| // 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 <vector> |
| |
| #include "base/check.h" |
| #include "base/ranges/algorithm.h" |
| #include "base/stl_util.h" |
| |
| // This class is DEPRECATED. Instead please use one of: |
| // - base::ScopedObservation for observing a single source. |
| // - base::ScopedMultiSourceObservation for observing multiple sources. |
| // |
| // 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. |
| // Basic example (as a member variable): |
| // |
| // class MyFooObserver : public FooObserver { |
| // ... |
| // private: |
| // ScopedObserver<Foo, FooObserver> observed_foo_{this}; |
| // }; |
| // |
| // For cases with methods not named AddObserver/RemoveObserver: |
| // |
| // class MyFooStateObserver : public FooStateObserver { |
| // ... |
| // private: |
| // ScopedObserver<Foo, |
| // FooStateObserver, |
| // &Foo::AddStateObserver, |
| // &Foo::RemoveStateObserver> |
| // observed_foo_{this}; |
| // }; |
| template <class Source, |
| class Observer, |
| void (Source::*AddObsFn)(Observer*) = &Source::AddObserver, |
| void (Source::*RemoveObsFn)(Observer*) = &Source::RemoveObserver> |
| class ScopedObserver { |
| public: |
| explicit ScopedObserver(Observer* observer) : observer_(observer) {} |
| ScopedObserver(const ScopedObserver&) = delete; |
| ScopedObserver& operator=(const ScopedObserver&) = delete; |
| ~ScopedObserver() { |
| RemoveAll(); |
| } |
| |
| // Adds the object passed to the constructor as an observer on |source|. |
| void Add(Source* source) { |
| sources_.push_back(source); |
| (source->*AddObsFn)(observer_); |
| } |
| |
| // Remove the object passed to the constructor as an observer from |source|. |
| void Remove(Source* source) { |
| auto it = base::ranges::find(sources_, source); |
| DCHECK(it != sources_.end()); |
| sources_.erase(it); |
| (source->*RemoveObsFn)(observer_); |
| } |
| |
| void RemoveAll() { |
| for (size_t i = 0; i < sources_.size(); ++i) |
| (sources_[i]->*RemoveObsFn)(observer_); |
| sources_.clear(); |
| } |
| |
| bool IsObserving(Source* source) const { |
| return base::Contains(sources_, source); |
| } |
| |
| bool IsObservingSources() const { return !sources_.empty(); } |
| |
| size_t GetSourcesCount() const { return sources_.size(); } |
| |
| private: |
| Observer* observer_; |
| |
| std::vector<Source*> sources_; |
| }; |
| |
| #endif // BASE_SCOPED_OBSERVER_H_ |