pub trait UndoLogs<T> {
    fn num_open_snapshots(&self) -> usize;
fn push(&mut self, undo: T);
fn clear(&mut self); fn in_snapshot(&self) -> bool { ... }
fn extend<I>(&mut self, undos: I)
        I: IntoIterator<Item = T>
, { ... } }
Expand description

A trait which allows undo actions (T) to be pushed which can be used to rollback actio at a later time if needed.

The undo actions themselves are opaque to UndoLogs, only specified Rollback implementations need to know what an action is and how to reverse it.

Required methods

How many open snapshots this undo log currently has

Pushes a new “undo item” onto the undo log. This method is invoked when some action is taken (e.g., a variable is unified). It records the info needed to reverse that action should an enclosing snapshot be rolleod back.

Removes all items from the undo log.

Provided methods

True if a snapshot has started, false otherwise

Extends the undo log with many undos.