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gecko/xpcom/glue/nsCOMPtr.h
L. David Baron 4f04bcdc57 Bug 976350 patch 1: Move the contents of nsTraceRefcnt.h into nsISupportsImpl.h. r=bsmedberg 
This makes sense since the file no longer contains anything with the
nsTraceRefcnt name in it, and it will allow renaming nsTraceRefcntImpl
back to nsTraceRefcnt.
2014-02-26 13:36:35 -08:00

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/Attributes.h"
#include "mozilla/TypeTraits.h"
#include "mozilla/Assertions.h"
#include "mozilla/NullPtr.h"
// Wrapping includes can speed up compiles (see "Large Scale C++ Software Design")
#ifndef nsDebug_h___
#include "nsDebug.h"
// for |NS_ABORT_IF_FALSE|, |NS_ASSERTION|
#endif
#ifndef nsISupportsUtils_h__
#include "nsISupportsUtils.h"
// for |nsresult|, |NS_ADDREF|, |NS_GET_TEMPLATE_IID| et al
#endif
#ifndef nscore_h___
#include "nscore.h"
// for |NS_COM_GLUE|
#endif
#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
#define NSCAP_FEATURE_INLINE_STARTASSIGNMENT
// under VC++, we win by inlining 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
template <class T>
struct already_AddRefed
/*
...cooperates with |nsCOMPtr| to allow you to assign in a pointer _without_
|AddRef|ing it. You might want to use this as a return type from a function
that produces an already |AddRef|ed pointer as a result.
See also |getter_AddRefs()|, |dont_AddRef()|, and |class nsGetterAddRefs|.
This type should be a nested class inside |nsCOMPtr<T>|.
Yes, |already_AddRefed| could have been implemented as an |nsCOMPtr_helper| to
avoid adding specialized machinery to |nsCOMPtr| ... but this is the simplest
case, and perhaps worth the savings in time and space that its specific
implementation affords over the more general solution offered by
|nsCOMPtr_helper|.
*/
{
/*
* Prohibit all one-argument overloads but already_AddRefed(T*) and
* already_AddRefed(decltype(nullptr)), and funnel the nullptr case through
* the T* constructor.
*/
template<typename N>
already_AddRefed(N,
typename mozilla::EnableIf<mozilla::IsNullPointer<N>::value,
int>::Type dummy = 0)
: mRawPtr(nullptr)
{
// nothing else to do here
}
already_AddRefed( T* aRawPtr )
: mRawPtr(aRawPtr)
{
// nothing else to do here
}
T* get() const { return mRawPtr; }
/**
* This helper is useful in cases like
*
* already_AddRefed<BaseClass>
* Foo()
* {
* nsRefPtr<SubClass> x = ...;
* return x.forget();
* }
*
* The autoconversion allows one to omit the idiom
*
* nsRefPtr<BaseClass> y = x.forget();
* return y.forget();
*/
template<class U>
operator already_AddRefed<U>()
{
U* tmp = mRawPtr;
mRawPtr = nullptr;
return already_AddRefed<U>(tmp);
}
/**
* This helper provides a static_cast replacement for already_AddRefed, so
* if you have
*
* already_AddRefed<Parent> F();
*
* you can write
*
* already_AddRefed<Child>
* G()
* {
* return F().downcast<Child>();
* }
*
* instead of
*
* return dont_AddRef(static_cast<Child*>(F().get()));
*/
template<class U>
already_AddRefed<U> downcast()
{
U* tmp = static_cast<U*>(mRawPtr);
mRawPtr = nullptr;
return already_AddRefed<U>(tmp);
}
T* mRawPtr;
};
template <class T>
inline
const already_AddRefed<T>
dont_AddRef( T* aRawPtr )
{
return already_AddRefed<T>(aRawPtr);
}
template <class T>
inline
const already_AddRefed<T>
dont_AddRef( const already_AddRefed<T> aAlreadyAddRefedPtr )
{
return aAlreadyAddRefedPtr;
}
class nsCOMPtr_helper
/*
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.
*/
{
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
NS_COM_GLUE
MOZ_STACK_CLASS
nsQueryInterface MOZ_FINAL
{
public:
explicit
nsQueryInterface( nsISupports* aRawPtr )
: mRawPtr(aRawPtr)
{
// nothing else to do here
}
nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const;
private:
nsISupports* mRawPtr;
};
class NS_COM_GLUE nsQueryInterfaceWithError
{
public:
nsQueryInterfaceWithError( nsISupports* aRawPtr, nsresult* error )
: mRawPtr(aRawPtr),
mErrorPtr(error)
{
// nothing else to do here
}
nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const;
private:
nsISupports* mRawPtr;
nsresult* mErrorPtr;
};
inline
nsQueryInterface
do_QueryInterface( nsISupports* aRawPtr )
{
return nsQueryInterface(aRawPtr);
}
inline
nsQueryInterfaceWithError
do_QueryInterface( nsISupports* aRawPtr, nsresult* error )
{
return nsQueryInterfaceWithError(aRawPtr, error);
}
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 <http://bugzilla.mozilla.org/show_bug.cgi?id=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 <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
}
////////////////////////////////////////////////////////////////////////////
// Using servicemanager with COMPtrs
class NS_COM_GLUE nsGetServiceByCID
{
public:
explicit nsGetServiceByCID(const nsCID& aCID)
: mCID(aCID)
{
// nothing else to do
}
nsresult NS_FASTCALL operator()( const nsIID&, void** ) const;
private:
const nsCID& mCID;
};
class NS_COM_GLUE nsGetServiceByCIDWithError
{
public:
nsGetServiceByCIDWithError( const nsCID& aCID, nsresult* aErrorPtr )
: mCID(aCID),
mErrorPtr(aErrorPtr)
{
// nothing else to do
}
nsresult NS_FASTCALL operator()( const nsIID&, void** ) const;
private:
const nsCID& mCID;
nsresult* mErrorPtr;
};
class NS_COM_GLUE nsGetServiceByContractID
{
public:
explicit nsGetServiceByContractID(const char* aContractID)
: mContractID(aContractID)
{
// nothing else to do
}
nsresult NS_FASTCALL operator()( const nsIID&, void** ) const;
private:
const char* mContractID;
};
class NS_COM_GLUE nsGetServiceByContractIDWithError
{
public:
nsGetServiceByContractIDWithError(const char* aContractID, nsresult* aErrorPtr)
: mContractID(aContractID),
mErrorPtr(aErrorPtr)
{
// nothing else to do
}
nsresult NS_FASTCALL operator()( const nsIID&, void** ) const;
private:
const char* mContractID;
nsresult* mErrorPtr;
};
class
nsCOMPtr_base
/*
...factors implementation for all template versions of |nsCOMPtr|.
This should really be an |nsCOMPtr<nsISupports>|, but this wouldn't work
because unlike the
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*> { ... };
*/
{
public:
nsCOMPtr_base( nsISupports* rawPtr = 0 )
: mRawPtr(rawPtr)
{
// nothing else to do here
}
NS_COM_GLUE NS_CONSTRUCTOR_FASTCALL ~nsCOMPtr_base()
{
NSCAP_LOG_RELEASE(this, mRawPtr);
if ( mRawPtr )
NSCAP_RELEASE(this, mRawPtr);
}
NS_COM_GLUE void NS_FASTCALL assign_with_AddRef( nsISupports* );
NS_COM_GLUE void NS_FASTCALL assign_from_qi( const nsQueryInterface, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_qi_with_error( const nsQueryInterfaceWithError&, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_gs_cid( const nsGetServiceByCID, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_gs_cid_with_error( const nsGetServiceByCIDWithError&, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_gs_contractid( const nsGetServiceByContractID, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_gs_contractid_with_error( const nsGetServiceByContractIDWithError&, const nsIID& );
NS_COM_GLUE void NS_FASTCALL assign_from_helper( const nsCOMPtr_helper&, const nsIID& );
NS_COM_GLUE void** NS_FASTCALL begin_assignment();
protected:
NS_MAY_ALIAS_PTR(nsISupports) mRawPtr;
void
assign_assuming_AddRef( nsISupports* newPtr )
{
/*
|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 = newPtr;
NSCAP_LOG_ASSIGNMENT(this, newPtr);
NSCAP_LOG_RELEASE(this, oldPtr);
if ( oldPtr )
NSCAP_RELEASE(this, oldPtr);
}
};
// template <class T> class nsGetterAddRefs;
template <class T>
class nsCOMPtr MOZ_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* newPtr )
{
T* oldPtr = mRawPtr;
mRawPtr = newPtr;
NSCAP_LOG_ASSIGNMENT(this, newPtr);
NSCAP_LOG_RELEASE(this, oldPtr);
if ( oldPtr )
NSCAP_RELEASE(this, oldPtr);
}
private:
T* 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)
// default constructor
{
NSCAP_LOG_ASSIGNMENT(this, 0);
}
nsCOMPtr( const nsCOMPtr<T>& aSmartPtr )
: NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
// copy-constructor
{
if ( mRawPtr )
NSCAP_ADDREF(this, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
}
nsCOMPtr( T* aRawPtr )
: NSCAP_CTOR_BASE(aRawPtr)
// construct from a raw pointer (of the right type)
{
if ( mRawPtr )
NSCAP_ADDREF(this, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
nsCOMPtr( const already_AddRefed<T>& aSmartPtr )
: NSCAP_CTOR_BASE(aSmartPtr.mRawPtr)
// construct from |dont_AddRef(expr)|
{
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
template<typename U>
nsCOMPtr( const already_AddRefed<U>& aSmartPtr )
: NSCAP_CTOR_BASE(static_cast<T*>(aSmartPtr.mRawPtr))
// construct from |dont_AddRef(expr)|
{
// 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*>(aSmartPtr.mRawPtr));
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
nsCOMPtr( const nsQueryInterface qi )
: NSCAP_CTOR_BASE(0)
// construct from |do_QueryInterface(expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi(qi, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsQueryInterfaceWithError& qi )
: NSCAP_CTOR_BASE(0)
// construct from |do_QueryInterface(expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi_with_error(qi, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsGetServiceByCID gs )
: NSCAP_CTOR_BASE(0)
// construct from |do_GetService(cid_expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid(gs, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsGetServiceByCIDWithError& gs )
: NSCAP_CTOR_BASE(0)
// construct from |do_GetService(cid_expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid_with_error(gs, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsGetServiceByContractID gs )
: NSCAP_CTOR_BASE(0)
// construct from |do_GetService(contractid_expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid(gs, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsGetServiceByContractIDWithError& gs )
: NSCAP_CTOR_BASE(0)
// construct from |do_GetService(contractid_expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid_with_error(gs, NS_GET_TEMPLATE_IID(T));
}
nsCOMPtr( const nsCOMPtr_helper& helper )
: NSCAP_CTOR_BASE(0)
// ...and finally, anything else we might need to construct from
// can exploit the |nsCOMPtr_helper| facility
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_helper(helper, NS_GET_TEMPLATE_IID(T));
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Assignment operators
nsCOMPtr<T>&
operator=( const nsCOMPtr<T>& rhs )
// copy assignment operator
{
assign_with_AddRef(rhs.mRawPtr);
return *this;
}
nsCOMPtr<T>&
operator=( T* rhs )
// assign from a raw pointer (of the right type)
{
assign_with_AddRef(rhs);
NSCAP_ASSERT_NO_QUERY_NEEDED();
return *this;
}
template<typename U>
nsCOMPtr<T>&
operator=( const already_AddRefed<U>& rhs )
// assign from |dont_AddRef(expr)|
{
// 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*>(rhs.mRawPtr));
NSCAP_ASSERT_NO_QUERY_NEEDED();
return *this;
}
nsCOMPtr<T>&
operator=( const nsQueryInterface rhs )
// assign from |do_QueryInterface(expr)|
{
assign_from_qi(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsQueryInterfaceWithError& rhs )
// assign from |do_QueryInterface(expr, &rv)|
{
assign_from_qi_with_error(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsGetServiceByCID rhs )
// assign from |do_GetService(cid_expr)|
{
assign_from_gs_cid(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsGetServiceByCIDWithError& rhs )
// assign from |do_GetService(cid_expr, &rv)|
{
assign_from_gs_cid_with_error(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsGetServiceByContractID rhs )
// assign from |do_GetService(contractid_expr)|
{
assign_from_gs_contractid(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsGetServiceByContractIDWithError& rhs )
// assign from |do_GetService(contractid_expr, &rv)|
{
assign_from_gs_contractid_with_error(rhs, NS_GET_TEMPLATE_IID(T));
return *this;
}
nsCOMPtr<T>&
operator=( const nsCOMPtr_helper& rhs )
// ...and finally, anything else we might need to assign from
// can exploit the |nsCOMPtr_helper| facility.
{
assign_from_helper(rhs, NS_GET_TEMPLATE_IID(T));
NSCAP_ASSERT_NO_QUERY_NEEDED();
return *this;
}
void
swap( nsCOMPtr<T>& rhs )
// ...exchange ownership with |rhs|; can save a pair of refcount operations
{
#ifdef NSCAP_FEATURE_USE_BASE
nsISupports* temp = rhs.mRawPtr;
#else
T* temp = rhs.mRawPtr;
#endif
NSCAP_LOG_ASSIGNMENT(&rhs, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, temp);
NSCAP_LOG_RELEASE(this, mRawPtr);
NSCAP_LOG_RELEASE(&rhs, temp);
rhs.mRawPtr = mRawPtr;
mRawPtr = temp;
// |rhs| maintains the same invariants, so we don't need to |NSCAP_ASSERT_NO_QUERY_NEEDED|
}
void
swap( T*& rhs )
// ...exchange ownership with |rhs|; can save a pair of refcount operations
{
#ifdef NSCAP_FEATURE_USE_BASE
nsISupports* temp = rhs;
#else
T* temp = rhs;
#endif
NSCAP_LOG_ASSIGNMENT(this, temp);
NSCAP_LOG_RELEASE(this, mRawPtr);
rhs = reinterpret_cast<T*>(mRawPtr);
mRawPtr = temp;
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Other pointer operators
already_AddRefed<T>
forget()
// return the value of mRawPtr and null out mRawPtr. Useful for
// already_AddRefed return values.
{
T* temp = 0;
swap(temp);
return already_AddRefed<T>(temp);
}
template <typename I>
void
forget( I** rhs )
// Set the target of rhs to the value of mRawPtr and null out mRawPtr.
// Useful to avoid unnecessary AddRef/Release pairs with "out"
// parameters where rhs bay be a T** or an I** where I is a base class
// of T.
{
NS_ASSERTION(rhs, "Null pointer passed to forget!");
NSCAP_LOG_RELEASE(this, mRawPtr);
*rhs = get();
mRawPtr = 0;
}
T*
get() const
/*
Prefer the implicit conversion provided automatically by |operator T*() const|.
Use |get()| to resolve ambiguity or to get a castable pointer.
*/
{
return reinterpret_cast<T*>(mRawPtr);
}
operator T*() const
/*
...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.
*/
{
return get();
}
T*
operator->() const
{
NS_ABORT_IF_FALSE(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator->().");
return get();
}
nsCOMPtr<T>*
get_address()
// This is not intended to be used by clients. See |address_of|
// below.
{
return this;
}
const nsCOMPtr<T>*
get_address() const
// This is not intended to be used by clients. See |address_of|
// below.
{
return this;
}
public:
T&
operator*() const
{
NS_ABORT_IF_FALSE(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' pointer 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)
// default constructor
{
NSCAP_LOG_ASSIGNMENT(this, 0);
}
nsCOMPtr( const nsCOMPtr<nsISupports>& aSmartPtr )
: nsCOMPtr_base(aSmartPtr.mRawPtr)
// copy constructor
{
if ( mRawPtr )
NSCAP_ADDREF(this, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
}
nsCOMPtr( nsISupports* aRawPtr )
: nsCOMPtr_base(aRawPtr)
// construct from a raw pointer (of the right type)
{
if ( mRawPtr )
NSCAP_ADDREF(this, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, aRawPtr);
}
nsCOMPtr( const already_AddRefed<nsISupports>& aSmartPtr )
: nsCOMPtr_base(aSmartPtr.mRawPtr)
// construct from |dont_AddRef(expr)|
{
NSCAP_LOG_ASSIGNMENT(this, aSmartPtr.mRawPtr);
}
nsCOMPtr( const nsQueryInterface qi )
: nsCOMPtr_base(0)
// assign from |do_QueryInterface(expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi(qi, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsQueryInterfaceWithError& qi )
: nsCOMPtr_base(0)
// assign from |do_QueryInterface(expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_qi_with_error(qi, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsGetServiceByCID gs )
: nsCOMPtr_base(0)
// assign from |do_GetService(cid_expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid(gs, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsGetServiceByCIDWithError& gs )
: nsCOMPtr_base(0)
// assign from |do_GetService(cid_expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_cid_with_error(gs, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsGetServiceByContractID gs )
: nsCOMPtr_base(0)
// assign from |do_GetService(contractid_expr)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid(gs, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsGetServiceByContractIDWithError& gs )
: nsCOMPtr_base(0)
// assign from |do_GetService(contractid_expr, &rv)|
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_gs_contractid_with_error(gs, NS_GET_IID(nsISupports));
}
nsCOMPtr( const nsCOMPtr_helper& helper )
: nsCOMPtr_base(0)
// ...and finally, anything else we might need to construct from
// can exploit the |nsCOMPtr_helper| facility
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_helper(helper, NS_GET_IID(nsISupports));
}
// Assignment operators
nsCOMPtr<nsISupports>&
operator=( const nsCOMPtr<nsISupports>& rhs )
// copy assignment operator
{
assign_with_AddRef(rhs.mRawPtr);
return *this;
}
nsCOMPtr<nsISupports>&
operator=( nsISupports* rhs )
// assign from a raw pointer (of the right type)
{
assign_with_AddRef(rhs);
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const already_AddRefed<nsISupports>& rhs )
// assign from |dont_AddRef(expr)|
{
assign_assuming_AddRef(rhs.mRawPtr);
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsQueryInterface rhs )
// assign from |do_QueryInterface(expr)|
{
assign_from_qi(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsQueryInterfaceWithError& rhs )
// assign from |do_QueryInterface(expr, &rv)|
{
assign_from_qi_with_error(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsGetServiceByCID rhs )
// assign from |do_GetService(cid_expr)|
{
assign_from_gs_cid(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsGetServiceByCIDWithError& rhs )
// assign from |do_GetService(cid_expr, &rv)|
{
assign_from_gs_cid_with_error(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsGetServiceByContractID rhs )
// assign from |do_GetService(contractid_expr)|
{
assign_from_gs_contractid(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsGetServiceByContractIDWithError& rhs )
// assign from |do_GetService(contractid_expr, &rv)|
{
assign_from_gs_contractid_with_error(rhs, NS_GET_IID(nsISupports));
return *this;
}
nsCOMPtr<nsISupports>&
operator=( const nsCOMPtr_helper& rhs )
// ...and finally, anything else we might need to assign from
// can exploit the |nsCOMPtr_helper| facility.
{
assign_from_helper(rhs, NS_GET_IID(nsISupports));
return *this;
}
void
swap( nsCOMPtr<nsISupports>& rhs )
// ...exchange ownership with |rhs|; can save a pair of refcount operations
{
nsISupports* temp = rhs.mRawPtr;
NSCAP_LOG_ASSIGNMENT(&rhs, mRawPtr);
NSCAP_LOG_ASSIGNMENT(this, temp);
NSCAP_LOG_RELEASE(this, mRawPtr);
NSCAP_LOG_RELEASE(&rhs, temp);
rhs.mRawPtr = mRawPtr;
mRawPtr = temp;
}
void
swap( nsISupports*& rhs )
// ...exchange ownership with |rhs|; can save a pair of refcount operations
{
nsISupports* temp = rhs;
NSCAP_LOG_ASSIGNMENT(this, temp);
NSCAP_LOG_RELEASE(this, mRawPtr);
rhs = mRawPtr;
mRawPtr = temp;
}
already_AddRefed<nsISupports>
forget()
// return the value of mRawPtr and null out mRawPtr. Useful for
// already_AddRefed return values.
{
nsISupports* temp = 0;
swap(temp);
return already_AddRefed<nsISupports>(temp);
}
void
forget( nsISupports** rhs )
// Set the target of rhs to the value of mRawPtr and null out mRawPtr.
// Useful to avoid unnecessary AddRef/Release pairs with "out"
// parameters.
{
NS_ASSERTION(rhs, "Null pointer passed to forget!");
*rhs = 0;
swap(*rhs);
}
// Other pointer operators
nsISupports*
get() const
/*
Prefer the implicit conversion provided automatically by
|operator nsISupports*() const|.
Use |get()| to resolve ambiguity or to get a castable pointer.
*/
{
return reinterpret_cast<nsISupports*>(mRawPtr);
}
operator nsISupports*() const
/*
...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.
*/
{
return get();
}
nsISupports*
operator->() const
{
NS_ABORT_IF_FALSE(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator->().");
return get();
}
nsCOMPtr<nsISupports>*
get_address()
// This is not intended to be used by clients. See |address_of|
// below.
{
return this;
}
const nsCOMPtr<nsISupports>*
get_address() const
// This is not intended to be used by clients. See |address_of|
// below.
{
return this;
}
public:
nsISupports&
operator*() const
{
NS_ABORT_IF_FALSE(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* rawPtr )
{
if ( rawPtr )
NSCAP_ADDREF(this, rawPtr);
assign_assuming_AddRef(reinterpret_cast<T*>(rawPtr));
}
template <class T>
void
nsCOMPtr<T>::assign_from_qi( const nsQueryInterface qi, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( qi(aIID, &newRawPtr) ) )
newRawPtr = 0;
assign_assuming_AddRef(static_cast<T*>(newRawPtr));
}
template <class T>
void
nsCOMPtr<T>::assign_from_qi_with_error( const nsQueryInterfaceWithError& qi, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( qi(aIID, &newRawPtr) ) )
newRawPtr = 0;
assign_assuming_AddRef(static_cast<T*>(newRawPtr));
}
template <class T>
void
nsCOMPtr<T>::assign_from_gs_cid( const nsGetServiceByCID gs, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( gs(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& gs, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( gs(aIID, &newRawPtr) ) )
newRawPtr = 0;
assign_assuming_AddRef(static_cast<T*>(newRawPtr));
}
template <class T>
void
nsCOMPtr<T>::assign_from_gs_contractid( const nsGetServiceByContractID gs, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( gs(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& gs, const nsIID& aIID )
{
void* newRawPtr;
if ( NS_FAILED( gs(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();
}
template <class T>
class nsGetterAddRefs
/*
...
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>|.
*/
{
public:
explicit
nsGetterAddRefs( nsCOMPtr<T>& aSmartPtr )
: mTargetSmartPtr(aSmartPtr)
{
// nothing else to do
}
#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 nsISupports**()
{
return reinterpret_cast<nsISupports**>(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)
{
// nothing else to do
}
#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 )
/*
Used around a |nsCOMPtr| when
...makes the class |nsGetterAddRefs<T>| invisible.
*/
{
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>& lhs, const nsCOMPtr<U>& rhs )
{
return static_cast<const T*>(lhs.get()) == static_cast<const U*>(rhs.get());
}
template <class T, class U>
inline
bool
operator!=( const nsCOMPtr<T>& lhs, const nsCOMPtr<U>& rhs )
{
return static_cast<const T*>(lhs.get()) != static_cast<const U*>(rhs.get());
}
// Comparing an |nsCOMPtr| to a raw pointer
template <class T, class U>
inline
bool
operator==( const nsCOMPtr<T>& lhs, const U* rhs )
{
return static_cast<const T*>(lhs.get()) == rhs;
}
template <class T, class U>
inline
bool
operator==( const U* lhs, const nsCOMPtr<T>& rhs )
{
return lhs == static_cast<const T*>(rhs.get());
}
template <class T, class U>
inline
bool
operator!=( const nsCOMPtr<T>& lhs, const U* rhs )
{
return static_cast<const T*>(lhs.get()) != rhs;
}
template <class T, class U>
inline
bool
operator!=( const U* lhs, const nsCOMPtr<T>& rhs )
{
return lhs != static_cast<const T*>(rhs.get());
}
// To avoid ambiguities caused by the presence of builtin |operator==|s
// creating a situation where one of the |operator==| defined above
// has a better conversion for one argument and the builtin has a
// better conversion for the other argument, define additional
// |operator==| without the |const| on the raw pointer.
// See bug 65664 for details.
#ifndef NSCAP_DONT_PROVIDE_NONCONST_OPEQ
template <class T, class U>
inline
bool
operator==( const nsCOMPtr<T>& lhs, U* rhs )
{
return static_cast<const T*>(lhs.get()) == const_cast<const U*>(rhs);
}
template <class T, class U>
inline
bool
operator==( U* lhs, const nsCOMPtr<T>& rhs )
{
return const_cast<const U*>(lhs) == static_cast<const T*>(rhs.get());
}
template <class T, class U>
inline
bool
operator!=( const nsCOMPtr<T>& lhs, U* rhs )
{
return static_cast<const T*>(lhs.get()) != const_cast<const U*>(rhs);
}
template <class T, class U>
inline
bool
operator!=( U* lhs, const nsCOMPtr<T>& rhs )
{
return const_cast<const U*>(lhs) != static_cast<const T*>(rhs.get());
}
#endif
// Comparing an |nsCOMPtr| to |0|
class NSCAP_Zero;
template <class T>
inline
bool
operator==( const nsCOMPtr<T>& lhs, NSCAP_Zero* rhs )
// specifically to allow |smartPtr == 0|
{
return static_cast<const void*>(lhs.get()) == reinterpret_cast<const void*>(rhs);
}
template <class T>
inline
bool
operator==( NSCAP_Zero* lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 == smartPtr|
{
return reinterpret_cast<const void*>(lhs) == static_cast<const void*>(rhs.get());
}
template <class T>
inline
bool
operator!=( const nsCOMPtr<T>& lhs, NSCAP_Zero* rhs )
// specifically to allow |smartPtr != 0|
{
return static_cast<const void*>(lhs.get()) != reinterpret_cast<const void*>(rhs);
}
template <class T>
inline
bool
operator!=( NSCAP_Zero* lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 != smartPtr|
{
return reinterpret_cast<const void*>(lhs) != static_cast<const void*>(rhs.get());
}
#ifdef HAVE_CPP_TROUBLE_COMPARING_TO_ZERO
// We need to explicitly define comparison operators for `int'
// because the compiler is lame.
template <class T>
inline
bool
operator==( const nsCOMPtr<T>& lhs, int rhs )
// specifically to allow |smartPtr == 0|
{
return static_cast<const void*>(lhs.get()) == reinterpret_cast<const void*>(rhs);
}
template <class T>
inline
bool
operator==( int lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 == smartPtr|
{
return reinterpret_cast<const void*>(lhs) == static_cast<const void*>(rhs.get());
}
#endif // !defined(HAVE_CPP_TROUBLE_COMPARING_TO_ZERO)
// Comparing any two [XP]COM objects for identity
inline
bool
SameCOMIdentity( nsISupports* lhs, nsISupports* rhs )
{
return nsCOMPtr<nsISupports>( do_QueryInterface(lhs) ) == nsCOMPtr<nsISupports>( do_QueryInterface(rhs) );
}
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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