/* http://www.linux-france.org/article/devl/lexyacc/minimanlexyacc-4.html */
%{

  /*#include "global.h"*/

#define YYSTYPE char *

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int yylex (void);
int yyerror (char *);

 char strbuff[1024];

 char *strExp = NULL;

%}

%token  NUM
%token  PLUS MINUS TIMES  DIV
%token  LPAR RPAR
%token  NL

%left PLUS MINUS
%left TIMES DIV
%left NEG

%start line
%%

line: exp    { strExp = $1; $$=$1; }
  ;

exp:
NUM                    { $$ = $1; }
| exp PLUS exp         { sprintf(strbuff,"(add %s %s)",$1,$3);
                         $$ = strdup(strbuff); }
| exp MINUS exp        { sprintf(strbuff,"(sub %s %s)",$1,$3);
                         $$ = strdup(strbuff); }
| exp TIMES exp        { sprintf(strbuff,"(mul %s %s)",$1,$3);
                         $$ = strdup(strbuff); }
| exp DIV exp          { sprintf(strbuff,"(div %s %s)",$1,$3);
                         $$ = strdup(strbuff); }
| MINUS exp %prec NEG  { sprintf(strbuff,"-%s",$2);
                         $$ = strdup(strbuff); }
| LPAR exp RPAR        { $$ = $2; }
  ;

%%

int yyerror(char *s) {
  printf("error: %s\n",s);
  return 1;
}

int main(int argc, char **argv) {
  yyparse();
  printf("Resultat: %s\n", strExp);
  return 0;
}