ObjFW  Diff

	/* Substitute variables and convert to RPN first */
	tokens = [OFMutableArray array];
	operators = [OFMutableArray array];
	for (OFString *token in [condition
	    componentsSeparatedByString: @" "
				options: OF_STRING_SKIP_EMPTY]) {
		unsigned precedence;
		of_unichar_t c;

		if ([token isEqual: @"("]) {
			[operators addObject: @"("];
			continue;
		}

		if ([token isEqual: @")"]) {

				[operators removeLastObject];
			}

			[operators addObject: token];
			continue;
		}

		c = [token characterAtIndex: 0];

		if ((c < '0' || c > '9') && c != '-')
			if ((token = [variables objectForKey: token]) == nil)
				@throw [OFInvalidFormatException exception];

		[tokens addObject:
		    [OFNumber numberWithDouble: token.doubleValue]];
	}