/gecko_api/include/nsIWeakReferenceUtils.h
C++ Header | 142 lines | 62 code | 18 blank | 62 comment | 0 complexity | 47d89cdcea82468e877e082745ee60ea MD5 | raw file
1/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ 2/* ***** BEGIN LICENSE BLOCK ***** 3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 4 * 5 * The contents of this file are subject to the Mozilla Public License Version 6 * 1.1 (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * http://www.mozilla.org/MPL/ 9 * 10 * Software distributed under the License is distributed on an "AS IS" basis, 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 12 * for the specific language governing rights and limitations under the 13 * License. 14 * 15 * The Original Code is mozilla.org code. 16 * 17 * The Initial Developer of the Original Code is 18 * Netscape Communications Corporation. 19 * Portions created by the Initial Developer are Copyright (C) 1998 20 * the Initial Developer. All Rights Reserved. 21 * 22 * Contributor(s): 23 * Scott Collins <scc@mozilla.org> (Original Author) 24 * 25 * Alternatively, the contents of this file may be used under the terms of 26 * either of the GNU General Public License Version 2 or later (the "GPL"), 27 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), 28 * in which case the provisions of the GPL or the LGPL are applicable instead 29 * of those above. If you wish to allow use of your version of this file only 30 * under the terms of either the GPL or the LGPL, and not to allow others to 31 * use your version of this file under the terms of the MPL, indicate your 32 * decision by deleting the provisions above and replace them with the notice 33 * and other provisions required by the GPL or the LGPL. If you do not delete 34 * the provisions above, a recipient may use your version of this file under 35 * the terms of any one of the MPL, the GPL or the LGPL. 36 * 37 * ***** END LICENSE BLOCK ***** */ 38 39#ifndef nsIWeakReferenceUtils_h__ 40#define nsIWeakReferenceUtils_h__ 41 42#ifndef nsCOMPtr_h__ 43#include "nsCOMPtr.h" 44#endif 45 46typedef nsCOMPtr<nsIWeakReference> nsWeakPtr; 47 48/** 49 * 50 */ 51 52// a type-safe shortcut for calling the |QueryReferent()| member function 53// T must inherit from nsIWeakReference, but the cast may be ambiguous. 54template <class T, class DestinationType> 55inline 56nsresult 57CallQueryReferent( T* aSource, DestinationType** aDestination ) 58 { 59 NS_PRECONDITION(aSource, "null parameter"); 60 NS_PRECONDITION(aDestination, "null parameter"); 61 62 return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType), 63 reinterpret_cast<void**>(aDestination)); 64 } 65 66 67class NS_COM_GLUE nsQueryReferent : public nsCOMPtr_helper 68 { 69 public: 70 nsQueryReferent( nsIWeakReference* aWeakPtr, nsresult* error ) 71 : mWeakPtr(aWeakPtr), 72 mErrorPtr(error) 73 { 74 // nothing else to do here 75 } 76 77 virtual nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const; 78 79 private: 80 nsIWeakReference* mWeakPtr; 81 nsresult* mErrorPtr; 82 }; 83 84inline 85const nsQueryReferent 86do_QueryReferent( nsIWeakReference* aRawPtr, nsresult* error = 0 ) 87 { 88 return nsQueryReferent(aRawPtr, error); 89 } 90 91 92 /** 93 * Deprecated, use |do_GetWeakReference| instead. 94 */ 95extern NS_COM_GLUE 96nsIWeakReference* 97NS_GetWeakReference( nsISupports* , nsresult* aResult=0 ); 98 99 /** 100 * |do_GetWeakReference| is a convenience function that bundles up all the work needed 101 * to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and 102 * call through to |GetWeakReference|, and put it into your |nsCOMPtr|. 103 * It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so: 104 * |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|. 105 */ 106inline 107already_AddRefed<nsIWeakReference> 108do_GetWeakReference( nsISupports* aRawPtr, nsresult* error = 0 ) 109 { 110 return NS_GetWeakReference(aRawPtr, error); 111 } 112 113inline 114void 115do_GetWeakReference( nsIWeakReference* aRawPtr, nsresult* error = 0 ) 116 { 117 // This signature exists solely to _stop_ you from doing a bad thing. 118 // Saying |do_GetWeakReference()| on a weak reference itself, 119 // is very likely to be a programmer error. 120 } 121 122template <class T> 123inline 124void 125do_GetWeakReference( already_AddRefed<T>& ) 126 { 127 // This signature exists solely to _stop_ you from doing the bad thing. 128 // Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by 129 // someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>. 130 } 131 132template <class T> 133inline 134void 135do_GetWeakReference( already_AddRefed<T>&, nsresult* ) 136 { 137 // This signature exists solely to _stop_ you from doing the bad thing. 138 // Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by 139 // someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>. 140 } 141 142#endif