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最简单的flex & bison例子

发布时间：2020-12-15 04:00:20 所属栏目：百科 来源：网络整理
导读：y.tab.h ? /* A Bison parser,made by GNU Bison 2.3.? */ ? ? /* Skeleton interface for Bison's Yacc-like parsers in C ? ? ??? Copyright (C) 1984,1989,1990,2000,2001,2002,2003,2004,2005,2006 ??? Free Software Foundation,Inc. ? ? ??? This prog

y.tab.h

?
/* A Bison parser,made by GNU Bison 2.3.? */
??
/* Skeleton interface for Bison's Yacc-like parsers in C
??
??? Copyright (C) 1984,1989,1990,2000,2001,2002,2003,2004,2005,2006
??? Free Software Foundation,Inc.
??
??? This program is free software; you can redistribute it and/or modify
??? it under the terms of the GNU General Public License as published by
??? the Free Software Foundation; either version 2,or (at your option)
??? any later version.
??
??? This program is distributed in the hope that it will be useful,
??? but WITHOUT ANY WARRANTY; without even the implied warranty of
??? MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.? See the
??? GNU General Public License for more details.
??
??? You should have received a copy of the GNU General Public License
??? along with this program; if not,write to the Free Software
??? Foundation,Inc.,51 Franklin Street,Fifth Floor,
??? Boston,MA 02110-1301,USA.? */
??
/* As a special exception,you may create a larger work that contains
??? part or all of the Bison parser skeleton and distribute that work
??? under terms of your choice,so long as that work isn't itself a
??? parser generator using the skeleton or a modified version thereof
??? as a parser skeleton.? Alternatively,if you modify or redistribute
??? the parser skeleton itself,you may (at your option) remove this
??? special exception,which will cause the skeleton and the resulting
??? Bison output files to be licensed under the GNU General Public
??? License without this special exception.
??
??? This special exception was added by the Free Software Foundation in
??? version 2.2 of Bison.? */
??
/* Tokens.? */
#ifndef YYTOKENTYPE
# define YYTOKENTYPE
??? /* Put the tokens into the symbol table,so that GDB and other debuggers
?????? know about them.? */
??? enum yytokentype {
????? DIGIT = 258,
????? LOWERCASELETTER = 259,
????? UPPERCASELETTER = 260,
????? OTHER = 261,
????? STOP = 262
??? };
#endif
/* Tokens.? */
#define DIGIT 258
#define LOWERCASELETTER 259
#define UPPERCASELETTER 260
#define OTHER 261
#define STOP 262
??
??
??
??
#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
typedef int YYSTYPE;
# define yystype YYSTYPE /* obsolescent; will be withdrawn */
# define YYSTYPE_IS_DECLARED 1
# define YYSTYPE_IS_TRIVIAL 1
#endif
??
extern YYSTYPE yylval;

token.l

?
/*
? * Copyright (c) 2009-2010,Oracle and/or its affiliates. All rights reserved.
? *
? * Redistribution and use in source and binary forms,with or without
? * modification,are permitted provided that the following conditions are met:
? *
? * * Redistributions of source code must retain the above copyright notice,
? *?? this list of conditions and the following disclaimer.
? *
? * * Redistributions in binary form must reproduce the above copyright notice,
? *?? this list of conditions and the following disclaimer in the documentation
? *?? and/or other materials provided with the distribution.
? *
? * * Neither the name of Oracle nor the names of its contributors
? *?? may be used to endorse or promote products derived from this software without
? *?? specific prior written permission.
? *
? * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
? * AND ANY EXPRESS OR IMPLIED WARRANTIES,INCLUDING,BUT NOT LIMITED TO,THE
? * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
? * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
? * LIABLE FOR ANY DIRECT,INDIRECT,INCIDENTAL,SPECIAL,EXEMPLARY,OR
? * CONSEQUENTIAL DAMAGES (INCLUDING,PROCUREMENT OF
? * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,DATA,OR PROFITS; OR BUSINESS
? * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,WHETHER IN
? * CONTRACT,STRICT LIABILITY,OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
? * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,EVEN IF ADVISED OF
? * THE POSSIBILITY OF SUCH DAMAGE.
? */
??
%{
#include "y.tab.h"
%}
%%
"q"?? return STOP;
"Q"?? return STOP;
[0-9] return DIGIT;
[a-z] return LOWERCASELETTER;
[A-Z] return UPPERCASELETTER;
.???? return OTHER;
%%

token.y

?

?
/*
? * Copyright (c) 2009-2010,EVEN IF ADVISED OF
? * THE POSSIBILITY OF SUCH DAMAGE.
? */
??
%{
#include <stdio.h>
%}
??
%token DIGIT LOWERCASELETTER UPPERCASELETTER OTHER STOP
??
%%
start :
???? | start something
???? ;
??
something : DIGIT { printf ( "DIGITn" );}
???? | LOWERCASELETTER { printf ( "LOWERCASELETTERn" );}
???? | UPPERCASELETTER { printf ( "UPPERCASELETTERn" );}
???? | OTHER { printf ( "OTHERn" );}
???? | STOP { exit (0);}
???? ;
%%
??
main()
{
???? // Intro
???? printf ( "Type something followed by Return. Type 'q' or 'Q' to end.n" );
???? printf ( "n" );
???? // Start the parser
???? return (yyparse());
}
??
yyerror(s)
char *s;
{
???? printf ( "yacc error: %sn" ,s);
}
??
yywrap()
{
???? return (0);
}

运行命令：flex token.l

会得到文件：lex.yy.c

运行命令：bison token.y

会得到文件：?token.tab.c

运行命令：gcc *

会得到文件 a.out

完成

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