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Diffstat (limited to 'xpcom/base/nsCOMPtr.h')
| -rw-r--r-- | xpcom/base/nsCOMPtr.h | 1170 |
1 files changed, 1170 insertions, 0 deletions
diff --git a/xpcom/base/nsCOMPtr.h b/xpcom/base/nsCOMPtr.h new file mode 100644 index 0000000000..3ee56e9800 --- /dev/null +++ b/xpcom/base/nsCOMPtr.h @@ -0,0 +1,1170 @@ +/* -*- 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/. */ + +#ifndef nsCOMPtr_h___ +#define nsCOMPtr_h___ + +/* + * Having problems? + * + * See the documentation at: + * https://firefox-source-docs.mozilla.org/xpcom/refptr.html + * + * + * nsCOMPtr + * better than a raw pointer + * for owning objects + * -- scc + */ + +#include <type_traits> + +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/Assertions.h" +#include "mozilla/Attributes.h" +#include "mozilla/RefPtr.h" +#include "nsCycleCollectionNoteChild.h" +#include "nsDebug.h" // for |NS_ASSERTION| +#include "nsISupportsUtils.h" // for |nsresult|, |NS_ADDREF|, |NS_GET_TEMPLATE_IID| et al + +/* + * WARNING: This file defines several macros for internal use only. These + * macros begin with the prefix |NSCAP_|. Do not use these macros in your own + * code. They are for internal use only for cross-platform compatibility, and + * are subject to change without notice. + */ + +#ifdef _MSC_VER +// Under VC++, we win by inlining StartAssignment. +# define NSCAP_FEATURE_INLINE_STARTASSIGNMENT + +// Also under VC++, at the highest warning level, we are overwhelmed with +// warnings about (unused) inline functions being removed. This is to be +// expected with templates, so we disable the warning. +# pragma warning(disable : 4514) +#endif + +#ifdef DEBUG +# define NSCAP_FEATURE_TEST_DONTQUERY_CASES +#endif + +#ifdef __GNUC__ +// Our use of nsCOMPtr_base::mRawPtr violates the C++ standard's aliasing +// rules. Mark it with the may_alias attribute so that gcc 3.3 and higher +// don't reorder instructions based on aliasing assumptions for +// this variable. Fortunately, gcc versions < 3.3 do not do any +// optimizations that break nsCOMPtr. + +# define NS_MAY_ALIAS_PTR(t) t* __attribute__((__may_alias__)) +#else +# define NS_MAY_ALIAS_PTR(t) t* +#endif + +/* + * The following three macros (NSCAP_ADDREF, NSCAP_RELEASE, and + * NSCAP_LOG_ASSIGNMENT) allow external clients the ability to add logging or + * other interesting debug facilities. In fact, if you want |nsCOMPtr| to + * participate in the standard logging facility, you provide + * (e.g., in "nsISupportsImpl.h") suitable definitions + * + * #define NSCAP_ADDREF(this, ptr) NS_ADDREF(ptr) + * #define NSCAP_RELEASE(this, ptr) NS_RELEASE(ptr) + */ + +#ifndef NSCAP_ADDREF +# define NSCAP_ADDREF(this, ptr) (ptr)->AddRef() +#endif + +#ifndef NSCAP_RELEASE +# define NSCAP_RELEASE(this, ptr) (ptr)->Release() +#endif + +// Clients can define |NSCAP_LOG_ASSIGNMENT| to perform logging. +#ifdef NSCAP_LOG_ASSIGNMENT +// Remember that |NSCAP_LOG_ASSIGNMENT| was defined by some client so that we +// know to instantiate |~nsGetterAddRefs| in turn to note the external +// assignment into the |nsCOMPtr|. +# define NSCAP_LOG_EXTERNAL_ASSIGNMENT +#else +// ...otherwise, just strip it out of the code +# define NSCAP_LOG_ASSIGNMENT(this, ptr) +#endif + +#ifndef NSCAP_LOG_RELEASE +# define NSCAP_LOG_RELEASE(this, ptr) +#endif + +namespace mozilla { +template <class T> +class OwningNonNull; +} // namespace mozilla + +template <class T> +inline already_AddRefed<T> dont_AddRef(T* aRawPtr) { + return already_AddRefed<T>(aRawPtr); +} + +template <class T> +inline already_AddRefed<T>&& dont_AddRef( + already_AddRefed<T>&& aAlreadyAddRefedPtr) { + return std::move(aAlreadyAddRefedPtr); +} + +/* + * An nsCOMPtr_helper transforms commonly called getters into typesafe forms + * that are more convenient to call, and more efficient to use with |nsCOMPtr|s. + * Good candidates for helpers are |QueryInterface()|, |CreateInstance()|, etc. + * + * Here are the rules for a helper: + * - it implements |operator()| to produce an interface pointer + * - (except for its name) |operator()| is a valid [XP]COM `getter' + * - the interface pointer that it returns is already |AddRef()|ed (as from + * any good getter) + * - it matches the type requested with the supplied |nsIID| argument + * - its constructor provides an optional |nsresult*| that |operator()| can + * fill in with an error when it is executed + * + * See |class nsGetInterface| for an example. + */ +class MOZ_STACK_CLASS nsCOMPtr_helper { + public: + virtual nsresult NS_FASTCALL operator()(const nsIID&, void**) const = 0; +}; + +/* + * nsQueryInterface could have been implemented as an nsCOMPtr_helper to avoid + * adding specialized machinery in nsCOMPtr, but do_QueryInterface is called + * often enough that the codesize savings are big enough to warrant the + * specialcasing. + */ +class MOZ_STACK_CLASS nsQueryInterfaceISupports { + public: + explicit nsQueryInterfaceISupports(nsISupports* aRawPtr) : mRawPtr(aRawPtr) {} + + nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const; + + private: + nsISupports* MOZ_OWNING_REF mRawPtr; +}; + +template <typename T> +class MOZ_STACK_CLASS nsQueryInterface final + : public nsQueryInterfaceISupports { + public: + explicit nsQueryInterface(T* aRawPtr) + : nsQueryInterfaceISupports(ToSupports(aRawPtr)) {} + + nsresult NS_FASTCALL operator()(const nsIID& aIID, void** aAnswer) const { + return nsQueryInterfaceISupports::operator()(aIID, aAnswer); + } +}; + +class MOZ_STACK_CLASS nsQueryInterfaceISupportsWithError { + public: + nsQueryInterfaceISupportsWithError(nsISupports* aRawPtr, nsresult* aError) + : mRawPtr(aRawPtr), mErrorPtr(aError) {} + + nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const; + + private: + nsISupports* MOZ_OWNING_REF mRawPtr; + nsresult* mErrorPtr; +}; + +template <typename T> +class MOZ_STACK_CLASS nsQueryInterfaceWithError final + : public nsQueryInterfaceISupportsWithError { + public: + explicit nsQueryInterfaceWithError(T* aRawPtr, nsresult* aError) + : nsQueryInterfaceISupportsWithError(ToSupports(aRawPtr), aError) {} + + nsresult NS_FASTCALL operator()(const nsIID& aIID, void** aAnswer) const { + return nsQueryInterfaceISupportsWithError::operator()(aIID, aAnswer); + } +}; + +namespace mozilla { +// PointedToType<> is needed so that do_QueryInterface() will work with a +// variety of smart pointer types in addition to raw pointers. These types +// include RefPtr<>, nsCOMPtr<>, and OwningNonNull<>. +template <class T> +using PointedToType = std::remove_pointer_t<decltype(&*std::declval<T>())>; +} // namespace mozilla + +template <class T> +inline nsQueryInterface<mozilla::PointedToType<T>> do_QueryInterface(T aPtr) { + return nsQueryInterface<mozilla::PointedToType<T>>(aPtr); +} + +template <class T> +inline nsQueryInterfaceWithError<mozilla::PointedToType<T>> do_QueryInterface( + T aRawPtr, nsresult* aError) { + return nsQueryInterfaceWithError<mozilla::PointedToType<T>>(aRawPtr, aError); +} + +template <class T> +inline void do_QueryInterface(already_AddRefed<T>&) { + // This signature exists solely to _stop_ you from doing the bad thing. + // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by + // someone else is an automatic leak. See bug 8221. +} + +template <class T> +inline void do_QueryInterface(already_AddRefed<T>&, nsresult*) { + // This signature exists solely to _stop_ you from doing the bad thing. + // Saying |do_QueryInterface()| on a pointer that is not otherwise owned by + // someone else is an automatic leak. See bug 8221. +} + +//////////////////////////////////////////////////////////////////////////// +// Using servicemanager with COMPtrs +class nsGetServiceByCID final { + public: + explicit nsGetServiceByCID(const nsCID& aCID) : mCID(aCID) {} + + nsresult NS_FASTCALL operator()(const nsIID&, void**) const; + + private: + const nsCID& mCID; +}; + +class nsGetServiceByCIDWithError final { + public: + nsGetServiceByCIDWithError(const nsCID& aCID, nsresult* aErrorPtr) + : mCID(aCID), mErrorPtr(aErrorPtr) {} + + nsresult NS_FASTCALL operator()(const nsIID&, void**) const; + + private: + const nsCID& mCID; + nsresult* mErrorPtr; +}; + +class nsGetServiceByContractID final { + public: + explicit nsGetServiceByContractID(const char* aContractID) + : mContractID(aContractID) {} + + nsresult NS_FASTCALL operator()(const nsIID&, void**) const; + + private: + const char* mContractID; +}; + +class nsGetServiceByContractIDWithError final { + public: + nsGetServiceByContractIDWithError(const char* aContractID, + nsresult* aErrorPtr) + : mContractID(aContractID), mErrorPtr(aErrorPtr) {} + + nsresult NS_FASTCALL operator()(const nsIID&, void**) const; + + private: + const char* mContractID; + nsresult* mErrorPtr; +}; + +class nsIWeakReference; + +// Weak references +class MOZ_STACK_CLASS nsQueryReferent final { + public: + nsQueryReferent(nsIWeakReference* aWeakPtr, nsresult* aError) + : mWeakPtr(aWeakPtr), mErrorPtr(aError) {} + + nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const; + + private: + nsIWeakReference* MOZ_NON_OWNING_REF mWeakPtr; + nsresult* mErrorPtr; +}; + +// template<class T> class nsGetterAddRefs; + +// Helper for assert_validity method +template <class T> +char (&TestForIID(decltype(&NS_GET_TEMPLATE_IID(T))))[2]; +template <class T> +char TestForIID(...); + +template <class T> +class MOZ_IS_REFPTR nsCOMPtr final { + private: + void assign_with_AddRef(nsISupports*); + template <typename U> + void assign_from_qi(const nsQueryInterface<U>, const nsIID&); + template <typename U> + void assign_from_qi_with_error(const nsQueryInterfaceWithError<U>&, + const nsIID&); + void assign_from_gs_cid(const nsGetServiceByCID, const nsIID&); + void assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&, + const nsIID&); + void assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&); + void assign_from_gs_contractid_with_error( + const nsGetServiceByContractIDWithError&, const nsIID&); + void assign_from_query_referent(const nsQueryReferent&, const nsIID&); + void assign_from_helper(const nsCOMPtr_helper&, const nsIID&); + void** begin_assignment(); + + void assign_assuming_AddRef(T* aNewPtr) { + T* oldPtr = mRawPtr; + mRawPtr = aNewPtr; + NSCAP_LOG_ASSIGNMENT(this, aNewPtr); + NSCAP_LOG_RELEASE(this, oldPtr); + if (oldPtr) { + NSCAP_RELEASE(this, oldPtr); + } + } + + private: + T* MOZ_OWNING_REF mRawPtr; + + void assert_validity() { + static_assert(1 < sizeof(TestForIID<T>(nullptr)), + "nsCOMPtr only works " + "for types with IIDs. Either use RefPtr; add an IID to " + "your type with NS_DECLARE_STATIC_IID_ACCESSOR/" + "NS_DEFINE_STATIC_IID_ACCESSOR; or make the nsCOMPtr point " + "to a base class with an IID."); + } + + public: + typedef T element_type; + + ~nsCOMPtr() { + NSCAP_LOG_RELEASE(this, mRawPtr); + if (mRawPtr) { + NSCAP_RELEASE(this, mRawPtr); + } + } + +#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES + void Assert_NoQueryNeeded() { + if (!mRawPtr) { + return; + } + if constexpr (std::is_same_v<T, nsISupports>) { + // FIXME: nsCOMPtr<nsISupports> never asserted this, and it currently + // fails... + return; + } + // This can't be defined in terms of do_QueryInterface because + // that bans casts from a class to itself. + void* out = nullptr; + mRawPtr->QueryInterface(NS_GET_TEMPLATE_IID(T), &out); + T* query_result = static_cast<T*>(out); + MOZ_ASSERT(query_result == mRawPtr, "QueryInterface needed"); + NS_RELEASE(query_result); + } + +# define NSCAP_ASSERT_NO_QUERY_NEEDED() Assert_NoQueryNeeded(); +#else +# define NSCAP_ASSERT_NO_QUERY_NEEDED() +#endif + + // Constructors + + nsCOMPtr() : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + } + + MOZ_IMPLICIT nsCOMPtr(decltype(nullptr)) : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + } + + nsCOMPtr(const nsCOMPtr<T>& aSmartPtr) : mRawPtr(aSmartPtr.mRawPtr) { + assert_validity(); + if (mRawPtr) { + NSCAP_ADDREF(this, mRawPtr); + } + NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr); + } + + template <class U> + MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr<U>& aSmartPtr) + : mRawPtr(aSmartPtr.get()) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U should be a subclass of T"); + assert_validity(); + if (mRawPtr) { + NSCAP_ADDREF(this, mRawPtr); + } + NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.get()); + } + + nsCOMPtr(nsCOMPtr<T>&& aSmartPtr) : mRawPtr(aSmartPtr.mRawPtr) { + assert_validity(); + aSmartPtr.mRawPtr = nullptr; + NSCAP_LOG_ASSIGNMENT(this, mRawPtr); + } + + template <class U> + MOZ_IMPLICIT nsCOMPtr(nsCOMPtr<U>&& aSmartPtr) + : mRawPtr(aSmartPtr.forget().template downcast<T>().take()) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U should be a subclass of T"); + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, mRawPtr); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + MOZ_IMPLICIT nsCOMPtr(T* aRawPtr) : mRawPtr(aRawPtr) { + assert_validity(); + if (mRawPtr) { + NSCAP_ADDREF(this, mRawPtr); + } + NSCAP_LOG_ASSIGNMENT(this, aRawPtr); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>& aSmartPtr) + : mRawPtr(aSmartPtr.take()) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, mRawPtr); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Construct from |otherComPtr.forget()|. + MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>&& aSmartPtr) + : mRawPtr(aSmartPtr.take()) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, mRawPtr); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Construct from |std::move(otherRefPtr)|. + template <typename U> + MOZ_IMPLICIT nsCOMPtr(RefPtr<U>&& aSmartPtr) + : mRawPtr(static_cast<already_AddRefed<T>>(aSmartPtr.forget()).take()) { + assert_validity(); + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + NSCAP_LOG_ASSIGNMENT(this, mRawPtr); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Construct from |already_AddRefed|. + template <typename U> + MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>& aSmartPtr) + : mRawPtr(static_cast<T*>(aSmartPtr.take())) { + assert_validity(); + // But make sure that U actually inherits from T. + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr)); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Construct from |otherComPtr.forget()|. + template <typename U> + MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>&& aSmartPtr) + : mRawPtr(static_cast<T*>(aSmartPtr.take())) { + assert_validity(); + // But make sure that U actually inherits from T. + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + NSCAP_LOG_ASSIGNMENT(this, static_cast<T*>(mRawPtr)); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Construct from |do_QueryInterface(expr)|. + template <typename U> + MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface<U> aQI) : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_qi(aQI, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_QueryInterface(expr, &rv)|. + template <typename U> + MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError<U>& aQI) + : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_qi_with_error(aQI, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_GetService(cid_expr)|. + MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS) : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_gs_cid(aGS, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_GetService(cid_expr, &rv)|. + MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS) + : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_gs_cid_with_error(aGS, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_GetService(contractid_expr)|. + MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS) : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_gs_contractid(aGS, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_GetService(contractid_expr, &rv)|. + MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS) + : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_gs_contractid_with_error(aGS, NS_GET_TEMPLATE_IID(T)); + } + + // Construct from |do_QueryReferent(ptr)| + MOZ_IMPLICIT nsCOMPtr(const nsQueryReferent& aQueryReferent) + : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_query_referent(aQueryReferent, NS_GET_TEMPLATE_IID(T)); + } + + // And finally, anything else we might need to construct from can exploit the + // nsCOMPtr_helper facility. + MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper) : mRawPtr(nullptr) { + assert_validity(); + NSCAP_LOG_ASSIGNMENT(this, nullptr); + assign_from_helper(aHelper, NS_GET_TEMPLATE_IID(T)); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // construct from |mozilla::NotNull|. + template <typename I, + typename = std::enable_if_t<!std::is_same_v<I, nsCOMPtr<T>> && + std::is_convertible_v<I, nsCOMPtr<T>>>> + MOZ_IMPLICIT nsCOMPtr(const mozilla::NotNull<I>& aSmartPtr) + : mRawPtr(nsCOMPtr<T>(aSmartPtr.get()).forget().take()) {} + + // construct from |mozilla::MovingNotNull|. + template <typename I, + typename = std::enable_if_t<!std::is_same_v<I, nsCOMPtr<T>> && + std::is_convertible_v<I, nsCOMPtr<T>>>> + MOZ_IMPLICIT nsCOMPtr(mozilla::MovingNotNull<I>&& aSmartPtr) + : mRawPtr( + nsCOMPtr<T>(std::move(aSmartPtr).unwrapBasePtr()).forget().take()) { + } + + // Defined in OwningNonNull.h + template <class U> + MOZ_IMPLICIT nsCOMPtr(const mozilla::OwningNonNull<U>& aOther); + + // Assignment operators + + nsCOMPtr<T>& operator=(const nsCOMPtr<T>& aRhs) { + assign_with_AddRef(ToSupports(aRhs.mRawPtr)); + return *this; + } + + template <class U> + nsCOMPtr<T>& operator=(const nsCOMPtr<U>& aRhs) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U should be a subclass of T"); + assign_with_AddRef(ToSupports(static_cast<T*>(aRhs.get()))); + return *this; + } + + nsCOMPtr<T>& operator=(nsCOMPtr<T>&& aRhs) { + assign_assuming_AddRef(aRhs.forget().take()); + return *this; + } + + template <class U> + nsCOMPtr<T>& operator=(nsCOMPtr<U>&& aRhs) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U should be a subclass of T"); + assign_assuming_AddRef(aRhs.forget().template downcast<T>().take()); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + nsCOMPtr<T>& operator=(T* aRhs) { + assign_with_AddRef(ToSupports(aRhs)); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + nsCOMPtr<T>& operator=(decltype(nullptr)) { + assign_assuming_AddRef(nullptr); + return *this; + } + + // Assign from |already_AddRefed|. + template <typename U> + nsCOMPtr<T>& operator=(already_AddRefed<U>& aRhs) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + assign_assuming_AddRef(static_cast<T*>(aRhs.take())); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + // Assign from |otherComPtr.forget()|. + template <typename U> + nsCOMPtr<T>& operator=(already_AddRefed<U>&& aRhs) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + assign_assuming_AddRef(static_cast<T*>(aRhs.take())); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + // Assign from |std::move(otherRefPtr)|. + template <typename U> + nsCOMPtr<T>& operator=(RefPtr<U>&& aRhs) { + // Make sure that U actually inherits from T + static_assert(std::is_base_of<T, U>::value, "U is not a subclass of T"); + assign_assuming_AddRef(static_cast<T*>(aRhs.forget().take())); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + // Assign from |do_QueryInterface(expr)|. + template <typename U> + nsCOMPtr<T>& operator=(const nsQueryInterface<U> aRhs) { + assign_from_qi(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_QueryInterface(expr, &rv)|. + template <typename U> + nsCOMPtr<T>& operator=(const nsQueryInterfaceWithError<U>& aRhs) { + assign_from_qi_with_error(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_GetService(cid_expr)|. + nsCOMPtr<T>& operator=(const nsGetServiceByCID aRhs) { + assign_from_gs_cid(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_GetService(cid_expr, &rv)|. + nsCOMPtr<T>& operator=(const nsGetServiceByCIDWithError& aRhs) { + assign_from_gs_cid_with_error(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_GetService(contractid_expr)|. + nsCOMPtr<T>& operator=(const nsGetServiceByContractID aRhs) { + assign_from_gs_contractid(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_GetService(contractid_expr, &rv)|. + nsCOMPtr<T>& operator=(const nsGetServiceByContractIDWithError& aRhs) { + assign_from_gs_contractid_with_error(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // Assign from |do_QueryReferent(ptr)|. + nsCOMPtr<T>& operator=(const nsQueryReferent& aRhs) { + assign_from_query_referent(aRhs, NS_GET_TEMPLATE_IID(T)); + return *this; + } + + // And finally, anything else we might need to assign from can exploit the + // nsCOMPtr_helper facility. + nsCOMPtr<T>& operator=(const nsCOMPtr_helper& aRhs) { + assign_from_helper(aRhs, NS_GET_TEMPLATE_IID(T)); + NSCAP_ASSERT_NO_QUERY_NEEDED(); + return *this; + } + + // Assign from |mozilla::NotNull|. + template <typename I, + typename = std::enable_if_t<std::is_convertible_v<I, nsCOMPtr<T>>>> + nsCOMPtr<T>& operator=(const mozilla::NotNull<I>& aSmartPtr) { + assign_assuming_AddRef(nsCOMPtr<T>(aSmartPtr.get()).forget().take()); + return *this; + } + + // Assign from |mozilla::MovingNotNull|. + template <typename I, + typename = std::enable_if_t<std::is_convertible_v<I, nsCOMPtr<T>>>> + nsCOMPtr<T>& operator=(mozilla::MovingNotNull<I>&& aSmartPtr) { + assign_assuming_AddRef( + nsCOMPtr<T>(std::move(aSmartPtr).unwrapBasePtr()).forget().take()); + return *this; + } + + // Defined in OwningNonNull.h + template <class U> + nsCOMPtr<T>& operator=(const mozilla::OwningNonNull<U>& aOther); + + // Exchange ownership with |aRhs|; can save a pair of refcount operations. + void swap(nsCOMPtr<T>& aRhs) { + T* temp = aRhs.mRawPtr; + NSCAP_LOG_ASSIGNMENT(&aRhs, mRawPtr); + NSCAP_LOG_ASSIGNMENT(this, temp); + NSCAP_LOG_RELEASE(this, mRawPtr); + NSCAP_LOG_RELEASE(&aRhs, temp); + aRhs.mRawPtr = mRawPtr; + mRawPtr = temp; + // |aRhs| maintains the same invariants, so we don't need to + // |NSCAP_ASSERT_NO_QUERY_NEEDED| + } + + // Exchange ownership with |aRhs|; can save a pair of refcount operations. + void swap(T*& aRhs) { + T* temp = aRhs; + NSCAP_LOG_ASSIGNMENT(this, temp); + NSCAP_LOG_RELEASE(this, mRawPtr); + aRhs = reinterpret_cast<T*>(mRawPtr); + mRawPtr = temp; + NSCAP_ASSERT_NO_QUERY_NEEDED(); + } + + // Other pointer operators + + // Return the value of mRawPtr and null out mRawPtr. Useful for + // already_AddRefed return values. + already_AddRefed<T> MOZ_MAY_CALL_AFTER_MUST_RETURN forget() { + T* temp = nullptr; + swap(temp); + return already_AddRefed<T>(temp); + } + + // Set the target of aRhs to the value of mRawPtr and null out mRawPtr. + // Useful to avoid unnecessary AddRef/Release pairs with "out" parameters + // where aRhs bay be a T** or an I** where I is a base class of T. + template <typename I> + void forget(I** aRhs) { + NS_ASSERTION(aRhs, "Null pointer passed to forget!"); + NSCAP_LOG_RELEASE(this, mRawPtr); + *aRhs = get(); + mRawPtr = nullptr; + } + + // Prefer the implicit conversion provided automatically by + // |operator T*() const|. Use |get()| to resolve ambiguity or to get a + // castable pointer. + T* get() const { return reinterpret_cast<T*>(mRawPtr); } + + // Makes an nsCOMPtr act like its underlying raw pointer type whenever it is + // used in a context where a raw pointer is expected. It is this operator + // that makes an nsCOMPtr substitutable for a raw pointer. + // + // Prefer the implicit use of this operator to calling |get()|, except where + // necessary to resolve ambiguity. + operator T*() const& { return get(); } + + // Don't allow implicit conversion of temporary nsCOMPtr to raw pointer, + // because the refcount might be one and the pointer will immediately become + // invalid. + operator T*() const&& = delete; + + // Needed to avoid the deleted operator above + explicit operator bool() const { return !!mRawPtr; } + + T* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN { + MOZ_ASSERT(mRawPtr != nullptr, + "You can't dereference a NULL nsCOMPtr with operator->()."); + return get(); + } + + // These are not intended to be used by clients. See |address_of| below. + nsCOMPtr<T>* get_address() { return this; } + const nsCOMPtr<T>* get_address() const { return this; } + + public: + T& operator*() const { + MOZ_ASSERT(mRawPtr != nullptr, + "You can't dereference a NULL nsCOMPtr with operator*()."); + return *get(); + } + + T** StartAssignment() { +#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT + return reinterpret_cast<T**>(begin_assignment()); +#else + assign_assuming_AddRef(nullptr); + return reinterpret_cast<T**>(&mRawPtr); +#endif + } +}; + +template <typename T> +inline void ImplCycleCollectionUnlink(nsCOMPtr<T>& aField) { + aField = nullptr; +} + +template <typename T> +inline void ImplCycleCollectionTraverse( + nsCycleCollectionTraversalCallback& aCallback, nsCOMPtr<T>& aField, + const char* aName, uint32_t aFlags = 0) { + CycleCollectionNoteChild(aCallback, aField.get(), aName, aFlags); +} + +template <class T> +void nsCOMPtr<T>::assign_with_AddRef(nsISupports* aRawPtr) { + if (aRawPtr) { + NSCAP_ADDREF(this, aRawPtr); + } + assign_assuming_AddRef(reinterpret_cast<T*>(aRawPtr)); +} + +template <class T> +template <typename U> +void nsCOMPtr<T>::assign_from_qi(const nsQueryInterface<U> aQI, + const nsIID& aIID) { + // Allow QIing to nsISupports from nsISupports as a special-case, since + // SameCOMIdentity uses it. + static_assert( + std::is_same_v<T, nsISupports> || + !(std::is_same_v<T, U> || std::is_base_of<T, U>::value), + "don't use do_QueryInterface for compile-time-determinable casts"); + void* newRawPtr; + if (NS_FAILED(aQI(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +template <typename U> +void nsCOMPtr<T>::assign_from_qi_with_error( + const nsQueryInterfaceWithError<U>& aQI, const nsIID& aIID) { + static_assert( + !(std::is_same_v<T, U> || std::is_base_of<T, U>::value), + "don't use do_QueryInterface for compile-time-determinable casts"); + void* newRawPtr; + if (NS_FAILED(aQI(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_gs_cid(const nsGetServiceByCID aGS, + const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(aGS(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_gs_cid_with_error( + const nsGetServiceByCIDWithError& aGS, const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(aGS(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_gs_contractid(const nsGetServiceByContractID aGS, + const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(aGS(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_gs_contractid_with_error( + const nsGetServiceByContractIDWithError& aGS, const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(aGS(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_query_referent( + const nsQueryReferent& aQueryReferent, const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(aQueryReferent(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void nsCOMPtr<T>::assign_from_helper(const nsCOMPtr_helper& helper, + const nsIID& aIID) { + void* newRawPtr; + if (NS_FAILED(helper(aIID, &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); +} + +template <class T> +void** nsCOMPtr<T>::begin_assignment() { + assign_assuming_AddRef(nullptr); + union { + T** mT; + void** mVoid; + } result; + result.mT = &mRawPtr; + return result.mVoid; +} + +template <class T> +inline nsCOMPtr<T>* address_of(nsCOMPtr<T>& aPtr) { + return aPtr.get_address(); +} + +template <class T> +inline const nsCOMPtr<T>* address_of(const nsCOMPtr<T>& aPtr) { + return aPtr.get_address(); +} + +/** + * This class is designed to be used for anonymous temporary objects in the + * argument list of calls that return COM interface pointers, e.g., + * + * nsCOMPtr<IFoo> fooP; + * ...->QueryInterface(iid, getter_AddRefs(fooP)) + * + * DO NOT USE THIS TYPE DIRECTLY IN YOUR CODE. Use |getter_AddRefs()| instead. + * + * When initialized with a |nsCOMPtr|, as in the example above, it returns + * a |void**|, a |T**|, or an |nsISupports**| as needed, that the outer call + * (|QueryInterface| in this case) can fill in. + * + * This type should be a nested class inside |nsCOMPtr<T>|. + */ +template <class T> +class nsGetterAddRefs { + public: + explicit nsGetterAddRefs(nsCOMPtr<T>& aSmartPtr) + : mTargetSmartPtr(aSmartPtr) {} + +#if defined(NSCAP_FEATURE_TEST_DONTQUERY_CASES) || \ + defined(NSCAP_LOG_EXTERNAL_ASSIGNMENT) + ~nsGetterAddRefs() { +# ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT + NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)), + mTargetSmartPtr.get()); +# endif + +# ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES + mTargetSmartPtr.Assert_NoQueryNeeded(); +# endif + } +#endif + + operator void**() { + return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment()); + } + + operator T**() { return mTargetSmartPtr.StartAssignment(); } + T*& operator*() { return *(mTargetSmartPtr.StartAssignment()); } + + private: + nsCOMPtr<T>& mTargetSmartPtr; +}; + +template <> +class nsGetterAddRefs<nsISupports> { + public: + explicit nsGetterAddRefs(nsCOMPtr<nsISupports>& aSmartPtr) + : mTargetSmartPtr(aSmartPtr) {} + +#ifdef NSCAP_LOG_EXTERNAL_ASSIGNMENT + ~nsGetterAddRefs() { + NSCAP_LOG_ASSIGNMENT(reinterpret_cast<void*>(address_of(mTargetSmartPtr)), + mTargetSmartPtr.get()); + } +#endif + + operator void**() { + return reinterpret_cast<void**>(mTargetSmartPtr.StartAssignment()); + } + + operator nsISupports**() { return mTargetSmartPtr.StartAssignment(); } + nsISupports*& operator*() { return *(mTargetSmartPtr.StartAssignment()); } + + private: + nsCOMPtr<nsISupports>& mTargetSmartPtr; +}; + +template <class T> +inline nsGetterAddRefs<T> getter_AddRefs(nsCOMPtr<T>& aSmartPtr) { + return nsGetterAddRefs<T>(aSmartPtr); +} + +template <class T, class DestinationType> +inline nsresult CallQueryInterface( + T* aSource, nsGetterAddRefs<DestinationType> aDestination) { + return CallQueryInterface(aSource, + static_cast<DestinationType**>(aDestination)); +} + +// Comparing two |nsCOMPtr|s + +template <class T, class U> +inline bool operator==(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs) { + return static_cast<const T*>(aLhs.get()) == static_cast<const U*>(aRhs.get()); +} + +template <class T, class U> +inline bool operator!=(const nsCOMPtr<T>& aLhs, const nsCOMPtr<U>& aRhs) { + return static_cast<const T*>(aLhs.get()) != static_cast<const U*>(aRhs.get()); +} + +// Comparing an |nsCOMPtr| to a raw pointer + +template <class T, class U> +inline bool operator==(const nsCOMPtr<T>& aLhs, const U* aRhs) { + return static_cast<const T*>(aLhs.get()) == aRhs; +} + +template <class T, class U> +inline bool operator==(const U* aLhs, const nsCOMPtr<T>& aRhs) { + return aLhs == static_cast<const T*>(aRhs.get()); +} + +template <class T, class U> +inline bool operator!=(const nsCOMPtr<T>& aLhs, const U* aRhs) { + return static_cast<const T*>(aLhs.get()) != aRhs; +} + +template <class T, class U> +inline bool operator!=(const U* aLhs, const nsCOMPtr<T>& aRhs) { + return aLhs != static_cast<const T*>(aRhs.get()); +} + +template <class T, class U> +inline bool operator==(const nsCOMPtr<T>& aLhs, U* aRhs) { + return static_cast<const T*>(aLhs.get()) == const_cast<const U*>(aRhs); +} + +template <class T, class U> +inline bool operator==(U* aLhs, const nsCOMPtr<T>& aRhs) { + return const_cast<const U*>(aLhs) == static_cast<const T*>(aRhs.get()); +} + +template <class T, class U> +inline bool operator!=(const nsCOMPtr<T>& aLhs, U* aRhs) { + return static_cast<const T*>(aLhs.get()) != const_cast<const U*>(aRhs); +} + +template <class T, class U> +inline bool operator!=(U* aLhs, const nsCOMPtr<T>& aRhs) { + return const_cast<const U*>(aLhs) != static_cast<const T*>(aRhs.get()); +} + +// Comparing an |nsCOMPtr| to |nullptr| + +template <class T> +inline bool operator==(const nsCOMPtr<T>& aLhs, decltype(nullptr)) { + return aLhs.get() == nullptr; +} + +template <class T> +inline bool operator==(decltype(nullptr), const nsCOMPtr<T>& aRhs) { + return nullptr == aRhs.get(); +} + +template <class T> +inline bool operator!=(const nsCOMPtr<T>& aLhs, decltype(nullptr)) { + return aLhs.get() != nullptr; +} + +template <class T> +inline bool operator!=(decltype(nullptr), const nsCOMPtr<T>& aRhs) { + return nullptr != aRhs.get(); +} + +// Comparing any two [XP]COM objects for identity + +inline bool SameCOMIdentity(nsISupports* aLhs, nsISupports* aRhs) { + return nsCOMPtr<nsISupports>(do_QueryInterface(aLhs)) == + nsCOMPtr<nsISupports>(do_QueryInterface(aRhs)); +} + +template <class SourceType, class DestinationType> +inline nsresult CallQueryInterface(nsCOMPtr<SourceType>& aSourcePtr, + DestinationType** aDestPtr) { + return CallQueryInterface(aSourcePtr.get(), aDestPtr); +} + +template <class T> +RefPtr<T>::RefPtr(const nsQueryReferent& aQueryReferent) { + void* newRawPtr; + if (NS_FAILED(aQueryReferent(NS_GET_TEMPLATE_IID(T), &newRawPtr))) { + newRawPtr = nullptr; + } + mRawPtr = static_cast<T*>(newRawPtr); +} + +template <class T> +RefPtr<T>::RefPtr(const nsCOMPtr_helper& aHelper) { + void* newRawPtr; + if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) { + newRawPtr = nullptr; + } + mRawPtr = static_cast<T*>(newRawPtr); +} + +template <class T> +RefPtr<T>& RefPtr<T>::operator=(const nsQueryReferent& aQueryReferent) { + void* newRawPtr; + if (NS_FAILED(aQueryReferent(NS_GET_TEMPLATE_IID(T), &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); + return *this; +} + +template <class T> +RefPtr<T>& RefPtr<T>::operator=(const nsCOMPtr_helper& aHelper) { + void* newRawPtr; + if (NS_FAILED(aHelper(NS_GET_TEMPLATE_IID(T), &newRawPtr))) { + newRawPtr = nullptr; + } + assign_assuming_AddRef(static_cast<T*>(newRawPtr)); + return *this; +} + +template <class T> +inline already_AddRefed<T> do_AddRef(const nsCOMPtr<T>& aObj) { + nsCOMPtr<T> ref(aObj); + return ref.forget(); +} + +// MOZ_DBG support + +template <class T> +std::ostream& operator<<(std::ostream& aOut, const nsCOMPtr<T>& aObj) { + return mozilla::DebugValue(aOut, aObj.get()); +} + +// ToRefPtr allows to move an nsCOMPtr<T> into a RefPtr<T>. Be mindful when +// using this, because usually RefPtr<T> should only be used with concrete T and +// nsCOMPtr<T> should only be used with XPCOM interface T. +template <class T> +RefPtr<T> ToRefPtr(nsCOMPtr<T>&& aObj) { + return aObj.forget(); +} + +// Integration with ResultExtensions.h +template <typename R> +auto ResultRefAsParam(nsCOMPtr<R>& aResult) { + return getter_AddRefs(aResult); +} + +namespace mozilla::detail { +template <typename T> +struct outparam_as_pointer; + +template <typename T> +struct outparam_as_pointer<nsGetterAddRefs<T>> { + using type = T**; +}; +} // namespace mozilla::detail + +#endif // !defined(nsCOMPtr_h___) |