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