- UndoStack(){
- current = NULL;
- // size must be initialised (thornley)
- size = 0;
- limit = 100; // the maximum number of undo steps stored. 0 means NO LIMIT.
- // Limit can be changed with UndoStack::SetStackLimit(int)
- }
- ///
- Undo *Pop(){
- Undo* result = NULL;
- if (current){
- result = current->undo;
- tmp = current;
- current = current->previous;
- delete tmp;
- size--;
- }
- else {
- size = 0; // for safety...
- }
- return result;
- }
- ///
- Undo* Top(){
- if (current)
- return current->undo;
- else
- return NULL;
- }
- ///
- ~UndoStack(){
- Clear();
- }
- ///
- void Clear(){
- Undo* tmp_undo = Pop();
- while (tmp_undo){
- delete tmp_undo;
- tmp_undo = Pop();
- }
- }
- ///
- void SetStackLimit(int limit_arg) {
- limit = limit_arg;
- }
-
- ///
- void Push(Undo* undo_arg){
- int i;
- StackAtom* tmp2;
- if (undo_arg){
- tmp = new StackAtom;
- tmp->undo = undo_arg;
- tmp->previous = current;
- current = tmp;
- size++;
- if (limit && size > limit){
- for (i=0; i<limit && tmp; i++)
- tmp = tmp->previous;
- while(tmp && tmp->previous){
- tmp2 = tmp->previous->previous;
- delete tmp->previous;
- size--;
- tmp->previous = tmp2;
- }
- }
- }
- }