1/*
2 * Copyright (C) 2013 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#ifndef ArrayBufferBuilder_h
32#define ArrayBufferBuilder_h
33
34#include "wtf/ArrayBuffer.h"
35#include "wtf/Noncopyable.h"
36#include "wtf/RefPtr.h"
37#include "wtf/text/WTFString.h"
38
39namespace WTF {
40
41// A utility class to build an ArrayBuffer instance. Validity must be checked
42// by isValid() before using an instance.
43class WTF_EXPORT ArrayBufferBuilder {
44    // Disallow copying since it's expensive and we don't want code to do it by
45    // accident.
46    WTF_MAKE_NONCOPYABLE(ArrayBufferBuilder);
47
48public:
49    // Creates an ArrayBufferBuilder using the default capacity.
50    ArrayBufferBuilder();
51
52    ArrayBufferBuilder(unsigned capacity)
53        : m_bytesUsed(0)
54        , m_variableCapacity(true)
55    {
56        m_buffer = ArrayBuffer::create(capacity, 1);
57    }
58
59    bool isValid() const
60    {
61        return m_buffer;
62    }
63
64    // Appending empty data is not allowed.
65    unsigned append(const char* data, unsigned length);
66
67    // Returns the accumulated data as an ArrayBuffer instance. If needed,
68    // creates a new ArrayBuffer instance and copies contents from the internal
69    // buffer to it. Otherwise, returns a PassRefPtr pointing to the internal
70    // buffer.
71    PassRefPtr<ArrayBuffer> toArrayBuffer();
72
73    // Converts the accumulated data into a String using the default encoding.
74    String toString();
75
76    // Number of bytes currently accumulated.
77    unsigned byteLength() const
78    {
79        return m_bytesUsed;
80    }
81
82    // Number of bytes allocated.
83    unsigned capacity() const
84    {
85        return m_buffer->byteLength();
86    }
87
88    void shrinkToFit();
89
90    const void* data() const
91    {
92        return m_buffer->data();
93    }
94
95    // If set to false, the capacity won't be expanded and when appended data
96    // overflows, the overflowed part will be dropped.
97    void setVariableCapacity(bool value)
98    {
99        m_variableCapacity = value;
100    }
101
102private:
103    // Expands the size of m_buffer to size + m_bytesUsed bytes. Returns true
104    // iff successful. If reallocation is needed, copies only data in
105    // [0, m_bytesUsed) range.
106    bool expandCapacity(unsigned size);
107
108    unsigned m_bytesUsed;
109    bool m_variableCapacity;
110    RefPtr<ArrayBuffer> m_buffer;
111};
112
113} // namespace WTF
114
115using WTF::ArrayBufferBuilder;
116
117#endif // ArrayBufferBuilder_h
118