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/*
* Copyright (C) 2011 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 Handle_h
#define Handle_h
#include "WriteBarrier.h"
#include <wtf/Assertions.h>
namespace JSC {
/*
A Handle is a smart pointer that updates automatically when the garbage
collector moves the object to which it points.
The base Handle class represents a temporary reference to a pointer whose
lifetime is guaranteed by something else.
*/
template <class T> class Handle;
// Creating a JSValue Handle is invalid
template <> class Handle<JSValue>;
// Forward declare WeakGCMap
template<typename KeyType, typename MappedType, typename FinalizerCallback, typename HashArg, typename KeyTraitsArg> class WeakGCMap;
class HandleBase {
friend class HandleHeap;
friend struct JSCallbackObjectData;
template <typename KeyType, typename MappedType, typename FinalizerCallback, typename HashArg, typename KeyTraitsArg> friend class WeakGCMap;
public:
bool operator!() const { return !m_slot || !*m_slot; }
// This conversion operator allows implicit conversion to bool but not to other integer types.
typedef JSValue (HandleBase::*UnspecifiedBoolType);
operator UnspecifiedBoolType*() const { return (m_slot && *m_slot) ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
protected:
HandleBase(HandleSlot slot)
: m_slot(slot)
{
}
void swap(HandleBase& other) { std::swap(m_slot, other.m_slot); }
HandleSlot slot() const { return m_slot; }
void setSlot(HandleSlot slot)
{
m_slot = slot;
}
private:
HandleSlot m_slot;
};
template <typename T> struct HandleTypes {
typedef T* ExternalType;
static ExternalType getFromSlot(HandleSlot slot) { return (slot && *slot) ? reinterpret_cast<ExternalType>(slot->asCell()) : 0; }
static JSValue toJSValue(T* cell) { return reinterpret_cast<JSCell*>(cell); }
template <typename U> static void validateUpcast() { T* temp; temp = (U*)0; }
};
template <> struct HandleTypes<Unknown> {
typedef JSValue ExternalType;
static ExternalType getFromSlot(HandleSlot slot) { return slot ? *slot : JSValue(); }
static JSValue toJSValue(const JSValue& v) { return v; }
template <typename U> static void validateUpcast() {}
};
template <typename Base, typename T> struct HandleConverter {
T* operator->()
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!static_cast<const Base*>(this)->get() || !static_cast<const Base*>(this)->get()->isZombie());
#endif
return static_cast<Base*>(this)->get();
}
const T* operator->() const
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!static_cast<const Base*>(this)->get() || !static_cast<const Base*>(this)->get()->isZombie());
#endif
return static_cast<const Base*>(this)->get();
}
T* operator*()
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!static_cast<const Base*>(this)->get() || !static_cast<const Base*>(this)->get()->isZombie());
#endif
return static_cast<Base*>(this)->get();
}
const T* operator*() const
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!static_cast<const Base*>(this)->get() || !static_cast<const Base*>(this)->get()->isZombie());
#endif
return static_cast<const Base*>(this)->get();
}
};
template <typename Base> struct HandleConverter<Base, Unknown> {
Handle<JSObject> asObject() const;
bool isObject() const { return jsValue().isObject(); }
bool getNumber(double number) const { return jsValue().getNumber(number); }
UString getString(ExecState*) const;
bool isUndefinedOrNull() const { return jsValue().isUndefinedOrNull(); }
private:
JSValue jsValue() const
{
#if ENABLE(JSC_ZOMBIES)
ASSERT(!static_cast<const Base*>(this)->get() || !static_cast<const Base*>(this)->get().isZombie());
#endif
return static_cast<const Base*>(this)->get();
}
};
template <typename T> class Handle : public HandleBase, public HandleConverter<Handle<T>, T> {
public:
template <typename A, typename B> friend class HandleConverter;
typedef typename HandleTypes<T>::ExternalType ExternalType;
template <typename U> Handle(Handle<U> o)
{
typename HandleTypes<T>::template validateUpcast<U>();
setSlot(o.slot());
}
void swap(Handle& other) { HandleBase::swap(other); }
ExternalType get() const { return HandleTypes<T>::getFromSlot(this->slot()); }
protected:
Handle(HandleSlot slot = 0)
: HandleBase(slot)
{
}
private:
friend class HandleHeap;
static Handle<T> wrapSlot(HandleSlot slot)
{
return Handle<T>(slot);
}
};
template <typename Base> Handle<JSObject> HandleConverter<Base, Unknown>::asObject() const
{
return Handle<JSObject>::wrapSlot(static_cast<const Base*>(this)->slot());
}
template <typename T, typename U> inline bool operator==(const Handle<T>& a, const Handle<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const Handle<T>& a, U* b)
{
return a.get() == b;
}
template <typename T, typename U> inline bool operator==(T* a, const Handle<U>& b)
{
return a == b.get();
}
template <typename T, typename U> inline bool operator!=(const Handle<T>& a, const Handle<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const Handle<T>& a, U* b)
{
return a.get() != b;
}
template <typename T, typename U> inline bool operator!=(T* a, const Handle<U>& b)
{
return a != b.get();
}
template <typename T, typename U> inline bool operator!=(const Handle<T>& a, JSValue b)
{
return a.get() != b;
}
template <typename T, typename U> inline bool operator!=(JSValue a, const Handle<U>& b)
{
return a != b.get();
}
}
#endif
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