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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 http://mozilla.org/MPL/2.0/. */
/* A class for non-null strong pointers to reference-counted objects. */
#ifndef mozilla_OwningNonNull_h
#define mozilla_OwningNonNull_h
#include "nsAutoPtr.h"
#include "nsCycleCollectionNoteChild.h"
namespace mozilla {
template<class T>
class OwningNonNull
{
public:
OwningNonNull() {}
MOZ_IMPLICIT OwningNonNull(T& aValue)
{
init(&aValue);
}
template<class U>
MOZ_IMPLICIT OwningNonNull(already_AddRefed<U>&& aValue)
{
init(aValue);
}
template<class U>
MOZ_IMPLICIT OwningNonNull(const OwningNonNull<U>& aValue)
{
init(aValue);
}
// This is no worse than get() in terms of const handling.
operator T&() const
{
MOZ_ASSERT(mInited);
MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
return *mPtr;
}
operator T*() const
{
MOZ_ASSERT(mInited);
MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
return mPtr;
}
// Conversion to bool is always true, so delete to catch errors
explicit operator bool() const = delete;
T*
operator->() const
{
MOZ_ASSERT(mInited);
MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
return mPtr;
}
OwningNonNull<T>&
operator=(T* aValue)
{
init(aValue);
return *this;
}
OwningNonNull<T>&
operator=(T& aValue)
{
init(&aValue);
return *this;
}
template<class U>
OwningNonNull<T>&
operator=(already_AddRefed<U>&& aValue)
{
init(aValue);
return *this;
}
template<class U>
OwningNonNull<T>&
operator=(const OwningNonNull<U>& aValue)
{
init(aValue);
return *this;
}
// Don't allow assigning nullptr, it makes no sense
void operator=(decltype(nullptr)) = delete;
already_AddRefed<T> forget()
{
#ifdef DEBUG
mInited = false;
#endif
return mPtr.forget();
}
template<class U>
void
forget(U** aOther)
{
#ifdef DEBUG
mInited = false;
#endif
mPtr.forget(aOther);
}
// Make us work with smart pointer helpers that expect a get().
T* get() const
{
MOZ_ASSERT(mInited);
MOZ_ASSERT(mPtr);
return mPtr;
}
template<typename U>
void swap(U& aOther)
{
mPtr.swap(aOther);
#ifdef DEBUG
mInited = mPtr;
#endif
}
// We have some consumers who want to check whether we're inited in non-debug
// builds as well. Luckily, we have the invariant that we're inited precisely
// when mPtr is non-null.
bool isInitialized() const
{
MOZ_ASSERT(!!mPtr == mInited, "mInited out of sync with mPtr?");
return mPtr;
}
protected:
template<typename U>
void init(U&& aValue)
{
mPtr = aValue;
MOZ_ASSERT(mPtr);
#ifdef DEBUG
mInited = true;
#endif
}
RefPtr<T> mPtr;
#ifdef DEBUG
bool mInited = false;
#endif
};
template <typename T>
inline void
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
OwningNonNull<T>& aField,
const char* aName,
uint32_t aFlags = 0)
{
CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags);
}
} // namespace mozilla
// Declared in nsCOMPtr.h
template<class T> template<class U>
nsCOMPtr<T>::nsCOMPtr(const mozilla::OwningNonNull<U>& aOther)
: nsCOMPtr(aOther.get())
{}
template<class T> template<class U>
nsCOMPtr<T>&
nsCOMPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
{
return operator=(aOther.get());
}
// Declared in mozilla/RefPtr.h
template<class T> template<class U>
RefPtr<T>::RefPtr(const mozilla::OwningNonNull<U>& aOther)
: RefPtr(aOther.get())
{}
template<class T> template<class U>
RefPtr<T>&
RefPtr<T>::operator=(const mozilla::OwningNonNull<U>& aOther)
{
return operator=(aOther.get());
}
#endif // mozilla_OwningNonNull_h
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