1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
#[cfg(feature = "reflect")]
use bevy_ecs::reflect::{ReflectComponent, ReflectMapEntities};
use bevy_ecs::{
component::Component,
entity::{Entity, EntityMapper, MapEntities},
world::{FromWorld, World},
};
use std::ops::Deref;
/// Holds a reference to the parent entity of this entity.
/// This component should only be present on entities that actually have a parent entity.
///
/// Parent entity must have this entity stored in its [`Children`] component.
/// It is hard to set up parent/child relationships manually,
/// consider using higher level utilities like [`BuildChildren::with_children`].
///
/// See [`HierarchyQueryExt`] for hierarchy related methods on [`Query`].
///
/// [`HierarchyQueryExt`]: crate::query_extension::HierarchyQueryExt
/// [`Query`]: bevy_ecs::system::Query
/// [`Children`]: super::children::Children
/// [`BuildChildren::with_children`]: crate::child_builder::BuildChildren::with_children
#[derive(Component, Debug, Eq, PartialEq)]
#[cfg_attr(feature = "reflect", derive(bevy_reflect::Reflect))]
#[cfg_attr(feature = "reflect", reflect(Component, MapEntities, PartialEq))]
pub struct Parent(pub(crate) Entity);
impl Parent {
/// Gets the [`Entity`] ID of the parent.
#[inline(always)]
pub fn get(&self) -> Entity {
self.0
}
/// Gets the parent [`Entity`] as a slice of length 1.
///
/// Useful for making APIs that require a type or homogeneous storage
/// for both [`Children`] & [`Parent`] that is agnostic to edge direction.
///
/// [`Children`]: super::children::Children
#[inline(always)]
pub fn as_slice(&self) -> &[Entity] {
std::slice::from_ref(&self.0)
}
}
// TODO: We need to impl either FromWorld or Default so Parent can be registered as Reflect.
// This is because Reflect deserialize by creating an instance and apply a patch on top.
// However Parent should only ever be set with a real user-defined entity. Its worth looking into
// better ways to handle cases like this.
impl FromWorld for Parent {
#[inline(always)]
fn from_world(_world: &mut World) -> Self {
Parent(Entity::PLACEHOLDER)
}
}
impl MapEntities for Parent {
fn map_entities<M: EntityMapper>(&mut self, entity_mapper: &mut M) {
self.0 = entity_mapper.map_entity(self.0);
}
}
impl Deref for Parent {
type Target = Entity;
#[inline(always)]
fn deref(&self) -> &Self::Target {
&self.0
}
}