%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "parser.h"
extern int yylval;
%}
%start E
%token number
%%
S :E {printf("%s",$1);}
;
E :E PLUS T {$$ = $1 + $3;}
|T {$$ = $1;}
;
T :T STAR F {$$ = $1 * $3;}
|F {$$ = $1;}
;
F :LP E RP {$$ = $2;}
|number {$$ = $1;}
;
%%
yylex(){
char ch;
ch = getchar();
switch(ch){
case '+':
return PLUS;
break;
case '*':
return STAR;
break;
case '(':
return LP;
break;
case ')':
return RP;
break;
default:
if(ch >= '0' && ch <= '9'){
ch -= '0';
yylval = ch;;
return (number);
}
else
return -1;
}
}
void main(){
yyparse();
}
Afternoon, I was doing my assignment about how to use yacc and the thing is that I don't know how to properly include a header file on a .y file. From what I've seen to various pages which describes how to write a .y file, there is nothing I've done wrong about writing this .y file. So please, help me!
These are the error message I got
embedded@embedded-P15xEMx:~/Project/Compiler$ yacc parser.y
parser.y:19.10-11: error: symbol LP is used, but is not defined as a token and has no rules
F :LP E RP {$$ = $2;}
^^
parser.y:13.12-15: error: symbol PLUS is used, but is not defined as a token and has no rules
E :E PLUS T {$$ = $1 + $3;}
^^^^
parser.y:19.15-16: error: symbol RP is used, but is not defined as a token and has no rules
F :LP E RP {$$ = $2;}
^^
parser.y:16.12-15: error: symbol STAR is used, but is not defined as a token and has no rules
T :T STAR F {$$ = $1 * $3;}
^^^^
And this is the header file I included
#ifndef _PARSER_H_
#define _PARSER_H_
#include <stdio.h>
#define PLUS 1
#define STAR 2
#define LP 3
#define RP 4
#define number 5
#endif
The token symbols can't be declared by yourself, you have to use Yacc to do it, like
%token PLUS
etc.