Struct EntityMap 

pub struct EntityMap { /* private fields */ }

A mapping from one set of entities to another.

The API generally follows HashMap, but each Entity is returned by value, as they are Copy.

This is typically used to coordinate data transfer between sets of entities, such as between a scene and the world or over the network. This is required as Entity identifiers are opaque; you cannot and do not want to reuse identifiers directly.

Implementations

impl EntityMap

pub fn insert(&mut self, from: Entity, to: Entity) -> Option<Entity>

Inserts an entities pair into the map.

If the map did not have from present, None is returned.

If the map did have from present, the value is updated, and the old value is returned.

pub fn remove(&mut self, entity: Entity) -> Option<Entity>

Removes an entity from the map, returning the mapped value of it if the entity was previously in the map.

pub fn entry( &mut self, entity: Entity, ) -> Entry<'_, Entity, Entity, RandomState>

Gets the given entity’s corresponding entry in the map for in-place manipulation.

pub fn get(&self, entity: Entity) -> Result<Entity, MapEntitiesError>

Returns the corresponding mapped entity.

pub fn keys(&self) -> impl Iterator<Item = Entity>

An iterator visiting all keys in arbitrary order.

pub fn values(&self) -> impl Iterator<Item = Entity>

An iterator visiting all values in arbitrary order.

pub fn len(&self) -> usize

Returns the number of elements in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Trait Implementations

impl Debug for EntityMap

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for EntityMap

fn default() -> EntityMap

Returns the “default value” for a type.