public Criterion convertExpression(LogicExpression expression, LogicContext context) {

		Criterion criterion = null;

		Operator operator = expression.getOperator();
		Operand rightOperand = expression.getRightOperand();
		Operand leftOperand = ((LogicExpressionBinary) expression).getLeftOperand();
		if (operator == null)
			criterion = createRootExpressionCriterion(expression);
		else {
			if (Operator.AND.equals(operator)) {
				Criterion rightCriterion = convertExpression((LogicExpression) rightOperand, context);
				Criterion leftCriterion = convertExpression((LogicExpression) leftOperand, context);
				criterion = Restrictions.and(rightCriterion, leftCriterion);
			} else if (Operator.OR.equals(operator)) {
				Criterion rightCriterion = convertExpression((LogicExpression) rightOperand, context);
				Criterion leftCriterion = convertExpression((LogicExpression) leftOperand, context);
				criterion = Restrictions.or(rightCriterion, leftCriterion);
			} else {
				if (leftOperand instanceof LogicComponent) {
					// if the left operand is component, then the right operand is an operand
					LogicComponent component = (LogicComponent) leftOperand;
					Operator componentOperator = expression.getOperator();
					Operand componentOperand = expression.getRightOperand();
					// insert the object to aliases
					if (StringUtils.isNotBlank(component.getObject())) {
						getAliases().add(component.getObject());
					}
					criterion = handleComponentExpression(component.getComponentProperty(), componentOperator, componentOperand, context.getIndexDate());
				} else {
					criterion = handleComparisonExpression(expression.getRootToken(), operator, rightOperand, context.getIndexDate());
					LogicExpression leftExpression = (LogicExpression) leftOperand;
					Operator leftOperator = leftExpression.getOperator();
					while(Operator.NOT.equals(leftOperator)) {
						criterion = Restrictions.not(criterion);
						leftOperand = ((LogicExpressionBinary) leftExpression).getLeftOperand();
						leftExpression = (LogicExpression) leftOperand;
						leftOperator = leftExpression.getOperator();
					}
					Criterion leftCriterion = convertExpression((LogicExpression) leftOperand, context);
					if (leftCriterion != null)
						criterion = Restrictions.and(criterion, leftCriterion);
				}
			}
		}
		return criterion;
	}