Struct CowMut 

pub struct CowMut<'a, T: Clone> { /* private fields */ }

A structure the engine may write, borrowed so that it is copied only when it is written.

The store shares its interner, topology and edge properties with the reader’s fold through Arcs. Handing the engine &mut to them meant Arc::make_mut up front, so every commit that ran the engine copied all three whole the first time after a fold, though most commits derive nothing (ledger row 126). Reads go through Deref, which never copies; the first &mut use (DerefMut) copies the shared value then, once.

Trait Implementations

impl<T: Clone> Deref for CowMut<'_, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: Clone> DerefMut for CowMut<'_, T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<'a, T: Clone> From<&'a mut Arc<T>> for CowMut<'a, T>

fn from(arc: &'a mut Arc<T>) -> Self

Converts to this type from the input type.

impl<'a, T: Clone> From<&'a mut T> for CowMut<'a, T>

fn from(value: &'a mut T) -> Self

Converts to this type from the input type.