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152 lines (124 loc) · 4.18 KB
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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 Local_h
#define Local_h
#include "Handle.h"
#include "VM.h"
/*
A strongly referenced handle whose lifetime is temporary, limited to a given
LocalScope. Use Locals for local values on the stack. It is an error to
create a Local outside of any LocalScope.
*/
namespace JSC {
template <typename T> class Local : public Handle<T> {
friend class LocalScope;
using Handle<T>::slot;
public:
typedef typename Handle<T>::ExternalType ExternalType;
Local(VM&, ExternalType = ExternalType());
Local(VM&, Handle<T>);
Local(const Local<T>&); // Adopting constructor. Used to return a Local to a calling function.
Local& operator=(ExternalType);
Local& operator=(Handle<T>);
private:
Local(HandleSlot, ExternalType); // Used by LocalScope::release() to move a Local to a containing scope.
void set(ExternalType);
};
template <typename T> inline Local<T>::Local(VM& vm, ExternalType value)
: Handle<T>(vm.heap.handleStack()->push())
{
set(value);
}
template <typename T> inline Local<T>::Local(VM& vm, Handle<T> other)
: Handle<T>(vm.heap.handleStack()->push())
{
set(other.get());
}
template <typename T> inline Local<T>::Local(const Local<T>& other)
: Handle<T>(other.slot())
{
const_cast<Local<T>&>(other).setSlot(0); // Prevent accidental sharing.
}
template <typename T> inline Local<T>::Local(HandleSlot slot, ExternalType value)
: Handle<T>(slot, value)
{
}
template <typename T> inline Local<T>& Local<T>::operator=(ExternalType value)
{
set(value);
return *this;
}
template <typename T> inline Local<T>& Local<T>::operator=(Handle<T> other)
{
set(other.get());
return *this;
}
template <typename T> inline void Local<T>::set(ExternalType externalType)
{
ASSERT(slot());
*slot() = externalType;
}
template <typename T, unsigned inlineCapacity = 0> class LocalStack {
typedef typename Handle<T>::ExternalType ExternalType;
public:
LocalStack(VM& vm)
: m_vm(vm)
, m_count(0)
{
}
ExternalType peek() const
{
ASSERT(m_count > 0);
return m_stack[m_count - 1].get();
}
ExternalType pop()
{
ASSERT(m_count > 0);
return m_stack[--m_count].get();
}
void push(ExternalType value)
{
if (m_count == m_stack.size())
m_stack.append(Local<T>(m_vm, value));
else
m_stack[m_count] = value;
m_count++;
}
bool isEmpty() const { return !m_count; }
unsigned size() const { return m_count; }
private:
VM& m_vm;
Vector<Local<T>, inlineCapacity> m_stack;
unsigned m_count;
};
}
namespace WTF {
template<typename T> struct VectorTraits<JSC::Local<T>> : SimpleClassVectorTraits {
static const bool needsDestruction = false;
static const bool canInitializeWithMemset = false;
static const bool canCompareWithMemcmp = false;
};
}
#endif