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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
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package org.apache.cayenne.exp.parser;

import org.apache.cayenne.exp.Expression;

/**
 * "Less Then" expression.
 * 
 * @since 1.1
 */
public class ASTLess extends ConditionNode {

	private static final long serialVersionUID = -3846841914847489596L;

	/**
	 * Constructor used by expression parser. Do not invoke directly.
	 */
	ASTLess(int id) {
		super(id);
	}

	public ASTLess() {
		super(ExpressionParserTreeConstants.JJTLESS);
	}

	public ASTLess(SimpleNode path, Object value) {
		super(ExpressionParserTreeConstants.JJTLESS);
		jjtAddChild(path, 0);
		jjtAddChild(new ASTScalar(value), 1);
		connectChildren();
	}

	@Override
	protected int getRequiredChildrenCount() {
		return 2;
	}

	@Override
	protected Boolean evaluateSubNode(Object o, Object[] evaluatedChildren) throws Exception {
		Object o2 = evaluatedChildren[1];
		Integer c = Evaluator.evaluator(o).compare(o, o2);
		if(c == null) {
			return null;
		}
		return c < 0 ? Boolean.TRUE : Boolean.FALSE;
	}

	/**
	 * Creates a copy of this expression node, without copying children.
	 */
	@Override
	public Expression shallowCopy() {
		return new ASTLess(id);
	}

	@Override
	protected String getExpressionOperator(int index) {
		return "<";
	}

	@Override
	public int getType() {
		return Expression.LESS_THAN;
	}
}