arithmetic.y

%{
void yyerror (char *s);
int yylex();
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
%}

%union {int num; char id;}
%start S
%token <num> number
%token <id> identifier

%%

S	:	E	{printf("\n"); exit(EXIT_SUCCESS);}
	;

E	:	T	
	|	E '+' {printf(" plus ");} T
	|	E '-' {printf(" sub ");} T
	;
	
T	:	F
	|	T '*' {printf(" mul ");} F	
	|	T '/' {printf(" div ");} F
	|	T '%' {printf(" mod ");} F
	;

F	:	P '^' {printf(" pow ");} F
	|	P
	;

P	:	identifier	{printf("{id: %c}",$1);}
	|	number		{printf("{num: %d}",$1);}
	|	'(' {printf("(");}  E ')' {printf(")");}	
	;

%%

int main(void){
	return yyparse();
} 

void yyerror(char *s){
	fprintf(stderr, "%s\n", s);
	printf("\nProgram terminated with errors.\n");
	exit(EXIT_FAILURE);
}