Trait EntityMapper

pub trait EntityMapper {
    // Required methods
    fn get_mapped(&mut self, source: Entity) -> Entity;
    fn set_mapped(&mut self, source: Entity, target: Entity);
}

Expand description

An implementor of this trait knows how to map an Entity into another Entity.

Usually this is done by using an [EntityHashMap<Entity>] to map source entities (mapper inputs) to the current world’s entities (mapper outputs).

More generally, this can be used to map Entity references between any two Worlds.

This is used by [MapEntities] implementers.

§Example

pub struct SimpleEntityMapper {
  map: EntityHashMap<Entity>,
}

// Example implementation of EntityMapper where we map an entity to another entity if it exists
// in the underlying `EntityHashMap`, otherwise we just return the original entity.
impl EntityMapper for SimpleEntityMapper {
    fn get_mapped(&mut self, entity: Entity) -> Entity {
        self.map.get(&entity).copied().unwrap_or(entity)
    }

    fn set_mapped(&mut self, source: Entity, target: Entity) {
        self.map.insert(source, target);
    }
}