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|
use std::any::{Any, TypeId};
use std::convert::Infallible;
use std::fmt::Debug;
use std::mem::{transmute_copy, ManuallyDrop};
use std::ptr::addr_of_mut;
use seq_macro::seq;
use crate::component::Component;
use crate::system::util::check_params_are_compatible;
use crate::ComponentStorage;
pub mod stateful;
mod util;
pub trait System<Impl>: 'static
{
type Input;
#[must_use]
fn initialize(self, input: Self::Input) -> Self;
fn run(&mut self, component_storage: &mut ComponentStorage);
fn into_type_erased(self) -> TypeErased;
fn get_local_component_mut<LocalComponent: Component>(
&mut self,
) -> Option<&mut LocalComponent>;
fn set_local_component<LocalComponent: Component>(
&mut self,
local_component: LocalComponent,
);
}
macro_rules! impl_system {
($c: tt) => {
seq!(I in 0..=$c {
impl<'world, Func, #(TParam~I,)*> System<fn(#(TParam~I,)*)>
for Func
where
Func: Fn(#(TParam~I,)*) + Copy + 'static,
#(TParam~I: Param<'world, Flags = NoInitParamFlag>,)*
{
type Input = Infallible;
fn initialize(self, _input: Self::Input) -> Self
{
self
}
fn run(&mut self, component_storage: &mut ComponentStorage)
{
#(
check_params_are_compatible!(I, TParam~I, $c);
)*
let func = *self;
func(#({
// SAFETY: All parameters are compatible so this is fine
let this = unsafe {
&mut *addr_of_mut!(*self)
};
// SAFETY: All parameters are compatible so this is fine
let component_storage = unsafe {
&mut *addr_of_mut!(*component_storage)
};
TParam~I::new(this, component_storage)
},)*);
}
fn into_type_erased(self) -> TypeErased
{
TypeErased {
data: Box::new(self),
func: Box::new(|data, component_storage| {
let me = data.downcast_mut::<Func>().unwrap();
me.run(component_storage);
}),
}
}
fn get_local_component_mut<LocalComponent: Component>(
&mut self,
) -> Option<&mut LocalComponent>
{
panic!("System does not have any local components");
}
fn set_local_component<LocalComponent: Component>(
&mut self,
_local_component: LocalComponent,
) {
panic!("System does not have any local components");
}
}
});
};
}
seq!(C in 0..=4 {
impl_system!(C);
});
pub trait Into<Impl>
{
type System;
fn into_system(self) -> Self::System;
}
pub struct TypeErased
{
data: Box<dyn Any>,
func: Box<TypeErasedFunc>,
}
impl TypeErased
{
pub fn run(&mut self, component_storage: &mut ComponentStorage)
{
(self.func)(self.data.as_mut(), component_storage);
}
}
impl Debug for TypeErased
{
fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
{
formatter.debug_struct("TypeErased").finish_non_exhaustive()
}
}
/// Function in [`TypeErased`] used to run the system.
type TypeErasedFunc = dyn Fn(&mut dyn Any, &mut ComponentStorage);
/// A parameter to a [`System`].
///
/// # Safety
/// The `is_compatible` function is used for safety so it must be implemented properly.
pub unsafe trait Param<'world>
{
type Input;
type Flags;
fn initialize<SystemImpl>(system: &mut impl System<SystemImpl>, input: Self::Input);
fn new<SystemImpl>(
system: &'world mut impl System<SystemImpl>,
component_storage: &'world mut ComponentStorage,
) -> Self;
fn is_compatible<Other: Param<'world>>() -> bool;
fn get_comparable() -> Box<dyn Any>;
}
pub struct NoInitParamFlag {}
/// A type which can be used as input to a [`System`].
pub trait Input: 'static {}
pub trait InputFilter
{
type Filtered: FilteredInputs;
}
pub trait FilteredInputs
{
type InOptions: OptionInputs;
fn into_in_options(self) -> Self::InOptions;
}
macro_rules! impl_filtered_inputs {
($cnt: tt) => {
seq!(I in 0..$cnt {
impl<#(Input~I: Input,)*> FilteredInputs for (#(Input~I,)*) {
type InOptions = (#(Option<Input~I>,)*);
fn into_in_options(self) -> Self::InOptions {
#![allow(clippy::unused_unit)]
(#(Some(self.I),)*)
}
}
});
};
}
seq!(N in 0..4 {
impl_filtered_inputs!(N);
});
pub trait OptionInputs
{
fn take<Input: 'static>(&mut self) -> TakeOptionInputResult<Input>;
}
macro_rules! impl_option_inputs {
($cnt: tt) => {
seq!(I in 0..$cnt {
impl<#(Input~I: 'static,)*> OptionInputs for (#(Option<Input~I>,)*) {
fn take<Input: 'static>(&mut self) -> TakeOptionInputResult<Input> {
#(
if TypeId::of::<Input~I>() == TypeId::of::<Input>() {
let input = match self.I.take() {
Some(input) => ManuallyDrop::new(input),
None => {
return TakeOptionInputResult::AlreadyTaken;
}
};
return TakeOptionInputResult::Found(
// SAFETY: It can be transmuted safely since it is the
// same type and the type is 'static
unsafe { transmute_copy(&input) }
);
}
)*
TakeOptionInputResult::NotFound
}
}
});
};
}
seq!(N in 0..4 {
impl_option_inputs!(N);
});
pub enum TakeOptionInputResult<Input>
{
Found(Input),
NotFound,
AlreadyTaken,
}
include!(concat!(env!("OUT_DIR"), "/system_input_impls.rs"));
|
