use alloc::boxed::Box;
use core::any::{Any, TypeId};
use hashbrown::HashMap;
use rustc_hash::FxBuildHasher;
use super::entity::{Entity, EntityAllocator};
use super::sparse_set::SparseSet;
trait ComponentStorage: Any {
fn as_any(&self) -> &dyn Any;
fn as_any_mut(&mut self) -> &mut dyn Any;
fn remove_entity(&mut self, entity: Entity);
fn contains_entity(&self, entity: Entity) -> bool;
fn is_empty(&self) -> bool;
}
impl<T: 'static> ComponentStorage for SparseSet<T> {
fn as_any(&self) -> &dyn Any {
self
}
fn as_any_mut(&mut self) -> &mut dyn Any {
self
}
fn remove_entity(&mut self, entity: Entity) {
self.remove(entity);
}
fn contains_entity(&self, entity: Entity) -> bool {
self.contains(entity)
}
fn is_empty(&self) -> bool {
self.is_empty()
}
}
pub struct World {
allocator: EntityAllocator,
storages: HashMap<TypeId, Box<dyn ComponentStorage>, FxBuildHasher>,
resources: HashMap<TypeId, Box<dyn Any>, FxBuildHasher>,
}
impl Default for World {
fn default() -> Self {
Self {
allocator: EntityAllocator::new(),
storages: HashMap::default(),
resources: HashMap::default(),
}
}
}
impl World {
pub fn new() -> Self {
Self::default()
}
pub fn spawn_empty(&mut self) -> Entity {
self.allocator.allocate()
}
pub fn despawn(&mut self, entity: Entity) -> bool {
if !self.allocator.deallocate(entity) {
return false;
}
for storage in self.storages.values_mut() {
storage.remove_entity(entity);
}
true
}
pub fn is_alive(&self, entity: Entity) -> bool {
self.allocator.is_alive(entity)
}
pub fn insert<T: 'static>(&mut self, entity: Entity, component: T) {
if !self.is_alive(entity) {
return;
}
let storage = self.storage_mut::<T>();
storage.insert(entity, component);
}
pub fn remove<T: 'static>(&mut self, entity: Entity) -> Option<T> {
let storage = self.storage_mut::<T>();
storage.remove(entity)
}
pub fn get<T: 'static>(&self, entity: Entity) -> Option<&T> {
self.storage::<T>()?.get(entity)
}
pub fn get_mut<T: 'static>(&mut self, entity: Entity) -> Option<&mut T> {
self.storage_mut::<T>().get_mut(entity)
}
pub fn has<T: 'static>(&self, entity: Entity) -> bool {
self.storage::<T>().is_some_and(|s| s.contains(entity))
}
pub fn has_type(&self, entity: Entity, type_id: TypeId) -> bool {
self.storages
.get(&type_id)
.is_some_and(|s| s.contains_entity(entity))
}
pub fn has_any_by_id(&self, type_id: TypeId) -> bool {
self.storages.get(&type_id).is_some_and(|s| !s.is_empty())
}
pub fn query<T: 'static>(&self) -> super::query::QueryBuilder<'_, T> {
super::query::QueryBuilder::new(self)
}
pub fn for_each_stable<T: 'static>(&mut self, mut visit: impl FnMut(&mut Self, Entity)) {
let count = self.storage::<T>().map_or(0, SparseSet::len);
for index in 0..count {
let entity = self
.storage::<T>()
.and_then(|storage| storage.entities().get(index))
.copied()
.expect("stable component storage changed during iteration");
visit(self, entity);
debug_assert_eq!(
self.storage::<T>().map_or(0, SparseSet::len),
count,
"for_each_stable callback inserted or removed the iterated component"
);
debug_assert_eq!(
self.storage::<T>()
.and_then(|storage| storage.entities().get(index))
.copied(),
Some(entity),
"for_each_stable callback reordered the iterated component storage"
);
}
}
pub(crate) fn storage<T: 'static>(&self) -> Option<&SparseSet<T>> {
self.storages
.get(&TypeId::of::<T>())
.map(|s| s.as_any().downcast_ref::<SparseSet<T>>().unwrap())
}
fn storage_mut<T: 'static>(&mut self) -> &mut SparseSet<T> {
self.storages
.entry(TypeId::of::<T>())
.or_insert_with(|| Box::new(SparseSet::<T>::new()))
.as_any_mut()
.downcast_mut::<SparseSet<T>>()
.unwrap()
}
pub fn insert_resource<T: 'static>(&mut self, value: T) {
self.resources.insert(TypeId::of::<T>(), Box::new(value));
}
pub fn resource<T: 'static>(&self) -> Option<&T> {
self.resources
.get(&TypeId::of::<T>())
.and_then(|v| v.downcast_ref::<T>())
}
pub fn resource_mut<T: 'static>(&mut self) -> Option<&mut T> {
self.resources
.get_mut(&TypeId::of::<T>())
.and_then(|v| v.downcast_mut::<T>())
}
pub fn remove_resource<T: 'static>(&mut self) -> Option<T> {
self.take_resource_box::<T>().map(|value| *value)
}
pub(crate) fn take_resource_box<T: 'static>(&mut self) -> Option<Box<T>> {
self.resources
.remove(&TypeId::of::<T>())
.and_then(|v| v.downcast::<T>().ok())
}
pub(crate) fn put_resource_box<T: 'static>(&mut self, value: Box<T>) {
self.resources.insert(TypeId::of::<T>(), value);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn stable_iteration_mutates_values_and_other_component_types() {
let mut world = World::new();
let first = world.spawn_empty();
let second = world.spawn_empty();
world.insert(first, 1u16);
world.insert(second, 2u16);
world.for_each_stable::<u16>(|world, entity| {
*world.get_mut::<u16>(entity).unwrap() += 10;
world.insert(entity, true);
});
assert_eq!(world.get::<u16>(first), Some(&11));
assert_eq!(world.get::<u16>(second), Some(&12));
assert_eq!(world.get::<bool>(first), Some(&true));
assert_eq!(world.get::<bool>(second), Some(&true));
}
#[test]
#[should_panic(expected = "inserted or removed the iterated component")]
fn stable_iteration_rejects_structural_changes_to_the_iterated_type() {
let mut world = World::new();
let entity = world.spawn_empty();
world.insert(entity, 1u16);
world.for_each_stable::<u16>(|world, entity| {
world.remove::<u16>(entity);
});
}
}