Trait EntityMapper

Source

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 implementors.

§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);
    }
}