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    
015    package org.apache.tapestry.listener;
016    
017    import java.util.Map;
018    
019    import ognl.ObjectPropertyAccessor;
020    import ognl.OgnlException;
021    
022    /**
023     * Exposes {@link org.apache.tapestry.IActionListener} listeners provided by the
024     * {@link org.apache.tapestry.listener.ListenerMap} as read-only properties of the map.
025     * 
026     * @author Howard Lewis Ship
027     * @since 2.2
028     */
029    
030    public class ListenerMapPropertyAccessor extends ObjectPropertyAccessor
031    {
032        /**
033         * Checks to see if the ListenerMapImpl provides the named listener, returning the listener if
034         * it does. Otherwise, invokes the super implementation.
035         */
036    
037        public Object getProperty(Map context, Object target, Object name) throws OgnlException
038        {
039            ListenerMap map = (ListenerMap) target;
040            String listenerName = (String) name;
041    
042            if (map.canProvideListener(listenerName))
043                return map.getListener(listenerName);
044    
045            return super.getProperty(context, target, name);
046        }
047    
048        /**
049         * Returns true if the ListenerMap contains the named listener, otherwise invokes
050         * super-implementation.
051         */
052    
053        public boolean hasGetProperty(Map context, Object target, Object oname) throws OgnlException
054        {
055            ListenerMap map = (ListenerMap) target;
056            String listenerName = (String) oname;
057    
058            if (map.canProvideListener(listenerName))
059                return true;
060    
061            return super.hasGetProperty(context, target, oname);
062        }
063    
064    }