Roll src/third_party/skia d32087a:1052f51
[chromium-blink-merge.git] / base / scoped_observer.h
blob422701bc2190fed7d6844ae18ce5385b24e1d498
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.
5 #ifndef BASE_SCOPED_OBSERVER_H_
6 #define BASE_SCOPED_OBSERVER_H_
8 #include <algorithm>
9 #include <vector>
11 #include "base/basictypes.h"
12 #include "base/logging.h"
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) {}
22 ~ScopedObserver() {
23 RemoveAll();
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_);
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_);
40 void RemoveAll() {
41 for (size_t i = 0; i < sources_.size(); ++i)
42 sources_[i]->RemoveObserver(observer_);
43 sources_.clear();
46 bool IsObserving(Source* source) const {
47 return std::find(sources_.begin(), sources_.end(), source) !=
48 sources_.end();
51 bool IsObservingSources() const { return !sources_.empty(); }
53 private:
54 Observer* observer_;
56 std::vector<Source*> sources_;
58 DISALLOW_COPY_AND_ASSIGN(ScopedObserver);
61 #endif // BASE_SCOPED_OBSERVER_H_