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