bison file

%{

#include <stdio.h>
#include <stdlib.h>
#include "polyn.h"
#include "symbtab.h"

extern int yylex();
extern int yyparse();
void yyerror(const char* s);
%}


%token T_INT
%token T_IDENT T_POLYN
%token T_PLUS T_MINUS T_MULTIPLY T_DIVIDE T_LROUND T_RROUND T_EQUAL
%token T_NEWLINE T_QUIT
%left T_PLUS T_MINUS
%left T_MULTIPLY T_DIVIDE

%start input

%union {
	int intval;
	char *chstr;
	struct Polyn *p;
}

%type <intval> expression T_INT
%type <chstr> assign T_IDENT
%type <p> poln T_POLYN

%%

input:
    %empty
    | input line
;

line:
    T_NEWLINE
    | expression T_NEWLINE { printf("\tResult: %i\n", $1); }
    | assign T_NEWLINE ;
    | T_QUIT T_NEWLINE { exit(0); }
;

assign:
    T_IDENT T_EQUAL poln {store($1, $3); }

;

poln:
    T_POLYN ;
    | poln T_PLUS poln ;
    | poln T_MINUS poln ;
;

expression:
    T_INT				{ $$ = $1; }
	  | expression T_PLUS expression	{ $$ = $1 + $3; }
	  | expression T_MINUS expression	{ $$ = $1 - $3; }
	  | expression T_MULTIPLY expression	{ $$ = $1 * $3; }
    | expression T_DIVIDE expression	  { $$ = $1 / $3; }
	  | T_LROUND expression T_RROUND		{ $$ = $2; }
;

%%

int main() {
	while (yyparse());
	return 0;
}

void yyerror(const char* s) {
	fprintf(stderr, "Parse error: %s\n", s);
}