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 *  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
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 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
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package org.apache.cayenne.exp.parser;

import org.apache.cayenne.exp.Expression;
import org.apache.cayenne.util.Util;

/**
 * "Not equal to" expression.
 * 
 * @author Andrus Adamchik
 */
public class ASTNotEqual extends ConditionNode {
    ASTNotEqual(int id) {
        super(id);
    }

    public ASTNotEqual() {
        super(ExpressionParserTreeConstants.JJTNOTEQUAL);
    }

    /**
     * Creates "Not Equal To" expression.
     */
    public ASTNotEqual(ASTPath path, Object value) {
        super(ExpressionParserTreeConstants.JJTNOTEQUAL);
        jjtAddChild(path, 0);
        jjtAddChild(new ASTScalar(value), 1);
        connectChildren();
    }

    @Override
    protected Object evaluateNode(Object o) throws Exception {
        int len = jjtGetNumChildren();
        if (len != 2) {
            return Boolean.FALSE;
        }

        Object o1 = evaluateChild(0, o);
        Object o2 = evaluateChild(1, o);
        return Util.nullSafeEquals(o1, o2) ? Boolean.FALSE : Boolean.TRUE;
    }

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

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

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