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gecko-dev/xpcom/glue/nsCOMPtr.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 http://mozilla.org/MPL/2.0/. */
#ifndef nsCOMPtr_h___
#define nsCOMPtr_h___
/*
* Having problems?
*
* See the User Manual at:
* http://www.mozilla.org/projects/xpcom/nsCOMPtr.html
*
*
* nsCOMPtr
* better than a raw pointer
* for owning objects
* -- scc
*/
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Move.h"
#include "mozilla/TypeTraits.h"
#include "nsDebug.h" // for |NS_ASSERTION|
#include "nsISupportsUtils.h" // for |nsresult|, |NS_ADDREF|, |NS_GET_TEMPLATE_IID| et al
#include "nsCycleCollectionNoteChild.h"
/*
* 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
#define NSCAP_FEATURE_USE_BASE
#ifdef DEBUG
#define NSCAP_FEATURE_TEST_DONTQUERY_CASES
#undef NSCAP_FEATURE_USE_BASE
//#define NSCAP_FEATURE_TEST_NONNULL_QUERY_SUCCEEDS
#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
#if defined(NSCAP_DISABLE_DEBUG_PTR_TYPES)
#define NSCAP_FEATURE_USE_BASE
#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 {
namespace dom {
template<class T> class OwningNonNull;
} // namespace dom
} // 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 mozilla::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 nsQueryInterface final
{
public:
explicit
nsQueryInterface(nsISupports* aRawPtr) : mRawPtr(aRawPtr) {}
nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const;
private:
nsISupports* MOZ_OWNING_REF mRawPtr;
};
class nsQueryInterfaceWithError final
{
public:
nsQueryInterfaceWithError(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;
};
inline nsQueryInterface
do_QueryInterface(nsISupports* aRawPtr)
{
return nsQueryInterface(aRawPtr);
}
inline nsQueryInterfaceWithError
do_QueryInterface(nsISupports* aRawPtr, nsresult* aError)
{
return nsQueryInterfaceWithError(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;
};
/**
* Factors implementation for all template versions of nsCOMPtr.
*
* Here's the way people normally do things like this:
*
* template<class T> class Foo { ... };
* template<> class Foo<void*> { ... };
* template<class T> class Foo<T*> : private Foo<void*> { ... };
*/
class nsCOMPtr_base
{
public:
explicit nsCOMPtr_base(nsISupports* aRawPtr = 0) : mRawPtr(aRawPtr) {}
NS_CONSTRUCTOR_FASTCALL ~nsCOMPtr_base()
{
NSCAP_LOG_RELEASE(this, mRawPtr);
if (mRawPtr) {
NSCAP_RELEASE(this, mRawPtr);
}
}
void NS_FASTCALL
assign_with_AddRef(nsISupports*);
void NS_FASTCALL
assign_from_qi(const nsQueryInterface, const nsIID&);
void NS_FASTCALL
assign_from_qi_with_error(const nsQueryInterfaceWithError&, const nsIID&);
void NS_FASTCALL
assign_from_gs_cid(const nsGetServiceByCID, const nsIID&);
void NS_FASTCALL
assign_from_gs_cid_with_error(const nsGetServiceByCIDWithError&, const nsIID&);
void NS_FASTCALL
assign_from_gs_contractid(const nsGetServiceByContractID, const nsIID&);
void NS_FASTCALL
assign_from_gs_contractid_with_error(const nsGetServiceByContractIDWithError&,
const nsIID&);
void NS_FASTCALL
assign_from_helper(const nsCOMPtr_helper&, const nsIID&);
void** NS_FASTCALL
begin_assignment();
protected:
NS_MAY_ALIAS_PTR(nsISupports) MOZ_OWNING_REF mRawPtr;
void assign_assuming_AddRef(nsISupports* aNewPtr)
{
// |AddRef()|ing the new value (before entering this function) before
// |Release()|ing the old lets us safely ignore the self-assignment case.
// We must, however, be careful only to |Release()| _after_ doing the
// assignment, in case the |Release()| leads to our _own_ destruction,
// which would, in turn, cause an incorrect second |Release()| of our old
// pointer. Thank <waterson@netscape.com> for discovering this.
nsISupports* oldPtr = mRawPtr;
mRawPtr = aNewPtr;
NSCAP_LOG_ASSIGNMENT(this, aNewPtr);
NSCAP_LOG_RELEASE(this, oldPtr);
if (oldPtr) {
NSCAP_RELEASE(this, oldPtr);
}
}
};
// template<class T> class nsGetterAddRefs;
template<class T>
class nsCOMPtr final
#ifdef NSCAP_FEATURE_USE_BASE
: private nsCOMPtr_base
#endif
{
#ifdef NSCAP_FEATURE_USE_BASE
#define NSCAP_CTOR_BASE(x) nsCOMPtr_base(x)
#else
#define NSCAP_CTOR_BASE(x) mRawPtr(x)
private:
void assign_with_AddRef(nsISupports*);
void assign_from_qi(const nsQueryInterface, const nsIID&);
void assign_from_qi_with_error(const nsQueryInterfaceWithError&, 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_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;
#endif
public:
typedef T element_type;
#ifndef NSCAP_FEATURE_USE_BASE
~nsCOMPtr()
{
NSCAP_LOG_RELEASE(this, mRawPtr);
if (mRawPtr) {
NSCAP_RELEASE(this, mRawPtr);
}
}
#endif
#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
void Assert_NoQueryNeeded()
{
if (mRawPtr) {
nsCOMPtr<T> query_result(do_QueryInterface(mRawPtr));
NS_ASSERTION(query_result.get() == mRawPtr, "QueryInterface needed");
}
}
#define NSCAP_ASSERT_NO_QUERY_NEEDED() Assert_NoQueryNeeded();
#else
#define NSCAP_ASSERT_NO_QUERY_NEEDED()
#endif
// Constructors
nsCOMPtr()
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
}
nsCOMPtr(const nsCOMPtr<T>& aSmartPtr)
: NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
{
if (mRawPtr) {
NSCAP_ADDREF(this, mRawPtr);
}
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
}
MOZ_IMPLICIT nsCOMPtr(T* aRawPtr)
: NSCAP_CTOR_BASE(aRawPtr)
{
if (mRawPtr) {
NSCAP_ADDREF(this, mRawPtr);
}
NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>& aSmartPtr)
: NSCAP_CTOR_BASE(aSmartPtr.take())
{
NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Construct from |otherComPtr.forget()|.
MOZ_IMPLICIT nsCOMPtr(already_AddRefed<T>&& aSmartPtr)
: NSCAP_CTOR_BASE(aSmartPtr.take())
{
NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Construct from |already_AddRefed|.
template<typename U>
MOZ_IMPLICIT nsCOMPtr(already_AddRefed<U>& aSmartPtr)
: NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
{
// But make sure that U actually inherits from T.
static_assert(mozilla::IsBaseOf<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)
: NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.take()))
{
// But make sure that U actually inherits from T.
static_assert(mozilla::IsBaseOf<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)|.
MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi(aQI, NS_GET_TEMPLATE_IID(T));
}
// Construct from |do_QueryInterface(expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi_with_error(aQI, NS_GET_TEMPLATE_IID(T));
}
// Construct from |do_GetService(cid_expr)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid(aGS, NS_GET_TEMPLATE_IID(T));
}
// Construct from |do_GetService(cid_expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid_with_error(aGS, NS_GET_TEMPLATE_IID(T));
}
// Construct from |do_GetService(contractid_expr)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid(aGS, NS_GET_TEMPLATE_IID(T));
}
// Construct from |do_GetService(contractid_expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid_with_error(aGS, 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)
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_helper(aHelper, NS_GET_TEMPLATE_IID(T));
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Defined in OwningNonNull.h
template<class U>
MOZ_IMPLICIT nsCOMPtr(const mozilla::dom::OwningNonNull<U>& aOther);
// Assignment operators
nsCOMPtr<T>& operator=(const nsCOMPtr<T>& aRhs)
{
assign_with_AddRef(aRhs.mRawPtr);
return *this;
}
nsCOMPtr<T>& operator=(T* aRhs)
{
assign_with_AddRef(aRhs);
NSCAP_ASSERT_NO_QUERY_NEEDED();
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(mozilla::IsBaseOf<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(mozilla::IsBaseOf<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 |do_QueryInterface(expr)|.
nsCOMPtr<T>& operator=(const nsQueryInterface aRhs)
{
assign_from_qi(aRhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
// Assign from |do_QueryInterface(expr, &rv)|.
nsCOMPtr<T>& operator=(const nsQueryInterfaceWithError& 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;
}
// 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;
}
// Defined in OwningNonNull.h
template<class U>
nsCOMPtr<T>& operator=(const mozilla::dom::OwningNonNull<U>& aOther);
// Exchange ownership with |aRhs|; can save a pair of refcount operations.
void swap(nsCOMPtr<T>& aRhs)
{
#ifdef NSCAP_FEATURE_USE_BASE
nsISupports* temp = aRhs.mRawPtr;
#else
T* temp = aRhs.mRawPtr;
#endif
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)
{
#ifdef NSCAP_FEATURE_USE_BASE
nsISupports* temp = aRhs;
#else
T* temp = aRhs;
#endif
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> forget()
{
T* temp = 0;
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 = 0;
}
// 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(); }
T* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
{
MOZ_ASSERT(mRawPtr != 0,
"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 != 0,
"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(0);
return reinterpret_cast<T**>(&mRawPtr);
#endif
}
};
/*
* Specializing nsCOMPtr for nsISupports allows us to use nsCOMPtr<nsISupports>
* the same way people use nsISupports* and void*, i.e., as a `catch-all'
* pointing to any valid [XP]COM interface. Otherwise, an nsCOMPtr<nsISupports>
* would only be able to point to the single [XP]COM-correct nsISupports
* instance within an object; extra querying ensues. Clients need to be able to
* pass around arbitrary interface pointers, without hassles, through
* intermediary code that doesn't know the exact type.
*/
template<>
class nsCOMPtr<nsISupports>
: private nsCOMPtr_base
{
public:
typedef nsISupports element_type;
// Constructors
nsCOMPtr()
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
}
nsCOMPtr(const nsCOMPtr<nsISupports>& aSmartPtr)
: nsCOMPtr_base(aSmartPtr.mRawPtr)
{
if (mRawPtr) {
NSCAP_ADDREF(this, mRawPtr);
}
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
}
MOZ_IMPLICIT nsCOMPtr(nsISupports* aRawPtr)
: nsCOMPtr_base(aRawPtr)
{
if (mRawPtr) {
NSCAP_ADDREF(this, mRawPtr);
}
NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
}
// Construct from |already_AddRefed|.
MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>& aSmartPtr)
: nsCOMPtr_base(aSmartPtr.take())
{
NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
}
// Construct from |otherComPtr.forget()|.
MOZ_IMPLICIT nsCOMPtr(already_AddRefed<nsISupports>&& aSmartPtr)
: nsCOMPtr_base(aSmartPtr.take())
{
NSCAP_LOG_ASSIGNMENT(this, mRawPtr);
}
// Construct from |do_QueryInterface(expr)|.
MOZ_IMPLICIT nsCOMPtr(const nsQueryInterface aQI)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi(aQI, NS_GET_IID(nsISupports));
}
// Construct from |do_QueryInterface(expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsQueryInterfaceWithError& aQI)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi_with_error(aQI, NS_GET_IID(nsISupports));
}
// Construct from |do_GetService(cid_expr)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCID aGS)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid(aGS, NS_GET_IID(nsISupports));
}
// Construct from |do_GetService(cid_expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByCIDWithError& aGS)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid_with_error(aGS, NS_GET_IID(nsISupports));
}
// Construct from |do_GetService(contractid_expr)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractID aGS)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid(aGS, NS_GET_IID(nsISupports));
}
// Construct from |do_GetService(contractid_expr, &rv)|.
MOZ_IMPLICIT nsCOMPtr(const nsGetServiceByContractIDWithError& aGS)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid_with_error(aGS, NS_GET_IID(nsISupports));
}
// And finally, anything else we might need to construct from can exploit
// the |nsCOMPtr_helper| facility
MOZ_IMPLICIT nsCOMPtr(const nsCOMPtr_helper& aHelper)
: nsCOMPtr_base(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_helper(aHelper, NS_GET_IID(nsISupports));
}
// Assignment operators
nsCOMPtr<nsISupports>& operator=(const nsCOMPtr<nsISupports>& aRhs)
{
assign_with_AddRef(aRhs.mRawPtr);
return *this;
}
nsCOMPtr<nsISupports>& operator=(nsISupports* aRhs)
{
assign_with_AddRef(aRhs);
return *this;
}
// Assign from |already_AddRefed|.
nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>& aRhs)
{
assign_assuming_AddRef(aRhs.take());
return *this;
}
// Assign from |otherComPtr.forget()|.
nsCOMPtr<nsISupports>& operator=(already_AddRefed<nsISupports>&& aRhs)
{
assign_assuming_AddRef(aRhs.take());
return *this;
}
// Assign from |do_QueryInterface(expr)|.
nsCOMPtr<nsISupports>& operator=(const nsQueryInterface aRhs)
{
assign_from_qi(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Assign from |do_QueryInterface(expr, &rv)|.
nsCOMPtr<nsISupports>& operator=(const nsQueryInterfaceWithError& aRhs)
{
assign_from_qi_with_error(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Assign from |do_GetService(cid_expr)|.
nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCID aRhs)
{
assign_from_gs_cid(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Assign from |do_GetService(cid_expr, &rv)|.
nsCOMPtr<nsISupports>& operator=(const nsGetServiceByCIDWithError& aRhs)
{
assign_from_gs_cid_with_error(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Assign from |do_GetService(contractid_expr)|.
nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractID aRhs)
{
assign_from_gs_contractid(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Assign from |do_GetService(contractid_expr, &rv)|.
nsCOMPtr<nsISupports>& operator=(const nsGetServiceByContractIDWithError& aRhs)
{
assign_from_gs_contractid_with_error(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// And finally, anything else we might need to assign from can exploit the
// nsCOMPtr_helper facility
nsCOMPtr<nsISupports>& operator=(const nsCOMPtr_helper& aRhs)
{
assign_from_helper(aRhs, NS_GET_IID(nsISupports));
return *this;
}
// Exchange ownership with |aRhs|; can save a pair of refcount operations.
void swap(nsCOMPtr<nsISupports>& aRhs)
{
nsISupports* 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;
}
// Exchange ownership with |aRhs|; can save a pair of refcount operations.
void swap(nsISupports*& aRhs)
{
nsISupports* temp = aRhs;
NSCAP_LOG_ASSIGNMENT(this, temp);
NSCAP_LOG_RELEASE(this, mRawPtr);
aRhs = mRawPtr;
mRawPtr = temp;
}
// Return the value of mRawPtr and null out mRawPtr. Useful for
// already_AddRefed return values.
already_AddRefed<nsISupports> forget()
{
nsISupports* temp = 0;
swap(temp);
return already_AddRefed<nsISupports>(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.
void forget(nsISupports** aRhs)
{
NS_ASSERTION(aRhs, "Null pointer passed to forget!");
*aRhs = 0;
swap(*aRhs);
}
// Other pointer operators
// Prefer the implicit conversion provided automatically by
// |operator nsISupports*() const|. Use |get()| to resolve ambiguity or to
// get a castable pointer.
nsISupports* get() const { return reinterpret_cast<nsISupports*>(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 nsISupports* () const { return get(); }
nsISupports* operator->() const MOZ_NO_ADDREF_RELEASE_ON_RETURN
{
MOZ_ASSERT(mRawPtr != 0,
"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<nsISupports>* get_address() { return this; }
const nsCOMPtr<nsISupports>* get_address() const { return this; }
public:
nsISupports& operator*() const
{
MOZ_ASSERT(mRawPtr != 0,
"You can't dereference a NULL nsCOMPtr with operator*().");
return *get();
}
nsISupports** StartAssignment()
{
#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
return reinterpret_cast<nsISupports**>(begin_assignment());
#else
assign_assuming_AddRef(0);
return reinterpret_cast<nsISupports**>(&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);
}
#ifndef NSCAP_FEATURE_USE_BASE
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>
void
nsCOMPtr<T>::assign_from_qi(const nsQueryInterface aQI, const nsIID& aIID)
{
void* newRawPtr;
if (NS_FAILED(aQI(aIID, &newRawPtr))) {
newRawPtr = 0;
}
assign_assuming_AddRef(static_cast<T*>(newRawPtr));
}
template<class T>
void
nsCOMPtr<T>::assign_from_qi_with_error(const nsQueryInterfaceWithError& aQI,
const nsIID& aIID)
{
void* newRawPtr;
if (NS_FAILED(aQI(aIID, &newRawPtr))) {
newRawPtr = 0;
}
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 = 0;
}
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 = 0;
}
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 = 0;
}
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 = 0;
}
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 = 0;
}
assign_assuming_AddRef(static_cast<T*>(newRawPtr));
}
template<class T>
void**
nsCOMPtr<T>::begin_assignment()
{
assign_assuming_AddRef(0);
union
{
T** mT;
void** mVoid;
} result;
result.mT = &mRawPtr;
return result.mVoid;
}
#endif
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 |0|
class NSCAP_Zero;
// Specifically to allow |smartPtr == 0|.
template<class T>
inline bool
operator==(const nsCOMPtr<T>& aLhs, NSCAP_Zero* aRhs)
{
return static_cast<const void*>(aLhs.get()) == reinterpret_cast<const void*>(aRhs);
}
// Specifically to allow |0 == smartPtr|.
template<class T>
inline bool
operator==(NSCAP_Zero* aLhs, const nsCOMPtr<T>& aRhs)
{
return reinterpret_cast<const void*>(aLhs) == static_cast<const void*>(aRhs.get());
}
// Specifically to allow |smartPtr != 0|.
template<class T>
inline bool
operator!=(const nsCOMPtr<T>& aLhs, NSCAP_Zero* aRhs)
{
return static_cast<const void*>(aLhs.get()) != reinterpret_cast<const void*>(aRhs);
}
// Specifically to allow |0 != smartPtr|.
template<class T>
inline bool
operator!=(NSCAP_Zero* aLhs, const nsCOMPtr<T>& aRhs)
{
return reinterpret_cast<const void*>(aLhs) != static_cast<const void*>(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);
}
#endif // !defined(nsCOMPtr_h___)
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