors.New("pow!"), ""),
+			"pow!",
+			errInfo,
+		}, {
+			errInfo.wrapConstructor(nil, "prefix"),
+			"prefix",
+			errInfo,
+		}}...)
+	}
+
+	runErrorTests(c, errorTests, true)
+}

vendor/github.com/juju/errors/example_test.go

@@ -0,0 +1,23 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	"fmt"
+
+	"github.com/juju/errors"
+)
+
+func ExampleTrace() {
+	var err1 error = fmt.Errorf("something wicked this way comes")
+	var err2 error = nil
+
+	// Tracing a non nil error will return an error
+	fmt.Println(errors.Trace(err1))
+	// Tracing nil will return nil
+	fmt.Println(errors.Trace(err2))
+
+	// Output: something wicked this way comes
+	// <nil>
+}

vendor/github.com/juju/errors/export_test.go

@@ -0,0 +1,12 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors
+
+// Since variables are declared before the init block, in order to get the goPath
+// we need to return it rather than just reference it.
+func GoPath() string {
+	return goPath
+}
+
+var TrimGoPath = trimGoPath

vendor/github.com/juju/errors/functions.go

@@ -0,0 +1,330 @@
+// Copyright 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors
+
+import (
+	"fmt"
+	"strings"
+)
+
+// New is a drop in replacement for the standard library errors module that records
+// the location that the error is created.
+//
+// For example:
+//    return errors.New("validation failed")
+//
+func New(message string) error {
+	err := &Err{message: message}
+	err.SetLocation(1)
+	return err
+}
+
+// Errorf creates a new annotated error and records the location that the
+// error is created.  This should be a drop in replacement for fmt.Errorf.
+//
+// For example:
+//    return errors.Errorf("validation failed: %s", message)
+//
+func Errorf(format string, args ...interface{}) error {
+	err := &Err{message: fmt.Sprintf(format, args...)}
+	err.SetLocation(1)
+	return err
+}
+
+// Trace adds the location of the Trace call to the stack.  The Cause of the
+// resulting error is the same as the error parameter.  If the other error is
+// nil, the result will be nil.
+//
+// For example:
+//   if err := SomeFunc(); err != nil {
+//       return errors.Trace(err)
+//   }
+//
+func Trace(other error) error {
+	if other == nil {
+		return nil
+	}
+	err := &Err{previous: other, cause: Cause(other)}
+	err.SetLocation(1)
+	return err
+}
+
+// Annotate is used to add extra context to an existing error. The location of
+// the Annotate call is recorded with the annotations. The file, line and
+// function are also recorded.
+//
+// For example:
+//   if err := SomeFunc(); err != nil {
+//       return errors.Annotate(err, "failed to frombulate")
+//   }
+//
+func Annotate(other error, message string) error {
+	if other == nil {
+		return nil
+	}
+	err := &Err{
+		previous: other,
+		cause:    Cause(other),
+		message:  message,
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// Annotatef is used to add extra context to an existing error. The location of
+// the Annotate call is recorded with the annotations. The file, line and
+// function are also recorded.
+//
+// For example:
+//   if err := SomeFunc(); err != nil {
+//       return errors.Annotatef(err, "failed to frombulate the %s", arg)
+//   }
+//
+func Annotatef(other error, format string, args ...interface{}) error {
+	if other == nil {
+		return nil
+	}
+	err := &Err{
+		previous: other,
+		cause:    Cause(other),
+		message:  fmt.Sprintf(format, args...),
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// DeferredAnnotatef annotates the given error (when it is not nil) with the given
+// format string and arguments (like fmt.Sprintf). If *err is nil, DeferredAnnotatef
+// does nothing. This method is used in a defer statement in order to annotate any
+// resulting error with the same message.
+//
+// For example:
+//
+//    defer DeferredAnnotatef(&err, "failed to frombulate the %s", arg)
+//
+func DeferredAnnotatef(err *error, format string, args ...interface{}) {
+	if *err == nil {
+		return
+	}
+	newErr := &Err{
+		message:  fmt.Sprintf(format, args...),
+		cause:    Cause(*err),
+		previous: *err,
+	}
+	newErr.SetLocation(1)
+	*err = newErr
+}
+
+// Wrap changes the Cause of the error. The location of the Wrap call is also
+// stored in the error stack.
+//
+// For example:
+//   if err := SomeFunc(); err != nil {
+//       newErr := &packageError{"more context", private_value}
+//       return errors.Wrap(err, newErr)
+//   }
+//
+func Wrap(other, newDescriptive error) error {
+	err := &Err{
+		previous: other,
+		cause:    newDescriptive,
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// Wrapf changes the Cause of the error, and adds an annotation. The location
+// of the Wrap call is also stored in the error stack.
+//
+// For example:
+//   if err := SomeFunc(); err != nil {
+//       return errors.Wrapf(err, simpleErrorType, "invalid value %q", value)
+//   }
+//
+func Wrapf(other, newDescriptive error, format string, args ...interface{}) error {
+	err := &Err{
+		message:  fmt.Sprintf(format, args...),
+		previous: other,
+		cause:    newDescriptive,
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// Mask masks the given error with the given format string and arguments (like
+// fmt.Sprintf), returning a new error that maintains the error stack, but
+// hides the underlying error type.  The error string still contains the full
+// annotations. If you want to hide the annotations, call Wrap.
+func Maskf(other error, format string, args ...interface{}) error {
+	if other == nil {
+		return nil
+	}
+	err := &Err{
+		message:  fmt.Sprintf(format, args...),
+		previous: other,
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// Mask hides the underlying error type, and records the location of the masking.
+func Mask(other error) error {
+	if other == nil {
+		return nil
+	}
+	err := &Err{
+		previous: other,
+	}
+	err.SetLocation(1)
+	return err
+}
+
+// Cause returns the cause of the given error.  This will be either the
+// original error, or the result of a Wrap or Mask call.
+//
+// Cause is the usual way to diagnose errors that may have been wrapped by
+// the other errors functions.
+func Cause(err error) error {
+	var diag error
+	if err, ok := err.(causer); ok {
+		diag = err.Cause()
+	}
+	if diag != nil {
+		return diag
+	}
+	return err
+}
+
+type causer interface {
+	Cause() error
+}
+
+type wrapper interface {
+	// Message returns the top level error message,
+	// not including the message from the Previous
+	// error.
+	Message() string
+
+	// Underlying returns the Previous error, or nil
+	// if there is none.
+	Underlying() error
+}
+
+type locationer interface {
+	Location() (string, int)
+}
+
+var (
+	_ wrapper    = (*Err)(nil)
+	_ locationer = (*Err)(nil)
+	_ causer     = (*Err)(nil)
+)
+
+// Details returns information about the stack of errors wrapped by err, in
+// the format:
+//
+// 	[{filename:99: error one} {otherfile:55: cause of error one}]
+//
+// This is a terse alternative to ErrorStack as it returns a single line.
+func Details(err error) string {
+	if err == nil {
+		return "[]"
+	}
+	var s []byte
+	s = append(s, '[')
+	for {
+		s = append(s, '{')
+		if err, ok := err.(locationer); ok {
+			file, line := err.Location()
+			if file != "" {
+				s = append(s, fmt.Sprintf("%s:%d", file, line)...)
+				s = append(s, ": "...)
+			}
+		}
+		if cerr, ok := err.(wrapper); ok {
+			s = append(s, cerr.Message()...)
+			err = cerr.Underlying()
+		} else {
+			s = append(s, err.Error()...)
+			err = nil
+		}
+		s = append(s, '}')
+		if err == nil {
+			break
+		}
+		s = append(s, ' ')
+	}
+	s = append(s, ']')
+	return string(s)
+}
+
+// ErrorStack returns a string representation of the annotated error. If the
+// error passed as the parameter is not an annotated error, the result is
+// simply the result of the Error() method on that error.
+//
+// If the error is an annotated error, a multi-line string is returned where
+// each line represents one entry in the annotation stack. The full filename
+// from the call stack is used in the output.
+//
+//     first error
+//     github.com/juju/errors/annotation_test.go:193:
+//     github.com/juju/errors/annotation_test.go:194: annotation
+//     github.com/juju/errors/annotation_test.go:195:
+//     github.com/juju/errors/annotation_test.go:196: more context
+//     github.com/juju/errors/annotation_test.go:197:
+func ErrorStack(err error) string {
+	return strings.Join(errorStack(err), "\n")
+}
+
+func errorStack(err error) []string {
+	if err == nil {
+		return nil
+	}
+
+	// We want the first error first
+	var lines []string
+	for {
+		var buff []byte
+		if err, ok := err.(locationer); ok {
+			file, line := err.Location()
+			// Strip off the leading GOPATH/src path elements.
+			file = trimGoPath(file)
+			if file != "" {
+				buff = append(buff, fmt.Sprintf("%s:%d", file, line)...)
+				buff = append(buff, ": "...)
+			}
+		}
+		if cerr, ok := err.(wrapper); ok {
+			message := cerr.Message()
+			buff = append(buff, message...)
+			// If there is a cause for this error, and it is different to the cause
+			// of the underlying error, then output the error string in the stack trace.
+			var cause error
+			if err1, ok := err.(causer); ok {
+				cause = err1.Cause()
+			}
+			err = cerr.Underlying()
+			if cause != nil && !sameError(Cause(err), cause) {
+				if message != "" {
+					buff = append(buff, ": "...)
+				}
+				buff = append(buff, cause.Error()...)
+			}
+		} else {
+			buff = append(buff, err.Error()...)
+			err = nil
+		}
+		lines = append(lines, string(buff))
+		if err == nil {
+			break
+		}
+	}
+	// reverse the lines to get the original error, which was at the end of
+	// the list, back to the start.
+	var result []string
+	for i := len(lines); i > 0; i-- {
+		result = append(result, lines[i-1])
+	}
+	return result
+}

vendor/github.com/juju/errors/functions_test.go

@@ -0,0 +1,305 @@
+// Copyright 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	jc "github.com/juju/testing/checkers"
+	gc "gopkg.in/check.v1"
+
+	"github.com/juju/errors"
+)
+
+type functionSuite struct {
+}
+
+var _ = gc.Suite(&functionSuite{})
+
+func (*functionSuite) TestNew(c *gc.C) {
+	err := errors.New("testing") //err newTest
+	c.Assert(err.Error(), gc.Equals, "testing")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["newTest"].String())
+}
+
+func (*functionSuite) TestErrorf(c *gc.C) {
+	err := errors.Errorf("testing %d", 42) //err errorfTest
+	c.Assert(err.Error(), gc.Equals, "testing 42")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["errorfTest"].String())
+}
+
+func (*functionSuite) TestTrace(c *gc.C) {
+	first := errors.New("first")
+	err := errors.Trace(first) //err traceTest
+	c.Assert(err.Error(), gc.Equals, "first")
+	c.Assert(errors.Cause(err), gc.Equals, first)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["traceTest"].String())
+
+	c.Assert(errors.Trace(nil), gc.IsNil)
+}
+
+func (*functionSuite) TestAnnotate(c *gc.C) {
+	first := errors.New("first")
+	err := errors.Annotate(first, "annotation") //err annotateTest
+	c.Assert(err.Error(), gc.Equals, "annotation: first")
+	c.Assert(errors.Cause(err), gc.Equals, first)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["annotateTest"].String())
+
+	c.Assert(errors.Annotate(nil, "annotate"), gc.IsNil)
+}
+
+func (*functionSuite) TestAnnotatef(c *gc.C) {
+	first := errors.New("first")
+	err := errors.Annotatef(first, "annotation %d", 2) //err annotatefTest
+	c.Assert(err.Error(), gc.Equals, "annotation 2: first")
+	c.Assert(errors.Cause(err), gc.Equals, first)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["annotatefTest"].String())
+
+	c.Assert(errors.Annotatef(nil, "annotate"), gc.IsNil)
+}
+
+func (*functionSuite) TestDeferredAnnotatef(c *gc.C) {
+	// NOTE: this test fails with gccgo
+	if runtime.Compiler == "gccgo" {
+		c.Skip("gccgo can't determine the location")
+	}
+	first := errors.New("first")
+	test := func() (err error) {
+		defer errors.DeferredAnnotatef(&err, "deferred %s", "annotate")
+		return first //err deferredAnnotate
+	}
+	err := test()
+	c.Assert(err.Error(), gc.Equals, "deferred annotate: first")
+	c.Assert(errors.Cause(err), gc.Equals, first)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["deferredAnnotate"].String())
+
+	err = nil
+	errors.DeferredAnnotatef(&err, "deferred %s", "annotate")
+	c.Assert(err, gc.IsNil)
+}
+
+func (*functionSuite) TestWrap(c *gc.C) {
+	first := errors.New("first") //err wrapFirst
+	detailed := errors.New("detailed")
+	err := errors.Wrap(first, detailed) //err wrapTest
+	c.Assert(err.Error(), gc.Equals, "detailed")
+	c.Assert(errors.Cause(err), gc.Equals, detailed)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["wrapFirst"].String())
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["wrapTest"].String())
+}
+
+func (*functionSuite) TestWrapOfNil(c *gc.C) {
+	detailed := errors.New("detailed")
+	err := errors.Wrap(nil, detailed) //err nilWrapTest
+	c.Assert(err.Error(), gc.Equals, "detailed")
+	c.Assert(errors.Cause(err), gc.Equals, detailed)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["nilWrapTest"].String())
+}
+
+func (*functionSuite) TestWrapf(c *gc.C) {
+	first := errors.New("first") //err wrapfFirst
+	detailed := errors.New("detailed")
+	err := errors.Wrapf(first, detailed, "value %d", 42) //err wrapfTest
+	c.Assert(err.Error(), gc.Equals, "value 42: detailed")
+	c.Assert(errors.Cause(err), gc.Equals, detailed)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["wrapfFirst"].String())
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["wrapfTest"].String())
+}
+
+func (*functionSuite) TestWrapfOfNil(c *gc.C) {
+	detailed := errors.New("detailed")
+	err := errors.Wrapf(nil, detailed, "value %d", 42) //err nilWrapfTest
+	c.Assert(err.Error(), gc.Equals, "value 42: detailed")
+	c.Assert(errors.Cause(err), gc.Equals, detailed)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["nilWrapfTest"].String())
+}
+
+func (*functionSuite) TestMask(c *gc.C) {
+	first := errors.New("first")
+	err := errors.Mask(first) //err maskTest
+	c.Assert(err.Error(), gc.Equals, "first")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["maskTest"].String())
+
+	c.Assert(errors.Mask(nil), gc.IsNil)
+}
+
+func (*functionSuite) TestMaskf(c *gc.C) {
+	first := errors.New("first")
+	err := errors.Maskf(first, "masked %d", 42) //err maskfTest
+	c.Assert(err.Error(), gc.Equals, "masked 42: first")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+	c.Assert(errors.Details(err), jc.Contains, tagToLocation["maskfTest"].String())
+
+	c.Assert(errors.Maskf(nil, "mask"), gc.IsNil)
+}
+
+func (*functionSuite) TestCause(c *gc.C) {
+	c.Assert(errors.Cause(nil), gc.IsNil)
+	c.Assert(errors.Cause(someErr), gc.Equals, someErr)
+
+	fmtErr := fmt.Errorf("simple")
+	c.Assert(errors.Cause(fmtErr), gc.Equals, fmtErr)
+
+	err := errors.Wrap(someErr, fmtErr)
+	c.Assert(errors.Cause(err), gc.Equals, fmtErr)
+
+	err = errors.Annotate(err, "annotated")
+	c.Assert(errors.Cause(err), gc.Equals, fmtErr)
+
+	err = errors.Maskf(err, "maksed")
+	c.Assert(errors.Cause(err), gc.Equals, err)
+
+	// Look for a file that we know isn't there.
+	dir := c.MkDir()
+	_, err = os.Stat(filepath.Join(dir, "not-there"))
+	c.Assert(os.IsNotExist(err), jc.IsTrue)
+
+	err = errors.Annotatef(err, "wrap it")
+	// Now the error itself isn't a 'IsNotExist'.
+	c.Assert(os.IsNotExist(err), jc.IsFalse)
+	// However if we use the Check method, it is.
+	c.Assert(os.IsNotExist(errors.Cause(err)), jc.IsTrue)
+}
+
+func (s *functionSuite) TestDetails(c *gc.C) {
+	if runtime.Compiler == "gccgo" {
+		c.Skip("gccgo can't determine the location")
+	}
+	c.Assert(errors.Details(nil), gc.Equals, "[]")
+
+	otherErr := fmt.Errorf("other")
+	checkDetails(c, otherErr, "[{other}]")
+
+	err0 := newEmbed("foo") //err TestStack#0
+	checkDetails(c, err0, "[{$TestStack#0$: foo}]")
+
+	err1 := errors.Annotate(err0, "bar") //err TestStack#1
+	checkDetails(c, err1, "[{$TestStack#1$: bar} {$TestStack#0$: foo}]")
+
+	err2 := errors.Trace(err1) //err TestStack#2
+	checkDetails(c, err2, "[{$TestStack#2$: } {$TestStack#1$: bar} {$TestStack#0$: foo}]")
+}
+
+type tracer interface {
+	StackTrace() []string
+}
+
+func (*functionSuite) TestErrorStack(c *gc.C) {
+	for i, test := range []struct {
+		message   string
+		generator func() error
+		expected  string
+		tracer    bool
+	}{
+		{
+			message: "nil",
+			generator: func() error {
+				return nil
+			},
+		}, {
+			message: "raw error",
+			generator: func() error {
+				return fmt.Errorf("raw")
+			},
+			expected: "raw",
+		}, {
+			message: "single error stack",
+			generator: func() error {
+				return errors.New("first error") //err single
+			},
+			expected: "$single$: first error",
+			tracer:   true,
+		}, {
+			message: "annotated error",
+			generator: func() error {
+				err := errors.New("first error")          //err annotated-0
+				return errors.Annotate(err, "annotation") //err annotated-1
+			},
+			expected: "" +
+				"$annotated-0$: first error\n" +
+				"$annotated-1$: annotation",
+			tracer: true,
+		}, {
+			message: "wrapped error",
+			generator: func() error {
+				err := errors.New("first error")                    //err wrapped-0
+				return errors.Wrap(err, newError("detailed error")) //err wrapped-1
+			},
+			expected: "" +
+				"$wrapped-0$: first error\n" +
+				"$wrapped-1$: detailed error",
+			tracer: true,
+		}, {
+			message: "annotated wrapped error",
+			generator: func() error {
+				err := errors.Errorf("first error")                  //err ann-wrap-0
+				err = errors.Wrap(err, fmt.Errorf("detailed error")) //err ann-wrap-1
+				return errors.Annotatef(err, "annotated")            //err ann-wrap-2
+			},
+			expected: "" +
+				"$ann-wrap-0$: first error\n" +
+				"$ann-wrap-1$: detailed error\n" +
+				"$ann-wrap-2$: annotated",
+			tracer: true,
+		}, {
+			message: "traced, and annotated",
+			generator: func() error {
+				err := errors.New("first error")           //err stack-0
+				err = errors.Trace(err)                    //err stack-1
+				err = errors.Annotate(err, "some context") //err stack-2
+				err = errors.Trace(err)                    //err stack-3
+				err = errors.Annotate(err, "more context") //err stack-4
+				return errors.Trace(err)                   //err stack-5
+			},
+			expected: "" +
+				"$stack-0$: first error\n" +
+				"$stack-1$: \n" +
+				"$stack-2$: some context\n" +
+				"$stack-3$: \n" +
+				"$stack-4$: more context\n" +
+				"$stack-5$: ",
+			tracer: true,
+		}, {
+			message: "uncomparable, wrapped with a value error",
+			generator: func() error {
+				err := newNonComparableError("first error")     //err mixed-0
+				err = errors.Trace(err)                         //err mixed-1
+				err = errors.Wrap(err, newError("value error")) //err mixed-2
+				err = errors.Maskf(err, "masked")               //err mixed-3
+				err = errors.Annotate(err, "more context")      //err mixed-4
+				return errors.Trace(err)                        //err mixed-5
+			},
+			expected: "" +
+				"first error\n" +
+				"$mixed-1$: \n" +
+				"$mixed-2$: value error\n" +
+				"$mixed-3$: masked\n" +
+				"$mixed-4$: more context\n" +
+				"$mixed-5$: ",
+			tracer: true,
+		},
+	} {
+		c.Logf("%v: %s", i, test.message)
+		err := test.generator()
+		expected := replaceLocations(test.expected)
+		stack := errors.ErrorStack(err)
+		ok := c.Check(stack, gc.Equals, expected)
+		if !ok {
+			c.Logf("%#v", err)
+		}
+		tracer, ok := err.(tracer)
+		c.Check(ok, gc.Equals, test.tracer)
+		if ok {
+			stackTrace := tracer.StackTrace()
+			c.Check(stackTrace, gc.DeepEquals, strings.Split(stack, "\n"))
+		}
+	}
+}

vendor/github.com/juju/errors/package_test.go

@@ -0,0 +1,95 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	gc "gopkg.in/check.v1"
+
+	"github.com/juju/errors"
+)
+
+func Test(t *testing.T) {
+	gc.TestingT(t)
+}
+
+func checkDetails(c *gc.C, err error, details string) {
+	c.Assert(err, gc.NotNil)
+	expectedDetails := replaceLocations(details)
+	c.Assert(errors.Details(err), gc.Equals, expectedDetails)
+}
+
+func checkErr(c *gc.C, err, cause error, msg string, details string) {
+	c.Assert(err, gc.NotNil)
+	c.Assert(err.Error(), gc.Equals, msg)
+	c.Assert(errors.Cause(err), gc.Equals, cause)
+	expectedDetails := replaceLocations(details)
+	c.Assert(errors.Details(err), gc.Equals, expectedDetails)
+}
+
+func replaceLocations(line string) string {
+	result := ""
+	for {
+		i := strings.Index(line, "$")
+		if i == -1 {
+			break
+		}
+		result += line[0:i]
+		line = line[i+1:]
+		i = strings.Index(line, "$")
+		if i == -1 {
+			panic("no second $")
+		}
+		result += location(line[0:i]).String()
+		line = line[i+1:]
+	}
+	result += line
+	return result
+}
+
+func location(tag string) Location {
+	loc, ok := tagToLocation[tag]
+	if !ok {
+		panic(fmt.Sprintf("tag %q not found", tag))
+	}
+	return loc
+}
+
+type Location struct {
+	file string
+	line int
+}
+
+func (loc Location) String() string {
+	return fmt.Sprintf("%s:%d", loc.file, loc.line)
+}
+
+var tagToLocation = make(map[string]Location)
+
+func setLocationsForErrorTags(filename string) {
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		panic(err)
+	}
+	filename = "github.com/juju/errors/" + filename
+	lines := strings.Split(string(data), "\n")
+	for i, line := range lines {
+		if j := strings.Index(line, "//err "); j >= 0 {
+			tag := line[j+len("//err "):]
+			if _, found := tagToLocation[tag]; found {
+				panic(fmt.Sprintf("tag %q already processed previously", tag))
+			}
+			tagToLocation[tag] = Location{file: filename, line: i + 1}
+		}
+	}
+}
+
+func init() {
+	setLocationsForErrorTags("error_test.go")
+	setLocationsForErrorTags("functions_test.go")
+}

vendor/github.com/juju/errors/path.go

@@ -0,0 +1,38 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors
+
+import (
+	"runtime"
+	"strings"
+)
+
+// prefixSize is used internally to trim the user specific path from the
+// front of the returned filenames from the runtime call stack.
+var prefixSize int
+
+// goPath is the deduced path based on the location of this file as compiled.
+var goPath string
+
+func init() {
+	_, file, _, ok := runtime.Caller(0)
+	if file == "?" {
+		return
+	}
+	if ok {
+		// We know that the end of the file should be:
+		// github.com/juju/errors/path.go
+		size := len(file)
+		suffix := len("github.com/juju/errors/path.go")
+		goPath = file[:size-suffix]
+		prefixSize = len(goPath)
+	}
+}
+
+func trimGoPath(filename string) string {
+	if strings.HasPrefix(filename, goPath) {
+		return filename[prefixSize:]
+	}
+	return filename
+}

vendor/github.com/juju/errors/path_test.go

@@ -0,0 +1,29 @@
+// Copyright 2013, 2014 Canonical Ltd.
+// Licensed under the LGPLv3, see LICENCE file for details.
+
+package errors_test
+
+import (
+	"path"
+
+	gc "gopkg.in/check.v1"
+
+	"github.com/juju/errors"
+)
+
+type pathSuite struct{}
+
+var _ = gc.Suite(&pathSuite{})
+
+func (*pathSuite) TestGoPathSet(c *gc.C) {
+	c.Assert(errors.GoPath(), gc.Not(gc.Equals), "")
+}
+
+func (*pathSuite) TestTrimGoPath(c *gc.C) {
+	relativeImport := "github.com/foo/bar/baz.go"
+	filename := path.Join(errors.GoPath(), relativeImport)
+	c.Assert(errors.TrimGoPath(filename), gc.Equals, relativeImport)
+
+	absoluteImport := "/usr/share/foo/bar/baz.go"
+	c.Assert(errors.TrimGoPath(absoluteImport), gc.Equals, absoluteImport)
+}