use std::ops::Deref;
use std::sync::atomic::{AtomicBool, Ordering};
use ref_cast::RefCast;
use crate::atomic::StaticAtomicPtr;
pub struct Flag<T> {
atomic: StaticAtomicPtr<T>,
present: AtomicBool,
}
impl<T: 'static> Flag<T> {
pub fn is_present(&self) -> bool {
self.present.load(Ordering::SeqCst)
}
}
#[derive(RefCast)]
#[repr(transparent)]
pub struct Accessor<T> {
pub flag: T,
}
impl<T: 'static> Flag<T> {
#[doc(hidden)]
pub const fn new(default: &'static T) -> Self {
Flag {
atomic: StaticAtomicPtr::new(default),
present: AtomicBool::new(false),
}
}
#[doc(hidden)]
pub const fn null() -> Self {
Flag {
atomic: StaticAtomicPtr::null(),
present: AtomicBool::new(false),
}
}
pub(crate) fn set(&self, value: T) {
let ptr = Box::leak(Box::new(value));
self.atomic.store(ptr);
self.present.store(true, Ordering::SeqCst);
}
}
impl Flag<bool> {
#[allow(clippy::trivially_copy_pass_by_ref)]
pub(crate) fn set_bool(&self, value: &'static bool) {
self.atomic.store(value);
self.present.store(true, Ordering::SeqCst);
}
}
impl<T: 'static> Deref for Flag<T> {
type Target = Accessor<T>;
fn deref(&self) -> &Self::Target {
Accessor::ref_cast(self.atomic.load())
}
}