81 lines
2.9 KiB
C
81 lines
2.9 KiB
C
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// Copyright 2010 The Chromium Authors
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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 COMPONENTS_PREFS_PREF_CHANGE_REGISTRAR_H_
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#define COMPONENTS_PREFS_PREF_CHANGE_REGISTRAR_H_
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#include <map>
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#include <string>
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#include "base/functional/callback.h"
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#include "base/memory/raw_ptr.h"
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#include "components/prefs/pref_observer.h"
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#include "components/prefs/prefs_export.h"
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class PrefService;
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// Automatically manages the registration of one or more pref change observers
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// with a PrefStore. Functions much like NotificationRegistrar, but specifically
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// manages observers of preference changes. When the Registrar is destroyed,
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// all registered observers are automatically unregistered with the PrefStore.
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class COMPONENTS_PREFS_EXPORT PrefChangeRegistrar final : public PrefObserver {
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public:
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// You can register this type of callback if you need to know the
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// path of the preference that is changing.
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using NamedChangeCallback = base::RepeatingCallback<void(const std::string&)>;
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PrefChangeRegistrar();
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PrefChangeRegistrar(const PrefChangeRegistrar&) = delete;
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PrefChangeRegistrar& operator=(const PrefChangeRegistrar&) = delete;
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~PrefChangeRegistrar();
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// Must be called before adding or removing observers. Can be called more
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// than once as long as the value of |service| doesn't change.
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void Init(PrefService* service);
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// Adds a pref observer for the specified pref |path| and |obs| observer
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// object. All registered observers will be automatically unregistered
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// when the registrar's destructor is called.
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//
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// The second version binds a callback that will receive the path of
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// the preference that is changing as its parameter.
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//
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// Only one observer may be registered per path.
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void Add(const std::string& path, const base::RepeatingClosure& obs);
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void Add(const std::string& path, const NamedChangeCallback& obs);
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// Removes the pref observer registered for |path|.
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void Remove(const std::string& path);
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// Removes all observers that have been previously added with a call to Add.
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void RemoveAll();
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// Returns true if no pref observers are registered.
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bool IsEmpty() const;
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// Check whether |pref| is in the set of preferences being observed.
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bool IsObserved(const std::string& pref);
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// Return the PrefService for this registrar.
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PrefService* prefs();
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const PrefService* prefs() const;
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private:
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// PrefObserver:
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void OnPreferenceChanged(PrefService* service,
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const std::string& pref_name) override;
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static void InvokeUnnamedCallback(const base::RepeatingClosure& callback,
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const std::string& pref_name);
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using ObserverMap = std::map<std::string, NamedChangeCallback>;
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ObserverMap observers_;
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raw_ptr<PrefService, DanglingUntriaged> service_;
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};
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#endif // COMPONENTS_PREFS_PREF_CHANGE_REGISTRAR_H_
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