| /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ |
| /* ***** BEGIN LICENSE BLOCK ***** |
| * Version: MPL 1.1/GPL 2.0/LGPL 2.1 |
| * |
| * The contents of this file are subject to the Mozilla 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/MPL/ |
| * |
| * 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): |
| * Pierre Phaneuf <pp@ludusdesign.com> |
| * Scott Collins <scc@ScottCollins.net> |
| * Dan Mosedale <dmose@mozilla.org> |
| * |
| * Alternatively, the contents of this file may be used under the terms of |
| * either of 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 MPL, 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 MPL, the GPL or the LGPL. |
| * |
| * ***** END LICENSE BLOCK ***** */ |
| |
| #ifndef nsISupportsUtils_h__ |
| #define nsISupportsUtils_h__ |
| |
| #ifndef nscore_h___ |
| #include "nscore.h" |
| #endif |
| |
| #ifndef nsISupportsBase_h__ |
| #include "nsISupportsBase.h" |
| #endif |
| |
| #ifndef nsError_h__ |
| #include "nsError.h" |
| #endif |
| |
| #ifndef nsDebug_h___ |
| #include "nsDebug.h" |
| #endif |
| |
| #ifndef nsISupportsImpl_h__ |
| #include "nsISupportsImpl.h" |
| #endif |
| |
| /** |
| * Macro for instantiating a new object that implements nsISupports. |
| * Note that you can only use this if you adhere to the no arguments |
| * constructor com policy (which you really should!). |
| * @param _result Where the new instance pointer is stored |
| * @param _type The type of object to call "new" with. |
| */ |
| #define NS_NEWXPCOM(_result,_type) \ |
| PR_BEGIN_MACRO \ |
| _result = new _type(); \ |
| PR_END_MACRO |
| |
| /** |
| * Macro for deleting an object that implements nsISupports. |
| * @param _ptr The object to delete. |
| */ |
| #define NS_DELETEXPCOM(_ptr) \ |
| PR_BEGIN_MACRO \ |
| delete (_ptr); \ |
| PR_END_MACRO |
| |
| /** |
| * 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() |
| |
| |
| extern "C++" { |
| // ...because some one is accidentally including this file inside |
| // an |extern "C"| |
| |
| |
| // Making this a |inline| |template| allows |expr| to be evaluated only once, |
| // yet still denies you the ability to |AddRef()| an |nsCOMPtr|. |
| template <class T> |
| inline |
| nsrefcnt |
| ns_if_addref( T expr ) |
| { |
| return expr ? expr->AddRef() : 0; |
| } |
| |
| } /* extern "C++" */ |
| |
| /** |
| * Macro for adding a reference to an interface that checks for NULL. |
| * @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) \ |
| PR_BEGIN_MACRO \ |
| (_ptr)->Release(); \ |
| (_ptr) = 0; \ |
| PR_END_MACRO |
| |
| /** |
| * Macro for releasing a reference to an interface. |
| * @param _ptr The interface pointer. |
| */ |
| #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. |
| */ |
| #define NS_RELEASE2(_ptr,_rv) \ |
| PR_BEGIN_MACRO \ |
| _rv = (_ptr)->Release(); \ |
| if (0 == (_rv)) (_ptr) = 0; \ |
| PR_END_MACRO |
| |
| /** |
| * Macro for releasing a reference to an interface that checks for NULL; |
| * @param _ptr The interface pointer. |
| */ |
| #define NS_IF_RELEASE(_ptr) \ |
| PR_BEGIN_MACRO \ |
| if (_ptr) { \ |
| (_ptr)->Release(); \ |
| (_ptr) = 0; \ |
| } \ |
| PR_END_MACRO |
| |
| /* |
| * 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 ) |
| { |
| NS_PRECONDITION(aSource, "null parameter"); |
| NS_PRECONDITION(aDestination, "null parameter"); |
| |
| return aSource->QueryInterface(NS_GET_TEMPLATE_IID(DestinationType), |
| reinterpret_cast<void**>(aDestination)); |
| } |
| |
| #endif /* __nsISupportsUtils_h */ |
