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use std::any::{Any, TypeId};
use std::fmt::Debug;
use std::ops::{Deref, DerefMut};
use seq_macro::seq;
use crate::system::{Input as SystemInput, Param as SystemParam, System};
use crate::ComponentStorage;
pub trait Component: SystemInput + Any
{
#[doc(hidden)]
fn as_any_mut(&mut self) -> &mut dyn Any;
#[doc(hidden)]
fn as_any(&self) -> &dyn Any;
}
impl dyn Component
{
pub fn downcast_mut<Real: 'static>(&mut self) -> Option<&mut Real>
{
self.as_any_mut().downcast_mut()
}
pub fn is<Other: 'static>(&self) -> bool
{
self.as_any().is::<Other>()
}
}
impl Debug for dyn Component
{
fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
{
formatter.debug_struct("Component").finish_non_exhaustive()
}
}
/// A sequence of components.
pub trait Sequence
{
type MutRefs<'component>
where
Self: 'component;
fn into_vec(self) -> Vec<Box<dyn Component>>;
fn type_ids() -> Vec<TypeId>;
fn from_components(components: &mut [Box<dyn Component>]) -> Self::MutRefs<'_>;
}
macro_rules! inner {
($c: tt) => {
seq!(I in 0..=$c {
impl<#(Comp~I: Component,)*> Sequence for (#(Comp~I,)*) {
type MutRefs<'component> = (#(&'component mut Comp~I,)*)
where Self: 'component;
fn into_vec(self) -> Vec<Box<dyn Component>> {
Vec::from_iter([#(Box::new(self.I) as Box<dyn Component>,)*])
}
fn type_ids() -> Vec<TypeId> {
vec![
#(
TypeId::of::<Comp~I>(),
)*
]
}
fn from_components(
components: &mut [Box<dyn Component>],
) -> Self::MutRefs<'_>
{
#(
let mut comp_~I = None;
)*
for comp in components.iter_mut() {
#(
if comp.is::<Comp~I>() {
comp_~I = Some(comp);
continue;
}
)*
}
(#(
comp_~I.unwrap().downcast_mut::<Comp~I>().unwrap(),
)*)
}
}
});
};
}
seq!(C in 0..=64 {
inner!(C);
});
/// Holds a component which is local to a single system.
#[derive(Debug)]
pub struct Local<'world, LocalComponent: Component>
{
local_component: &'world mut LocalComponent,
}
impl<'world, LocalComponent> Local<'world, LocalComponent>
where
LocalComponent: Component,
{
fn new(local_component: &'world mut LocalComponent) -> Self
{
Self { local_component }
}
}
unsafe impl<'world, LocalComponent> SystemParam<'world> for Local<'world, LocalComponent>
where
LocalComponent: Component,
{
type Flags = ();
type Input = LocalComponent;
fn initialize<SystemImpl>(system: &mut impl System<SystemImpl>, input: Self::Input)
{
system.set_local_component(input);
}
fn new<SystemImpl>(
system: &'world mut impl System<SystemImpl>,
_component_storage: &'world mut ComponentStorage,
) -> Self
{
let local_component = system
.get_local_component_mut::<LocalComponent>()
.expect("Local component is uninitialized");
Self::new(local_component)
}
fn is_compatible<Other: SystemParam<'world>>() -> bool
{
let other_comparable = Other::get_comparable();
let Some(other_type_id) = other_comparable.downcast_ref::<TypeId>() else {
return true;
};
TypeId::of::<LocalComponent>() != *other_type_id
}
fn get_comparable() -> Box<dyn Any>
{
Box::new(TypeId::of::<LocalComponent>())
}
}
impl<'world, LocalComponent> Deref for Local<'world, LocalComponent>
where
LocalComponent: Component,
{
type Target = LocalComponent;
fn deref(&self) -> &Self::Target
{
self.local_component
}
}
impl<'world, LocalComponent> DerefMut for Local<'world, LocalComponent>
where
LocalComponent: Component,
{
fn deref_mut(&mut self) -> &mut Self::Target
{
self.local_component
}
}
|
