/*
 * Simple Calculator
 * Author: Jia Yu,
 * School: Univ of California Riverside
 * Date: April 9, 2003
 */

/* Infix notation calculator--calc */

/* Everything up to "%}" is copied verbatim to the top of yac.c. (output file)*/
%{
#include <math.h>
#include <iostream>
#include <stdio.h>
#include <string>
#include "tok.h"
using namespace std;
void yyerror (const char *s);
int yylex(void);
%}

// Here we define the types and names of the components of YYSTYPE, which 
// is the type of the semantic portion of parse-stack entries.  
// union members for lexical values of tokens

%union{
  int int_val;  
}

// Specify in order of increasing precedence the names of the tokens, 
// their associativity, and which components of the union YYSTYPE 
// their lexical values will occupy.

%token <int_val> NUM
%type <int_val> exp
%left  MINUS PLUS
%left  MULT DIV
%left  NEG     /* negation--unary minus */
// Specify the start symbol of the grammar.
%start input

%%
// Specify the grammar rules and their associated semantic actions.

input:   
        | exp               { printf("= %d \n ", $1); }        
        | error             { printf("error \n");}
        ;

exp:      NUM                { $$=$1; }
        | exp PLUS  exp      { $$=$1+$3; }
        | exp MINUS exp      { $$=$1-$3;    }
        | exp MULT exp       { $$ = $1 * $3;    }
        | exp DIV exp        { $$ = $1 / $3;    }
        | '(' exp ')'        { $$ = $2;         }
        ;
%%
/* Called by yyparse on error */
void yyerror (string s)  
{
  extern int yylineno;
  extern char* yytext;
  cerr<<"ERROR: "<<s<<" at symbol " <<yytext;
  cerr<<" on line " <<(yylineno-1) <<endl;
  exit(1);
}

void yyerror (const char * s)
{
  yyerror(string(s));
}