| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_SUPPORTS_USER_DATA_H_ |
| #define BASE_SUPPORTS_USER_DATA_H_ |
| |
| #include <map> |
| |
| #include "base/base_export.h" |
| #include "base/memory/linked_ptr.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/threading/thread_checker.h" |
| |
| namespace base { |
| |
| // This is a helper for classes that want to allow users to stash random data by |
| // key. At destruction all the objects will be destructed. |
| class BASE_EXPORT SupportsUserData { |
| public: |
| SupportsUserData(); |
| |
| // Derive from this class and add your own data members to associate extra |
| // information with this object. Alternatively, add this as a public base |
| // class to any class with a virtual destructor. |
| class BASE_EXPORT Data { |
| public: |
| virtual ~Data() {} |
| }; |
| |
| // The user data allows the clients to associate data with this object. |
| // Multiple user data values can be stored under different keys. |
| // This object will TAKE OWNERSHIP of the given data pointer, and will |
| // delete the object if it is changed or the object is destroyed. |
| Data* GetUserData(const void* key) const; |
| void SetUserData(const void* key, Data* data); |
| void RemoveUserData(const void* key); |
| |
| // SupportsUserData is not thread-safe, and on debug build will assert it is |
| // only used on one thread. Calling this method allows the caller to hand |
| // the SupportsUserData instance across threads. Use only if you are taking |
| // full control of the synchronization of that hand over. |
| void DetachUserDataThread(); |
| |
| protected: |
| virtual ~SupportsUserData(); |
| |
| private: |
| typedef std::map<const void*, linked_ptr<Data> > DataMap; |
| |
| // Externally-defined data accessible by key. |
| DataMap user_data_; |
| // Guards usage of |user_data_| |
| ThreadChecker thread_checker_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SupportsUserData); |
| }; |
| |
| // Adapter class that releases a refcounted object when the |
| // SupportsUserData::Data object is deleted. |
| template <typename T> |
| class UserDataAdapter : public base::SupportsUserData::Data { |
| public: |
| static T* Get(const SupportsUserData* supports_user_data, const void* key) { |
| UserDataAdapter* data = |
| static_cast<UserDataAdapter*>(supports_user_data->GetUserData(key)); |
| return data ? static_cast<T*>(data->object_.get()) : NULL; |
| } |
| |
| UserDataAdapter(T* object) : object_(object) {} |
| T* release() { return object_.release(); } |
| |
| private: |
| scoped_refptr<T> object_; |
| |
| DISALLOW_COPY_AND_ASSIGN(UserDataAdapter); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_SUPPORTS_USER_DATA_H_ |