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.OgnlContext;
021    import ognl.OgnlException;
022    import ognl.OgnlRuntime;
023    import ognl.PropertyAccessor;
024    import ognl.enhance.ExpressionCompiler;
025    import ognl.enhance.UnsupportedCompilationException;
026    
027    /**
028     * Exposes {@link org.apache.tapestry.IActionListener} listeners provided
029     * by the {@link org.apache.tapestry.listener.ListenerMap} as read-only
030     * properties of the map.
031     * 
032     * @author Howard Lewis Ship
033     * @since 2.2
034     */
035    
036    public class ListenerMapPropertyAccessor extends ObjectPropertyAccessor implements PropertyAccessor
037    {
038    
039        /**
040         * Checks to see if the ListenerMapImpl provides the named listener,
041         * returning the listener if it does. Otherwise, invokes the super
042         * implementation.
043         */
044    
045        public Object getProperty(Map context, Object target, Object name)
046            throws OgnlException
047        {
048            ListenerMap map = (ListenerMap) target;
049            String listenerName = (String) name;
050    
051            if (map.canProvideListener(listenerName))
052                return map.getListener(listenerName);
053    
054            return super.getProperty(context, target, name);
055        }
056    
057        /**
058         * Returns true if the ListenerMap contains the named listener, otherwise
059         * invokes super-implementation.
060         */
061    
062        public boolean hasGetProperty(Map context, Object target, Object oname)
063            throws OgnlException
064        {
065            ListenerMap map = (ListenerMap) target;
066            String listenerName = (String) oname;
067    
068            if (map.canProvideListener(listenerName)) return true;
069    
070            return super.hasGetProperty(context, target, oname);
071        }
072        
073        public Class getPropertyClass(OgnlContext context, Object target, Object name)
074        {
075            ListenerMap map = (ListenerMap) target;
076            String listenerName = (String) name;
077            
078            if (map.canProvideListener(listenerName))
079                return map.getListener(listenerName).getClass();
080            
081            return super.getPropertyClass(context, target, name);
082        }
083        
084        public String getSourceAccessor(OgnlContext context, Object target, Object name)
085        {
086            ListenerMap map = (ListenerMap) target;
087            String listenerName = ((String)name).replaceAll("\"", "");
088            
089            if (map.canProvideListener(listenerName)) {
090                
091                Class type = OgnlRuntime.getCompiler().getInterfaceClass(map.getListener(listenerName).getClass());
092                
093                ExpressionCompiler.addCastString(context, "((" + type.getName() + ")");
094                
095                context.setCurrentAccessor(ListenerMap.class);
096                context.setCurrentType(type);
097                
098                return ".getListener(" + name + "))";
099            }
100            
101            return super.getSourceAccessor(context, target, name);
102        }
103        
104        public String getSourceSetter(OgnlContext context, Object target, Object name)
105        {
106            throw new UnsupportedCompilationException("Can't set listeners on ListenerMap.");
107        }
108    }