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 <a href="http://mina.apache.org">Apache MINA Project</a>
30 */
31 public abstract class ConsumeToDynamicTerminatorDecodingState implements DecodingState {
32
33 private IoBuffer buffer;
34
35 /**
36 * {@inheritDoc}
37 */
38 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
39 int beginPos = in.position();
40 int terminatorPos = -1;
41 int limit = in.limit();
42
43 for (int i = beginPos; i < limit; i++) {
44 byte b = in.get(i);
45 if (isTerminator(b)) {
46 terminatorPos = i;
47 break;
48 }
49 }
50
51 if (terminatorPos >= 0) {
52 IoBuffer product;
53
54 if (beginPos < terminatorPos) {
55 in.limit(terminatorPos);
56
57 if (buffer == null) {
58 product = in.slice();
59 } else {
60 buffer.put(in);
61 product = buffer.flip();
62 buffer = null;
63 }
64
65 in.limit(limit);
66 } else {
67 // When input contained only terminator rather than actual data...
68 if (buffer == null) {
69 product = IoBuffer.allocate(0);
70 } else {
71 product = buffer.flip();
72 buffer = null;
73 }
74 }
75 in.position(terminatorPos + 1);
76 return finishDecode(product, out);
77 }
78
79 if (buffer == null) {
80 buffer = IoBuffer.allocate(in.remaining());
81 buffer.setAutoExpand(true);
82 }
83 buffer.put(in);
84 return this;
85 }
86
87 /**
88 * {@inheritDoc}
89 */
90 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
91 IoBuffer product;
92 // When input contained only terminator rather than actual data...
93 if (buffer == null) {
94 product = IoBuffer.allocate(0);
95 } else {
96 product = buffer.flip();
97 buffer = null;
98 }
99 return finishDecode(product, out);
100 }
101
102 /**
103 * Determines whether the specified <code>byte</code> is a terminator.
104 *
105 * @param b the <code>byte</code> to check.
106 * @return <code>true</code> if <code>b</code> is a terminator,
107 * <code>false</code> otherwise.
108 */
109 protected abstract boolean isTerminator(byte b);
110
111 /**
112 * Invoked when this state has reached the terminator byte.
113 *
114 * @param product the read bytes not including the terminator.
115 * @param out the current {@link ProtocolDecoderOutput} used to write
116 * decoded messages.
117 * @return the next state if a state transition was triggered (use
118 * <code>this</code> for loop transitions) or <code>null</code> if
119 * the state machine has reached its end.
120 * @throws Exception if the read data violated protocol specification.
121 */
122 protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception;
123 }