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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 details for NotificationService
      6 // notifications.
      7 
      8 #ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_DETAILS_H_
      9 #define CONTENT_PUBLIC_BROWSER_NOTIFICATION_DETAILS_H_
     10 
     11 #include "base/basictypes.h"
     12 #include "content/common/content_export.h"
     13 
     14 namespace content {
     15 
     16 // Do not declare a NotificationDetails directly--use either
     17 // "Details<detailsclassname>(detailsclasspointer)" or
     18 // NotificationService::NoDetails().
     19 class CONTENT_EXPORT NotificationDetails {
     20  public:
     21   NotificationDetails() : ptr_(NULL) {}
     22   NotificationDetails(const NotificationDetails& other) : ptr_(other.ptr_) {}
     23   ~NotificationDetails() {}
     24 
     25   // NotificationDetails can be used as the index for a map; this method
     26   // returns the pointer to the current details as an identifier, for use as a
     27   // map index.
     28   uintptr_t map_key() const { return reinterpret_cast<uintptr_t>(ptr_); }
     29 
     30   bool operator!=(const NotificationDetails& other) const {
     31     return ptr_ != other.ptr_;
     32   }
     33 
     34   bool operator==(const NotificationDetails& other) const {
     35     return ptr_ == other.ptr_;
     36   }
     37 
     38  protected:
     39    explicit NotificationDetails(const void* ptr) : ptr_(ptr) {}
     40 
     41   // Declaring this const allows Details<T> to be used with both T = Foo and
     42   // T = const Foo.
     43   const void* ptr_;
     44 };
     45 
     46 template <class T>
     47 class Details : public NotificationDetails {
     48  public:
     49   // TODO(erg): Our code hard relies on implicit conversion
     50   Details(T* ptr) : NotificationDetails(ptr) {}  // NOLINT
     51   Details(const NotificationDetails& other)      // NOLINT
     52     : NotificationDetails(other) {}
     53 
     54   T* operator->() const { return ptr(); }
     55   // The casts here allow this to compile with both T = Foo and T = const Foo.
     56   T* ptr() const { return static_cast<T*>(const_cast<void*>(ptr_)); }
     57 };
     58 
     59 }  // namespace content
     60 
     61 #endif  // CONTENT_PUBLIC_BROWSER_NOTIFICATION_DETAILS_H_
     62