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moved changes history tracking from the UndoRedoDomainModel to the se…
…parate class
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,217 @@ | ||
| using CoreCraft.ChangesTracking; | ||
| using CoreCraft.Exceptions; | ||
| using CoreCraft.Persistence; | ||
| using CoreCraft.Persistence.History; | ||
|
|
||
| namespace CoreCraft; | ||
|
|
||
| /// <summary> | ||
| /// Tracks changes history for a model and provides undo/redo functionality. | ||
| /// </summary> | ||
| public class ChangesHistory | ||
| { | ||
| private readonly DomainModel _model; | ||
|
|
||
| private readonly Stack<IModelChanges> _undoStack; | ||
| private readonly Stack<IModelChanges> _redoStack; | ||
|
|
||
| /// <summary> | ||
| /// Ctor | ||
| /// </summary> | ||
| public ChangesHistory(DomainModel model) | ||
| { | ||
| _model = model; | ||
|
|
||
| _undoStack = new Stack<IModelChanges>(); | ||
| _redoStack = new Stack<IModelChanges>(); | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Undo stack of model changes | ||
| /// </summary> | ||
| public IReadOnlyCollection<IModelChanges> UndoStack => _undoStack; | ||
|
|
||
| /// <summary> | ||
| /// Redo stack of model changes | ||
| /// </summary> | ||
| public IReadOnlyCollection<IModelChanges> RedoStack => _redoStack; | ||
|
|
||
| /// <summary> | ||
| /// Raised when model has changed | ||
| /// </summary> | ||
| public event EventHandler? Changed; | ||
|
|
||
| /// <summary> | ||
| /// Saves changes happened since the last save operation | ||
| /// </summary> | ||
| /// <param name="token">Cancellation token</param> | ||
| /// <param name="storage">A storage where a model will be saved</param> | ||
| /// <param name="historyStorage">A storage where a model changes history will be saved</param> | ||
| public async Task Update(IStorage storage, IHistoryStorage? historyStorage = null, CancellationToken token = default) | ||
| { | ||
| try | ||
| { | ||
| var changes = _undoStack.Reverse().ToList(); | ||
| if (changes.Count > 0) | ||
| { | ||
| var merged = MergeChanges(changes); | ||
| // merge operation can combine actions line Add and Remove, which will cause | ||
| // resulting IModelChanges object contain no changes | ||
| if (merged.HasChanges()) | ||
| { | ||
| await _model.Scheduler.RunParallel(() => | ||
| { | ||
| storage.Update(merged); | ||
| historyStorage?.Save(changes); | ||
| }, token); | ||
|
|
||
| // TODO(#8): saving operation executes in thread pool | ||
| // and launched by 'async void' methods. If two | ||
| // sequential savings happened, clearing of the stacks | ||
| // can cause data race (just after first save we will clear stack | ||
| // with new changes, made after first save started). | ||
| Clear(); | ||
| } | ||
| } | ||
| } | ||
| catch (Exception ex) | ||
| { | ||
| throw new ModelSaveException("Model update has failed", ex); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Saves the model's undo/redo history to the provided storage. | ||
| /// </summary> | ||
| /// <param name="storage">A storage to write</param> | ||
| /// <param name="token">Cancellation token</param> | ||
| /// <exception cref="ModelSaveException">Throws when an error occurred while saving model changes history</exception> | ||
| public async Task Save(IHistoryStorage storage, CancellationToken token = default) | ||
| { | ||
| try | ||
| { | ||
| var changes = _undoStack.Reverse().ToList(); | ||
| if (changes.Count > 0) | ||
| { | ||
| await _model.Scheduler.RunParallel(() => storage.Save(changes), token); | ||
|
|
||
| // TODO(#8): saving operation executes in thread pool | ||
| // and launched by 'async void' methods. If two | ||
| // sequential savings happened, clearing of the stacks | ||
| // can cause data race (just after first save we will clear stack | ||
| // with new changes, made after first save started). | ||
| Clear(); | ||
| } | ||
| } | ||
| catch (Exception ex) | ||
| { | ||
| throw new ModelSaveException("Model changes saving has failed", ex); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Loads the model's undo/redo history from the provided storage. | ||
| /// </summary> | ||
| /// <param name="storage">A storage to write</param> | ||
| /// <param name="token">Cancellation token</param> | ||
| public async Task Load(IHistoryStorage storage, CancellationToken token = default) | ||
| { | ||
| if (_undoStack.Count > 0 || _redoStack.Count > 0) | ||
| { | ||
| return; | ||
| } | ||
|
|
||
| var changes = await LoadHistory(storage, token); | ||
|
|
||
| foreach (var change in changes) | ||
| { | ||
| _undoStack.Push(change); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Clears the model's undo/redo history | ||
| /// </summary> | ||
| public void Clear() | ||
| { | ||
| if (_undoStack.Count > 0 || _redoStack.Count > 0) | ||
| { | ||
| _undoStack.Clear(); | ||
| _redoStack.Clear(); | ||
|
|
||
| Changed?.Invoke(this, EventArgs.Empty); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Undo latest changes | ||
| /// </summary> | ||
| public async Task Undo() | ||
| { | ||
| if (_undoStack.Count > 0) | ||
| { | ||
| var changes = _undoStack.Pop(); | ||
| _redoStack.Push(changes); | ||
| await _model.Apply(changes.Invert()); | ||
|
|
||
| Changed?.Invoke(this, EventArgs.Empty); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Redo changes which were undone previously | ||
| /// </summary> | ||
| public async Task Redo() | ||
| { | ||
| if (_redoStack.Count > 0) | ||
| { | ||
| var changes = _redoStack.Pop(); | ||
| _undoStack.Push(changes); | ||
| await _model.Apply(changes); | ||
|
|
||
| Changed?.Invoke(this, EventArgs.Empty); | ||
| } | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// History has changes | ||
| /// </summary> | ||
| /// <returns>True - if history has some changes in it</returns> | ||
| public bool HasChanges() | ||
| { | ||
| return _undoStack.Count > 0; | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Pushes the provided model changes to the undo stack | ||
| /// </summary> | ||
| /// <param name="change"></param> | ||
| public void Push(IModelChanges change) | ||
| { | ||
| _undoStack.Push(change); | ||
| _redoStack.Clear(); | ||
|
|
||
| Changed?.Invoke(this, EventArgs.Empty); | ||
| } | ||
|
|
||
| private Task<IEnumerable<IModelChanges>> LoadHistory( | ||
| IHistoryStorage storage, | ||
| CancellationToken token = default) | ||
| { | ||
| // TODO: Write explanation why we can use UnsafeModelShards here | ||
| var shards = _model.UnsafeModelShards; | ||
|
|
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| return _model.Scheduler.Enqueue(() => storage.Load(shards), token); | ||
| } | ||
|
|
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| private static IModelChanges MergeChanges(IReadOnlyList<IModelChanges> changes) | ||
| { | ||
| var merged = (IMutableModelChanges)changes[0]; | ||
| for (var i = 1; i < changes.Count; i++) | ||
| { | ||
| merged = merged.Merge(changes[i]); | ||
| } | ||
|
|
||
| return merged; | ||
| } | ||
| } |
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