Struct InferCtxtUndoLogs 

pub(crate) struct InferCtxtUndoLogs<'db> {
    logs: Vec<UndoLog<'db>>,
    num_open_snapshots: usize,
}

The combined undo log for all the various unification tables. For each change to the storage for any kind of inference variable, we record an UndoLog entry in the vector here.

Fields

logs: Vec<UndoLog<'db>>

num_open_snapshots: usize

Implementations

impl<'db> InferCtxtUndoLogs<'db>

pub(crate) fn start_snapshot(&mut self) -> Snapshot

pub(crate) fn region_constraints_in_snapshot( &self, s: &Snapshot, ) -> impl Iterator<Item = &UndoLog<'db>> + Clone

pub(crate) fn opaque_types_in_snapshot(&self, s: &Snapshot) -> bool

fn assert_open_snapshot(&self, snapshot: &Snapshot)

Trait Implementations

impl<'db> Clone for InferCtxtUndoLogs<'db>

fn clone(&self) -> InferCtxtUndoLogs<'db>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'db> Default for InferCtxtUndoLogs<'db>

fn default() -> InferCtxtUndoLogs<'db>

Returns the “default value” for a type.

impl<'db> Index<usize> for InferCtxtUndoLogs<'db>

type Output = UndoLog<'db>

The returned type after indexing.

fn index(&self, key: usize) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<'db> IndexMut<usize> for InferCtxtUndoLogs<'db>

fn index_mut(&mut self, key: usize) -> &mut Self::Output

Performs the mutable indexing (container[index]) operation.

impl<'db, T> UndoLogs<T> for InferCtxtUndoLogs<'db>

where UndoLog<'db>: From<T>,

The UndoLogs trait defines how we undo a particular kind of action (of type T). We can undo any action that is convertible into an UndoLog (per the From impls above).

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 rolled back.

fn clear(&mut self)

Removes all items from the undo log.

fn extend<J>(&mut self, undos: J)

where Self: Sized, J: IntoIterator<Item = T>,

Extends the undo log with many undos.

fn in_snapshot(&self) -> bool

True if a snapshot has started, false otherwise