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

193 lines
4.6 KiB
Go

package pongo2
import (
"bytes"
"fmt"
"io"
)
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
isTplString bool
name string
tpl string
size int
// Calculation
tokens []*Token
parser *Parser
// first come, first serve (it's important to not override existing entries in here)
level int
parent *Template
child *Template
blocks map[string]*NodeWrapper
exportedMacros map[string]*tagMacroNode
// Output
root *nodeDocument
}
func newTemplateString(set *TemplateSet, tpl []byte) (*Template, error) {
return newTemplate(set, "<string>", true, tpl)
}
func newTemplate(set *TemplateSet, name string, isTplString bool, tpl []byte) (*Template, error) {
strTpl := string(tpl)
// Create the template
t := &Template{
set: set,
isTplString: isTplString,
name: name,
tpl: strTpl,
size: len(strTpl),
blocks: make(map[string]*NodeWrapper),
exportedMacros: make(map[string]*tagMacroNode),
}
// Tokenize it
tokens, err := lex(name, strTpl)
if err != nil {
return nil, err
}
t.tokens = tokens
// For debugging purposes, show all tokens:
/*for i, t := range tokens {
fmt.Printf("%3d. %s\n", i, t)
}*/
// Parse it
err = t.parse()
if err != nil {
return nil, err
}
return t, nil
}
func (tpl *Template) execute(context Context, writer TemplateWriter) error {
// Determine the parent to be executed (for template inheritance)
parent := tpl
for parent.parent != nil {
parent = parent.parent
}
// Create context if none is given
newContext := make(Context)
newContext.Update(tpl.set.Globals)
if context != nil {
newContext.Update(context)
if len(newContext) > 0 {
// Check for context name syntax
err := newContext.checkForValidIdentifiers()
if err != nil {
return err
}
// Check for clashes with macro names
for k := range newContext {
_, has := tpl.exportedMacros[k]
if has {
return &Error{
Filename: tpl.name,
Sender: "execution",
ErrorMsg: fmt.Sprintf("Context key name '%s' clashes with macro '%s'.", k, k),
}
}
}
}
}
// Create operational context
ctx := newExecutionContext(parent, newContext)
// Run the selected document
if err := parent.root.Execute(ctx, writer); 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
}
// Executes the template with the given context and writes to writer (io.Writer)
// 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 {
buf, err := tpl.newBufferAndExecute(context)
if err != nil {
return err
}
_, err = buf.WriteTo(writer)
if err != nil {
return err
}
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.newBufferAndExecute(context)
if err != nil {
return nil, err
}
return buffer.Bytes(), nil
}
// Executes the template and returns the rendered template as a string
func (tpl *Template) Execute(context Context) (string, error) {
// Execute template
buffer, err := tpl.newBufferAndExecute(context)
if err != nil {
return "", err
}
return buffer.String(), nil
}