<> <> <> <> <> DIRECTORY TiogaPrivate USING [Change, Event, EventBody, SubEvent, SubEventBody, UndoProc, World]; UndoEventImpl: CEDAR PROGRAM EXPORTS TiogaPrivate = BEGIN OPEN TiogaPrivate; CreateEvent: PUBLIC PROC RETURNS [Event] = { RETURN [NEW[EventBody _ [subevents: NIL]]] }; NoteEvent: PUBLIC PROC [world: World, undoProc: UndoProc, undoRef: REF Change] = { event: Event ~ IF world=NIL THEN NIL ELSE world.currentEvent; IF event = NIL THEN RETURN; event.subevents _ NEW[SubEventBody _ [next: event.subevents, undoProc: undoProc, undoRef: undoRef]]; }; UndoEvent: PUBLIC PROC [world: World, undoEvent: Event] = { <> <> sub: SubEvent; IF undoEvent=NIL THEN RETURN; sub _ undoEvent.subevents; undoEvent.subevents _ NIL; UNTIL sub=NIL DO sub.undoProc[world, sub.undoRef]; sub _ sub.next; ENDLOOP; }; ResetEvent: PUBLIC PROC [event: Event] = { IF event # NIL THEN event.subevents _ NIL }; EmptyEvent: PUBLIC PROC [event: Event] RETURNS [BOOL] = { RETURN [event=NIL OR event.subevents=NIL] }; END.