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);
}
/// <summary>
/// Undoes the execution of a previous <see cref="IUnit"/>.
/// </summary>
/// <exception cref="InvalidOperationException">
/// Occurs if there are no previously executed units to undo.</exception>
public UnitResult Undo(object ownerKey)
{
if (ownerKey == null)
{
return(Undo());
}
if (!undoableDictionary.TryGetValue(ownerKey,
out UnitCollection <IUndoableUnit> undoableUnits))
{
throw new InvalidOperationException("No undoable units for the specified owner key.");
}
IUndoableUnit undoableUnit = undoableUnits.Pop();
if (!repeatableDictionary.TryGetValue(ownerKey,
out UnitCollection <IInternalUnit> repeatableUnits))
{
throw new InvalidOperationException("No repeatable units for the specified owner key.");
}
repeatableUnits.RemoveLast();
var eventArgs = new CancellableUndoServiceEventArgs(undoableUnit)
{
OwnerKey = ownerKey
};
OnUndoing(eventArgs);
if (eventArgs.Cancel)
{
undoableUnits.AddLast(undoableUnit);
return(UnitResult.Cancelled);
}
if (!redoableDictionary.TryGetValue(ownerKey,
out UnitCollection <IUndoableUnit> redoableUnits))
{
redoableUnits = new UnitCollection <IUndoableUnit>();
redoableDictionary[ownerKey] = redoableUnits;
}
redoableUnits.AddLast(undoableUnit);
var result = undoableUnit.Undo();
TrimIfRequired(ownerKey);
OnUndone(new UndoServiceEventArgs(undoableUnit));
return(result);
}
/// <summary>
/// Performs the execution of a <see cref="IUnit"/>
/// instance that has been undone, then places it back
/// into the command stack.
/// </summary>
public UnitResult Redo(object ownerKey)
{
if (ownerKey == null)
{
return(Redo());
}
if (!redoableDictionary.TryGetValue(ownerKey,
out UnitCollection <IUndoableUnit> redoableUnits))
{
throw new InvalidOperationException("No units to be redone for the specified owner key.");
}
IUndoableUnit unit = redoableUnits.Pop();
var eventArgs = new CancellableUndoServiceEventArgs(unit);
OnRedoing(eventArgs);
if (eventArgs.Cancel)
{
redoableUnits.AddLast(unit);
return(UnitResult.Cancelled);
}
var internalUnit = (IInternalUnit)unit;
if (!repeatableDictionary.TryGetValue(ownerKey,
out UnitCollection <IInternalUnit> repeatableUnits))
{
repeatableUnits = new UnitCollection <IInternalUnit>();
}
repeatableUnits.AddLast(internalUnit);
if (!undoableDictionary.TryGetValue(ownerKey,
out UnitCollection <IUndoableUnit> undoableUnits))
{
undoableUnits = new UnitCollection <IUndoableUnit>();
}
undoableUnits.AddLast(unit);
UnitResult result = internalUnit.PerformUnit(internalUnit.Argument, UnitMode.Redo);
TrimIfRequired(ownerKey);
OnRedone(new UndoServiceEventArgs(unit));
return(result);
}