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use crate::tag::{read_tag, set_tag, strip, Tag};
use std::marker::PhantomData;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(transparent)]
pub struct Shared<'shield, V, T>
where
V: 'shield,
T: Tag,
{
pub(crate) data: usize,
_m0: PhantomData<&'shield ()>,
_m1: PhantomData<V>,
_m2: PhantomData<T>,
}
impl<'shield, V, T> Shared<'shield, V, T>
where
V: 'shield,
T: Tag,
{
pub fn null() -> Self {
unsafe { Self::from_raw(0) }
}
pub unsafe fn from_ptr(ptr: *mut V) -> Self {
Self::from_raw(ptr as usize)
}
pub unsafe fn from_raw(data: usize) -> Self {
Self {
data,
_m0: PhantomData,
_m1: PhantomData,
_m2: PhantomData,
}
}
pub fn into_raw(self) -> usize {
self.data
}
pub fn as_ptr(&self) -> *mut V {
strip::<T>(self.data) as *mut V
}
pub unsafe fn as_ref(&self) -> Option<&'shield V> {
self.as_ptr().as_ref()
}
pub unsafe fn as_mut_ref(&mut self) -> Option<&'shield mut V> {
let ptr = self.as_ptr();
if !ptr.is_null() {
Some(&mut *ptr)
} else {
None
}
}
pub unsafe fn as_ref_unchecked(&self) -> &'shield V {
&*self.as_ptr()
}
pub unsafe fn as_mut_ref_unchecked(&mut self) -> &'shield mut V {
&mut *self.as_ptr()
}
pub fn is_null(&self) -> bool {
self.as_ptr().is_null()
}
pub fn tag(&self) -> T {
let bits = read_tag::<T>(self.data);
Tag::deserialize(bits)
}
pub fn with_tag(&self, tag: T) -> Self {
let bits = tag.serialize();
let data = set_tag::<T>(self.data, bits);
unsafe { Self::from_raw(data) }
}
}