UnitResult Undo() { if (globallyRepeatableUnits.Count < 1) { throw new InvalidOperationException("No unit to undo."); } IUndoableUnit undoableUnit = globallyUndoableUnits.Pop(); IInternalUnit repeatableUnit = globallyRepeatableUnits.Pop(); var eventArgs = new CancellableUndoServiceEventArgs(undoableUnit); OnUndoing(eventArgs); if (eventArgs.Cancel) { globallyUndoableUnits.AddLast(undoableUnit); globallyRepeatableUnits.AddLast(repeatableUnit); return(UnitResult.Cancelled); } globallyRedoableUnits.AddLast(undoableUnit); UnitResult result = undoableUnit.Undo(); OnUndone(new UndoServiceEventArgs(undoableUnit)); return(result); }
UnitResult PerformUnit <T>(UndoableUnitBase <T> unit, T argument) { var eventArgs = new CancellableUndoServiceEventArgs(unit); OnExecuting(eventArgs); if (eventArgs.Cancel) { return(UnitResult.Cancelled); } globallyRedoableUnits.Clear(); globallyRepeatableUnits.AddLast(unit); globallyUndoableUnits.AddLast(unit); UnitResult result = unit.PerformUnit(argument, UnitMode.FirstTime); TrimIfRequired(); OnExecuted(new UndoServiceEventArgs(unit)); return(result); }