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use std::boxed::FnBox;
use std::ops::Deref;
use parking_lot::{Once, OnceState, RwLock};
use std::cell::UnsafeCell;
use std::sync::atomic::AtomicBool;
#[macro_export(local_inner_macros)]
#[doc(hidden)]
macro_rules! __safe_static_internal {
($(#[$attr:meta])* ($($vis:tt)*) static lazy $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
__safe_static_internal!(@LAZY TY, $(#[$attr])*, ($($vis)*), $N, $T, $e);
safe_static!($($t)*);
};
($(#[$attr:meta])* ($($vis:tt)*) static uninit $N:ident : $T:ty; $($t:tt)*) => {
__safe_static_internal!(@UNINIT TY, $(#[$attr])*, ($($vis)*), $N, $T);
};
(@LAZY TY, $(#[$attr:meta])*, ($($vis:tt)*), $N:ident, $T:ty, $e:expr) => {
$(#[$attr])*
$($vis)* static $N: $crate::SafeLazy<$T> = $crate::SafeLazy { instance: unsafe { $crate::SafeLazyInstance::new() }, init_fn: || { $e } };
};
(@UNINIT TY, $(#[$attr:meta])*, ($($vis:tt)*), $N:ident, $T:ty) => {
$(#[$attr])*
$($vis)* static $N: $crate::SafeUninit<$T> = unsafe { $crate::SafeUninit::new() };
};
() => ()
}
#[macro_export(local_inner_macros)]
macro_rules! safe_static {
($(#[$attr:meta])* static lazy $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* () static lazy $N : $T = $e; $($t)*);
};
($(#[$attr:meta])* pub static lazy $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* (pub) static lazy $N : $T = $e; $($t)*);
};
($(#[$attr:meta])* pub ($($vis:tt)+) static lazy $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* (pub ($($vis)+)) static lazy $N : $T = $e; $($t)*);
};
($(#[$attr:meta])* static uninit $N:ident : $T:ty; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* () static uninit $N : $T; $($t)*);
};
($(#[$attr:meta])* pub static uninit $N:ident : $T:ty; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* (pub) static uninit $N : $T; $($t)*);
};
($(#[$attr:meta])* pub ($($vis:tt)+) static uninit $N:ident : $T:ty; $($t:tt)*) => {
__safe_static_internal!($(#[$attr])* (pub ($($vis)+)) static uninit $N : $T; $($t)*);
};
() => ()
}
pub struct SafeLazy<T>
where
T: 'static,
{
#[doc(hidden)]
pub instance: SafeLazyInstance<T>,
#[doc(hidden)]
pub init_fn: fn() -> T,
}
unsafe impl<T> Sync for SafeLazy<T> where T: Send + Sync {}
#[doc(hidden)]
pub struct SafeLazyInstance<T> {
instance: UnsafeCell<Option<T>>,
once: Once,
}
impl<T> SafeLazyInstance<T> {
#[doc(hidden)]
pub const unsafe fn new() -> Self {
Self {
instance: UnsafeCell::new(None),
once: Once::new(),
}
}
}
impl<T> Deref for SafeLazy<T> {
type Target = T;
fn deref(&self) -> &T {
let ptr = &*self as *const Self;
self.instance.once.call_once(move || unsafe {
*self.instance.instance.get() = Some((self.init_fn)());
ALLOCATED
.write()
.as_mut()
.unwrap()
.push(Deallocator(Box::new(move || {
*(*ptr).instance.instance.get() = None
})));
});
unsafe { (*self.instance.instance.get()).as_ref().unwrap() }
}
}
pub struct SafeUninit<T>
where
T: 'static,
{
instance: UnsafeCell<Option<T>>,
once: Once,
}
impl<T> SafeUninit<T> {
#[doc(hidden)]
pub const unsafe fn new() -> Self {
Self {
instance: UnsafeCell::new(None),
once: Once::new(),
}
}
pub fn init(&self, instance: T) {
self.once
.call_once(|| unsafe { *self.instance.get() = Some(instance) });
let ptr = &*self as *const Self;
ALLOCATED
.write()
.as_mut()
.unwrap()
.push(Deallocator(Box::new(move || unsafe {
(*(*ptr).instance.get()) = None
})));
}
}
impl<T> Deref for SafeUninit<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
let state = self.once.state();
if state != OnceState::Done {
panic!("Uninitialized `SafeUninit`");
}
unsafe { (&*self.instance.get()) }.as_ref().unwrap()
}
}
pub(crate) static EXITING: AtomicBool = AtomicBool::new(false);
unsafe impl<T> Sync for SafeUninit<T> where T: Send + Sync {}
pub(crate) static ALLOCATED: RwLock<Option<Vec<Deallocator>>> = RwLock::new(None);
pub(crate) struct Deallocator(pub(crate) Box<dyn FnBox()>);
unsafe impl Send for Deallocator {}
unsafe impl Sync for Deallocator {}