80 lines
1.7 KiB
Plaintext
80 lines
1.7 KiB
Plaintext
%{
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// Copyright (c) 2015 The golex Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This is an example program using golex run time library.
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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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"unicode"
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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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}
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func rune2Class(r rune) int {
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if r >= 0 && r < 0x80 { // Keep ASCII as it is.
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return int(r)
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}
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if unicode.IsLetter(r) {
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return classUnicodeLeter
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}
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if unicode.IsDigit(r) {
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return classUnicodeDigit
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}
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return classOther
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}
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func newLexer(src io.Reader, dst io.Writer, 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) { panic(err) }
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return &lexer{lx}
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}
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func (l *lexer) Lex(lval *yySymType) int {
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c := l.Enter()
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%}
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%yyc c
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%yyn c = l.Next()
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%yym l.Mark()
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digit [0-9]|{unicodeDigit}
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identifier {letter}({letter}|{digit})*
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int {digit}+
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letter [_a-zA-Z]|{unicodeLetter}
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unicodeDigit \x81
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unicodeLetter \x80
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op [-+*/]
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%%
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c = l.Rule0()
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[ \t\r\n]+
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[/][/][^\n]+ lval.token = string(l.TokenBytes(nil)); return COMMENT
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func lval.token = string(l.TokenBytes(nil)); return FUNC
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{identifier} lval.token = string(l.TokenBytes(nil)); return IDENT
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{int} lval.token = string(l.TokenBytes(nil)); return INT
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{op} lval.token = string(l.TokenBytes(nil)); return OP
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%%
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if c, ok := l.Abort(); ok { return int(c) }
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goto yyAction
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}
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