Struct rustc_infer::infer::undo_log::InferCtxtUndoLogs

pub(crate) struct InferCtxtUndoLogs<'tcx> {
    logs: Vec<UndoLog<'tcx>>,
    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<'tcx>>

num_open_snapshots: usize

Implementations

impl<'tcx> InferCtxtUndoLogs<'tcx>

pub fn start_snapshot(&mut self) -> Snapshot<'tcx>

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

pub(crate) fn region_constraints(
    &self
) -> impl Iterator<Item = &UndoLog<'tcx>> + Clone

fn assert_open_snapshot(&self, snapshot: &Snapshot<'tcx>)

Trait Implementations

impl Default for InferCtxtUndoLogs<'_>

fn default() -> Self

Returns the “default value” for a type.

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

type Output = UndoLog<'tcx>

The returned type after indexing.

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

Performs the indexing (container[index]) operation.

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

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

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

impl<'tcx, T> UndoLogs<T> for InferCtxtUndoLogs<'tcx> where
    UndoLog<'tcx>: From<T>, 

The UndoLogs trait defines how we undo a particular kind of action (of type T). We can undo any action that is convertable into a 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 rolleod 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