/**
 * test/demos/parser/parser.yy
 * Copyright (C) 2008 Markus Broeker
 */

%{
   #include <stdio.h>
   #include <ctype.h>

   int regs[26];
   int base;

   int yyerror();
   int yylex();
%}

%start list
%token DIGIT LETTER
%left MINUS PLUS MUL DIV
%left UMINUS
%%

list:
	/* empty */
	| list stat '\n'
	| list error '\n' { yyerrok; };

stat:
	expr { (void) printf( "RESULT: %d\n", $1 ); }
	| LETTER '=' expr { regs[$1] = $3; }
	;

expr:
	'(' expr ')'
	{
		$$ = $2;
	}
	| expr PLUS expr
	{
		$$ = $1 + $3;
	}
	| expr MINUS expr
	{
		$$ = $1 - $3;
	}
	| expr MUL expr
	{
		$$ = $1 * $3;
	}
	| expr DIV expr
	{
			$$ = $1 / $3;
	}
	| MINUS expr  %prec UMINUS
	{
		$$ = -$2;
	}
	| LETTER
	{
		$$ = regs[$1];
	}
	|  number
	;

number:
	DIGIT
	{
		$$ = $1; base = ($1==0) ? 8 : 10;
	}
	| number DIGIT
	{
		$$ = base * $1 + $2;
	}
	;
%%

int yyerror()
{
	printf("ERROR\n");
	return 0;
}

int yywrap()
{
	return 1;
}