final int _compileIndex_(final String string) {
		if ((string == null) || string.isEmpty()) return -1;
		final char symbol = string.charAt(0);
		if ((symbol < '0') || (symbol > '9')) return -1;
		try {
			return Integer.parseInt(string);
		} catch (final NumberFormatException e) {
			return -1;
		}
	}