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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SERVICES_APP_SERVICE_PUBLIC_CPP_INSTANCE_UPDATE_H_
#define COMPONENTS_SERVICES_APP_SERVICE_PUBLIC_CPP_INSTANCE_UPDATE_H_
#include <string>
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "components/services/app_service/public/cpp/instance.h"
namespace apps {
class Instance;
// Wraps two Instance's, a prior state and a delta on top of that state. The
// state is conceptually the "sum" of all of the previous deltas, with
// "addition" or "merging" simply being that the most recent version of each
// field "wins".
//
// The state may be nullptr, meaning that there are no previous deltas.
// Alternatively, the delta may be nullptr, meaning that there is no change in
// state. At least one of state and delta must be non-nullptr.
//
// The combination of the two (state and delta) can answer questions such as:
// - What is the app's launch_id? If the delta knows, that's the answer.
// Otherwise, ask the state.
// - Is the app launched? Likewise, if the delta says yes or no, that's the
// answer. Otherwise, the delta says "unknown", ask the state.
//
// An InstanceUpdate is read-only once constructed. All of its fields and
// methods are const. The constructor caller must guarantee that the Instance
// pointer remain valid for the lifetime of the AppUpdate.
class InstanceUpdate {
public:
// Modifies |state| by copying over all of |delta|'s known fields: those
// fields whose values aren't "unknown" or invalid. The |state| may not be
// nullptr.
static void Merge(Instance* state, const Instance* delta);
// Returns true if |state| exists and is equal to |delta|, or |delta| are
// nullptr. Return false otherwise.
static bool Equals(const Instance* state, const Instance* delta);
// At most one of |state| or |delta| may be nullptr.
InstanceUpdate(const Instance* state, const Instance* delta);
InstanceUpdate(const InstanceUpdate&) = delete;
InstanceUpdate& operator=(const InstanceUpdate&) = delete;
// Returns whether this is the first update for the given window.
// Equivalently, there are no previous deltas for the window.
bool StateIsNull() const;
// Returns true if this update represents the creation of an instance, which
// will now be visible to the user.
bool IsCreation() const;
// Returns true if this update represents the destruction of an instance.
bool IsDestruction() const;
const std::string& AppId() const;
const base::UnguessableToken& InstanceId() const;
aura::Window* Window() const;
bool WindowChanged() const;
const std::string& LaunchId() const;
bool LaunchIdChanged() const;
InstanceState State() const;
bool StateChanged() const;
base::Time LastUpdatedTime() const;
bool LastUpdatedTimeChanged() const;
content::BrowserContext* BrowserContext() const;
bool BrowserContextChanged() const;
private:
raw_ptr<const Instance> state_;
raw_ptr<const Instance> delta_;
};
} // namespace apps
#endif // COMPONENTS_SERVICES_APP_SERVICE_PUBLIC_CPP_INSTANCE_UPDATE_H_
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