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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #ifndef BASE_SCOPED_OBSERVER_H_ | 5 #ifndef BASE_SCOPED_OBSERVER_H_ |
| 6 #define BASE_SCOPED_OBSERVER_H_ | 6 #define BASE_SCOPED_OBSERVER_H_ |
| 7 | 7 |
| 8 #include <algorithm> | 8 #include <algorithm> |
| 9 #include <vector> | 9 #include <vector> |
| 10 | 10 |
| 11 #include "base/basictypes.h" | 11 #include "base/basictypes.h" |
| 12 #include "base/logging.h" | |
| 13 | 12 |
| 14 // ScopedObserver is used to keep track of the set of sources an object has | 13 // 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 | 14 // 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. | 15 // removes the object as an observer from all sources it has been added to. |
| 17 template <class Source, class Observer> | 16 template <class Source, class Observer> |
| 18 class ScopedObserver { | 17 class ScopedObserver { |
| 19 public: | 18 public: |
| 20 explicit ScopedObserver(Observer* observer) : observer_(observer) {} | 19 explicit ScopedObserver(Observer* observer) : observer_(observer) {} |
| 21 | 20 |
| 22 ~ScopedObserver() { | 21 ~ScopedObserver() { |
| 23 RemoveAll(); | 22 RemoveAll(); |
| 24 } | 23 } |
| 25 | 24 |
| 26 // Adds the object passed to the constructor as an observer on |source|. | 25 // Adds the object passed to the constructor as an observer on |source|. |
| 27 void Add(Source* source) { | 26 void Add(Source* source) { |
| 28 sources_.push_back(source); | 27 sources_.push_back(source); |
| 29 source->AddObserver(observer_); | 28 source->AddObserver(observer_); |
| 30 } | 29 } |
| 31 | 30 |
| 32 // Remove the object passed to the constructor as an observer from |source|. | 31 // Remove the object passed to the constructor as an observer from |source|. |
| 33 void Remove(Source* source) { | 32 void Remove(Source* source) { |
| 34 auto it = std::find(sources_.begin(), sources_.end(), source); | 33 sources_.erase(std::find(sources_.begin(), sources_.end(), source)); |
| 35 DCHECK(it != sources_.end()); | |
| 36 sources_.erase(it); | |
| 37 source->RemoveObserver(observer_); | 34 source->RemoveObserver(observer_); |
| 38 } | 35 } |
| 39 | 36 |
| 40 void RemoveAll() { | 37 void RemoveAll() { |
| 41 for (size_t i = 0; i < sources_.size(); ++i) | 38 for (size_t i = 0; i < sources_.size(); ++i) |
| 42 sources_[i]->RemoveObserver(observer_); | 39 sources_[i]->RemoveObserver(observer_); |
| 43 sources_.clear(); | 40 sources_.clear(); |
| 44 } | 41 } |
| 45 | 42 |
| 46 bool IsObserving(Source* source) const { | 43 bool IsObserving(Source* source) const { |
| 47 return std::find(sources_.begin(), sources_.end(), source) != | 44 return std::find(sources_.begin(), sources_.end(), source) != |
| 48 sources_.end(); | 45 sources_.end(); |
| 49 } | 46 } |
| 50 | 47 |
| 51 private: | 48 private: |
| 52 Observer* observer_; | 49 Observer* observer_; |
| 53 | 50 |
| 54 std::vector<Source*> sources_; | 51 std::vector<Source*> sources_; |
| 55 | 52 |
| 56 DISALLOW_COPY_AND_ASSIGN(ScopedObserver); | 53 DISALLOW_COPY_AND_ASSIGN(ScopedObserver); |
| 57 }; | 54 }; |
| 58 | 55 |
| 59 #endif // BASE_SCOPED_OBSERVER_H_ | 56 #endif // BASE_SCOPED_OBSERVER_H_ |
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