xpcom/ds/nsIObserverService.idl

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsISupports.idl"
   7
   8 interface nsIObserver;
   9 interface nsISimpleEnumerator;
  10
  11 /**
  12  * nsIObserverService
  13  *
  14  * Service allows a client listener (nsIObserver) to register and unregister for
  15  * notifications of specific string referenced topic. Service also provides a
  16  * way to notify registered listeners and a way to enumerate registered client
  17  * listeners.
  18  */
  19
  20 [scriptable, builtinclass, uuid(D07F5192-E3D1-11d2-8ACD-00105A1B8860)]
  21 interface nsIObserverService : nsISupports
  22 {
  23
  24     /**
  25      * AddObserver
  26      *
  27      * Registers a given listener for a notifications regarding the specified
  28      * topic.
  29      *
  30      * @param anObserve : The interface pointer which will receive notifications.
  31      * @param aTopic    : The notification topic or subject.
  32      * @param ownsWeak  : If set to false, the nsIObserverService will hold a
  33      *                    strong reference to |anObserver|.  If set to true and
  34      *                    |anObserver| supports the nsIWeakReference interface,
  35      *                    a weak reference will be held.  Otherwise an error will be
  36      *                    returned.
  37      */
  38     void addObserver( in nsIObserver anObserver, in string aTopic,
  39                       [optional] in boolean ownsWeak);
  40
  41     /**
  42      * removeObserver
  43      *
  44      * Unregisters a given listener from notifications regarding the specified
  45      * topic.
  46      *
  47      * @param anObserver : The interface pointer which will stop recieving
  48      *                     notifications.
  49      * @param aTopic     : The notification topic or subject.
  50      */
  51     void removeObserver( in nsIObserver anObserver, in string aTopic );
  52
  53     /**
  54      * notifyObservers
  55      *
  56      * Notifies all registered listeners of the given topic.
  57      * Must not be used with shutdown topics (will assert
  58      * on the parent process).
  59      *
  60      * @param aSubject : Notification specific interface pointer.
  61      * @param aTopic   : The notification topic or subject.
  62      * @param someData : Notification specific wide string.
  63      */
  64     void notifyObservers( in nsISupports aSubject,
  65                           in string aTopic,
  66                           [optional] in wstring someData );
  67
  68     /**
  69      * hasObservers
  70      *
  71      * Checks to see if there are registered listeners for the given topic.
  72      *
  73      * Implemented in "nsObserverService.cpp".
  74      *
  75      * @param aTopic   : The notification topic or subject.
  76      * @param aFound : An out parameter; True if there are registered observers,
  77      * False otherwise.
  78      */
  79     [noscript, notxpcom, nostdcall] boolean hasObservers(in string aTopic);
  80
  81     %{C++
  82     /**
  83      * notifyWhenScriptSafe
  84      *
  85      * Notifies all registered listeners of the given topic once it is safe to
  86      * run script.
  87      *
  88      * Implemented in "nsObserverService.cpp".
  89      *
  90      * @param aSubject : Notification specific interface pointer.
  91      * @param aTopic   : The notification topic or subject.
  92      * @param someData : Notification specific wide string.
  93      */
  94     nsresult NotifyWhenScriptSafe(nsISupports* aSubject,
  95                                   const char* aTopic,
  96                                   const char16_t* aData = nullptr);
  97     %}
  98
  99     /**
 100      * enumerateObservers
 101      *
 102      * Returns an enumeration of all registered listeners.
 103      *
 104      * @param aTopic   : The notification topic or subject.
 105      */
 106     nsISimpleEnumerator enumerateObservers( in string aTopic );
 107
 108
 109 };