pjs/xpcom/ds/nsSharedBufferList.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is Mozilla strings.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
* Scott Collins <scc@mozilla.org> (original author)
*
*/
#include "nsSharedBufferList.h"
#include "nsAlgorithm.h"
// for |copy_string|
#include <new.h>
void
nsSharedBufferList::DestroyBuffers()
{
// destroy the entire list of buffers, without bothering to manage their links
Buffer* next_buffer;
for ( Buffer* cur_buffer=mFirstBuffer; cur_buffer; cur_buffer=next_buffer )
{
next_buffer = cur_buffer->mNext;
operator delete(cur_buffer);
}
mFirstBuffer = mLastBuffer = 0;
mTotalDataLength = 0;
}
nsSharedBufferList::~nsSharedBufferList()
{
DestroyBuffers();
}
nsSharedBufferList::Buffer*
nsSharedBufferList::NewBuffer( const PRUnichar* aData, PRUint32 aDataLength, PRUint32 aAdditionalSpace )
{
size_t object_size = ((sizeof(Buffer) + sizeof(PRUnichar) - 1) / sizeof(PRUnichar)) * sizeof(PRUnichar);
PRUint32 buffer_length = aDataLength + aAdditionalSpace;
size_t buffer_size = size_t(buffer_length) * sizeof(PRUnichar);
void* object_ptr = operator new(object_size + buffer_size);
if ( object_ptr )
{
typedef PRUnichar* PRUnichar_ptr;
PRUnichar* buffer_ptr = PRUnichar_ptr(NS_STATIC_CAST(unsigned char*, object_ptr) + object_size);
if ( aDataLength )
{
PRUnichar* toBegin = buffer_ptr;
copy_string(aData, aData+aDataLength, toBegin);
}
return new (object_ptr) Buffer(buffer_ptr, buffer_ptr+aDataLength, buffer_ptr, buffer_ptr+buffer_length);
}
return 0;
}
void
nsSharedBufferList::LinkBuffer( Buffer* aPrevBuffer, Buffer* aNewBuffer, Buffer* aNextBuffer )
{
NS_ASSERTION(aNewBuffer, "aNewBuffer");
NS_ASSERTION(aPrevBuffer || mFirstBuffer == aNextBuffer, "aPrevBuffer || mFirstBuffer == aNextBuffer");
NS_ASSERTION(!aPrevBuffer || aPrevBuffer->mNext == aNextBuffer, "!aPrevBuffer || aPrevBuffer->mNext == aNextBuffer");
NS_ASSERTION(aNextBuffer || mLastBuffer == aPrevBuffer, "aNextBuffer || mLastBuffer == aPrevBuffer");
NS_ASSERTION(!aNextBuffer || aNextBuffer->mPrev == aPrevBuffer, "!aNextBuffer || aNextBuffer->mPrev == aPrevBuffer");
if ( (aNewBuffer->mPrev = aPrevBuffer) )
aPrevBuffer->mNext = aNewBuffer;
else
mFirstBuffer = aNewBuffer;
if ( (aNewBuffer->mNext = aNextBuffer) )
aNextBuffer->mPrev = aNewBuffer;
else
mLastBuffer = aNewBuffer;
mTotalDataLength += aNewBuffer->DataLength();
}
void
nsSharedBufferList::SplitBuffer( const Position& aSplitPosition )
{
Buffer* bufferToSplit = aSplitPosition.mBuffer;
NS_ASSERTION(bufferToSplit, "bufferToSplit");
ptrdiff_t splitOffset = aSplitPosition.mPosInBuffer - bufferToSplit->DataStart();
NS_ASSERTION(0 <= splitOffset && splitOffset <= bufferToSplit->DataLength(), "|splitOffset| within buffer");
if ( (bufferToSplit->DataLength() >> 1) > splitOffset )
{
Buffer* new_buffer = NewBuffer(bufferToSplit->DataStart(), PRUint32(splitOffset));
LinkBuffer(bufferToSplit->mPrev, new_buffer, bufferToSplit);
bufferToSplit->DataStart(aSplitPosition.mPosInBuffer);
}
else
{
Buffer* new_buffer = NewBuffer(bufferToSplit->DataStart()+splitOffset, PRUint32(bufferToSplit->DataLength()-splitOffset));
LinkBuffer(bufferToSplit, new_buffer, bufferToSplit->mNext);
bufferToSplit->DataEnd(aSplitPosition.mPosInBuffer);
}
}
nsSharedBufferList::Buffer*
nsSharedBufferList::UnlinkBuffer( Buffer* aBufferToUnlink )
{
NS_ASSERTION(aBufferToUnlink, "aBufferToUnlink");
Buffer* prev_buffer = aBufferToUnlink->mPrev;
Buffer* next_buffer = aBufferToUnlink->mNext;
if ( prev_buffer )
prev_buffer->mNext = next_buffer;
else
mFirstBuffer = next_buffer;
if ( next_buffer )
next_buffer->mPrev = prev_buffer;
else
mLastBuffer = prev_buffer;
mTotalDataLength -= aBufferToUnlink->DataLength();
return aBufferToUnlink;
}