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repo-template/vendor/github.com/flosch/pongo2/parser.go

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package pongo2
import (
"bytes"
"fmt"
"strings"
)
type INode interface {
Execute(*ExecutionContext, *bytes.Buffer) *Error
}
type IEvaluator interface {
INode
GetPositionToken() *Token
Evaluate(*ExecutionContext) (*Value, *Error)
FilterApplied(name string) bool
}
// The parser provides you a comprehensive and easy tool to
// work with the template document and arguments provided by
// the user for your custom tag.
//
// The parser works on a token list which will be provided by pongo2.
// A token is a unit you can work with. Tokens are either of type identifier,
// string, number, keyword, HTML or symbol.
//
// (See Token's documentation for more about tokens)
type Parser struct {
name string
idx int
tokens []*Token
last_token *Token
// if the parser parses a template document, here will be
// a reference to it (needed to access the template through Tags)
template *Template
}
// Creates a new parser to parse tokens.
// Used inside pongo2 to parse documents and to provide an easy-to-use
// parser for tag authors
func newParser(name string, tokens []*Token, template *Template) *Parser {
p := &Parser{
name: name,
tokens: tokens,
template: template,
}
if len(tokens) > 0 {
p.last_token = tokens[len(tokens)-1]
}
return p
}
// Consume one token. It will be gone forever.
func (p *Parser) Consume() {
p.ConsumeN(1)
}
// Consume N tokens. They will be gone forever.
func (p *Parser) ConsumeN(count int) {
p.idx += count
}
// Returns the current token.
func (p *Parser) Current() *Token {
return p.Get(p.idx)
}
// Returns the CURRENT token if the given type matches.
// Consumes this token on success.
func (p *Parser) MatchType(typ TokenType) *Token {
if t := p.PeekType(typ); t != nil {
p.Consume()
return t
}
return nil
}
// Returns the CURRENT token if the given type AND value matches.
// Consumes this token on success.
func (p *Parser) Match(typ TokenType, val string) *Token {
if t := p.Peek(typ, val); t != nil {
p.Consume()
return t
}
return nil
}
// Returns the CURRENT token if the given type AND *one* of
// the given values matches.
// Consumes this token on success.
func (p *Parser) MatchOne(typ TokenType, vals ...string) *Token {
for _, val := range vals {
if t := p.Peek(typ, val); t != nil {
p.Consume()
return t
}
}
return nil
}
// Returns the CURRENT token if the given type matches.
// It DOES NOT consume the token.
func (p *Parser) PeekType(typ TokenType) *Token {
return p.PeekTypeN(0, typ)
}
// Returns the CURRENT token if the given type AND value matches.
// It DOES NOT consume the token.
func (p *Parser) Peek(typ TokenType, val string) *Token {
return p.PeekN(0, typ, val)
}
// Returns the CURRENT token if the given type AND *one* of
// the given values matches.
// It DOES NOT consume the token.
func (p *Parser) PeekOne(typ TokenType, vals ...string) *Token {
for _, v := range vals {
t := p.PeekN(0, typ, v)
if t != nil {
return t
}
}
return nil
}
// Returns the tokens[current position + shift] token if the
// given type AND value matches for that token.
// DOES NOT consume the token.
func (p *Parser) PeekN(shift int, typ TokenType, val string) *Token {
t := p.Get(p.idx + shift)
if t != nil {
if t.Typ == typ && t.Val == val {
return t
}
}
return nil
}
// Returns the tokens[current position + shift] token if the given type matches.
// DOES NOT consume the token for that token.
func (p *Parser) PeekTypeN(shift int, typ TokenType) *Token {
t := p.Get(p.idx + shift)
if t != nil {
if t.Typ == typ {
return t
}
}
return nil
}
// Returns the UNCONSUMED token count.
func (p *Parser) Remaining() int {
return len(p.tokens) - p.idx
}
// Returns the total token count.
func (p *Parser) Count() int {
return len(p.tokens)
}
// Returns tokens[i] or NIL (if i >= len(tokens))
func (p *Parser) Get(i int) *Token {
if i < len(p.tokens) {
return p.tokens[i]
}
return nil
}
// Returns tokens[current-position + shift] or NIL
// (if (current-position + i) >= len(tokens))
func (p *Parser) GetR(shift int) *Token {
i := p.idx + shift
return p.Get(i)
}
// 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.
func (p *Parser) Error(msg string, token *Token) *Error {
if token == nil {
// Set current token
token = p.Current()
if token == nil {
// Set to last token
if len(p.tokens) > 0 {
token = p.tokens[len(p.tokens)-1]
}
}
}
var line, col int
if token != nil {
line = token.Line
col = token.Col
}
return &Error{
Template: p.template,
Filename: p.name,
Sender: "parser",
Line: line,
Column: col,
Token: token,
ErrorMsg: msg,
}
}
// Wraps all nodes between starting tag and "{% endtag %}" and provides
// one simple interface to execute the wrapped nodes.
// It returns a parser to process provided arguments to the tag.
func (p *Parser) WrapUntilTag(names ...string) (*NodeWrapper, *Parser, *Error) {
wrapper := &NodeWrapper{}
tagArgs := make([]*Token, 0)
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)
if tag_ident != nil {
// We've found a (!) end-tag
found := false
for _, n := range names {
if tag_ident.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 {
// Okay, end the wrapping here
wrapper.Endtag = tag_ident.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)
}
}
}
}
}
// Otherwise process next element to be wrapped
node, err := p.parseDocElement()
if err != nil {
return nil, nil, err
}
wrapper.nodes = append(wrapper.nodes, node)
}
return nil, nil, p.Error(fmt.Sprintf("Unexpected EOF, expected tag %s.", strings.Join(names, " or ")),
p.last_token)
}