public static TokenType getNegRelation(TokenType relation) {
		switch (relation) {
		case EQL:
			return TokenType.NEQ;
		case LSS:
			return TokenType.GEQ;
		case LEQ:
			return TokenType.GRE;
		case NEQ:
			return TokenType.EQL;
		case GEQ:
			return TokenType.LSS;
		case GRE:
			return TokenType.LEQ;
		default:
			throw new IllegalArgumentException("The relation value is not comparator:" + relation);
		}
	}