mirror of
https://github.com/go-gitea/gitea.git
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274 lines
4.4 KiB
Go
274 lines
4.4 KiB
Go
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package lexer
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import (
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"bytes"
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"fmt"
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"github.com/gobwas/glob/util/runes"
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"unicode/utf8"
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)
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const (
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char_any = '*'
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char_comma = ','
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char_single = '?'
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char_escape = '\\'
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char_range_open = '['
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char_range_close = ']'
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char_terms_open = '{'
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char_terms_close = '}'
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char_range_not = '!'
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char_range_between = '-'
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)
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var specials = []byte{
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char_any,
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char_single,
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char_escape,
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char_range_open,
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char_range_close,
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char_terms_open,
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char_terms_close,
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}
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func Special(c byte) bool {
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return bytes.IndexByte(specials, c) != -1
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}
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type tokens []Token
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func (i *tokens) shift() (ret Token) {
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ret = (*i)[0]
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copy(*i, (*i)[1:])
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*i = (*i)[:len(*i)-1]
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return
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}
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func (i *tokens) push(v Token) {
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*i = append(*i, v)
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}
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func (i *tokens) empty() bool {
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return len(*i) == 0
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}
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var eof rune = 0
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type lexer struct {
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data string
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pos int
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err error
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tokens tokens
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termsLevel int
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lastRune rune
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lastRuneSize int
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hasRune bool
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}
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func NewLexer(source string) *lexer {
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l := &lexer{
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data: source,
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tokens: tokens(make([]Token, 0, 4)),
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}
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return l
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}
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func (l *lexer) Next() Token {
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if l.err != nil {
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return Token{Error, l.err.Error()}
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}
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if !l.tokens.empty() {
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return l.tokens.shift()
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}
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l.fetchItem()
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return l.Next()
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}
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func (l *lexer) peek() (r rune, w int) {
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if l.pos == len(l.data) {
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return eof, 0
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}
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r, w = utf8.DecodeRuneInString(l.data[l.pos:])
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if r == utf8.RuneError {
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l.errorf("could not read rune")
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r = eof
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w = 0
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}
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return
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}
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func (l *lexer) read() rune {
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if l.hasRune {
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l.hasRune = false
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l.seek(l.lastRuneSize)
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return l.lastRune
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}
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r, s := l.peek()
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l.seek(s)
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l.lastRune = r
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l.lastRuneSize = s
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return r
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}
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func (l *lexer) seek(w int) {
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l.pos += w
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}
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func (l *lexer) unread() {
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if l.hasRune {
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l.errorf("could not unread rune")
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return
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}
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l.seek(-l.lastRuneSize)
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l.hasRune = true
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}
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func (l *lexer) errorf(f string, v ...interface{}) {
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l.err = fmt.Errorf(f, v...)
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}
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func (l *lexer) inTerms() bool {
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return l.termsLevel > 0
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}
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func (l *lexer) termsEnter() {
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l.termsLevel++
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}
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func (l *lexer) termsLeave() {
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l.termsLevel--
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}
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var inTextBreakers = []rune{char_single, char_any, char_range_open, char_terms_open}
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var inTermsBreakers = append(inTextBreakers, char_terms_close, char_comma)
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func (l *lexer) fetchItem() {
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r := l.read()
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switch {
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case r == eof:
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l.tokens.push(Token{EOF, ""})
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case r == char_terms_open:
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l.termsEnter()
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l.tokens.push(Token{TermsOpen, string(r)})
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case r == char_comma && l.inTerms():
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l.tokens.push(Token{Separator, string(r)})
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case r == char_terms_close && l.inTerms():
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l.tokens.push(Token{TermsClose, string(r)})
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l.termsLeave()
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case r == char_range_open:
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l.tokens.push(Token{RangeOpen, string(r)})
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l.fetchRange()
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case r == char_single:
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l.tokens.push(Token{Single, string(r)})
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case r == char_any:
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if l.read() == char_any {
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l.tokens.push(Token{Super, string(r) + string(r)})
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} else {
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l.unread()
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l.tokens.push(Token{Any, string(r)})
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}
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default:
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l.unread()
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var breakers []rune
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if l.inTerms() {
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breakers = inTermsBreakers
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} else {
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breakers = inTextBreakers
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}
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l.fetchText(breakers)
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}
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}
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func (l *lexer) fetchRange() {
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var wantHi bool
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var wantClose bool
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var seenNot bool
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for {
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r := l.read()
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if r == eof {
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l.errorf("unexpected end of input")
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return
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}
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if wantClose {
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if r != char_range_close {
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l.errorf("expected close range character")
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} else {
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l.tokens.push(Token{RangeClose, string(r)})
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}
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return
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}
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if wantHi {
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l.tokens.push(Token{RangeHi, string(r)})
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wantClose = true
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continue
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}
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if !seenNot && r == char_range_not {
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l.tokens.push(Token{Not, string(r)})
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seenNot = true
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continue
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}
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if n, w := l.peek(); n == char_range_between {
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l.seek(w)
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l.tokens.push(Token{RangeLo, string(r)})
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l.tokens.push(Token{RangeBetween, string(n)})
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wantHi = true
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continue
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}
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l.unread() // unread first peek and fetch as text
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l.fetchText([]rune{char_range_close})
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wantClose = true
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}
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}
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func (l *lexer) fetchText(breakers []rune) {
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var data []rune
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var escaped bool
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reading:
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for {
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r := l.read()
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if r == eof {
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break
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}
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if !escaped {
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if r == char_escape {
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escaped = true
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continue
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}
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if runes.IndexRune(breakers, r) != -1 {
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l.unread()
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break reading
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}
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}
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escaped = false
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data = append(data, r)
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}
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if len(data) > 0 {
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l.tokens.push(Token{Text, string(data)})
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}
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}
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