linux下的bison报错，求高手指教！急

2013-05-30 02:59:48 657 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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想用flex+bison写个简单的编译器，生成三地址中间代码。结果bison的编译就一堆警告。。。大概是说定义的文法没有用之类的。

这个是flex文件



%option noyywrap nodefault yylineno



%{

#include "compiler.h"

#include "parsing.tab.h"

%}



%%

"+" |

"-" |

"*" |

"/" |

"=" |

";" |

"(" |

")" |	

"{" |

"}"	{ return yytext[0];}



">"     { yylval.cmp = 1; return CMP; }

"<"     { yylval.cmp = 2; return CMP; }

"!="    { yylval.cmp = 3; return CMP; }

"=="    { yylval.cmp = 4; return CMP; }

">="    { yylval.cmp = 5; return CMP; }

"<="    { yylval.cmp = 6; return CMP; }



"if"    { return IF; }

"else"  { return ELSE; }

"while" { return WHILE; }

"do"    { return DO; }

"break" { return BREAK;}



"&&"	{ return AND;}

"||"	{ return OR;}



"int"	{ yylval.type=1; return TYPE;}

"float"	{ yylval.type=2; return TYPE;}

"bool"	{ yylval.type=3; return TYPE;}



[0-9]+		{ yylval.i=atoi(yytext); return INTEGER;}

[0-9]+"."[0-9]*	{ yylval.d=atof(yytext); return FLOAT;}

"true" |

"false" 	{ yylval.b=strdup(yytext); return BOOLEAN;}



[a-zA-Z][a-zA-Z0-9]*  { yylval.s = lookup(yytext); return ID; }



"//".*

[ \t\n]



.	{ yyerror("error input %c\n",*yytext);}

%%

这个是bison文件，所有的警告都在这里





%{

#include <stdio.h>

#include <stdlib.h>

#include "compiler.h"

%}



%union{

	struct ast *a;



	double d;  

	int i;

	char * b;



	struct symbol *s;



	int cmp;

	int type;

}





%token <i> INTEGER 

%token <d> FLOAT 

%token <b> BOOLEAN

%token <s> ID

%token EOL



%token IF ELSE WHILE DO BREAK

%token AND OR



%token <type> TYPE



%nonassoc <cmp> CMP

%right '='

%left '+' '-'

%left '*' '/'



%type <a> block 

%type <a> decls decl type

%type <a> stmts stmt loc bool 

%type <a> join equality expr term unary factor



%start calclist



%%



block: '{' decls stmts '}'	{ $$=$3;}

;



decls: decls decl	

;

decl: type ID ';'	

;

type: type '[' INTEGER ']'

	| TYPE 		{ $$=newast('X',S1,NULL);}

;



stmts: stmts stmt	{ $$=newast('C',$1,$2);}

;

stmt: loc '=' bool ';'				{ $$=newast('=',$1,$3);}

	| IF '(' bool ')' stmt 			{ $$=newflow('I',$3,$5,NULL);}

	| IF '(' bool ')' stmt ELSE stmt	{ $$=newflow('I',$3,$5,$7);}	

	| WHILE '(' bool ')' stmt		{ $$=newflow('W',$3,$5,NULL);}

	| DO stmt WHILE '(' bool ')' ';'	{ $$=newflow('D',$5,$2,NULL);}

	| BREAK ';'				{ $$=newast('B',NULL,NULL);}

	| block 

;



loc: loc '[' bool ']'		{ $$=newast('[',$1,$3);}

	| ID			{ $$=newref($1);}

;

bool: bool OR join		{ $$=newast('|',$1,$3);}

	| join

;

join: join AND equality		{ $$=newast('&',$1,$3);}

	| equality

;

equality: equality CMP expr	{ $$=newcmp($2,$1,$3);}

	| expr

;

expr: expr '+' term		{ $$=newast('+',$1,$3);}

	| expr '-' term		{ $$=newast('-',$1,$3);}

	| term

;

term: term '*' unary		{ $$=newast('*',$1,$3);}

	| term '/' unary	{ $$=newast('/',$1,$3);}

	| unary

;

unary: '!' unary		{ $$=newast('!',$2,NULL);}

	| '-' unary		{ $$=newast('M',$2,NULL);}

	| factor

;

factor: '(' bool ')' 	{ $$=$2;}

	| loc

	| INTEGER	{ $$=newint($1);}

	| FLOAT		{ $$=newflo($1);}

	| BOOLEAN	{ $$=newbol($1);}

;



calclist:

	| calclist block EOL	{ $2;printf("end\n");}

;

%%

警告大概如下：
parsing.y: 警告: 14 nonterminals useless in grammar
parsing.y: 警告: 36 rules useless in grammar
parsing.y:38.11-15: 警告: nonterminal useless in grammar: block
...(省略)
parsing.y:47.8-41: 警告: rule useless in grammar: block: '{' decls stmts '}'
...(省略)

求高手分析上面定义的文法是否不可以用在bison中，还是我哪里写错了。。。

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