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
36namespace webrtc {
37
38// Implement a template version of a notifier.
39template <class T>
40class Notifier : public T {
41 public:
42  Notifier() {
43  }
44
45  virtual void RegisterObserver(ObserverInterface* observer) {
46    ASSERT(observer != NULL);
47    observers_.push_back(observer);
48  }
49
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
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