UndoService 2.0.2

UndoService

Simple undo/redo service based on the momento pattern. It uses delegates to access state. It can track changes to different parts of the application individually, while using one unified interface for performing undo/redo. This reduces the memory imprint and facilitates modular design. See the unit tests for examples of usage. https://github.com/peterdongan/UndoService

The simplest approach is to use a single UndoService for application state. Alternatively you can use separate UndoServices for different sections in conjunction with an AggregatedUndoService. This means that the whole of the application state does not need to be recorded on each change.

UndoService Class

This can be used by itself to record state and perform undo/redo actions, or it can be used as a subservice of AggregateUndoService to manage changes to a particular segment. In the latter case, Undo() and Redo() should only be invoked via the AggregateUndoService. View the unit tests for example of both forms of use.

UndoService Constructor

Set the type that is used to record the state. Pass the delegate methods that are used to get and set the state. (If necessary use a wrapper to match the expected signature.) Optionally set a cap on the number of states stored.

UndoService(GetState<T> getState, SetState<T> setState, int? cap)	

If there is no cap then stacks are used for the undo and the redo stack. If there is a cap then a dropout stack is used for the undo stack.

UndoService Properties

Check CanUndo and CanRedo properties before invoking Undo() or Redo() respectively.

bool CanUndo
bool CanRedo

UndoService Methods

Invoke RecordState() to add the current state to the undo history.

void RecordState() 
void Undo()
void Redo()
void ClearStacks()
void ClearUndoStacks()

AggregateUndoService Class

This can be used with multiple UndoServices to manage Undo/Redo across separate segments of the application. In this case, the child UndoServices look after change tracking and Undo/Redo is done via the AggregateUndoService. Most of the members are similar to UndoService so they are not duplicated here.

AggregateUndoService Constructor

Pass an array of the UndoServices that are used for different parts of the application.

AggregateUndoService(IUndoService[] subUndoServices)

LICENCE

MIT