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|
use std::panic::{RefUnwindSafe, UnwindSafe};
use seq_macro::seq;
use crate::component::local::SystemWithLocalComponents;
use crate::component::Parts as ComponentParts;
use crate::system::initializable::{Initializable, MaybeInitializableParamTuple};
use crate::system::{Into as IntoSystem, Metadata, Param, System, TypeErased};
use crate::World;
/// A stateful system.
pub struct Stateful<Func>
{
func: Func,
local_components: Vec<ComponentParts>,
}
macro_rules! impl_system {
($c: tt) => {
seq!(I in 0..$c {
impl<'world, Func, #(TParam~I,)*>
System<'world, fn(&'world (), #(TParam~I,)*)> for Stateful<Func>
where
Func: Fn(#(TParam~I,)*) + Copy + RefUnwindSafe + UnwindSafe + 'static,
#(TParam~I: Param<'world, Input: 'static>,)*
{
type Callbacks = Callbacks;
fn run<'this>(&'this self, world: &'world World, metadata: Metadata)
where
'this: 'world
{
let func = self.func;
func(#({
TParam~I::new(&world, &metadata)
},)*);
}
fn finish(self) -> (TypeErased, Self::Callbacks)
{
let Self { func, local_components } = self;
let callbacks = Callbacks { local_components };
let type_erased = TypeErased {
run: Box::new(move |world, metadata| {
// SAFETY: The caller of TypeErased::run ensures the lifetime
// is correct
let world = unsafe { &*std::ptr::from_ref(world) };
func(#({
TParam~I::new(&world, &metadata)
},)*);
}),
};
(type_erased, callbacks)
}
}
impl<'world, Func, #(TParam~I,)*>
Initializable<'world, fn(&'world (), #(TParam~I,)*)> for Stateful<Func>
where
Func: Fn(#(TParam~I,)*) + Copy + RefUnwindSafe + UnwindSafe + 'static,
#(TParam~I: Param<'world, Input: 'static>,)*
(#(TParam~I,)*): MaybeInitializableParamTuple<'world, Self>
{
type Inputs = <
(#(TParam~I,)*) as MaybeInitializableParamTuple<'world, Self>
>::Inputs;
fn initialize(mut self, inputs: Self::Inputs) -> Self
{
init_initializable_params::<_, (#(TParam~I,)*)>(&mut self, inputs);
self
}
}
impl<Func, #(TParam~I,)*> IntoSystem<fn(#(TParam~I,)*)>
for Func
where
Func: Fn(#(TParam~I,)*) + Copy + 'static,
{
type System = Stateful<Func>;
fn into_system(self) -> Self::System
{
Self::System {
func: self,
local_components: Vec::new(), // TODO: Use Vec::with_capacity
}
}
}
});
};
}
seq!(C in 1..16 {
impl_system!(C);
});
impl<Func> SystemWithLocalComponents for Stateful<Func>
{
fn add_local_component(&mut self, component_parts: ComponentParts)
{
self.local_components.push(component_parts);
}
}
#[derive(Debug)]
pub struct Callbacks
{
local_components: Vec<ComponentParts>,
}
impl crate::system::Callbacks for Callbacks
{
fn on_created(&mut self, world: &mut World, metadata: Metadata)
{
for local_comp_parts in self.local_components.drain(..) {
world.add_component(metadata.ent_id, local_comp_parts);
}
}
}
fn init_initializable_params<'world, SystemT, Params>(
system: &mut SystemT,
inputs: Params::Inputs,
) where
Params: MaybeInitializableParamTuple<'world, SystemT>,
{
Params::init_initializable(system, inputs);
}
|
