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// Copyright 2016 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 UI_BASE_WINDOW_TRACKER_TEMPLATE_H_
#define UI_BASE_WINDOW_TRACKER_TEMPLATE_H_
#include <vector>
#include "base/macros.h"
#include "base/stl_util.h"
namespace ui {
// This class is used to track an ordered list of objects that support an
// observer interface with the function OnWindowDestroying(). When the object
// is destroyed it is removed from the ordered list of objects.
// Examples of T include aura::Window and its corresponding
// aura::WindowObserver interface.
template <class T, class TObserver>
class WindowTrackerTemplate : public TObserver {
public:
// A vector<> is used for tracking the windows (instead of a set<>) because
// the user may want to know about the order of the windows that have been
// added.
using WindowList = std::vector<T*>;
explicit WindowTrackerTemplate(const WindowList& windows) {
for (T* window : windows)
Add(window);
}
WindowTrackerTemplate() {}
~WindowTrackerTemplate() override { RemoveAll(); }
// Returns the set of windows being observed.
const WindowList& windows() const { return windows_; }
// Adds |window| to the set of Windows being tracked.
void Add(T* window) {
if (base::ContainsValue(windows_, window))
return;
window->AddObserver(this);
windows_.push_back(window);
}
void RemoveAll() {
for (T* window : windows_)
window->RemoveObserver(this);
windows_.clear();
}
// Removes |window| from the set of windows being tracked.
void Remove(T* window) {
auto iter = std::find(windows_.begin(), windows_.end(), window);
if (iter != windows_.end()) {
window->RemoveObserver(this);
windows_.erase(iter);
}
}
T* Pop() {
DCHECK(!windows_.empty());
T* result = windows_[0];
Remove(result);
return result;
}
// Returns true if |window| was previously added and has not been removed or
// deleted.
bool Contains(T* window) const {
return base::ContainsValue(windows_, window);
}
// Observer overrides:
void OnWindowDestroying(T* window) override {
DCHECK(Contains(window));
Remove(window);
}
private:
WindowList windows_;
DISALLOW_COPY_AND_ASSIGN(WindowTrackerTemplate);
};
} // namespace ui
#endif // UI_BASE_WINDOW_TRACKER_TEMPLATE_H_
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