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gecko-dev/xpcom/glue/nsCOMPtr.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: NPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Netscape Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/NPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Scott Collins <scc@mozilla.org> (original author)
* L. David Baron <dbaron@dbaron.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the NPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the NPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#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
*/
// Wrapping includes can speed up compiles (see "Large Scale C++ Software Design")
#ifndef nsDebug_h___
#include "nsDebug.h"
// for |NS_PRECONDITION|
#endif
#ifndef nsISupportsUtils_h__
#include "nsISupportsUtils.h"
// for |nsresult|, |NS_ADDREF|, |NS_GET_IID| et al
#endif
#ifndef nscore_h___
#include "nscore.h"
// for |NS_..._CAST|, |NS_COM|
#endif
/*
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 NS_DEBUG
#define NSCAP_FEATURE_TEST_DONTQUERY_CASES
#undef NSCAP_FEATURE_USE_BASE
//#define NSCAP_FEATURE_TEST_NONNULL_QUERY_SUCCEEDS
#endif
/*
|...TEST_DONTQUERY_CASES| and |...DEBUG_PTR_TYPES| introduce some code that is
problematic on a select few of our platforms, e.g., QNX. Therefore, I'm providing
a mechanism by which these features can be explicitly disabled from the command-line.
*/
#ifdef NSCAP_DISABLE_TEST_DONTQUERY_CASES
#undef NSCAP_FEATURE_TEST_DONTQUERY_CASES
#endif
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
// 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
#ifdef HAVE_CPP_BOOL
typedef bool NSCAP_BOOL;
#else
typedef PRBool NSCAP_BOOL;
#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 "nsTraceRefcnt.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
/*
WARNING:
VC++4.2 is very picky. To compile under VC++4.2, the classes must be defined
in an order that satisfies:
nsDerivedSafe < nsCOMPtr
already_AddRefed < nsCOMPtr
nsCOMPtr < nsGetterAddRefs
The other compilers probably won't complain, so please don't reorder these
classes, on pain of breaking 4.2 compatibility.
*/
template <class T>
class nsDerivedSafe : public T
/*
No client should ever see or have to type the name of this class. It is the
artifact that makes it a compile-time error to call |AddRef| and |Release|
on a |nsCOMPtr|. DO NOT USE THIS TYPE DIRECTLY IN YOUR CODE.
See |nsCOMPtr::operator->|, |nsCOMPtr::operator*|, et al.
This type should be a nested class inside |nsCOMPtr<T>|.
*/
{
private:
#ifdef HAVE_CPP_ACCESS_CHANGING_USING
using T::AddRef;
using T::Release;
#else
nsrefcnt AddRef(void);
nsrefcnt Release(void);
#endif
#if !defined(AIX) && !defined(IRIX)
void operator delete( void*, size_t ); // NOT TO BE IMPLEMENTED
// declaring |operator delete| private makes calling delete on an interface pointer a compile error
#endif
nsDerivedSafe<T>& operator=( const T& ); // NOT TO BE IMPLEMENTED
// you may not call |operator=()| through a dereferenced |nsCOMPtr|, because you'd get the wrong one
/*
Compiler warnings and errors: nsDerivedSafe operator=() hides inherited operator=().
If you see that, that means somebody checked in a [XP]COM interface class that declares an
|operator=()|, and that's _bad_. So bad, in fact, that this declaration exists explicitly
to stop people from doing it.
*/
protected:
nsDerivedSafe(); // NOT TO BE IMPLEMENTED
/*
This ctor exists to avoid compile errors and warnings about nsDeriviedSafe using the
default ctor but inheriting classes without an empty ctor. See bug 209667.
*/
};
#if !defined(HAVE_CPP_ACCESS_CHANGING_USING) && defined(NEED_CPP_UNUSED_IMPLEMENTATIONS)
template <class T>
nsrefcnt
nsDerivedSafe<T>::AddRef()
{
return 0;
}
template <class T>
nsrefcnt
nsDerivedSafe<T>::Release()
{
return 0;
}
#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|.
*/
{
already_AddRefed( T* aRawPtr )
: mRawPtr(aRawPtr)
{
// nothing else to do here
}
T* get() const { return mRawPtr; }
T* mRawPtr;
};
template <class T>
inline
const already_AddRefed<T>
getter_AddRefs( T* aRawPtr )
/*
...makes typing easier, because it deduces the template type, e.g.,
you write |dont_AddRef(fooP)| instead of |already_AddRefed<IFoo>(fooP)|.
*/
{
return already_AddRefed<T>(aRawPtr);
}
template <class T>
inline
const already_AddRefed<T>
getter_AddRefs( const already_AddRefed<T> aAlreadyAddRefedPtr )
{
return aAlreadyAddRefedPtr;
}
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 nsQueryInterface| for an example.
*/
{
public:
virtual nsresult operator()( const nsIID&, void** ) const = 0;
};
class NS_COM nsQueryInterface : public nsCOMPtr_helper
{
public:
nsQueryInterface( nsISupports* aRawPtr, nsresult* error )
: mRawPtr(aRawPtr),
mErrorPtr(error)
{
// nothing else to do here
}
virtual nsresult operator()( const nsIID& aIID, void** ) const;
private:
nsISupports* mRawPtr;
nsresult* mErrorPtr;
};
inline
const nsQueryInterface
do_QueryInterface( nsISupports* aRawPtr, nsresult* error = 0 )
{
return nsQueryInterface(aRawPtr, error);
}
template <class T>
inline
void
do_QueryInterface( already_AddRefed<T>& )
{
// This signature exists soley 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 soley 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>.
}
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 ~nsCOMPtr_base();
NS_COM void assign_with_AddRef( nsISupports* );
NS_COM void assign_from_helper( const nsCOMPtr_helper&, const nsIID& );
NS_COM void** 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
#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_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();
}
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_IID(T));
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
// For debug only --- this particular helper doesn't need to do the
// |NSCAP_ASSERT_NO_QUERY_NEEDED()| test. In fact, with the logging
// changes, skipping the query test prevents infinite recursion.
nsCOMPtr( const nsQueryInterface& helper )
: NSCAP_CTOR_BASE(0)
{
NSCAP_LOG_ASSIGNMENT(this, 0);
assign_from_helper(helper, NS_GET_IID(T));
}
#endif
// 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;
}
nsCOMPtr<T>&
operator=( const already_AddRefed<T>& rhs )
// assign from |dont_AddRef(expr)|
{
assign_assuming_AddRef(rhs.mRawPtr);
NSCAP_ASSERT_NO_QUERY_NEEDED();
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_IID(T));
NSCAP_ASSERT_NO_QUERY_NEEDED();
return *this;
}
#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
// For debug only --- this particular helper doesn't need to do the
// |NSCAP_ASSERT_NO_QUERY_NEEDED()| test. In fact, with the logging
// changes, skipping the query test prevents infinite recursion.
nsCOMPtr<T>&
operator=( const nsQueryInterface& rhs )
{
assign_from_helper(rhs, NS_GET_IID(T));
return *this;
}
#endif
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 = NS_REINTERPRET_CAST(T*, mRawPtr);
mRawPtr = temp;
NSCAP_ASSERT_NO_QUERY_NEEDED();
}
// Other pointer operators
nsDerivedSafe<T>*
get() const
/*
Prefer the implicit conversion provided automatically by |operator nsDerivedSafe<T>*() const|.
Use |get()| _only_ to resolve ambiguity.
Returns a |nsDerivedSafe<T>*| to deny clients the use of |AddRef| and |Release|.
*/
{
return NS_REINTERPRET_CAST(nsDerivedSafe<T>*, mRawPtr);
}
operator nsDerivedSafe<T>*() const
/*
...makes an |nsCOMPtr| act like its underlying raw pointer type (except against |AddRef()|, |Release()|,
and |delete|) 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();
}
nsDerivedSafe<T>*
operator->() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator->().");
return get();
}
#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
// broken version for IRIX
nsCOMPtr<T>*
get_address() const
// This is not intended to be used by clients. See |address_of|
// below.
{
return NS_CONST_CAST(nsCOMPtr<T>*, this);
}
#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
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;
}
#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
public:
nsDerivedSafe<T>&
operator*() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator*().");
return *get();
}
#if 0
private:
friend class nsGetterAddRefs<T>;
#endif
T**
StartAssignment()
{
#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
return NS_REINTERPRET_CAST(T**, begin_assignment());
#else
assign_assuming_AddRef(0);
return NS_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.
*/
NS_SPECIALIZE_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 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 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;
}
// Other pointer operators
nsDerivedSafe<nsISupports>*
get() const
/*
Prefer the implicit conversion provided automatically by |operator nsDerivedSafe<nsISupports>*() const|.
Use |get()| _only_ to resolve ambiguity.
Returns a |nsDerivedSafe<nsISupports>*| to deny clients the use of |AddRef| and |Release|.
*/
{
return NS_REINTERPRET_CAST(nsDerivedSafe<nsISupports>*, mRawPtr);
}
operator nsDerivedSafe<nsISupports>*() const
/*
...makes an |nsCOMPtr| act like its underlying raw pointer type (except against |AddRef()|, |Release()|,
and |delete|) 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();
}
nsDerivedSafe<nsISupports>*
operator->() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator->().");
return get();
}
#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
// broken version for IRIX
nsCOMPtr<nsISupports>*
get_address() const
// This is not intended to be used by clients. See |address_of|
// below.
{
return NS_CONST_CAST(nsCOMPtr<nsISupports>*, this);
}
#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
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;
}
#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
public:
nsDerivedSafe<nsISupports>&
operator*() const
{
NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator*().");
return *get();
}
#if 0
private:
friend class nsGetterAddRefs<nsISupports>;
#endif
nsISupports**
StartAssignment()
{
#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
return NS_REINTERPRET_CAST(nsISupports**, begin_assignment());
#else
assign_assuming_AddRef(0);
return NS_REINTERPRET_CAST(nsISupports**, &mRawPtr);
#endif
}
};
#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(NS_REINTERPRET_CAST(T*, rawPtr));
}
template <class T>
void
nsCOMPtr<T>::assign_from_helper( const nsCOMPtr_helper& helper, const nsIID& aIID )
{
T* newRawPtr;
if ( NS_FAILED( helper(aIID, NS_REINTERPRET_CAST(void**, &newRawPtr)) ) )
newRawPtr = 0;
assign_assuming_AddRef(newRawPtr);
}
template <class T>
void**
nsCOMPtr<T>::begin_assignment()
{
assign_assuming_AddRef(0);
return NS_REINTERPRET_CAST(void**, &mRawPtr);
}
#endif
#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
// This is the broken version for IRIX, which can't handle the version below.
template <class T>
inline
nsCOMPtr<T>*
address_of( const nsCOMPtr<T>& aPtr )
{
return aPtr.get_address();
}
#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
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();
}
#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
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(NS_REINTERPRET_CAST(void *, address_of(mTargetSmartPtr)), mTargetSmartPtr.get());
#endif
#ifdef NSCAP_FEATURE_TEST_DONTQUERY_CASES
mTargetSmartPtr.Assert_NoQueryNeeded();
#endif
}
#endif
operator void**()
{
return NS_REINTERPRET_CAST(void**, mTargetSmartPtr.StartAssignment());
}
operator nsISupports**()
{
return NS_REINTERPRET_CAST(nsISupports**, mTargetSmartPtr.StartAssignment());
}
operator T**()
{
return mTargetSmartPtr.StartAssignment();
}
T*&
operator*()
{
return *(mTargetSmartPtr.StartAssignment());
}
private:
nsCOMPtr<T>& mTargetSmartPtr;
};
NS_SPECIALIZE_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(NS_REINTERPRET_CAST(void *, address_of(mTargetSmartPtr)), mTargetSmartPtr.get());
}
#endif
operator void**()
{
return NS_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);
}
// Comparing two |nsCOMPtr|s
template <class T, class U>
inline
NSCAP_BOOL
operator==( const nsCOMPtr<T>& lhs, const nsCOMPtr<U>& rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) == NS_STATIC_CAST(const U*, rhs.get());
}
template <class T, class U>
inline
NSCAP_BOOL
operator!=( const nsCOMPtr<T>& lhs, const nsCOMPtr<U>& rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) != NS_STATIC_CAST(const U*, rhs.get());
}
// Comparing an |nsCOMPtr| to a raw pointer
template <class T, class U>
inline
NSCAP_BOOL
operator==( const nsCOMPtr<T>& lhs, const U* rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) == rhs;
}
template <class T, class U>
inline
NSCAP_BOOL
operator==( const U* lhs, const nsCOMPtr<T>& rhs )
{
return lhs == NS_STATIC_CAST(const T*, rhs.get());
}
template <class T, class U>
inline
NSCAP_BOOL
operator!=( const nsCOMPtr<T>& lhs, const U* rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) != rhs;
}
template <class T, class U>
inline
NSCAP_BOOL
operator!=( const U* lhs, const nsCOMPtr<T>& rhs )
{
return lhs != NS_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.
// This is defined by an autoconf test, but VC++ also has a bug that
// prevents us from using these. (It also, fortunately, has the bug
// that we don't need them either.)
#if defined(_MSC_VER) && (_MSC_VER < 1310)
#define NSCAP_DONT_PROVIDE_NONCONST_OPEQ
#endif
#ifndef NSCAP_DONT_PROVIDE_NONCONST_OPEQ
template <class T, class U>
inline
NSCAP_BOOL
operator==( const nsCOMPtr<T>& lhs, U* rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) == NS_CONST_CAST(const U*, rhs);
}
template <class T, class U>
inline
NSCAP_BOOL
operator==( U* lhs, const nsCOMPtr<T>& rhs )
{
return NS_CONST_CAST(const U*, lhs) == NS_STATIC_CAST(const T*, rhs.get());
}
template <class T, class U>
inline
NSCAP_BOOL
operator!=( const nsCOMPtr<T>& lhs, U* rhs )
{
return NS_STATIC_CAST(const T*, lhs.get()) != NS_CONST_CAST(const U*, rhs);
}
template <class T, class U>
inline
NSCAP_BOOL
operator!=( U* lhs, const nsCOMPtr<T>& rhs )
{
return NS_CONST_CAST(const U*, lhs) != NS_STATIC_CAST(const T*, rhs.get());
}
#endif
// Comparing an |nsCOMPtr| to |0|
class NSCAP_Zero;
template <class T>
inline
NSCAP_BOOL
operator==( const nsCOMPtr<T>& lhs, NSCAP_Zero* rhs )
// specifically to allow |smartPtr == 0|
{
return NS_STATIC_CAST(const void*, lhs.get()) == NS_REINTERPRET_CAST(const void*, rhs);
}
template <class T>
inline
NSCAP_BOOL
operator==( NSCAP_Zero* lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 == smartPtr|
{
return NS_REINTERPRET_CAST(const void*, lhs) == NS_STATIC_CAST(const void*, rhs.get());
}
template <class T>
inline
NSCAP_BOOL
operator!=( const nsCOMPtr<T>& lhs, NSCAP_Zero* rhs )
// specifically to allow |smartPtr != 0|
{
return NS_STATIC_CAST(const void*, lhs.get()) != NS_REINTERPRET_CAST(const void*, rhs);
}
template <class T>
inline
NSCAP_BOOL
operator!=( NSCAP_Zero* lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 != smartPtr|
{
return NS_REINTERPRET_CAST(const void*, lhs) != NS_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
NSCAP_BOOL
operator==( const nsCOMPtr<T>& lhs, int rhs )
// specifically to allow |smartPtr == 0|
{
return NS_STATIC_CAST(const void*, lhs.get()) == NS_REINTERPRET_CAST(const void*, rhs);
}
template <class T>
inline
NSCAP_BOOL
operator==( int lhs, const nsCOMPtr<T>& rhs )
// specifically to allow |0 == smartPtr|
{
return NS_REINTERPRET_CAST(const void*, lhs) == NS_STATIC_CAST(const void*, rhs.get());
}
#endif // !defined(HAVE_CPP_TROUBLE_COMPARING_TO_ZERO)
// Comparing any two [XP]COM objects for identity
inline
NSCAP_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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