use crate::private::ArchetypeMetadata;
use smallvec::SmallVec;
use std::alloc;
use std::any::{Any, TypeId};
use std::ops::Deref;
pub trait ArchetypeState: Send + Sync + 'static {
fn ty(&self) -> TypeId;
fn as_ptr(&self) -> *const u8;
fn forget(self);
fn metadata(&self) -> ArchetypeMetadata;
fn as_any(&self) -> &dyn Any;
fn as_any_mut(&mut self) -> &mut dyn Any;
fn num_components(&self) -> usize;
fn component_ids(&self) -> SmallVec<[TypeId; 32]> {
let meta = self.metadata();
(meta.component_type_ids)()
}
}
pub trait StaticArchetype: Sized + ArchetypeState {
const N_COMPONENTS: usize;
fn metadata() -> ArchetypeMetadata;
fn into_any(self) -> AnyState {
AnyState(Box::new(self))
}
}
pub struct AnyState(Box<dyn ArchetypeState>);
impl AnyState {
pub fn downcast_ref<T: ArchetypeState>(&self) -> Option<&T> {
self.0.as_any().downcast_ref()
}
pub fn downcast_mut<T: ArchetypeState>(&mut self) -> Option<&mut T> {
self.0.as_any_mut().downcast_mut()
}
pub fn downcast<T: ArchetypeState>(self) -> Option<T> {
if let Some(val) = self.downcast_ref::<T>() {
let val = unsafe { (val as *const T).read() };
self.forget();
Some(val)
} else {
None
}
}
}
impl<T: StaticArchetype> From<T> for AnyState {
fn from(state: T) -> Self {
state.into_any()
}
}
impl ArchetypeState for AnyState {
fn ty(&self) -> TypeId {
self.0.ty()
}
fn as_ptr(&self) -> *const u8 {
self.0.as_ptr()
}
fn forget(self) {
let val: &dyn ArchetypeState = self.0.deref();
let layout = alloc::Layout::for_value(val);
let ptr = Box::into_raw(self.0);
if layout.size() != 0 {
unsafe {
assert!(!ptr.is_null());
alloc::dealloc(ptr as *mut u8, layout);
};
}
}
fn metadata(&self) -> ArchetypeMetadata {
self.0.metadata()
}
fn as_any(&self) -> &dyn Any {
self.0.as_any()
}
fn as_any_mut(&mut self) -> &mut dyn Any {
self.0.as_any_mut()
}
fn num_components(&self) -> usize {
self.0.num_components()
}
}
impl ArchetypeState for () {
fn ty(&self) -> TypeId {
TypeId::of::<()>()
}
fn as_ptr(&self) -> *const u8 {
self as *const _ as *const u8
}
fn forget(self) {}
fn metadata(&self) -> ArchetypeMetadata {
ArchetypeMetadata {
type_id: TypeId::of::<Self>(),
component_type_ids: || Default::default(),
component_infos: || Default::default(),
size: 0,
needs_drop: false,
drop_fn: |_| {},
}
}
fn as_any(&self) -> &dyn Any {
self
}
fn as_any_mut(&mut self) -> &mut dyn Any {
self
}
fn num_components(&self) -> usize {
0
}
}
impl StaticArchetype for () {
const N_COMPONENTS: usize = 0;
fn metadata() -> ArchetypeMetadata {
ArchetypeMetadata {
type_id: TypeId::of::<Self>(),
component_type_ids: || Default::default(),
component_infos: || Default::default(),
size: 0,
needs_drop: false,
drop_fn: |_| {},
}
}
}