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-rw-r--r--xpcom/base/StaticLocalPtr.h253
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diff --git a/xpcom/base/StaticLocalPtr.h b/xpcom/base/StaticLocalPtr.h
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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
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-11 17:55:38 +0000