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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PREFS_PREF_STORE_H_
#define COMPONENTS_PREFS_PREF_STORE_H_
#include <memory>
#include <string_view>
#include "base/memory/ref_counted.h"
#include "base/observer_list_types.h"
#include "base/values.h"
#include "components/prefs/prefs_export.h"
// This is an abstract interface for reading and writing from/to a persistent
// preference store, used by PrefService. An implementation using a JSON file
// can be found in JsonPrefStore, while an implementation without any backing
// store for testing can be found in TestingPrefStore. Furthermore, there is
// CommandLinePrefStore, which bridges command line options to preferences and
// ConfigurationPolicyPrefStore, which is used for hooking up configuration
// policy with the preference subsystem.
class COMPONENTS_PREFS_EXPORT PrefStore : public base::RefCounted<PrefStore> {
public:
// Observer interface for monitoring PrefStore.
class COMPONENTS_PREFS_EXPORT Observer : public base::CheckedObserver {
public:
// Called when the value for the given `key` in the store changes.
virtual void OnPrefValueChanged(std::string_view key) {}
// Notification about the PrefStore being fully initialized.
virtual void OnInitializationCompleted(bool succeeded) {}
};
PrefStore() = default;
PrefStore(const PrefStore&) = delete;
PrefStore& operator=(const PrefStore&) = delete;
// Add and remove observers.
virtual void AddObserver(Observer* observer) {}
virtual void RemoveObserver(Observer* observer) {}
virtual bool HasObservers() const;
// Whether the store has completed all asynchronous initialization.
virtual bool IsInitializationComplete() const;
// Get the value for a given preference `key` and stores it in `*result`.
// `*result` is only modified if the return value is true and if `result`
// is not NULL. Ownership of the `*result` value remains with the PrefStore.
virtual bool GetValue(std::string_view key,
const base::Value** result) const = 0;
// Get all the values.
virtual base::Value::Dict GetValues() const = 0;
protected:
friend class base::RefCounted<PrefStore>;
virtual ~PrefStore() = default;
};
#endif // COMPONENTS_PREFS_PREF_STORE_H_
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