// Copyright (c) 2011 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 CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
#define CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
#pragma once
#include <string>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/observer_list.h"
#include "chrome/browser/prefs/pref_value_map.h"
#include "chrome/common/persistent_pref_store.h"
// PersistentPrefStore that directs all write operations into a 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 OverlayPersistentPrefStore : public PersistentPrefStore,
public PrefStore::Observer {
public:
explicit OverlayPersistentPrefStore(PersistentPrefStore* underlay);
virtual ~OverlayPersistentPrefStore();
// Returns true if a value has been set for the |key| in this
// OverlayPersistentPrefStore, 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);
virtual void RemoveObserver(PrefStore::Observer* observer);
virtual bool IsInitializationComplete() const;
virtual ReadResult GetValue(const std::string& key,
const Value** result) const;
// Methods of PersistentPrefStore.
virtual ReadResult GetMutableValue(const std::string& key, Value** result);
virtual void SetValue(const std::string& key, Value* value);
virtual void SetValueSilently(const std::string& key, Value* value);
virtual void RemoveValue(const std::string& key);
virtual bool ReadOnly() const;
virtual PrefReadError ReadPrefs();
virtual bool WritePrefs();
virtual void ScheduleWritePrefs();
virtual void CommitPendingWrite();
virtual void ReportValueChanged(const std::string& key);
private:
// Methods of PrefStore::Observer.
virtual void OnPrefValueChanged(const std::string& key);
virtual void OnInitializationCompleted();
ObserverList<PrefStore::Observer, true> observers_;
PrefValueMap overlay_;
scoped_refptr<PersistentPrefStore> underlay_;
DISALLOW_COPY_AND_ASSIGN(OverlayPersistentPrefStore);
};
#endif // CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_