| // 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 BASE_SCOPED_OBSERVER_H_ |
| #define BASE_SCOPED_OBSERVER_H_ |
| |
| #include <stddef.h> |
| |
| #include <algorithm> |
| #include <vector> |
| |
| #include "base/logging.h" |
| #include "base/macros.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) { |
| auto it = std::find(sources_.begin(), sources_.end(), source); |
| DCHECK(it != sources_.end()); |
| sources_.erase(it); |
| 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 ContainsValue(sources_, source); |
| } |
| |
| bool IsObservingSources() const { return !sources_.empty(); } |
| |
| private: |
| Observer* observer_; |
| |
| std::vector<Source*> sources_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ScopedObserver); |
| }; |
| |
| #endif // BASE_SCOPED_OBSERVER_H_ |