1 // Copyright (c) 2012 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_SCOPED_OBSERVER_H_ 6 #define BASE_SCOPED_OBSERVER_H_ 7 8 #include <algorithm> 9 #include <vector> 10 11 #include "base/basictypes.h" 12 13 // ScopedObserver is used to keep track of the set of sources an object has 14 // attached itself to as an observer. When ScopedObserver is destroyed it 15 // removes the object as an observer from all sources it has been added to. 16 template <class Source, class Observer> 17 class ScopedObserver { 18 public: ScopedObserver(Observer * observer)19 explicit ScopedObserver(Observer* observer) : observer_(observer) {} 20 ~ScopedObserver()21 ~ScopedObserver() { 22 RemoveAll(); 23 } 24 25 // Adds the object passed to the constructor as an observer on |source|. Add(Source * source)26 void Add(Source* source) { 27 sources_.push_back(source); 28 source->AddObserver(observer_); 29 } 30 31 // Remove the object passed to the constructor as an observer from |source|. Remove(Source * source)32 void Remove(Source* source) { 33 sources_.erase(std::find(sources_.begin(), sources_.end(), source)); 34 source->RemoveObserver(observer_); 35 } 36 RemoveAll()37 void RemoveAll() { 38 for (size_t i = 0; i < sources_.size(); ++i) 39 sources_[i]->RemoveObserver(observer_); 40 sources_.clear(); 41 } 42 IsObserving(Source * source)43 bool IsObserving(Source* source) const { 44 return std::find(sources_.begin(), sources_.end(), source) != 45 sources_.end(); 46 } 47 48 private: 49 Observer* observer_; 50 51 std::vector<Source*> sources_; 52 53 DISALLOW_COPY_AND_ASSIGN(ScopedObserver); 54 }; 55 56 #endif // BASE_SCOPED_OBSERVER_H_ 57