70 lines
1.2 KiB
Go
70 lines
1.2 KiB
Go
package main
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import (
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"bufio"
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"go/token"
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"io"
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"github.com/cznic/golex/lex"
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)
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// Allocate Character classes anywhere in [0x80, 0xFF].
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const (
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classUnicodeLeter = iota + 0x80
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classUnicodeDigit
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classOther
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)
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type lexer struct {
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*lex.Lexer
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stateStack []int
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}
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func newLexer(src io.Reader, fName string) *lexer {
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file := token.NewFileSet().AddFile(fName, -1, 1<<31-1)
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lx, err := lex.New(file, bufio.NewReader(src), lex.RuneClass(rune2Class))
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if err != nil {
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panic(err)
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}
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return &lexer{lx, []int{0}}
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}
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func (l *lexer) ungetN(n int) []byte {
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l.Unget(l.Lookahead())
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chars := l.Token()
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for i := 1; i <= n; i++ {
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char := chars[len(chars)-i]
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l.Unget(char)
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}
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buf := l.TokenBytes(nil)
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buf = buf[:len(buf)-n]
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return buf
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}
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func (l *lexer) pushState(state int) {
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l.stateStack = append(l.stateStack, state)
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}
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func (l *lexer) popState() {
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len := len(l.stateStack)
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if len <= 1 {
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return
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}
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l.stateStack = l.stateStack[:len-1]
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}
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func (l *lexer) begin(state int) {
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len := len(l.stateStack)
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l.stateStack = l.stateStack[:len-1]
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l.stateStack = append(l.stateStack, state)
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}
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func (l *lexer) getCurrentState() int {
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return l.stateStack[len(l.stateStack)-1]
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}
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