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use crate::alloc::{vec, vec::Vec};
use core::any::{type_name, TypeId};
use core::ptr::NonNull;
use core::{fmt, mem};
use crate::archetype::TypeInfo;
use crate::Component;
pub unsafe trait DynamicBundle {
#[doc(hidden)]
fn with_ids<T>(&self, f: impl FnOnce(&[TypeId]) -> T) -> T;
#[doc(hidden)]
fn type_info(&self) -> Vec<TypeInfo>;
#[doc(hidden)]
unsafe fn put(self, f: impl FnMut(*mut u8, TypeInfo));
}
pub unsafe trait Bundle: DynamicBundle {
#[doc(hidden)]
fn with_static_ids<T>(f: impl FnOnce(&[TypeId]) -> T) -> T;
#[doc(hidden)]
fn static_type_info() -> Vec<TypeInfo>;
#[doc(hidden)]
unsafe fn get(f: impl FnMut(TypeInfo) -> Option<NonNull<u8>>) -> Result<Self, MissingComponent>
where
Self: Sized;
}
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct MissingComponent(&'static str);
impl MissingComponent {
pub fn new<T: Component>() -> Self {
Self(type_name::<T>())
}
}
impl fmt::Display for MissingComponent {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "missing {} component", self.0)
}
}
#[cfg(feature = "std")]
impl std::error::Error for MissingComponent {}
macro_rules! tuple_impl {
($($name: ident),*) => {
unsafe impl<$($name: Component),*> DynamicBundle for ($($name,)*) {
fn with_ids<T>(&self, f: impl FnOnce(&[TypeId]) -> T) -> T {
Self::with_static_ids(f)
}
fn type_info(&self) -> Vec<TypeInfo> {
Self::static_type_info()
}
#[allow(unused_variables, unused_mut)]
unsafe fn put(self, mut f: impl FnMut(*mut u8, TypeInfo)) {
#[allow(non_snake_case)]
let ($(mut $name,)*) = self;
$(
f(
(&mut $name as *mut $name).cast::<u8>(),
TypeInfo::of::<$name>()
);
mem::forget($name);
)*
}
}
unsafe impl<$($name: Component),*> Bundle for ($($name,)*) {
fn with_static_ids<T>(f: impl FnOnce(&[TypeId]) -> T) -> T {
const N: usize = count!($($name),*);
let mut xs: [(usize, TypeId); N] = [$((mem::align_of::<$name>(), TypeId::of::<$name>())),*];
xs.sort_unstable_by(|x, y| x.0.cmp(&y.0).reverse().then(x.1.cmp(&y.1)));
let mut ids = [TypeId::of::<()>(); N];
for (slot, &(_, id)) in ids.iter_mut().zip(xs.iter()) {
*slot = id;
}
f(&ids)
}
fn static_type_info() -> Vec<TypeInfo> {
let mut xs = vec![$(TypeInfo::of::<$name>()),*];
xs.sort_unstable();
xs
}
#[allow(unused_variables, unused_mut)]
unsafe fn get(mut f: impl FnMut(TypeInfo) -> Option<NonNull<u8>>) -> Result<Self, MissingComponent> {
#[allow(non_snake_case)]
let ($(mut $name,)*) = ($(
f(TypeInfo::of::<$name>()).ok_or_else(MissingComponent::new::<$name>)?
.as_ptr()
.cast::<$name>(),)*
);
Ok(($($name.read(),)*))
}
}
}
}
macro_rules! count {
() => { 0 };
($x: ident $(, $rest: ident)*) => { 1 + count!($($rest),*) };
}
smaller_tuples_too!(tuple_impl, O, N, M, L, K, J, I, H, G, F, E, D, C, B, A);