/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You 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.commons.io.output;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.io.Serializable;

 import java.util.UUID;

 import org.apache.commons.io.TaggedIOException;

 /**

  * An output stream decorator that tags potential exceptions so that the

  * stream that caused the exception can easily be identified. This is

  * done by using the {@link TaggedIOException} class to wrap all thrown

  * {@link IOException}s. See below for an example of using this class.

  * <pre>

  * TaggedOutputStream stream = new TaggedOutputStream(...);

  * try {

  *     // Processing that may throw an IOException either from this stream

  *     // or from some other IO activity like temporary files, etc.

  *     writeToStream(stream);

  * } catch (IOException e) {

  *     if (stream.isCauseOf(e)) {

  *         // The exception was caused by this stream.

  *         // Use e.getCause() to get the original exception.

  *     } else {

  *         // The exception was caused by something else.

  *     }

  * }

  * </pre>

  * <p>

  * Alternatively, the {@link #throwIfCauseOf(Exception)} method can be

  * used to let higher levels of code handle the exception caused by this

  * stream while other processing errors are being taken care of at this

  * lower level.

  * <pre>

  * TaggedOutputStream stream = new TaggedOutputStream(...);

  * try {

  *     writeToStream(stream);

  * } catch (IOException e) {

  *     stream.throwIfCauseOf(e);

  *     // ... or process the exception that was caused by something else

  * }

  * </pre>

  *

  * @see TaggedIOException

  * @since 2.0

  */

 public class TaggedOutputStream extends ProxyOutputStream {

     /**

      * The unique tag associated with exceptions from stream.

      */

     private final Serializable tag = UUID.randomUUID();

     /**

      * Creates a tagging decorator for the given output stream.

      *

      * @param proxy output stream to be decorated

      */

     public TaggedOutputStream(final OutputStream proxy) {

         super(proxy);

     }

     /**

      * Tests if the given exception was caused by this stream.

      *

      * @param exception an exception

      * @return {@code true} if the exception was thrown by this stream,

      *         {@code false} otherwise

      */

     public boolean isCauseOf(final Exception exception) {

         return TaggedIOException.isTaggedWith(exception, tag);

     }

     /**

      * Re-throws the original exception thrown by this stream. This method

      * first checks whether the given exception is a {@link TaggedIOException}

      * wrapper created by this decorator, and then unwraps and throws the

      * original wrapped exception. Returns normally if the exception was

      * not thrown by this stream.

      *

      * @param exception an exception

      * @throws IOException original exception, if any, thrown by this stream

      */

     public void throwIfCauseOf(final Exception exception) throws IOException {

         TaggedIOException.throwCauseIfTaggedWith(exception, tag);

     }

     /**

      * Tags any IOExceptions thrown, wrapping and re-throwing.

      *

      * @param e The IOException thrown

      * @throws IOException if an I/O error occurs

      */

     @Override

     protected void handleIOException(final IOException e) throws IOException {

         throw new TaggedIOException(e, tag);

     }

 }