138 lines
3.2 KiB
Go
138 lines
3.2 KiB
Go
package chroma
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import (
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"bytes"
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)
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type delegatingLexer struct {
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root Lexer
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language Lexer
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}
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// DelegatingLexer combines two lexers to handle the common case of a language embedded inside another, such as PHP
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// inside HTML or PHP inside plain text.
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//
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// It takes two lexer as arguments: a root lexer and a language lexer. First everything is scanned using the language
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// lexer, which must return "Other" for unrecognised tokens. Then all "Other" tokens are lexed using the root lexer.
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// Finally, these two sets of tokens are merged.
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//
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// The lexers from the template lexer package use this base lexer.
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func DelegatingLexer(root Lexer, language Lexer) Lexer {
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return &delegatingLexer{
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root: root,
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language: language,
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}
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}
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func (d *delegatingLexer) Config() *Config {
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return d.language.Config()
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}
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// An insertion is the character range where language tokens should be inserted.
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type insertion struct {
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start, end int
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tokens []Token
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}
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func (d *delegatingLexer) Tokenise(options *TokeniseOptions, text string) (Iterator, error) {
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tokens, err := Tokenise(Coalesce(d.language), options, text)
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if err != nil {
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return nil, err
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}
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// Compute insertions and gather "Other" tokens.
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others := &bytes.Buffer{}
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insertions := []*insertion{}
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var insert *insertion
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offset := 0
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var last Token
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for _, t := range tokens {
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if t.Type == Other {
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if last != EOF && insert != nil && last.Type != Other {
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insert.end = offset
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}
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others.WriteString(t.Value)
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} else {
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if last == EOF || last.Type == Other {
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insert = &insertion{start: offset}
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insertions = append(insertions, insert)
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}
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insert.tokens = append(insert.tokens, t)
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}
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last = t
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offset += len(t.Value)
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}
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if len(insertions) == 0 {
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return d.root.Tokenise(options, text)
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}
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// Lex the other tokens.
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rootTokens, err := Tokenise(Coalesce(d.root), options, others.String())
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if err != nil {
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return nil, err
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}
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// Interleave the two sets of tokens.
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var out []Token
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offset = 0 // Offset into text.
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tokenIndex := 0
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nextToken := func() Token {
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if tokenIndex >= len(rootTokens) {
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return EOF
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}
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t := rootTokens[tokenIndex]
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tokenIndex++
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return t
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}
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insertionIndex := 0
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nextInsertion := func() *insertion {
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if insertionIndex >= len(insertions) {
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return nil
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}
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i := insertions[insertionIndex]
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insertionIndex++
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return i
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}
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t := nextToken()
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i := nextInsertion()
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for t != EOF || i != nil {
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// fmt.Printf("%d->%d:%q %d->%d:%q\n", offset, offset+len(t.Value), t.Value, i.start, i.end, Stringify(i.tokens...))
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if t == EOF || (i != nil && i.start < offset+len(t.Value)) {
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var l Token
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l, t = splitToken(t, i.start-offset)
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if l != EOF {
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out = append(out, l)
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offset += len(l.Value)
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}
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out = append(out, i.tokens...)
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offset += i.end - i.start
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if t == EOF {
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t = nextToken()
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}
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i = nextInsertion()
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} else {
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out = append(out, t)
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offset += len(t.Value)
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t = nextToken()
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}
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}
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return Literator(out...), nil
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}
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func splitToken(t Token, offset int) (l Token, r Token) {
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if t == EOF {
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return EOF, EOF
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}
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if offset == 0 {
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return EOF, t
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}
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if offset == len(t.Value) {
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return t, EOF
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}
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l = t.Clone()
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r = t.Clone()
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l.Value = l.Value[:offset]
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r.Value = r.Value[offset:]
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return
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}
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