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      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_
     60