notification_registrar.h revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
6#define CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
7
8#include <vector>
9
10#include "base/basictypes.h"
11#include "base/threading/non_thread_safe.h"
12#include "content/common/content_export.h"
13
14namespace content {
15
16class NotificationObserver;
17class NotificationSource;
18
19// Aids in registering for notifications and ensures that all registered
20// notifications are unregistered when the class is destroyed.
21//
22// The intended use is that you make a NotificationRegistrar member in your
23// class and use it to register your notifications instead of going through the
24// notification service directly. It will automatically unregister them for
25// you.
26class CONTENT_EXPORT NotificationRegistrar :
27    NON_EXPORTED_BASE(public base::NonThreadSafe) {
28 public:
29  // This class must not be derived from (we don't have a virtual destructor so
30  // it won't work). Instead, use it as a member in your class.
31  NotificationRegistrar();
32  ~NotificationRegistrar();
33
34  // Wrappers around NotificationService::[Add|Remove]Observer.
35  void Add(NotificationObserver* observer,
36           int type,
37           const NotificationSource& source);
38  void Remove(NotificationObserver* observer,
39              int type,
40              const NotificationSource& source);
41
42  // Unregisters all notifications.
43  void RemoveAll();
44
45  // Returns true if no notifications are registered.
46  bool IsEmpty() const;
47
48  // Returns true if there is already a registered notification with the
49  // specified details.
50  bool IsRegistered(NotificationObserver* observer,
51                    int type,
52                    const NotificationSource& source);
53
54 private:
55  struct Record;
56
57  // We keep registered notifications in a simple vector. This means we'll do
58  // brute-force searches when removing them individually, but individual
59  // removal is uncommon, and there will typically only be a couple of
60  // notifications anyway.
61  typedef std::vector<Record> RecordVector;
62
63  // Lists all notifications we're currently registered for.
64  RecordVector registered_;
65
66  DISALLOW_COPY_AND_ASSIGN(NotificationRegistrar);
67};
68
69}  // namespace content
70
71#endif  // CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
72