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 consumes all bytes until a fixed (ASCII)
27 * character is reached. The terminator is skipped.
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 ConsumeToDynamicTerminatorDecodingState implements
33 DecodingState {
34
35 private IoBuffer buffer;
36
37 /**
38 * {@inheritDoc}
39 */
40 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
41 throws Exception {
42 int beginPos = in.position();
43 int terminatorPos = -1;
44 int limit = in.limit();
45
46 for (int i = beginPos; i < limit; i++) {
47 byte b = in.get(i);
48 if (isTerminator(b)) {
49 terminatorPos = i;
50 break;
51 }
52 }
53
54 if (terminatorPos >= 0) {
55 IoBuffer product;
56
57 if (beginPos < terminatorPos) {
58 in.limit(terminatorPos);
59
60 if (buffer == null) {
61 product = in.slice();
62 } else {
63 buffer.put(in);
64 product = buffer.flip();
65 buffer = null;
66 }
67
68 in.limit(limit);
69 } else {
70 // When input contained only terminator rather than actual data...
71 if (buffer == null) {
72 product = IoBuffer.allocate(0);
73 } else {
74 product = buffer.flip();
75 buffer = null;
76 }
77 }
78 in.position(terminatorPos + 1);
79 return finishDecode(product, out);
80 } else {
81 if (buffer == null) {
82 buffer = IoBuffer.allocate(in.remaining());
83 buffer.setAutoExpand(true);
84 }
85 buffer.put(in);
86 return this;
87 }
88 }
89
90 /**
91 * {@inheritDoc}
92 */
93 public DecodingState finishDecode(ProtocolDecoderOutput out)
94 throws Exception {
95 IoBuffer product;
96 // When input contained only terminator rather than actual data...
97 if (buffer == null) {
98 product = IoBuffer.allocate(0);
99 } else {
100 product = buffer.flip();
101 buffer = null;
102 }
103 return finishDecode(product, out);
104 }
105
106 /**
107 * Determines whether the specified <code>byte</code> is a terminator.
108 *
109 * @param b the <code>byte</code> to check.
110 * @return <code>true</code> if <code>b</code> is a terminator,
111 * <code>false</code> otherwise.
112 */
113 protected abstract boolean isTerminator(byte b);
114
115 /**
116 * Invoked when this state has reached the terminator byte.
117 *
118 * @param product the read bytes not including the terminator.
119 * @param out the current {@link ProtocolDecoderOutput} used to write
120 * decoded messages.
121 * @return the next state if a state transition was triggered (use
122 * <code>this</code> for loop transitions) or <code>null</code> if
123 * the state machine has reached its end.
124 * @throws Exception if the read data violated protocol specification.
125 */
126 protected abstract DecodingState finishDecode(IoBuffer product,
127 ProtocolDecoderOutput out) throws Exception;
128 }