Trait SingletonInverseVariableSupply 

pub trait SingletonInverseVariableSupply<V, E>: Supply
where
    V: Eq + Hash + Clone + Send + Sync + 'static,
    E: Clone + Send + Sync + 'static,
{
    // Required methods
    fn get_inverse_singleton(&self, value: &V) -> Option<E>;
    fn insert(&self, value: V, entity: E);
    fn remove(&self, value: &V) -> Option<E>;
    fn clear(&self);
    fn len(&self) -> usize;

    // Provided methods
    fn update(&self, old_value: Option<&V>, new_value: V, entity: E) { ... }
    fn is_empty(&self) -> bool { ... }
}

Supply that provides O(1) lookup of the entity pointing to a value.

For a chained variable where entity.previous = value, this supply answers: “Given value, which entity has entity.previous == value?”

This is essential for efficient chain manipulation in moves.

Required Methods

fn get_inverse_singleton(&self, value: &V) -> Option<E>

Gets the entity that points to the given value, if any.

Returns None if no entity currently points to this value.

fn insert(&self, value: V, entity: E)

Registers that an entity now points to a value.

Called when a variable change causes entity.var = value.

fn remove(&self, value: &V) -> Option<E>

Removes the mapping for a value.

Called when the entity that pointed to this value changes.

fn clear(&self)

Clears all mappings.

fn len(&self) -> usize

Returns the number of tracked mappings.

Provided Methods

fn update(&self, old_value: Option<&V>, new_value: V, entity: E)

Updates the mapping: removes old value mapping, adds new.

fn is_empty(&self) -> bool

Returns true if no mappings exist.

Implementors

impl<V, E> SingletonInverseVariableSupply<V, E> for ExternalizedSingletonInverseVariableSupply<V, E>

where V: Eq + Hash + Clone + Send + Sync + 'static, E: Clone + Send + Sync + 'static,