| // Copyright 2018 The Fuchsia 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 PERIDOT_BIN_SESSIONMGR_STORY_MODEL_STORY_OBSERVER_H_ |
| #define PERIDOT_BIN_SESSIONMGR_STORY_MODEL_STORY_OBSERVER_H_ |
| |
| #include <fuchsia/modular/storymodel/cpp/fidl.h> |
| #include <lib/fxl/macros.h> |
| |
| namespace modular { |
| |
| // Implemented bv StoryModelOwner. A client of StoryObserver can query the |
| // current state of a StoryModel or register a callback to be notified of |
| // changes. |
| class StoryObserver { |
| public: |
| StoryObserver() = default; |
| virtual ~StoryObserver() = default; |
| |
| // Registers |listener| as a callback for StoryModel updates. If |this| is |
| // destroyed, or the StoryModelOwner that created |this| is destroyed, all |
| // registered listeners will also be destroyed. |
| // |
| // Clients may learn that the StoryModelOwner is destroyed by deferring |
| // a callback in the capture list of |listener|. Example: |
| // |
| // auto on_abandoned = [] { /* do some cleanup */ }; |
| // observer.RegisterListener( |
| // [on_destroy = fit::defer(on_abandoned)] |
| // (const StoryModel& model) { |
| // /* do something with the update */ |
| // }); |
| // |
| // Note that the received StoryModel is only valid for the lifetime |
| // of the call to |listener|. |
| virtual void RegisterListener( |
| fit::function<void(const fuchsia::modular::storymodel::StoryModel& model)> |
| listener) = 0; |
| |
| // Returns the current state of the StoryModel. |
| virtual const fuchsia::modular::storymodel::StoryModel& model() = 0; |
| |
| private: |
| FXL_DISALLOW_COPY_AND_ASSIGN(StoryObserver); |
| }; |
| |
| } // namespace modular |
| |
| #endif // PERIDOT_BIN_SESSIONMGR_STORY_MODEL_STORY_OBSERVER_H_ |