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use crate::components::{Children, Parent};
use bevy_ecs::{Commands, Entity, Query, World, WorldWriter};
pub fn run_on_hierarchy<T, S>(
children_query: &Query<&Children>,
state: &mut S,
entity: Entity,
parent_result: Option<T>,
mut previous_result: Option<T>,
run: &mut dyn FnMut(&mut S, Entity, Option<T>, Option<T>) -> Option<T>,
) -> Option<T>
where
T: Clone,
{
let children = children_query
.get::<Children>(entity)
.ok()
.map(|children| children.0.iter().cloned().collect::<Vec<Entity>>());
let parent_result = run(state, entity, parent_result, previous_result);
previous_result = None;
if let Some(children) = children {
for child in children {
previous_result = run_on_hierarchy(
children_query,
state,
child,
parent_result.clone(),
previous_result,
run,
);
}
} else {
previous_result = parent_result;
}
previous_result
}
pub struct DespawnRecursive {
entity: Entity,
}
fn despawn_with_children_recursive(world: &mut World, entity: Entity) {
if let Ok(parent) = world.get::<Parent>(entity).map(|parent| parent.0) {
if let Ok(mut children) = world.get_mut::<Children>(parent) {
children.retain(|c| *c != entity);
}
}
despawn_with_children_recursive_inner(world, entity);
}
fn despawn_with_children_recursive_inner(world: &mut World, entity: Entity) {
if let Some(children) = world
.get::<Children>(entity)
.ok()
.map(|children| children.0.iter().cloned().collect::<Vec<Entity>>())
{
for e in children {
despawn_with_children_recursive(world, e);
}
}
world.despawn(entity).unwrap();
}
impl WorldWriter for DespawnRecursive {
fn write(self: Box<Self>, world: &mut World) {
despawn_with_children_recursive(world, self.entity);
}
}
pub trait DespawnRecursiveExt {
fn despawn_recursive(&mut self, entity: Entity) -> &mut Self;
}
impl DespawnRecursiveExt for Commands {
fn despawn_recursive(&mut self, entity: Entity) -> &mut Self {
self.write_world(DespawnRecursive { entity })
}
}
#[cfg(test)]
mod tests {
use super::DespawnRecursiveExt;
use crate::{components::Children, hierarchy::BuildChildren};
use bevy_ecs::{Commands, Resources, World};
#[test]
fn despawn_recursive() {
let mut world = World::default();
let mut resources = Resources::default();
let mut command_buffer = Commands::default();
command_buffer.set_entity_reserver(world.get_entity_reserver());
command_buffer.spawn((0u32, 0u64)).with_children(|parent| {
parent.spawn((0u32, 0u64));
});
command_buffer.spawn((1u32, 1u64));
let grandparent_entity = command_buffer.current_entity().unwrap();
command_buffer.with_children(|parent| {
parent.spawn((2u32, 2u64));
parent.with_children(|parent| {
parent.spawn((3u32, 3u64)).with_children(|parent| {
parent.spawn((4u32, 4u64));
});
parent.spawn((5u32, 5u64));
});
});
command_buffer.spawn((0u32, 0u64));
command_buffer.apply(&mut world, &mut resources);
let parent_entity = world.get::<Children>(grandparent_entity).unwrap()[0];
command_buffer.despawn_recursive(parent_entity);
command_buffer.apply(&mut world, &mut resources);
let results = world
.query::<(&u32, &u64)>()
.iter()
.map(|(a, b)| (*a, *b))
.collect::<Vec<_>>();
{
let children = world.get::<Children>(grandparent_entity).unwrap();
assert_eq!(
children.iter().any(|&i| i == parent_entity),
false,
"grandparent should no longer know about its child which has been removed"
);
}
assert_eq!(
results,
vec![(0u32, 0u64), (0u32, 0u64), (0u32, 0u64), (1u32, 1u64)]
);
}
}