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| 1 // Copyright 2016 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 MEDIA_BASE_STATE_H_ |
| 6 #define MEDIA_BASE_STATE_H_ |
| 7 |
| 8 #include <unordered_set> |
| 9 |
| 10 #include "base/memory/ref_counted.h" |
| 11 #include "media/base/media_export.h" |
| 12 |
| 13 namespace media { |
| 14 |
| 15 // Subclass this to include actual state + getters and setters. Setters will |
| 16 // call StateChanged() as needed. |
| 17 // TODO(liberato): StatePartition? StateGroup? |
| 18 class MEDIA_EXPORT State : public base::RefCountedThreadSafe<State> { |
| 19 public: |
| 20 // Client (state machine, probably) that's notified about state |
| 21 // changes so that it can schedule state machine runs. |
| 22 class Client { |
| 23 public: |
| 24 virtual ~Client() {} |
| 25 |
| 26 // Notify the client that some property has changed. |
| 27 virtual void OnStateChanged() = 0; |
| 28 }; |
| 29 |
| 30 public: |
| 31 // Add a client to us. Must be valid until we're destroyed, or until |
| 32 // it's unregistered. |
| 33 void RegisterClient(Client* client); |
| 34 |
| 35 // Unregister a previously-registered client. |
| 36 void UnregisterClient(Client* client); |
| 37 |
| 38 protected: |
| 39 State(); |
| 40 virtual ~State(); |
| 41 |
| 42 friend class base::RefCountedThreadSafe<State>; |
| 43 |
| 44 // Called by subclass to notify that a state has changed. This can |
| 45 // happen in response to a setter, or if the state changes by itself |
| 46 // (such as state subclasses that provide access to external state). |
| 47 void StateChanged(); |
| 48 |
| 49 private: |
| 50 std::unordered_set<Client*> clients_; |
| 51 |
| 52 DISALLOW_COPY_AND_ASSIGN(State); |
| 53 }; |
| 54 |
| 55 } // namespace media |
| 56 |
| 57 #endif // MEDIA_BASE_STATE_H_ |
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