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
26 * an underlying reader, simulating eof when this limit is reached.
27 *
28 * This stream can typically be used to constrain a client with regard to a readAheadLimit
29 * of an underlying stream, to avoid overrunning this limit and hence
30 * lose the opportunity do to reset.
31 */
32 public class BoundedReader extends Reader {
33
34 private final Reader target;
35
36 int pos = 0;
37
38 int readAheadLimit;
39
40 public BoundedReader(Reader target, int readAheadLimit) throws IOException {
41 this.target = target;
42 target.mark(readAheadLimit);
43 this.readAheadLimit = readAheadLimit;
44 }
45
46
47 @Override public void close() throws IOException {
48 target.close();
49 }
50
51 @Override public void reset() throws IOException {
52 pos = 0;
53 target.reset();
54 }
55
56 @Override public void mark(int readAheadLimit) throws IOException {
57 this.readAheadLimit = readAheadLimit;
58 target.mark(readAheadLimit);
59 }
60
61 @Override public int read() throws IOException {
62 if (pos >= readAheadLimit) return -1;
63 pos++;
64 return target.read();
65 }
66
67 @Override public int read(char[] cbuf, int off, int len) throws IOException{
68 int c;
69 for (int i = 0; i < len; i++){
70 c = read();
71 if (c == -1) return i;
72 cbuf[off + i] = (char) c;
73 }
74 return len;
75 }
76 }