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 #ifndef BASE_PREFS_PREF_STORE_H_ 6 #define BASE_PREFS_PREF_STORE_H_ 7 8 #include <string> 9 10 #include "base/basictypes.h" 11 #include "base/memory/ref_counted.h" 12 #include "base/prefs/base_prefs_export.h" 13 14 namespace base { 15 class Value; 16 } 17 18 // This is an abstract interface for reading and writing from/to a persistent 19 // preference store, used by PrefService. An implementation using a JSON file 20 // can be found in JsonPrefStore, while an implementation without any backing 21 // store for testing can be found in TestingPrefStore. Furthermore, there is 22 // CommandLinePrefStore, which bridges command line options to preferences and 23 // ConfigurationPolicyPrefStore, which is used for hooking up configuration 24 // policy with the preference subsystem. 25 class BASE_PREFS_EXPORT PrefStore : public base::RefCounted<PrefStore> { 26 public: 27 // Observer interface for monitoring PrefStore. 28 class BASE_PREFS_EXPORT Observer { 29 public: 30 // Called when the value for the given |key| in the store changes. 31 virtual void OnPrefValueChanged(const std::string& key) = 0; 32 // Notification about the PrefStore being fully initialized. 33 virtual void OnInitializationCompleted(bool succeeded) = 0; 34 35 protected: 36 virtual ~Observer() {} 37 }; 38 39 PrefStore() {} 40 41 // Add and remove observers. 42 virtual void AddObserver(Observer* observer) {} 43 virtual void RemoveObserver(Observer* observer) {} 44 virtual bool HasObservers() const; 45 46 // Whether the store has completed all asynchronous initialization. 47 virtual bool IsInitializationComplete() const; 48 49 // Get the value for a given preference |key| and stores it in |*result|. 50 // |*result| is only modified if the return value is true and if |result| 51 // is not NULL. Ownership of the |*result| value remains with the PrefStore. 52 virtual bool GetValue(const std::string& key, 53 const base::Value** result) const = 0; 54 55 protected: 56 friend class base::RefCounted<PrefStore>; 57 virtual ~PrefStore() {} 58 59 private: 60 DISALLOW_COPY_AND_ASSIGN(PrefStore); 61 }; 62 63 #endif // BASE_PREFS_PREF_STORE_H_ 64