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/*
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "wtf/ArrayBufferBuilder.h"
#include "wtf/Assertions.h"
#include <limits>
namespace WTF {
static const int defaultBufferCapacity = 32768;
ArrayBufferBuilder::ArrayBufferBuilder()
: m_bytesUsed(0)
, m_variableCapacity(true)
{
m_buffer = ArrayBuffer::create(defaultBufferCapacity, 1);
}
bool ArrayBufferBuilder::expandCapacity(unsigned sizeToIncrease)
{
unsigned currentBufferSize = m_buffer->byteLength();
// If the size of the buffer exceeds max of unsigned, it can't be grown any
// more.
if (sizeToIncrease > std::numeric_limits<unsigned>::max() - m_bytesUsed)
return false;
unsigned newBufferSize = m_bytesUsed + sizeToIncrease;
// Grow exponentially if possible.
unsigned exponentialGrowthNewBufferSize = std::numeric_limits<unsigned>::max();
if (currentBufferSize <= std::numeric_limits<unsigned>::max() / 2)
exponentialGrowthNewBufferSize = currentBufferSize * 2;
if (exponentialGrowthNewBufferSize > newBufferSize)
newBufferSize = exponentialGrowthNewBufferSize;
// Copy existing data in current buffer to new buffer.
RefPtr<ArrayBuffer> newBuffer = ArrayBuffer::create(newBufferSize, 1);
if (!newBuffer)
return false;
memcpy(newBuffer->data(), m_buffer->data(), m_bytesUsed);
m_buffer = newBuffer;
return true;
}
unsigned ArrayBufferBuilder::append(const char* data, unsigned length)
{
ASSERT(length > 0);
unsigned currentBufferSize = m_buffer->byteLength();
ASSERT(m_bytesUsed <= currentBufferSize);
unsigned remainingBufferSpace = currentBufferSize - m_bytesUsed;
unsigned bytesToSave = length;
if (length > remainingBufferSpace) {
if (m_variableCapacity) {
if (!expandCapacity(length))
return 0;
} else {
bytesToSave = remainingBufferSpace;
}
}
memcpy(static_cast<char*>(m_buffer->data()) + m_bytesUsed, data, bytesToSave);
m_bytesUsed += bytesToSave;
return bytesToSave;
}
PassRefPtr<ArrayBuffer> ArrayBufferBuilder::toArrayBuffer()
{
// Fully used. Return m_buffer as-is.
if (m_buffer->byteLength() == m_bytesUsed)
return m_buffer;
return m_buffer->slice(0, m_bytesUsed);
}
String ArrayBufferBuilder::toString()
{
return String(static_cast<const char*>(m_buffer->data()), m_bytesUsed);
}
void ArrayBufferBuilder::shrinkToFit()
{
ASSERT(m_bytesUsed <= m_buffer->byteLength());
if (m_buffer->byteLength() > m_bytesUsed)
m_buffer = m_buffer->slice(0, m_bytesUsed);
}
} // namespace WTF
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