162 lines
3.2 KiB
C++
162 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* A class for non-null strong pointers to reference-counted objects. */
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#ifndef mozilla_OwningNonNull_h
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#define mozilla_OwningNonNull_h
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#include "nsAutoPtr.h"
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#include "nsCycleCollectionNoteChild.h"
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namespace mozilla {
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template<class T>
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class OwningNonNull
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{
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public:
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OwningNonNull() {}
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MOZ_IMPLICIT OwningNonNull(T& aValue)
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{
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init(&aValue);
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}
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template<class U>
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MOZ_IMPLICIT OwningNonNull(already_AddRefed<U>&& aValue)
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{
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init(aValue);
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}
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// This is no worse than get() in terms of const handling.
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operator T&() const
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{
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MOZ_ASSERT(mInited);
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MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
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return *mPtr;
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}
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operator T*() const
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{
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MOZ_ASSERT(mInited);
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MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
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return mPtr;
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}
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// Conversion to bool is always true, so delete to catch errors
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explicit operator bool() const = delete;
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T*
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operator->() const
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{
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MOZ_ASSERT(mInited);
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MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
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return mPtr;
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}
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OwningNonNull<T>&
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operator=(T* aValue)
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{
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init(aValue);
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return *this;
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}
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OwningNonNull<T>&
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operator=(T& aValue)
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{
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init(&aValue);
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return *this;
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}
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OwningNonNull<T>&
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operator=(already_AddRefed<T>&& aValue)
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{
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init(aValue);
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return *this;
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}
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// Don't allow assigning nullptr, it makes no sense
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void operator=(decltype(nullptr)) = delete;
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already_AddRefed<T> forget()
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{
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#ifdef DEBUG
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mInited = false;
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#endif
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return mPtr.forget();
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}
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// Make us work with smart pointer helpers that expect a get().
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T* get() const
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{
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MOZ_ASSERT(mInited);
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MOZ_ASSERT(mPtr);
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return mPtr;
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}
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template<typename U>
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void swap(U& aOther)
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{
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mPtr.swap(aOther);
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}
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protected:
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template<typename U>
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void init(U&& aValue)
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{
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mPtr = aValue;
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MOZ_ASSERT(mPtr);
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#ifdef DEBUG
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mInited = true;
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#endif
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}
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RefPtr<T> mPtr;
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#ifdef DEBUG
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bool mInited = false;
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#endif
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};
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template <typename T>
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inline void
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ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
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OwningNonNull<T>& aField,
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const char* aName,
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uint32_t aFlags = 0)
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{
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CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
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}
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} // namespace mozilla
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// Declared in nsCOMPtr.h
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template<class T> template<class U>
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nsCOMPtr<T>::nsCOMPtr(const mozilla::OwningNonNull<U>& aOther)
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: nsCOMPtr(aOther.get())
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{}
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template<class T> template<class U>
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nsCOMPtr<T>&
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nsCOMPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
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{
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return operator=(aOther.get());
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}
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// Declared in mozilla/RefPtr.h
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template<class T> template<class U>
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RefPtr<T>::RefPtr(const mozilla::OwningNonNull<U>& aOther)
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: RefPtr(aOther.get())
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{}
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template<class T> template<class U>
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RefPtr<T>&
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RefPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
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{
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return operator=(aOther.get());
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}
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#endif // mozilla_OwningNonNull_h
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