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_OVERLAY_USER_PREF_STORE_H_ 6 #define BASE_PREFS_OVERLAY_USER_PREF_STORE_H_ 7 8 #include <map> 9 #include <string> 10 11 #include "base/basictypes.h" 12 #include "base/memory/ref_counted.h" 13 #include "base/observer_list.h" 14 #include "base/prefs/base_prefs_export.h" 15 #include "base/prefs/persistent_pref_store.h" 16 #include "base/prefs/pref_value_map.h" 17 18 // PersistentPrefStore that directs all write operations into an in-memory 19 // PrefValueMap. Read operations are first answered by the PrefValueMap. 20 // If the PrefValueMap does not contain a value for the requested key, 21 // the look-up is passed on to an underlying PersistentPrefStore |underlay_|. 22 class BASE_PREFS_EXPORT OverlayUserPrefStore : public PersistentPrefStore, 23 public PrefStore::Observer { 24 public: 25 explicit OverlayUserPrefStore(PersistentPrefStore* underlay); 26 27 // Returns true if a value has been set for the |key| in this 28 // OverlayUserPrefStore, i.e. if it potentially overrides a value 29 // from the |underlay_|. 30 virtual bool IsSetInOverlay(const std::string& key) const; 31 32 // Methods of PrefStore. 33 virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE; 34 virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE; 35 virtual size_t NumberOfObservers() const OVERRIDE; 36 virtual bool IsInitializationComplete() const OVERRIDE; 37 virtual bool GetValue(const std::string& key, 38 const base::Value** result) const OVERRIDE; 39 40 // Methods of PersistentPrefStore. 41 virtual bool GetMutableValue(const std::string& key, 42 base::Value** result) OVERRIDE; 43 virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE; 44 virtual void SetValueSilently(const std::string& key, 45 base::Value* value) OVERRIDE; 46 virtual void RemoveValue(const std::string& key) OVERRIDE; 47 virtual void MarkNeedsEmptyValue(const std::string& key) OVERRIDE; 48 virtual bool ReadOnly() const OVERRIDE; 49 virtual PrefReadError GetReadError() const OVERRIDE; 50 virtual PrefReadError ReadPrefs() OVERRIDE; 51 virtual void ReadPrefsAsync(ReadErrorDelegate* delegate) OVERRIDE; 52 virtual void CommitPendingWrite() OVERRIDE; 53 virtual void ReportValueChanged(const std::string& key) OVERRIDE; 54 55 // Methods of PrefStore::Observer. 56 virtual void OnPrefValueChanged(const std::string& key) OVERRIDE; 57 virtual void OnInitializationCompleted(bool succeeded) OVERRIDE; 58 59 void RegisterOverlayPref(const std::string& key); 60 void RegisterOverlayPref(const std::string& overlay_key, 61 const std::string& underlay_key); 62 63 protected: 64 virtual ~OverlayUserPrefStore(); 65 66 private: 67 typedef std::map<std::string, std::string> NamesMap; 68 69 const std::string& GetOverlayKey(const std::string& underlay_key) const; 70 const std::string& GetUnderlayKey(const std::string& overlay_key) const; 71 72 // Returns true if |key| corresponds to a preference that shall be stored in 73 // an in-memory PrefStore that is not persisted to disk. 74 bool ShallBeStoredInOverlay(const std::string& key) const; 75 76 ObserverList<PrefStore::Observer, true> observers_; 77 PrefValueMap overlay_; 78 scoped_refptr<PersistentPrefStore> underlay_; 79 NamesMap overlay_to_underlay_names_map_; 80 NamesMap underlay_to_overlay_names_map_; 81 82 DISALLOW_COPY_AND_ASSIGN(OverlayUserPrefStore); 83 }; 84 85 #endif // BASE_PREFS_OVERLAY_USER_PREF_STORE_H_ 86
