content/public/browser/notification_source.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 // This file defines the type used to provide sources for NotificationService
   6 // notifications.
   7
   8 #ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_SOURCE_H_
   9 #define CONTENT_PUBLIC_BROWSER_NOTIFICATION_SOURCE_H_
  10
  11 #include "base/basictypes.h"
  12 #include "content/common/content_export.h"
  13
  14 namespace content {
  15
  16 // Do not declare a NotificationSource directly--use either
  17 // "Source<sourceclassname>(sourceclasspointer)" or
  18 // NotificationService::AllSources().
  19 class CONTENT_EXPORT NotificationSource {
  20  public:
  21    NotificationSource(const NotificationSource& other) : ptr_(other.ptr_) {}
  22   ~NotificationSource() {}
  23
  24   // NotificationSource can be used as the index for a map; this method
  25   // returns the pointer to the current source as an identifier, for use as a
  26   // map index.
  27   uintptr_t map_key() const { return reinterpret_cast<uintptr_t>(ptr_); }
  28
  29   bool operator!=(const NotificationSource& other) const {
  30     return ptr_ != other.ptr_;
  31   }
  32   bool operator==(const NotificationSource& other) const {
  33     return ptr_ == other.ptr_;
  34   }
  35
  36  protected:
  37   explicit NotificationSource(const void* ptr) : ptr_(ptr) {}
  38
  39   // Declaring this const allows Source<T> to be used with both T = Foo and
  40   // T = const Foo.
  41   const void* ptr_;
  42 };
  43
  44 template <class T>
  45 class Source : public NotificationSource {
  46  public:
  47   // TODO(erg): Our code hard relies on implicit conversion
  48   Source(const T* ptr) : NotificationSource(ptr) {}  // NOLINT
  49   Source(const NotificationSource& other)      // NOLINT
  50     : NotificationSource(other) {}
  51
  52   T* operator->() const { return ptr(); }
  53   // The casts here allow this to compile with both T = Foo and T = const Foo.
  54   T* ptr() const { return static_cast<T*>(const_cast<void*>(ptr_)); }
  55 };
  56
  57 }  // namespace content
  58
  59 #endif  // CONTENT_PUBLIC_BROWSER_NOTIFICATION_SOURCE_H_