1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.filter.codec.statemachine;
21
22 import org.apache.mina.core.buffer.IoBuffer;
23 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
24
25 /**
26 * {@link DecodingState} which skips data until {@link #canSkip(byte)} returns
27 * <tt>false</tt>.
28 *
29 * @author The Apache MINA Project (dev@mina.apache.org)
30 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (jeu, 26 jun 2008) $
31 */
32 public abstract class SkippingState implements DecodingState {
33
34 private int skippedBytes;
35
36 /**
37 * {@inheritDoc}
38 */
39 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
40 throws Exception {
41 int beginPos = in.position();
42 int limit = in.limit();
43 for (int i = beginPos; i < limit; i++) {
44 byte b = in.get(i);
45 if (!canSkip(b)) {
46 in.position(i);
47 int answer = this.skippedBytes;
48 this.skippedBytes = 0;
49 return finishDecode(answer);
50 } else {
51 skippedBytes++;
52 }
53 }
54
55 in.position(limit);
56 return this;
57 }
58
59 /**
60 * {@inheritDoc}
61 */
62 public DecodingState finishDecode(ProtocolDecoderOutput out)
63 throws Exception {
64 return finishDecode(skippedBytes);
65 }
66
67 /**
68 * Called to determine whether the specified byte can be skipped.
69 *
70 * @param b the byte to check.
71 * @return <code>true</code> if the byte can be skipped.
72 */
73 protected abstract boolean canSkip(byte b);
74
75 /**
76 * Invoked when this state cannot skip any more bytes.
77 *
78 * @param skippedBytes the number of bytes skipped.
79 * @return the next state if a state transition was triggered (use
80 * <code>this</code> for loop transitions) or <code>null</code> if
81 * the state machine has reached its end.
82 * @throws Exception if the read data violated protocol specification.
83 */
84 protected abstract DecodingState finishDecode(int skippedBytes)
85 throws Exception;
86 }