001    // Copyright 2008, 2010 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.tapestry5.internal.services;
016    
017    import java.io.IOException;
018    
019    import org.apache.tapestry5.TrackableComponentEventCallback;
020    import org.apache.tapestry5.services.ComponentEventResultProcessor;
021    
022    /**
023     * A wrapper around {@link ComponentEventResultProcessor} that encapsulates capturing the exception.
024     */
025    @SuppressWarnings("unchecked")
026    public class ComponentResultProcessorWrapper implements TrackableComponentEventCallback
027    {
028        private boolean aborted;
029    
030        private IOException exception;
031    
032        private final ComponentEventResultProcessor processor;
033    
034        public ComponentResultProcessorWrapper(ComponentEventResultProcessor processor)
035        {
036            this.processor = processor;
037        }
038    
039        public boolean handleResult(Object result)
040        {
041            if (aborted)
042                throw new IllegalStateException(
043                        "Event callback has already received and processed a result value and can not do so again.");
044    
045            try
046            {
047                processor.processResultValue(result);
048            }
049            catch (IOException ex)
050            {
051                exception = ex;
052            }
053    
054            aborted = true;
055    
056            return true;
057        }
058    
059        /**
060         * Returns true if {@link org.apache.tapestry5.ComponentEventCallback#handleResult(Object)} was invoked, false
061         * otherwise.
062         * 
063         * @return true if the event was aborted
064         */
065        public boolean isAborted()
066        {
067            return aborted;
068        }
069    
070        public void rethrow() throws IOException
071        {
072            if (exception != null)
073                throw exception;
074        }
075    
076    }