maint-5-2/tapestry-core/src/main/java/org/apache/tapestry5/internal/services/ComponentResultProcessorWrapper.java

// Copyright 2008, 2010 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry5.internal.services;

import java.io.IOException;

import org.apache.tapestry5.TrackableComponentEventCallback;
import org.apache.tapestry5.services.ComponentEventResultProcessor;

/**
 * A wrapper around {@link ComponentEventResultProcessor} that encapsulates capturing the exception.
 */
@SuppressWarnings("unchecked")
public class ComponentResultProcessorWrapper implements TrackableComponentEventCallback
{
    private boolean aborted;

    private IOException exception;

    private final ComponentEventResultProcessor processor;

    public ComponentResultProcessorWrapper(ComponentEventResultProcessor processor)
    {
        this.processor = processor;
    }

    public boolean handleResult(Object result)
    {
        if (aborted)
            throw new IllegalStateException(
                    "Event callback has already received and processed a result value and can not do so again.");

        try
        {
            processor.processResultValue(result);
        }
        catch (IOException ex)
        {
            exception = ex;
        }

        aborted = true;

        return true;
    }

    /**
     * Returns true if {@link org.apache.tapestry5.ComponentEventCallback#handleResult(Object)} was invoked, false
     * otherwise.
     * 
     * @return true if the event was aborted
     */
    public boolean isAborted()
    {
        return aborted;
    }

    public void rethrow() throws IOException
    {
        if (exception != null)
            throw exception;
    }

}