1 // Copyright (c) 2010 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_PREFS_PREF_CHANGE_REGISTRAR_H_ 6 #define BASE_PREFS_PREF_CHANGE_REGISTRAR_H_ 7 8 #include <map> 9 #include <string> 10 11 #include "base/basictypes.h" 12 #include "base/callback.h" 13 #include "base/prefs/base_prefs_export.h" 14 #include "base/prefs/pref_observer.h" 15 16 class PrefService; 17 18 // Automatically manages the registration of one or more pref change observers 19 // with a PrefStore. Functions much like NotificationRegistrar, but specifically 20 // manages observers of preference changes. When the Registrar is destroyed, 21 // all registered observers are automatically unregistered with the PrefStore. 22 class BASE_PREFS_EXPORT PrefChangeRegistrar : public PrefObserver { 23 public: 24 // You can register this type of callback if you need to know the 25 // path of the preference that is changing. 26 typedef base::Callback<void(const std::string&)> NamedChangeCallback; 27 28 PrefChangeRegistrar(); 29 virtual ~PrefChangeRegistrar(); 30 31 // Must be called before adding or removing observers. Can be called more 32 // than once as long as the value of |service| doesn't change. 33 void Init(PrefService* service); 34 35 // Adds a pref observer for the specified pref |path| and |obs| observer 36 // object. All registered observers will be automatically unregistered 37 // when the registrar's destructor is called. 38 // 39 // The second version binds a callback that will receive the path of 40 // the preference that is changing as its parameter. 41 // 42 // Only one observer may be registered per path. 43 void Add(const char* path, const base::Closure& obs); 44 void Add(const char* path, const NamedChangeCallback& obs); 45 46 // Removes the pref observer registered for |path|. 47 void Remove(const char* path); 48 49 // Removes all observers that have been previously added with a call to Add. 50 void RemoveAll(); 51 52 // Returns true if no pref observers are registered. 53 bool IsEmpty() const; 54 55 // Check whether |pref| is in the set of preferences being observed. 56 bool IsObserved(const std::string& pref); 57 58 // Check whether any of the observed preferences has the managed bit set. 59 bool IsManaged(); 60 61 // Return the PrefService for this registrar. 62 PrefService* prefs(); 63 const PrefService* prefs() const; 64 65 private: 66 // PrefObserver: 67 virtual void OnPreferenceChanged(PrefService* service, 68 const std::string& pref_name) OVERRIDE; 69 70 static void InvokeUnnamedCallback(const base::Closure& callback, 71 const std::string& pref_name); 72 73 typedef std::map<std::string, NamedChangeCallback> ObserverMap; 74 75 ObserverMap observers_; 76 PrefService* service_; 77 78 DISALLOW_COPY_AND_ASSIGN(PrefChangeRegistrar); 79 }; 80 81 #endif // BASE_PREFS_PREF_CHANGE_REGISTRAR_H_ 82
