1/*
2* Copyright (C) 2012 Google Inc. All rights reserved.
3*
4* Redistribution and use in source and binary forms, with or without
5* modification, are permitted provided that the following conditions are
6* met:
7*
8* * Redistributions of source code must retain the above copyright
9* notice, this list of conditions and the following disclaimer.
10* * Redistributions in binary form must reproduce the above
11* copyright notice, this list of conditions and the following disclaimer
12* in the documentation and/or other materials provided with the
13* distribution.
14* * Neither the name of Google Inc. nor the names of its
15* contributors may be used to endorse or promote products derived from
16* this software without specific prior written permission.
17*
18* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29*/
30
31#pragma once
32
33#include <wtf/Deque.h>
34
35namespace WTF {
36
37template <typename T, size_t BlockSize> class StreamBuffer {
38private:
39 typedef Vector<T> Block;
40public:
41 StreamBuffer()
42 : m_size(0)
43 , m_readOffset(0)
44 {
45 }
46
47 ~StreamBuffer()
48 {
49 }
50
51 bool isEmpty() const { return !size(); }
52
53 void append(const T* data, size_t size)
54 {
55 if (!size)
56 return;
57
58 m_size += size;
59 while (size) {
60 if (!m_buffer.size() || m_buffer.last()->size() == BlockSize)
61 m_buffer.append(std::make_unique<Block>());
62 size_t appendSize = std::min(BlockSize - m_buffer.last()->size(), size);
63 m_buffer.last()->append(data, appendSize);
64 data += appendSize;
65 size -= appendSize;
66 }
67 }
68
69 // This function consume data in the fist block.
70 // Specified size must be less than over equal to firstBlockSize().
71 void consume(size_t size)
72 {
73 ASSERT(m_size >= size);
74 if (!m_size)
75 return;
76
77 ASSERT(m_buffer.size() > 0);
78 ASSERT(m_readOffset + size <= m_buffer.first()->size());
79 m_readOffset += size;
80 m_size -= size;
81 if (m_readOffset >= m_buffer.first()->size()) {
82 m_readOffset = 0;
83 m_buffer.removeFirst();
84 }
85 }
86
87 size_t size() const { return m_size; }
88
89 const T* firstBlockData() const
90 {
91 if (!m_size)
92 return 0;
93 ASSERT(m_buffer.size() > 0);
94 return &m_buffer.first()->data()[m_readOffset];
95 }
96
97 size_t firstBlockSize() const
98 {
99 if (!m_size)
100 return 0;
101 ASSERT(m_buffer.size() > 0);
102 return m_buffer.first()->size() - m_readOffset;
103 }
104
105private:
106 size_t m_size;
107 size_t m_readOffset;
108 Deque<std::unique_ptr<Block>> m_buffer;
109};
110
111} // namespace WTF
112
113using WTF::StreamBuffer;
114