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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_PREFS_OVERLAY_USER_PREF_STORE_H_
#define BASE_PREFS_OVERLAY_USER_PREF_STORE_H_
#include <map>
#include <string>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/observer_list.h"
#include "base/prefs/base_prefs_export.h"
#include "base/prefs/persistent_pref_store.h"
#include "base/prefs/pref_value_map.h"
// PersistentPrefStore that directs all write operations into an in-memory
// PrefValueMap. Read operations are first answered by the PrefValueMap.
// If the PrefValueMap does not contain a value for the requested key,
// the look-up is passed on to an underlying PersistentPrefStore |underlay_|.
class BASE_PREFS_EXPORT OverlayUserPrefStore : public PersistentPrefStore,
public PrefStore::Observer {
public:
explicit OverlayUserPrefStore(PersistentPrefStore* underlay);
// Returns true if a value has been set for the |key| in this
// OverlayUserPrefStore, i.e. if it potentially overrides a value
// from the |underlay_|.
virtual bool IsSetInOverlay(const std::string& key) const;
// Methods of PrefStore.
virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE;
virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
virtual size_t NumberOfObservers() const OVERRIDE;
virtual bool IsInitializationComplete() const OVERRIDE;
virtual bool GetValue(const std::string& key,
const base::Value** result) const OVERRIDE;
// Methods of PersistentPrefStore.
virtual bool GetMutableValue(const std::string& key,
base::Value** result) OVERRIDE;
virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE;
virtual void SetValueSilently(const std::string& key,
base::Value* value) OVERRIDE;
virtual void RemoveValue(const std::string& key) OVERRIDE;
virtual void MarkNeedsEmptyValue(const std::string& key) OVERRIDE;
virtual bool ReadOnly() const OVERRIDE;
virtual PrefReadError GetReadError() const OVERRIDE;
virtual PrefReadError ReadPrefs() OVERRIDE;
virtual void ReadPrefsAsync(ReadErrorDelegate* delegate) OVERRIDE;
virtual void CommitPendingWrite() OVERRIDE;
virtual void ReportValueChanged(const std::string& key) OVERRIDE;
// Methods of PrefStore::Observer.
virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
void RegisterOverlayPref(const std::string& key);
void RegisterOverlayPref(const std::string& overlay_key,
const std::string& underlay_key);
protected:
virtual ~OverlayUserPrefStore();
private:
typedef std::map<std::string, std::string> NamesMap;
const std::string& GetOverlayKey(const std::string& underlay_key) const;
const std::string& GetUnderlayKey(const std::string& overlay_key) const;
// Returns true if |key| corresponds to a preference that shall be stored in
// an in-memory PrefStore that is not persisted to disk.
bool ShallBeStoredInOverlay(const std::string& key) const;
ObserverList<PrefStore::Observer, true> observers_;
PrefValueMap overlay_;
scoped_refptr<PersistentPrefStore> underlay_;
NamesMap overlay_to_underlay_names_map_;
NamesMap underlay_to_overlay_names_map_;
DISALLOW_COPY_AND_ASSIGN(OverlayUserPrefStore);
};
#endif // BASE_PREFS_OVERLAY_USER_PREF_STORE_H_
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