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1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  You may obtain a copy of the License at:
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.codec.embedder;
17  
18  import java.util.Collection;
19  
20  /**
21   * A helper that wraps an encoder or a decoder (codec) so that they can be used
22   * without doing actual I/O in unit tests or higher level codecs.  Please refer
23   * to {@link EncoderEmbedder} and {@link DecoderEmbedder} for more information.
24   *
25   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
26   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
27   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
28   */
29  public interface CodecEmbedder<E> {
30      /**
31       * Offers an input object to the pipeline of this embedder.
32       *
33       * @return {@code true} if and only if there is something to read in the
34       *         product queue (see {@link #poll()} and {@link #peek()})
35       */
36      boolean offer(Object input);
37  
38      /**
39       * Signals the pipeline that the encoding or decoding has been finished and
40       * no more data will be offered.
41       *
42       * @return {@code true} if and only if there is something to read in the
43       *         product queue (see {@link #poll()} and {@link #peek()})
44       */
45      boolean finish();
46  
47      /**
48       * Consumes an encoded or decoded output from the product queue. The output
49       * object is generated by the offered input objects.
50       *
51       * @return an encoded or decoded object.
52       *         {@code null} if and only if there is no output object left in the
53       *         product queue.
54       */
55      E poll();
56  
57      /**
58       * Reads an encoded or decoded output from the head of the product queue.
59       * The difference from {@link #poll()} is that it does not remove the
60       * retrieved object from the product queue.
61       *
62       * @return an encoded or decoded object.
63       *         {@code null} if and only if there is no output object left in the
64       *         product queue.
65       */
66      E peek();
67  
68      /**
69       * Consumes all encoded or decoded output from the product queue.  The
70       * output object is generated by the offered input objects.  The behavior
71       * of this method is identical with {@link Collection#toArray()} except that
72       * the product queue is cleared.
73       *
74       * @return an array of all encoded or decoded objects.
75       *         An empty array is returned if and only if there is no output
76       *         object left in the product queue.
77       */
78      Object[] pollAll();
79  
80      /**
81       * Consumes all encoded or decoded output from the product queue.  The
82       * output object is generated by the offered input objects.  The behavior
83       * of this method is identical with {@link Collection#toArray(Object[])}
84       * except that the product queue is cleared.
85       *
86       * @return an array of all encoded or decoded objects.
87       *         An empty array is returned if and only if there is no output
88       *         object left in the product queue.
89       */
90      <T> T[] pollAll(T[] a);
91  
92      /**
93       * Returns the number of encoded or decoded output in the product queue.
94       */
95      int size();
96  }