1 // Copyright 2012 The Chromium Authors 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 COMPONENTS_PREFS_PREF_STORE_H_ 6 #define COMPONENTS_PREFS_PREF_STORE_H_ 7 8 #include <memory> 9 #include <string> 10 11 #include "base/memory/ref_counted.h" 12 #include "base/strings/string_piece.h" 13 #include "base/values.h" 14 #include "components/prefs/prefs_export.h" 15 16 // This is an abstract interface for reading and writing from/to a persistent 17 // preference store, used by PrefService. An implementation using a JSON file 18 // can be found in JsonPrefStore, while an implementation without any backing 19 // store for testing can be found in TestingPrefStore. Furthermore, there is 20 // CommandLinePrefStore, which bridges command line options to preferences and 21 // ConfigurationPolicyPrefStore, which is used for hooking up configuration 22 // policy with the preference subsystem. 23 class COMPONENTS_PREFS_EXPORT PrefStore : public base::RefCounted<PrefStore> { 24 public: 25 // Observer interface for monitoring PrefStore. 26 class COMPONENTS_PREFS_EXPORT Observer { 27 public: 28 // Called when the value for the given |key| in the store changes. 29 virtual void OnPrefValueChanged(const std::string& key) = 0; 30 // Notification about the PrefStore being fully initialized. 31 virtual void OnInitializationCompleted(bool succeeded) = 0; 32 33 protected: ~Observer()34 virtual ~Observer() {} 35 }; 36 PrefStore()37 PrefStore() {} 38 39 PrefStore(const PrefStore&) = delete; 40 PrefStore& operator=(const PrefStore&) = delete; 41 42 // Add and remove observers. AddObserver(Observer * observer)43 virtual void AddObserver(Observer* observer) {} RemoveObserver(Observer * observer)44 virtual void RemoveObserver(Observer* observer) {} 45 virtual bool HasObservers() const; 46 47 // Whether the store has completed all asynchronous initialization. 48 virtual bool IsInitializationComplete() const; 49 50 // Get the value for a given preference |key| and stores it in |*result|. 51 // |*result| is only modified if the return value is true and if |result| 52 // is not NULL. Ownership of the |*result| value remains with the PrefStore. 53 virtual bool GetValue(base::StringPiece key, 54 const base::Value** result) const = 0; 55 56 // Get all the values. 57 virtual base::Value::Dict GetValues() const = 0; 58 59 protected: 60 friend class base::RefCounted<PrefStore>; ~PrefStore()61 virtual ~PrefStore() {} 62 }; 63 64 #endif // COMPONENTS_PREFS_PREF_STORE_H_ 65