Trait rustc_data_structures::undo_log::UndoLogs

pub trait UndoLogs<T> {
    // Required methods
    fn num_open_snapshots(&self) -> usize;
    fn push(&mut self, undo: T);
    fn clear(&mut self);

    // Provided methods
    fn in_snapshot(&self) -> bool { ... }
    fn extend<I>(&mut self, undos: I)
       where Self: Sized,
             I: IntoIterator<Item = T> { ... }
}

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

fn num_open_snapshots(&self) -> usize

How many open snapshots this undo log currently has

fn push(&mut self, undo: T)

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.

fn clear(&mut self)

Removes all items from the undo log.

Provided Methods

fn in_snapshot(&self) -> bool

True if a snapshot has started, false otherwise

fn extend<I>(&mut self, undos: I)where Self: Sized, I: IntoIterator<Item = T>,

Extends the undo log with many undos.

Implementors