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/* calculator. */
%{
#include <stdio.h>
#include <stdlib.h>
#include "lexer.h"
void yyerror(const char *msg);
// Here is an example how to create custom data structure
typedef struct custom_data {
char* name;
int counter;
} custom_data;
%}
%union{
double dval;
int ival;
struct custom_data* cval; // define the pointer type for custom data structure
}
%define parse.error verbose
%locations
%start input
%token MULT DIV PLUS MINUS EQUAL L_PAREN R_PAREN END
%token <dval> NUMBER
%type <dval> exp
%type <cval> input
%left PLUS MINUS
%left MULT DIV
%nonassoc UMINUS
%%
input: {
$$ = malloc(sizeof(custom_data)); $$->name = "input"; $$->counter = 0;
}
| input line {
$$ = $1; $1->counter++;
}
;
line: exp EQUAL END { printf("\t%f\n", $1); };
exp: NUMBER { $$ = $1; }
| exp PLUS exp { $$ = $1 + $3; }
| exp MINUS exp { $$ = $1 - $3; }
| exp MULT exp { $$ = $1 * $3; }
| exp DIV exp {
if ($3==0) yyerror("divide by zero"); else $$ = $1 / $3;
}
| MINUS exp %prec UMINUS { $$ = -$2; }
| L_PAREN exp R_PAREN { $$ = $2; }
;
%%
int main(int argc, char **argv)
{
if (argc > 1) {
yyin = fopen(argv[1], "r");
if (yyin == NULL){
printf("syntax: %s filename\n", argv[0]);
}
}
yyparse(); // Calls yylex() for tokens.
return 0;
}
void yyerror(const char *msg)
{
printf("** Line %d: %s\n", yylloc.first_line, msg);
}
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