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 #include "base/logging.h" 13 14 // ScopedObserver is used to keep track of the set of sources an object has 15 // attached itself to as an observer. When ScopedObserver is destroyed it 16 // removes the object as an observer from all sources it has been added to. 17 template <class Source, class Observer> 18 class ScopedObserver { 19 public: 20 explicit ScopedObserver(Observer* observer) : observer_(observer) {} 21 22 ~ScopedObserver() { 23 RemoveAll(); 24 } 25 26 // Adds the object passed to the constructor as an observer on |source|. 27 void Add(Source* source) { 28 sources_.push_back(source); 29 source->AddObserver(observer_); 30 } 31 32 // Remove the object passed to the constructor as an observer from |source|. 33 void Remove(Source* source) { 34 auto it = std::find(sources_.begin(), sources_.end(), source); 35 DCHECK(it != sources_.end()); 36 sources_.erase(it); 37 source->RemoveObserver(observer_); 38 } 39 40 void RemoveAll() { 41 for (size_t i = 0; i < sources_.size(); ++i) 42 sources_[i]->RemoveObserver(observer_); 43 sources_.clear(); 44 } 45 46 bool IsObserving(Source* source) const { 47 return std::find(sources_.begin(), sources_.end(), source) != 48 sources_.end(); 49 } 50 51 private: 52 Observer* observer_; 53 54 std::vector<Source*> sources_; 55 56 DISALLOW_COPY_AND_ASSIGN(ScopedObserver); 57 }; 58 59 #endif // BASE_SCOPED_OBSERVER_H_ 60
