1 /*
2  * libjingle
3  * Copyright 2011 Google Inc.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  *  1. Redistributions of source code must retain the above copyright notice,
9  *     this list of conditions and the following disclaimer.
10  *  2. Redistributions in binary form must reproduce the above copyright notice,
11  *     this list of conditions and the following disclaimer in the documentation
12  *     and/or other materials provided with the distribution.
13  *  3. The name of the author may not be used to endorse or promote products
14  *     derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #ifndef TALK_APP_WEBRTC_NOTIFIER_H_
29 #define TALK_APP_WEBRTC_NOTIFIER_H_
30 
31 #include <list>
32 
33 #include "talk/app/webrtc/mediastreaminterface.h"
34 #include "webrtc/base/common.h"
35 
36 namespace webrtc {
37 
38 // Implement a template version of a notifier.
39 template <class T>
40 class Notifier : public T {
41  public:
Notifier()42   Notifier() {
43   }
44 
RegisterObserver(ObserverInterface * observer)45   virtual void RegisterObserver(ObserverInterface* observer) {
46     ASSERT(observer != NULL);
47     observers_.push_back(observer);
48   }
49 
UnregisterObserver(ObserverInterface * observer)50   virtual void UnregisterObserver(ObserverInterface* observer) {
51     for (std::list<ObserverInterface*>::iterator it = observers_.begin();
52          it != observers_.end(); it++) {
53       if (*it == observer) {
54         observers_.erase(it);
55         break;
56       }
57     }
58   }
59 
FireOnChanged()60   void FireOnChanged() {
61     // Copy the list of observers to avoid a crash if the observer object
62     // unregisters as a result of the OnChanged() call. If the same list is used
63     // UnregisterObserver will affect the list make the iterator invalid.
64     std::list<ObserverInterface*> observers = observers_;
65     for (std::list<ObserverInterface*>::iterator it = observers.begin();
66          it != observers.end(); ++it) {
67       (*it)->OnChanged();
68     }
69   }
70 
71  protected:
72   std::list<ObserverInterface*> observers_;
73 };
74 
75 }  // namespace webrtc
76 
77 #endif  // TALK_APP_WEBRTC_NOTIFIER_H_
78