1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.voicemail.impl.mail;
18
19import java.io.IOException;
20import java.io.InputStream;
21
22/**
23 * A filtering InputStream that allows single byte "peeks" without consuming the byte. The client of
24 * this stream can call peek() to see the next available byte in the stream and a subsequent read
25 * will still return the peeked byte.
26 */
27public class PeekableInputStream extends InputStream {
28  private final InputStream mIn;
29  private boolean mPeeked;
30  private int mPeekedByte;
31
32  public PeekableInputStream(InputStream in) {
33    this.mIn = in;
34  }
35
36  @Override
37  public int read() throws IOException {
38    if (!mPeeked) {
39      return mIn.read();
40    } else {
41      mPeeked = false;
42      return mPeekedByte;
43    }
44  }
45
46  public int peek() throws IOException {
47    if (!mPeeked) {
48      mPeekedByte = read();
49      mPeeked = true;
50    }
51    return mPeekedByte;
52  }
53
54  @Override
55  public int read(byte[] b, int offset, int length) throws IOException {
56    if (!mPeeked) {
57      return mIn.read(b, offset, length);
58    } else {
59      b[0] = (byte) mPeekedByte;
60      mPeeked = false;
61      int r = mIn.read(b, offset + 1, length - 1);
62      if (r == -1) {
63        return 1;
64      } else {
65        return r + 1;
66      }
67    }
68  }
69
70  @Override
71  public int read(byte[] b) throws IOException {
72    return read(b, 0, b.length);
73  }
74
75  @Override
76  public String toString() {
77    return String.format(
78        "PeekableInputStream(in=%s, peeked=%b, peekedByte=%d)",
79        mIn.toString(), mPeeked, mPeekedByte);
80  }
81}
82