15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Copyright (c) 2012 The Chromium Authors. All rights reserved. 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// found in the LICENSE file. 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef BASE_SCOPED_OBSERVER_H_ 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define BASE_SCOPED_OBSERVER_H_ 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <algorithm> 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <vector> 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/basictypes.h" 1229b820f8d84e3bc97d62552e54923c42407f2f29Ben Murdoch#include "base/logging.h" 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// ScopedObserver is used to keep track of the set of sources an object has 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// attached itself to as an observer. When ScopedObserver is destroyed it 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// removes the object as an observer from all sources it has been added to. 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)template <class Source, class Observer> 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class ScopedObserver { 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) explicit ScopedObserver(Observer* observer) : observer_(observer) {} 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ~ScopedObserver() { 23c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch RemoveAll(); 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Adds the object passed to the constructor as an observer on |source|. 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void Add(Source* source) { 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sources_.push_back(source); 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) source->AddObserver(observer_); 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Remove the object passed to the constructor as an observer from |source|. 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void Remove(Source* source) { 3429b820f8d84e3bc97d62552e54923c42407f2f29Ben Murdoch auto it = std::find(sources_.begin(), sources_.end(), source); 3529b820f8d84e3bc97d62552e54923c42407f2f29Ben Murdoch DCHECK(it != sources_.end()); 3629b820f8d84e3bc97d62552e54923c42407f2f29Ben Murdoch sources_.erase(it); 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) source->RemoveObserver(observer_); 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 40c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch void RemoveAll() { 41c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch for (size_t i = 0; i < sources_.size(); ++i) 42c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch sources_[i]->RemoveObserver(observer_); 43c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch sources_.clear(); 44c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch } 45c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) bool IsObserving(Source* source) const { 47c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch return std::find(sources_.begin(), sources_.end(), source) != 48c5cede9ae108bb15f6b7a8aea21c7e1fefa2834cBen Murdoch sources_.end(); 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) Observer* observer_; 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) std::vector<Source*> sources_; 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DISALLOW_COPY_AND_ASSIGN(ScopedObserver); 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif // BASE_SCOPED_OBSERVER_H_ 60