001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry.components;
016
017import org.apache.tapestry.AbstractComponent;
018import org.apache.tapestry.IMarkupWriter;
019import org.apache.tapestry.IRender;
020import org.apache.tapestry.IRequestCycle;
021
022/**
023 *  A component which delegates it's behavior to another object.
024 *
025 *  [<a href="../../../../../ComponentReference/Delegator.html">Component Reference</a>]
026 *
027 *  @author Howard Lewis Ship
028 * 
029 **/
030
031public abstract class Delegator extends AbstractComponent
032{
033    /**
034     *  Gets its delegate and invokes {@link IRender#render(IMarkupWriter, IRequestCycle)}
035     *  on it.
036     *
037     **/
038
039    protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
040    {
041        IRender delegate = getDelegate();
042        
043        if (delegate != null)
044                delegate.render(writer, cycle);
045    }
046    
047    public abstract IRender getDelegate();
048}