/*
* $Id: AbstractAttributeEvaluator.java 833737 2009-11-07 19:17:09Z apetrelli $
*
* 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.tiles.evaluator;
import org.apache.tiles.Attribute;
import org.apache.tiles.Expression;
import org.apache.tiles.request.Request;
/**
* Abstract class to link a correct evaluation of an attribute, by evaluating
* {@link Attribute#getValue()} and then {@link Attribute#getExpressionObject()}.
*
* @version $Rev: 833737 $ $Date: 2009-11-07 20:17:09 +0100 (Sat, 07 Nov 2009) $
* @since 2.1.2
*/
public abstract class AbstractAttributeEvaluator implements AttributeEvaluator {
/** {@inheritDoc} */
public Object evaluate(Attribute attribute, Request request) {
if (attribute == null) {
throw new IllegalArgumentException("The attribute cannot be null");
}
Object retValue = attribute.getValue();
if (retValue == null) {
Expression expression = attribute.getExpressionObject();
if (expression != null) {
retValue = evaluate(attribute.getExpressionObject()
.getExpression(), request);
}
}
return retValue;
}
}