mirror of
https://github.com/classilla/tenfourfox.git
synced 2024-09-10 11:54:40 +00:00
146 lines
5.2 KiB
C++
146 lines
5.2 KiB
C++
/* -*- 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 nsISupportsUtils_h__
|
|
#define nsISupportsUtils_h__
|
|
|
|
#include "nscore.h"
|
|
#include "nsISupportsBase.h"
|
|
#include "nsError.h"
|
|
#include "nsDebug.h"
|
|
#include "nsISupportsImpl.h"
|
|
#include "mozilla/RefPtr.h"
|
|
#include "mozilla/TypeTraits.h"
|
|
|
|
/**
|
|
* Macro for adding a reference to an interface.
|
|
* @param _ptr The interface pointer.
|
|
*/
|
|
#define NS_ADDREF(_ptr) \
|
|
(_ptr)->AddRef()
|
|
|
|
/**
|
|
* Macro for adding a reference to this. This macro should be used
|
|
* because NS_ADDREF (when tracing) may require an ambiguous cast
|
|
* from the pointers primary type to nsISupports. This macro sidesteps
|
|
* that entire problem.
|
|
*/
|
|
#define NS_ADDREF_THIS() \
|
|
AddRef()
|
|
|
|
|
|
// Making this a |inline| |template| allows |aExpr| to be evaluated only once,
|
|
// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
|
|
template<class T>
|
|
inline void
|
|
ns_if_addref(T aExpr)
|
|
{
|
|
if (aExpr) {
|
|
aExpr->AddRef();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Macro for adding a reference to an interface that checks for nullptr.
|
|
* @param _expr The interface pointer.
|
|
*/
|
|
#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
|
|
|
|
/*
|
|
* Given these declarations, it explicitly OK and efficient to end a `getter' with:
|
|
*
|
|
* NS_IF_ADDREF(*result = mThing);
|
|
*
|
|
* even if |mThing| is an |nsCOMPtr|. If |mThing| is an |nsCOMPtr|, however, it is still
|
|
* _illegal_ to say |NS_IF_ADDREF(mThing)|.
|
|
*/
|
|
|
|
/**
|
|
* Macro for releasing a reference to an interface.
|
|
* @param _ptr The interface pointer.
|
|
*/
|
|
#define NS_RELEASE(_ptr) \
|
|
do { \
|
|
(_ptr)->Release(); \
|
|
(_ptr) = 0; \
|
|
} while (0)
|
|
|
|
/**
|
|
* Macro for releasing a reference to this interface.
|
|
*/
|
|
#define NS_RELEASE_THIS() \
|
|
Release()
|
|
|
|
/**
|
|
* Macro for releasing a reference to an interface, except that this
|
|
* macro preserves the return value from the underlying Release call.
|
|
* The interface pointer argument will only be NULLed if the reference count
|
|
* goes to zero.
|
|
*
|
|
* @param _ptr The interface pointer.
|
|
* @param _rc The reference count.
|
|
*/
|
|
#define NS_RELEASE2(_ptr, _rc) \
|
|
do { \
|
|
_rc = (_ptr)->Release(); \
|
|
if (0 == (_rc)) (_ptr) = 0; \
|
|
} while (0)
|
|
|
|
/**
|
|
* Macro for releasing a reference to an interface that checks for nullptr;
|
|
* @param _ptr The interface pointer.
|
|
*/
|
|
#define NS_IF_RELEASE(_ptr) \
|
|
do { \
|
|
if (_ptr) { \
|
|
(_ptr)->Release(); \
|
|
(_ptr) = 0; \
|
|
} \
|
|
} while (0)
|
|
|
|
/*
|
|
* Often you have to cast an implementation pointer, e.g., |this|, to an
|
|
* |nsISupports*|, but because you have multiple inheritance, a simple cast
|
|
* is ambiguous. One could simply say, e.g., (given a base |nsIBase|),
|
|
* |static_cast<nsIBase*>(this)|; but that disguises the fact that what
|
|
* you are really doing is disambiguating the |nsISupports|. You could make
|
|
* that more obvious with a double cast, e.g., |static_cast<nsISupports*>
|
|
(* static_cast<nsIBase*>(this))|, but that is bulky and harder to read...
|
|
*
|
|
* The following macro is clean, short, and obvious. In the example above,
|
|
* you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
|
|
*/
|
|
|
|
#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
|
|
static_cast<nsISupports*>(static_cast<__unambiguousBase>(__expr))
|
|
|
|
// a type-safe shortcut for calling the |QueryInterface()| member function
|
|
template<class T, class DestinationType>
|
|
inline nsresult
|
|
CallQueryInterface(T* aSource, DestinationType** aDestination)
|
|
{
|
|
// We permit nsISupports-to-nsISupports here so that one can still obtain
|
|
// the canonical nsISupports pointer with CallQueryInterface.
|
|
static_assert(!mozilla::IsSame<T, DestinationType>::value ||
|
|
mozilla::IsSame<DestinationType, nsISupports>::value,
|
|
"don't use CallQueryInterface for compile-time-determinable casts");
|
|
|
|
NS_PRECONDITION(aSource, "null parameter");
|
|
NS_PRECONDITION(aDestination, "null parameter");
|
|
|
|
return aSource->QueryInterface(NS_GET_TEMPLATE_IID(DestinationType),
|
|
reinterpret_cast<void**>(aDestination));
|
|
}
|
|
|
|
template <class SourceType, class DestinationType>
|
|
inline nsresult
|
|
CallQueryInterface(RefPtr<SourceType>& aSourcePtr, DestinationType** aDestPtr)
|
|
{
|
|
return CallQueryInterface(aSourcePtr.get(), aDestPtr);
|
|
}
|
|
|
|
#endif /* __nsISupportsUtils_h */
|