1 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 Mozilla Foundation
18 : * Portions created by the Initial Developer are Copyright (C) 2011
19 : * the Initial Developer. All Rights Reserved.
20 : *
21 : * Contributor(s):
22 : * Mounir Lamouri <mounir.lamouri@mozilla.com> (Original Author)
23 : *
24 : * Alternatively, the contents of this file may be used under the terms of
25 : * either of the GNU General Public License Version 2 or later (the "GPL"),
26 : * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
27 : * in which case the provisions of the GPL or the LGPL are applicable instead
28 : * of those above. If you wish to allow use of your version of this file only
29 : * under the terms of either the GPL or the LGPL, and not to allow others to
30 : * use your version of this file under the terms of the MPL, indicate your
31 : * decision by deleting the provisions above and replace them with the notice
32 : * and other provisions required by the GPL or the LGPL. If you do not delete
33 : * the provisions above, a recipient may use your version of this file under
34 : * the terms of any one of the MPL, the GPL or the LGPL.
35 : *
36 : * ***** END LICENSE BLOCK ***** */
37 :
38 : #ifndef mozilla_Observer_h
39 : #define mozilla_Observer_h
40 :
41 : #include "nsTArray.h"
42 :
43 : namespace mozilla {
44 :
45 : /**
46 : * Observer<T> provides a way for a class to observe something.
47 : * When an event has to be broadcasted to all Observer<T>, Notify() method
48 : * is called.
49 : * T represents the type of the object passed in argument to Notify().
50 : *
51 : * @see ObserverList.
52 : */
53 : template <class T>
54 : class Observer
55 0 : {
56 : public:
57 0 : virtual ~Observer() { }
58 : virtual void Notify(const T& aParam) = 0;
59 : };
60 :
61 : /**
62 : * ObserverList<T> tracks Observer<T> and can notify them when Broadcast() is
63 : * called.
64 : * T represents the type of the object passed in argument to Broadcast() and
65 : * sent to Observer<T> objects through Notify().
66 : *
67 : * @see Observer.
68 : */
69 : template <class T>
70 : class ObserverList
71 0 : {
72 : public:
73 : /**
74 : * Note: When calling AddObserver, it's up to the caller to make sure the
75 : * object isn't going to be release as long as RemoveObserver hasn't been
76 : * called.
77 : *
78 : * @see RemoveObserver()
79 : */
80 0 : void AddObserver(Observer<T>* aObserver) {
81 0 : mObservers.AppendElement(aObserver);
82 0 : }
83 :
84 0 : void RemoveObserver(Observer<T>* aObserver) {
85 0 : mObservers.RemoveElement(aObserver);
86 0 : }
87 :
88 0 : PRUint32 Length() {
89 0 : return mObservers.Length();
90 : }
91 :
92 0 : void Broadcast(const T& aParam) {
93 0 : PRUint32 size = mObservers.Length();
94 0 : for (PRUint32 i=0; i<size; ++i) {
95 0 : mObservers[i]->Notify(aParam);
96 : }
97 0 : }
98 :
99 : protected:
100 : nsTArray<Observer<T>*> mObservers;
101 : };
102 :
103 : } // namespace mozilla
104 :
105 : #endif // mozilla_Observer_h
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