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/*
* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef WTF_PassRefPtr_h
#define WTF_PassRefPtr_h
#include "wtf/Allocator.h"
#include "wtf/Assertions.h"
#include "wtf/RawPtr.h"
#include "wtf/TypeTraits.h"
namespace WTF {
template <typename T> class RefPtr;
template <typename T> class PassRefPtr;
template <typename T> PassRefPtr<T> adoptRef(T*);
inline void adopted(const void*) {}
// requireAdoption() is not overloaded for WTF::RefCounted, which has a built-in
// assumption that adoption is required. requireAdoption() is for bootstrapping
// alternate reference count classes that are compatible with ReftPtr/PassRefPtr
// but cannot have adoption checks enabled by default, such as skia's
// SkRefCnt. The purpose of requireAdoption() is to enable adoption checks only
// once it is known that the object will be used with RefPtr/PassRefPtr.
inline void requireAdoption(const void*) {}
template <typename T> ALWAYS_INLINE void refIfNotNull(T* ptr)
{
if (LIKELY(ptr != 0)) {
requireAdoption(ptr);
ptr->ref();
}
}
template <typename T> ALWAYS_INLINE void derefIfNotNull(T* ptr)
{
if (LIKELY(ptr != 0))
ptr->deref();
}
template <typename T> class PassRefPtr {
DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
public:
PassRefPtr() : m_ptr(nullptr) {}
PassRefPtr(std::nullptr_t) : m_ptr(nullptr) {}
PassRefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
template <typename U> PassRefPtr(const RawPtr<U>& ptr, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(ptr.get()) { refIfNotNull(m_ptr); }
explicit PassRefPtr(T& ptr) : m_ptr(&ptr) { m_ptr->ref(); }
// It somewhat breaks the type system to allow transfer of ownership out of
// a const PassRefPtr. However, it makes it much easier to work with
// PassRefPtr temporaries, and we don't have a need to use real const
// PassRefPtrs anyway.
PassRefPtr(const PassRefPtr& o) : m_ptr(o.leakRef()) {}
template <typename U> PassRefPtr(const PassRefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(o.leakRef()) {}
ALWAYS_INLINE ~PassRefPtr() { derefIfNotNull(m_ptr); }
template <typename U> PassRefPtr(const RefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
T* get() const { return m_ptr; }
T* leakRef() const WARN_UNUSED_RETURN;
T& operator*() const { return *m_ptr; }
T* operator->() const { return m_ptr; }
bool operator!() const { return !m_ptr; }
// This conversion operator allows implicit conversion to bool but not to
// other integer types.
typedef T* (PassRefPtr::*UnspecifiedBoolType);
operator UnspecifiedBoolType() const { return m_ptr ? &PassRefPtr::m_ptr : 0; }
friend PassRefPtr adoptRef<T>(T*);
private:
enum AdoptRefTag { AdoptRef };
PassRefPtr(T* ptr, AdoptRefTag) : m_ptr(ptr) {}
PassRefPtr& operator=(const PassRefPtr&)
{
static_assert(!sizeof(T*), "PassRefPtr should never be assigned to");
return *this;
}
mutable T* m_ptr;
};
template <typename T>
template <typename U> inline PassRefPtr<T>::PassRefPtr(const RefPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
: m_ptr(o.get())
{
T* ptr = m_ptr;
refIfNotNull(ptr);
}
template <typename T> inline T* PassRefPtr<T>::leakRef() const
{
T* ptr = m_ptr;
m_ptr = nullptr;
return ptr;
}
template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const RefPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, U* b)
{
return a.get() == b;
}
template <typename T, typename U> inline bool operator==(T* a, const PassRefPtr<U>& b)
{
return a == b.get();
}
template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const RawPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator==(const RawPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() == b.get();
}
template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const RefPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, U* b)
{
return a.get() != b;
}
template <typename T, typename U> inline bool operator!=(T* a, const PassRefPtr<U>& b)
{
return a != b.get();
}
template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const RawPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T, typename U> inline bool operator!=(const RawPtr<T>& a, const PassRefPtr<U>& b)
{
return a.get() != b.get();
}
template <typename T> PassRefPtr<T> adoptRef(T* p)
{
adopted(p);
return PassRefPtr<T>(p, PassRefPtr<T>::AdoptRef);
}
template <typename T, typename U> inline PassRefPtr<T> static_pointer_cast(const PassRefPtr<U>& p)
{
return adoptRef(static_cast<T*>(p.leakRef()));
}
template <typename T> inline T* getPtr(const PassRefPtr<T>& p)
{
return p.get();
}
} // namespace WTF
using WTF::PassRefPtr;
using WTF::adoptRef;
using WTF::static_pointer_cast;
#endif // WTF_PassRefPtr_h
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