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346 lines
7.5 KiB
Go
346 lines
7.5 KiB
Go
// Package xml is an XML1.0 lexer following the specifications at http://www.w3.org/TR/xml/.
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package xml // import "github.com/tdewolff/parse/xml"
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import (
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"io"
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"strconv"
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"github.com/tdewolff/parse"
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"github.com/tdewolff/parse/buffer"
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)
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// TokenType determines the type of token, eg. a number or a semicolon.
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type TokenType uint32
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// TokenType values.
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const (
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ErrorToken TokenType = iota // extra token when errors occur
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CommentToken
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DOCTYPEToken
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CDATAToken
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StartTagToken
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StartTagPIToken
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StartTagCloseToken
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StartTagCloseVoidToken
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StartTagClosePIToken
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EndTagToken
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AttributeToken
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TextToken
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)
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// String returns the string representation of a TokenType.
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func (tt TokenType) String() string {
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switch tt {
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case ErrorToken:
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return "Error"
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case CommentToken:
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return "Comment"
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case DOCTYPEToken:
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return "DOCTYPE"
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case CDATAToken:
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return "CDATA"
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case StartTagToken:
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return "StartTag"
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case StartTagPIToken:
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return "StartTagPI"
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case StartTagCloseToken:
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return "StartTagClose"
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case StartTagCloseVoidToken:
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return "StartTagCloseVoid"
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case StartTagClosePIToken:
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return "StartTagClosePI"
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case EndTagToken:
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return "EndTag"
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case AttributeToken:
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return "Attribute"
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case TextToken:
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return "Text"
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}
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return "Invalid(" + strconv.Itoa(int(tt)) + ")"
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}
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////////////////////////////////////////////////////////////////
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// Lexer is the state for the lexer.
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type Lexer struct {
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r *buffer.Lexer
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err error
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inTag bool
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text []byte
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attrVal []byte
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}
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// NewLexer returns a new Lexer for a given io.Reader.
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func NewLexer(r io.Reader) *Lexer {
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return &Lexer{
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r: buffer.NewLexer(r),
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}
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}
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// Err returns the error encountered during lexing, this is often io.EOF but also other errors can be returned.
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func (l *Lexer) Err() error {
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err := l.r.Err()
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if err != nil {
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return err
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}
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return l.err
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}
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// Restore restores the NULL byte at the end of the buffer.
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func (l *Lexer) Restore() {
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l.r.Restore()
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}
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// Next returns the next Token. It returns ErrorToken when an error was encountered. Using Err() one can retrieve the error message.
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func (l *Lexer) Next() (TokenType, []byte) {
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l.text = nil
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var c byte
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if l.inTag {
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l.attrVal = nil
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for { // before attribute name state
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if c = l.r.Peek(0); c == ' ' || c == '\t' || c == '\n' || c == '\r' {
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l.r.Move(1)
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continue
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}
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break
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}
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if c == 0 {
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l.err = parse.NewErrorLexer("unexpected null character", l.r)
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return ErrorToken, nil
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} else if c != '>' && (c != '/' && c != '?' || l.r.Peek(1) != '>') {
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return AttributeToken, l.shiftAttribute()
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}
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start := l.r.Pos()
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l.inTag = false
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if c == '/' {
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l.r.Move(2)
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l.text = l.r.Lexeme()[start:]
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return StartTagCloseVoidToken, l.r.Shift()
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} else if c == '?' {
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l.r.Move(2)
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l.text = l.r.Lexeme()[start:]
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return StartTagClosePIToken, l.r.Shift()
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} else {
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l.r.Move(1)
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l.text = l.r.Lexeme()[start:]
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return StartTagCloseToken, l.r.Shift()
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}
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}
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for {
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c = l.r.Peek(0)
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if c == '<' {
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if l.r.Pos() > 0 {
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return TextToken, l.r.Shift()
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}
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c = l.r.Peek(1)
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if c == '/' {
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l.r.Move(2)
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return EndTagToken, l.shiftEndTag()
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} else if c == '!' {
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l.r.Move(2)
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if l.at('-', '-') {
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l.r.Move(2)
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return CommentToken, l.shiftCommentText()
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} else if l.at('[', 'C', 'D', 'A', 'T', 'A', '[') {
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l.r.Move(7)
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return CDATAToken, l.shiftCDATAText()
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} else if l.at('D', 'O', 'C', 'T', 'Y', 'P', 'E') {
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l.r.Move(8)
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return DOCTYPEToken, l.shiftDOCTYPEText()
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}
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l.r.Move(-2)
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} else if c == '?' {
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l.r.Move(2)
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l.inTag = true
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return StartTagPIToken, l.shiftStartTag()
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}
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l.r.Move(1)
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l.inTag = true
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return StartTagToken, l.shiftStartTag()
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} else if c == 0 {
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if l.r.Pos() > 0 {
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return TextToken, l.r.Shift()
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}
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l.err = parse.NewErrorLexer("unexpected null character", l.r)
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return ErrorToken, nil
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}
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l.r.Move(1)
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}
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}
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// Text returns the textual representation of a token. This excludes delimiters and additional leading/trailing characters.
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func (l *Lexer) Text() []byte {
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return l.text
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}
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// AttrVal returns the attribute value when an AttributeToken was returned from Next.
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func (l *Lexer) AttrVal() []byte {
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return l.attrVal
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}
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////////////////////////////////////////////////////////////////
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// The following functions follow the specifications at http://www.w3.org/html/wg/drafts/html/master/syntax.html
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func (l *Lexer) shiftDOCTYPEText() []byte {
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inString := false
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inBrackets := false
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for {
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c := l.r.Peek(0)
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if c == '"' {
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inString = !inString
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} else if (c == '[' || c == ']') && !inString {
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inBrackets = (c == '[')
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} else if c == '>' && !inString && !inBrackets {
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l.text = l.r.Lexeme()[9:]
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l.r.Move(1)
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return l.r.Shift()
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} else if c == 0 {
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l.text = l.r.Lexeme()[9:]
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return l.r.Shift()
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}
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l.r.Move(1)
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}
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}
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func (l *Lexer) shiftCDATAText() []byte {
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for {
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c := l.r.Peek(0)
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if c == ']' && l.r.Peek(1) == ']' && l.r.Peek(2) == '>' {
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l.text = l.r.Lexeme()[9:]
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l.r.Move(3)
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return l.r.Shift()
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} else if c == 0 {
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l.text = l.r.Lexeme()[9:]
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return l.r.Shift()
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}
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l.r.Move(1)
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}
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}
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func (l *Lexer) shiftCommentText() []byte {
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for {
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c := l.r.Peek(0)
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if c == '-' && l.r.Peek(1) == '-' && l.r.Peek(2) == '>' {
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l.text = l.r.Lexeme()[4:]
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l.r.Move(3)
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return l.r.Shift()
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} else if c == 0 {
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return l.r.Shift()
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}
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l.r.Move(1)
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}
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}
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func (l *Lexer) shiftStartTag() []byte {
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nameStart := l.r.Pos()
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for {
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if c := l.r.Peek(0); c == ' ' || c == '>' || (c == '/' || c == '?') && l.r.Peek(1) == '>' || c == '\t' || c == '\n' || c == '\r' || c == 0 {
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break
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}
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l.r.Move(1)
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}
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l.text = l.r.Lexeme()[nameStart:]
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return l.r.Shift()
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}
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func (l *Lexer) shiftAttribute() []byte {
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nameStart := l.r.Pos()
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var c byte
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for { // attribute name state
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if c = l.r.Peek(0); c == ' ' || c == '=' || c == '>' || (c == '/' || c == '?') && l.r.Peek(1) == '>' || c == '\t' || c == '\n' || c == '\r' || c == 0 {
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break
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}
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l.r.Move(1)
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}
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nameEnd := l.r.Pos()
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for { // after attribute name state
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if c = l.r.Peek(0); c == ' ' || c == '\t' || c == '\n' || c == '\r' {
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l.r.Move(1)
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continue
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}
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break
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}
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if c == '=' {
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l.r.Move(1)
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for { // before attribute value state
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if c = l.r.Peek(0); c == ' ' || c == '\t' || c == '\n' || c == '\r' {
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l.r.Move(1)
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continue
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}
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break
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}
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attrPos := l.r.Pos()
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delim := c
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if delim == '"' || delim == '\'' { // attribute value single- and double-quoted state
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l.r.Move(1)
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for {
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c = l.r.Peek(0)
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if c == delim {
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l.r.Move(1)
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break
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} else if c == 0 {
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break
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}
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l.r.Move(1)
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if c == '\t' || c == '\n' || c == '\r' {
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l.r.Lexeme()[l.r.Pos()-1] = ' '
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}
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}
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} else { // attribute value unquoted state
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for {
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if c = l.r.Peek(0); c == ' ' || c == '>' || (c == '/' || c == '?') && l.r.Peek(1) == '>' || c == '\t' || c == '\n' || c == '\r' || c == 0 {
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break
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}
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l.r.Move(1)
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}
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}
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l.attrVal = l.r.Lexeme()[attrPos:]
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} else {
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l.r.Rewind(nameEnd)
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l.attrVal = nil
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}
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l.text = l.r.Lexeme()[nameStart:nameEnd]
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return l.r.Shift()
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}
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func (l *Lexer) shiftEndTag() []byte {
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for {
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c := l.r.Peek(0)
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if c == '>' {
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l.text = l.r.Lexeme()[2:]
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l.r.Move(1)
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break
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} else if c == 0 {
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l.text = l.r.Lexeme()[2:]
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break
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}
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l.r.Move(1)
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}
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end := len(l.text)
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for end > 0 {
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if c := l.text[end-1]; c == ' ' || c == '\t' || c == '\n' || c == '\r' {
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end--
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continue
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}
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break
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}
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l.text = l.text[:end]
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return l.r.Shift()
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}
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////////////////////////////////////////////////////////////////
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func (l *Lexer) at(b ...byte) bool {
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for i, c := range b {
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if l.r.Peek(i) != c {
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return false
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}
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}
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return true
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}
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