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 package org.apache.maven.shared.filtering;
20
21 import java.io.IOException;
22 import java.io.Reader;
23
24 /**
25 * A reader that imposes a limit to the number of bytes that can be read from an underlying reader, simulating eof when
26 * this limit is reached. This stream can typically be used to constrain a client with regard to a readAheadLimit of an
27 * underlying stream, to avoid overrunning this limit and hence lose the opportunity do to reset.
28 */
29 public class BoundedReader extends Reader {
30
31 private final Reader target;
32
33 int pos = 0;
34
35 int readAheadLimit;
36
37 /**
38 * @param target {@link Reader}
39 * @param readAheadLimit read ahead limit.
40 * @throws IOException in case of a failure.
41 */
42 public BoundedReader(Reader target, int readAheadLimit) throws IOException {
43 this.target = target;
44 target.mark(readAheadLimit);
45 this.readAheadLimit = readAheadLimit;
46 }
47
48 @Override
49 public void close() throws IOException {
50 target.close();
51 }
52
53 @Override
54 public void reset() throws IOException {
55 pos = 0;
56 target.reset();
57 }
58
59 @Override
60 public void mark(int theReadAheadLimit) throws IOException {
61 this.readAheadLimit = theReadAheadLimit;
62 target.mark(theReadAheadLimit);
63 }
64
65 @Override
66 public int read() throws IOException {
67 if (pos >= readAheadLimit) {
68 return -1;
69 }
70 pos++;
71 return target.read();
72 }
73
74 @Override
75 public int read(char[] cbuf, int off, int len) throws IOException {
76 int c;
77 for (int i = 0; i < len; i++) {
78 c = read();
79 if (c == -1) {
80 return i;
81 }
82 cbuf[off + i] = (char) c;
83 }
84 return len;
85 }
86 }