/* Thanks to: https://github.com/meyerd/flex-bison-example */

%{

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

extern int yylex();
extern int yyparse();
extern FILE* yyin;

void yyerror(const char* s);

int r;

show_register() {
	printf("R: %i\n",r);
}

load_register(int value) {
	r = value;
}

clear_register(void) {
	r = 0;
}

store_register(int address) {
	printf("store %i at %x\n",r,address);
} 

%}
%union {
	int ival;
	float fval;
}

%token<ival> T_INT
%token T_LOAD
%token T_STORE
%token T_CLEAR
%token T_NEWLINE T_QUIT

%type<ival> value

%start assembler

%%

assembler:
	statement_list 
;

statement_list:
	| statement T_NEWLINE { show_register(); } statement_list
;

statement: 
	command
	| T_LOAD value	{ load_register($2); }
	| T_STORE value	{ store_register($2); }
	| T_CLEAR 	{ clear_register(); }
;

command: T_QUIT T_NEWLINE { printf("bye!\n"); exit(0); }
;

value: T_INT			{ $$ = $1; }
;

%%

int main() {
	yyin = stdin;

	do {
		yyparse();
	} while(!feof(yyin));

	return 0;
}

void yyerror(const char* s) {
	fprintf(stderr, "Parse error: %s\n", s);
	exit(1);
}