// Copyright (c) 2012 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BUTIL_SCOPED_OBSERVER_H_ #define BUTIL_SCOPED_OBSERVER_H_ #include <algorithm> #include <vector> #include "butil/basictypes.h" // ScopedObserver is used to keep track of the set of sources an object has // attached itself to as an observer. When ScopedObserver is destroyed it // removes the object as an observer from all sources it has been added to. template <class Source, class Observer> class ScopedObserver { public: explicit ScopedObserver(Observer* observer) : observer_(observer) {} ~ScopedObserver() { RemoveAll(); } // Adds the object passed to the constructor as an observer on |source|. void Add(Source* source) { sources_.push_back(source); source->AddObserver(observer_); } // Remove the object passed to the constructor as an observer from |source|. void Remove(Source* source) { sources_.erase(std::find(sources_.begin(), sources_.end(), source)); source->RemoveObserver(observer_); } void RemoveAll() { for (size_t i = 0; i < sources_.size(); ++i) sources_[i]->RemoveObserver(observer_); sources_.clear(); } bool IsObserving(Source* source) const { return std::find(sources_.begin(), sources_.end(), source) != sources_.end(); } private: Observer* observer_; std::vector<Source*> sources_; DISALLOW_COPY_AND_ASSIGN(ScopedObserver); }; #endif // BUTIL_SCOPED_OBSERVER_H_