    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
    015package org.apache.tapestry5.internal.services;
    016
    017import java.io.IOException;
    018
    019import org.apache.tapestry5.TrackableComponentEventCallback;
    020import org.apache.tapestry5.services.ComponentEventResultProcessor;
    021
    022/**
    023 * A wrapper around {@link ComponentEventResultProcessor} that encapsulates capturing the exception.
    024 */
    025@SuppressWarnings("unchecked")
    026public 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}