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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.
 ****************************************************************/

package org.apache.cayenne.exp.parser;

import java.io.PrintWriter;

import org.apache.cayenne.exp.Expression;
import org.apache.cayenne.exp.ExpressionException;
import org.apache.cayenne.exp.ExpressionParameter;

/**
 * A named expression parameter.
 * 
 * @since 1.1
 * @author Andrus Adamchik
 */
public class ASTNamedParameter extends ASTScalar {
    ASTNamedParameter(int id) {
        super(id);
    }

    public ASTNamedParameter() {
        super(ExpressionParserTreeConstants.JJTNAMEDPARAMETER);
    }

    public ASTNamedParameter(Object value) {
        super(ExpressionParserTreeConstants.JJTNAMEDPARAMETER);
        setValue(value);
    }

    @Override
    protected Object evaluateNode(Object o) throws Exception {
        throw new ExpressionException(
            "Uninitialized parameter: " + value + ", call 'expWithParameters' first.");
    }

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

    @Override
    public void setValue(Object value) {
        if (value == null) {
            throw new ExpressionException("Null Parameter value");
        }

        String name = value.toString().trim();
        if (name.length() == 0) {
            throw new ExpressionException("Empty Parameter value");
        }

        super.setValue(new ExpressionParameter(name));
    }
    
    /**
     * @since 3.0
     */
    @Override
    public void encodeAsEJBQL(PrintWriter pw, String rootId) {
        if(value != null) {
            String valueString = value.toString();
            if(valueString.length() > 1 && valueString.charAt(0) == '$') {
                pw.print(':');
                pw.print(valueString.substring(1));
                return;
            }
        }
        
        super.encodeAsEJBQL(pw, rootId);
    }
}
