calc.phpy

/*
 * calculator
 */

%token NUMBER

%left '+' '-'
%left '*' '/'

%%

start:	lines;

lines: /* empty */
	| lines line
        ;

line	: expr { return $1; }
	| '\n' { return '(empty line ignored)'; }
	| error { return false; }
	;

expr	: expr '+' expr { $$ = $1 + $3; }
	| expr '-' expr { $$ = $1 - $3; }
	| expr '*' expr { $$ = $1 * $3; }
	| expr '/' expr { $$ = $1 / $3; }
	| '(' expr ')' { $$ = $2; }
	| NUMBER { $$ = $1; }
	;

%%

	protected static function yylex()
	{
		$lexbuf = self::$lexbuf;

		if (preg_match('/^(\d+)/', $lexbuf, $matches)) {
			self::$yylval = (int)$matches[1];
			self::$lexbuf = substr($lexbuf, strlen($matches[1]));
			return self::NUMBER;
		}
		$ret = ord($lexbuf);
		self::$lexbuf = substr($lexbuf, 1);
		return $ret;
	}

	protected static function yyerror($msg)
	{
		throw new Exception($msg);
	}
}

$lexbuf = rand(1000, 9999).'+'.rand(1000, 9999);

$resultKMyacc = KMyacc::yyparse($lexbuf);
$resultPHP    = eval('return '.$lexbuf. ';');
var_dump(
	'raw    : ' . $lexbuf,
	'KMyacc : ' . $resultKMyacc,
	'PHP    : ' . $resultPHP
);