content/public/browser/notification_registrar.h

   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
  14 namespace content {
  15
  16 class NotificationObserver;
  17 class 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.
  26 class 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_