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_view> 10 11 #include "base/memory/ref_counted.h" 12 #include "base/observer_list_types.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 : public base::CheckedObserver { 27 public: 28 // Called when the value for the given `key` in the store changes. OnPrefValueChanged(std::string_view key)29 virtual void OnPrefValueChanged(std::string_view key) {} 30 // Notification about the PrefStore being fully initialized. OnInitializationCompleted(bool succeeded)31 virtual void OnInitializationCompleted(bool succeeded) {} 32 }; 33 34 PrefStore() = default; 35 36 PrefStore(const PrefStore&) = delete; 37 PrefStore& operator=(const PrefStore&) = delete; 38 39 // Add and remove observers. AddObserver(Observer * observer)40 virtual void AddObserver(Observer* observer) {} RemoveObserver(Observer * observer)41 virtual void RemoveObserver(Observer* observer) {} 42 virtual bool HasObservers() const; 43 44 // Whether the store has completed all asynchronous initialization. 45 virtual bool IsInitializationComplete() const; 46 47 // Get the value for a given preference `key` and stores it in `*result`. 48 // `*result` is only modified if the return value is true and if `result` 49 // is not NULL. Ownership of the `*result` value remains with the PrefStore. 50 virtual bool GetValue(std::string_view key, 51 const base::Value** result) const = 0; 52 53 // Get all the values. 54 virtual base::Value::Dict GetValues() const = 0; 55 56 protected: 57 friend class base::RefCounted<PrefStore>; 58 virtual ~PrefStore() = default; 59 }; 60 61 #endif // COMPONENTS_PREFS_PREF_STORE_H_ 62