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 *  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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 *  Unless required by applicable law or agreed to in writing,
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package org.apache.cayenne.exp.parser;

import java.io.PrintWriter;

import org.apache.cayenne.exp.Expression;

/**
 * Boolean true expression element
 * 
 * Notice that there is one ASTTrue and one ASTFalse instead of a ASTBoolean with a
 * Boolean value. The main reason for doing this is that a common ASTBoolean will have
 * operand count of 1 and that will default to a prepared statmenet like " where ? and
 * (...)", but we only need " where true and (...)".
 * 
 * @see ASTFalse
 * @author halset
 * @since 3.0
 */
public class ASTTrue extends ConditionNode {

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

    public ASTTrue() {
        super(ExpressionParserTreeConstants.JJTTRUE);
    }

    protected Object evaluateNode(Object o) throws Exception {
        return Boolean.TRUE;
    }

    protected String getExpressionOperator(int index) {
        throw new UnsupportedOperationException("No operator for '"
                + ExpressionParserTreeConstants.jjtNodeName[id]
                + "'");
    }

    public Expression shallowCopy() {
        return new ASTTrue(id);
    }

    public int getType() {
        return Expression.TRUE;
    }
    
    public void encodeAsString(PrintWriter pw) {
        pw.print("true");
    }

}
