def undo(self,
change=None,
drop=False,
task_handle=taskhandle.NullTaskHandle()):
"""Redo done changes from the history
When `change` is `None`, the last done change will be undone.
If change is not `None` it should be an item from
`self.undo_list`; this change and all changes that depend on
it will be undone. In both cases the list of undone changes
will be returned.
If `drop` is `True`, the undone change will not be appended to
the redo list.
"""
if not self._undo_list:
raise exceptions.HistoryError("Undo list is empty")
if change is None:
change = self.undo_list[-1]
dependencies = self._find_dependencies(self.undo_list, change)
self._move_front(self.undo_list, dependencies)
self._perform_undos(len(dependencies), task_handle)
result = self.redo_list[-len(dependencies):]
if drop:
del self.redo_list[-len(dependencies):]
return result
def redo(self, change=None, task_handle=taskhandle.NullTaskHandle()):
"""Redo undone changes from the history
When `change` is `None`, the last undone change will be
redone. If change is not `None` it should be an item from
`self.redo_list`; this change and all changes that depend on
it will be redone. In both cases the list of redone changes
will be returned.
"""
if not self.redo_list:
raise exceptions.HistoryError("Redo list is empty")
if change is None:
change = self.redo_list[-1]
dependencies = self._find_dependencies(self.redo_list, change)
self._move_front(self.redo_list, dependencies)
self._perform_redos(len(dependencies), task_handle)
return self.undo_list[-len(dependencies):]
def undo(self):
if self.old_contents is None:
raise exceptions.HistoryError(
'Undoing a change that is not performed yet!')
self._operations.write_file(self.resource, self.old_contents)
