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