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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
#ifndef mozilla_StaticLocalPtr_h
#define mozilla_StaticLocalPtr_h
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/RefPtr.h"
namespace mozilla {
/**
* StaticLocalAutoPtr and StaticLocalRefPtr are like UniquePtr and RefPtr,
* except they are suitable for use as "magic static" local variables -- that
* is, they are able to take advantage of C++11's guarantee of thread safety
* during initialization by atomically constructing both the smart pointer
* itself as well as the object being pointed to.
*
* A static local instance of StaticLocal{Auto,Ref}Ptr does not cause the
* compiler to emit any atexit calls. In order to accomplish this,
* StaticLocal{Auto,Ref}Ptr must have a trivial destructor. As a consequence,
* it does not delete/release its raw pointer upon destruction.
*
* The clang plugin, run as part of our "static analysis" builds, makes it a
* compile-time error to use StaticLocal{Auto,Ref}Ptr as anything except a
* static local variable.
*
* StaticLocal{Auto,Ref}Ptr have a limited interface as compared to
* ns{Auto,Ref}Ptr; this is intentional, since their range of acceptable uses is
* smaller.
*/
template <typename T>
class MOZ_STATIC_LOCAL_CLASS StaticLocalAutoPtr final {
public:
explicit StaticLocalAutoPtr(T* aRawPtr) : mRawPtr(aRawPtr) {}
StaticLocalAutoPtr(StaticLocalAutoPtr<T>&& aOther) : mRawPtr(aOther.mRawPtr) {
aOther.mRawPtr = nullptr;
}
StaticLocalAutoPtr<T>& operator=(T* aRhs) {
Assign(aRhs);
return *this;
}
T* get() const { return mRawPtr; }
operator T*() const { return get(); }
T* operator->() const {
MOZ_ASSERT(mRawPtr);
return get();
}
T& operator*() const { return *get(); }
T* forget() {
T* temp = mRawPtr;
mRawPtr = nullptr;
return temp;
}
private:
StaticLocalAutoPtr(const StaticLocalAutoPtr<T>& aOther) = delete;
// We do not allow assignment as the intention of this class is to only
// assign to mRawPtr during construction.
StaticLocalAutoPtr& operator=(const StaticLocalAutoPtr<T>& aOther) = delete;
StaticLocalAutoPtr& operator=(StaticLocalAutoPtr<T>&&) = delete;
void Assign(T* aNewPtr) {
MOZ_ASSERT(!aNewPtr || mRawPtr != aNewPtr);
T* oldPtr = mRawPtr;
mRawPtr = aNewPtr;
delete oldPtr;
}
T* mRawPtr;
};
template <typename T>
class MOZ_STATIC_LOCAL_CLASS StaticLocalRefPtr final {
public:
explicit StaticLocalRefPtr(T* aRawPtr) : mRawPtr(nullptr) {
AssignWithAddref(aRawPtr);
}
explicit StaticLocalRefPtr(already_AddRefed<T>& aPtr) : mRawPtr(nullptr) {
AssignAssumingAddRef(aPtr.take());
}
explicit StaticLocalRefPtr(already_AddRefed<T>&& aPtr) : mRawPtr(nullptr) {
AssignAssumingAddRef(aPtr.take());
}
StaticLocalRefPtr(const StaticLocalRefPtr<T>& aPtr)
: StaticLocalRefPtr(aPtr.mRawPtr) {}
StaticLocalRefPtr(StaticLocalRefPtr<T>&& aPtr) : mRawPtr(aPtr.mRawPtr) {
aPtr.mRawPtr = nullptr;
}
StaticLocalRefPtr<T>& operator=(T* aRhs) {
AssignWithAddref(aRhs);
return *this;
}
already_AddRefed<T> forget() {
T* temp = mRawPtr;
mRawPtr = nullptr;
return already_AddRefed<T>(temp);
}
T* get() const { return mRawPtr; }
operator T*() const { return get(); }
T* operator->() const {
MOZ_ASSERT(mRawPtr);
return get();
}
T& operator*() const { return *get(); }
private:
// We do not allow assignment as the intention of this class is to only
// assign to mRawPtr during construction.
StaticLocalRefPtr<T>& operator=(const StaticLocalRefPtr<T>& aRhs) = delete;
StaticLocalRefPtr<T>& operator=(StaticLocalRefPtr<T>&& aRhs) = delete;
void AssignWithAddref(T* aNewPtr) {
if (aNewPtr) {
aNewPtr->AddRef();
}
AssignAssumingAddRef(aNewPtr);
}
void AssignAssumingAddRef(T* aNewPtr) {
T* oldPtr = mRawPtr;
mRawPtr = aNewPtr;
if (oldPtr) {
oldPtr->Release();
}
}
T* MOZ_OWNING_REF mRawPtr;
};
namespace StaticLocalPtr_internal {
class Zero;
} // namespace StaticLocalPtr_internal
#define REFLEXIVE_EQUALITY_OPERATORS(type1, type2, eq_fn, ...) \
template <__VA_ARGS__> \
inline bool operator==(type1 lhs, type2 rhs) { \
return eq_fn; \
} \
\
template <__VA_ARGS__> \
inline bool operator==(type2 lhs, type1 rhs) { \
return rhs == lhs; \
} \
\
template <__VA_ARGS__> \
inline bool operator!=(type1 lhs, type2 rhs) { \
return !(lhs == rhs); \
} \
\
template <__VA_ARGS__> \
inline bool operator!=(type2 lhs, type1 rhs) { \
return !(lhs == rhs); \
}
// StaticLocalAutoPtr (in)equality operators
template <class T, class U>
inline bool operator==(const StaticLocalAutoPtr<T>& aLhs,
const StaticLocalAutoPtr<U>& aRhs) {
return aLhs.get() == aRhs.get();
}
template <class T, class U>
inline bool operator!=(const StaticLocalAutoPtr<T>& aLhs,
const StaticLocalAutoPtr<U>& aRhs) {
return !(aLhs == aRhs);
}
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalAutoPtr<T>&, const U*,
lhs.get() == rhs, class T, class U)
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalAutoPtr<T>&, U*, lhs.get() == rhs,
class T, class U)
// Let us compare StaticLocalAutoPtr to 0.
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalAutoPtr<T>&,
StaticLocalPtr_internal::Zero*,
lhs.get() == nullptr, class T)
// StaticLocalRefPtr (in)equality operators
template <class T, class U>
inline bool operator==(const StaticLocalRefPtr<T>& aLhs,
const StaticLocalRefPtr<U>& aRhs) {
return aLhs.get() == aRhs.get();
}
template <class T, class U>
inline bool operator!=(const StaticLocalRefPtr<T>& aLhs,
const StaticLocalRefPtr<U>& aRhs) {
return !(aLhs == aRhs);
}
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalRefPtr<T>&, const U*,
lhs.get() == rhs, class T, class U)
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalRefPtr<T>&, U*, lhs.get() == rhs,
class T, class U)
// Let us compare StaticLocalRefPtr to 0.
REFLEXIVE_EQUALITY_OPERATORS(const StaticLocalRefPtr<T>&,
StaticLocalPtr_internal::Zero*,
lhs.get() == nullptr, class T)
#undef REFLEXIVE_EQUALITY_OPERATORS
} // namespace mozilla
// Declared in mozilla/RefPtr.h
template <class T>
template <class U>
RefPtr<T>::RefPtr(const mozilla::StaticLocalRefPtr<U>& aOther)
: RefPtr(aOther.get()) {}
template <class T>
template <class U>
RefPtr<T>& RefPtr<T>::operator=(const mozilla::StaticLocalRefPtr<U>& aOther) {
return operator=(aOther.get());
}
template <class T>
inline already_AddRefed<T> do_AddRef(
const mozilla::StaticLocalRefPtr<T>& aObj) {
RefPtr<T> ref(aObj);
return ref.forget();
}
#endif // mozilla_StaticLocalPtr_h