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/*
* Copyright (C) 2010 Apple 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:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
*/
#ifndef HandleStack_h
#define HandleStack_h
#include "Assertions.h"
#include "BlockStack.h"
#include "Handle.h"
#include <wtf/UnusedParam.h>
namespace JSC {
class LocalScope;
class HeapRootVisitor;
class HandleStack {
public:
class Frame {
public:
HandleSlot m_next;
HandleSlot m_end;
};
HandleStack();
void enterScope(Frame&);
void leaveScope(Frame&);
HandleSlot push();
void visit(HeapRootVisitor&);
private:
void grow();
void zapTo(Frame&);
HandleSlot findFirstAfter(HandleSlot);
#ifndef NDEBUG
size_t m_scopeDepth;
#endif
BlockStack<JSValue> m_blockStack;
Frame m_frame;
};
inline void HandleStack::enterScope(Frame& lastFrame)
{
#ifndef NDEBUG
++m_scopeDepth;
#endif
lastFrame = m_frame;
}
inline void HandleStack::zapTo(Frame& lastFrame)
{
#ifdef NDEBUG
UNUSED_PARAM(lastFrame);
#else
const Vector<HandleSlot>& blocks = m_blockStack.blocks();
if (lastFrame.m_end != m_frame.m_end) { // Zapping to a frame in a different block.
int i = blocks.size() - 1;
for ( ; blocks[i] + m_blockStack.blockLength != lastFrame.m_end; --i) {
for (int j = m_blockStack.blockLength - 1; j >= 0; --j)
blocks[i][j] = JSValue();
}
for (HandleSlot it = blocks[i] + m_blockStack.blockLength - 1; it != lastFrame.m_next - 1; --it)
*it = JSValue();
return;
}
for (HandleSlot it = m_frame.m_next - 1; it != lastFrame.m_next - 1; --it)
*it = JSValue();
#endif
}
inline void HandleStack::leaveScope(Frame& lastFrame)
{
#ifndef NDEBUG
--m_scopeDepth;
#endif
zapTo(lastFrame);
if (lastFrame.m_end != m_frame.m_end) // Popping to a frame in a different block.
m_blockStack.shrink(lastFrame.m_end);
m_frame = lastFrame;
}
inline HandleSlot HandleStack::push()
{
ASSERT(m_scopeDepth); // Creating a Local outside of a LocalScope is a memory leak.
if (m_frame.m_next == m_frame.m_end)
grow();
return m_frame.m_next++;
}
}
#endif
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