Trait rustc_data_structures::undo_log::Snapshots
source · pub trait Snapshots<T>: UndoLogs<T> {
type Snapshot;
// Required methods
fn actions_since_snapshot(&self, snapshot: &Self::Snapshot) -> &[T];
fn start_snapshot(&mut self) -> Self::Snapshot;
fn rollback_to<R>(
&mut self,
storage: impl FnOnce() -> R,
snapshot: Self::Snapshot,
)
where R: Rollback<T>;
fn commit(&mut self, snapshot: Self::Snapshot);
// Provided method
fn has_changes(&self, snapshot: &Self::Snapshot) -> bool { ... }
}
Expand description
A trait which extends UndoLogs
to allow snapshots to be done at specific points. Each snapshot can then be used to
rollback any changes to an underlying data structures if they were not desirable.
Each snapshot must be consumed linearly with either rollback_to
or commit
.
Required Associated Types§
Required Methods§
sourcefn actions_since_snapshot(&self, snapshot: &Self::Snapshot) -> &[T]
fn actions_since_snapshot(&self, snapshot: &Self::Snapshot) -> &[T]
Returns the slice of actions that were taken since the snapshot began.
sourcefn start_snapshot(&mut self) -> Self::Snapshot
fn start_snapshot(&mut self) -> Self::Snapshot
Starts a new snapshot. That snapshot must eventually either be committed via a call to commit or rollback via rollback_to. Snapshots can be nested (i.e., you can start a snapshot whilst another snapshot is in progress) but you must then commit or rollback the inner snapshot before attempting to commit or rollback the outer snapshot.
sourcefn rollback_to<R>(
&mut self,
storage: impl FnOnce() -> R,
snapshot: Self::Snapshot,
)where
R: Rollback<T>,
fn rollback_to<R>(
&mut self,
storage: impl FnOnce() -> R,
snapshot: Self::Snapshot,
)where
R: Rollback<T>,
Rollback (undo) the changes made to storage
since the snapshot.
Provided Methods§
sourcefn has_changes(&self, snapshot: &Self::Snapshot) -> bool
fn has_changes(&self, snapshot: &Self::Snapshot) -> bool
Returns true if self
has made any changes since snapshot started.