third_party/WebKit/Source/wtf/ArrayBufferBuilder.h

   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
  39 namespace WTF {
  40
  41 // A utility class to build an ArrayBuffer instance. Validity must be checked
  42 // by isValid() before using an instance.
  43 class 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
  48 public:
  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
 102 private:
 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
 115 using WTF::ArrayBufferBuilder;
 116
 117 #endif // ArrayBufferBuilder_h