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use crate::kind::Trivial;
use crate::ExternType;
use core::ffi::c_void;
use core::fmt::{self, Debug, Display};
use core::marker::PhantomData;
use core::mem::MaybeUninit;
use core::ops::{Deref, DerefMut};
use core::pin::Pin;
#[repr(C)]
pub struct SharedPtr<T>
where
T: SharedPtrTarget,
{
repr: [*mut c_void; 2],
ty: PhantomData<T>,
}
impl<T> SharedPtr<T>
where
T: SharedPtrTarget,
{
pub fn null() -> Self {
let mut shared_ptr = MaybeUninit::<SharedPtr<T>>::uninit();
let new = shared_ptr.as_mut_ptr().cast();
unsafe {
T::__null(new);
shared_ptr.assume_init()
}
}
pub fn new(value: T) -> Self
where
T: ExternType<Kind = Trivial>,
{
let mut shared_ptr = MaybeUninit::<SharedPtr<T>>::uninit();
let new = shared_ptr.as_mut_ptr().cast();
unsafe {
T::__new(value, new);
shared_ptr.assume_init()
}
}
pub fn is_null(&self) -> bool {
let this = self as *const Self as *const c_void;
let ptr = unsafe { T::__get(this) };
ptr.is_null()
}
pub fn as_ref(&self) -> Option<&T> {
let this = self as *const Self as *const c_void;
unsafe { T::__get(this).as_ref() }
}
pub fn as_mut(&mut self) -> Option<Pin<&mut T>> {
let this = self as *mut Self as *mut c_void;
unsafe {
let mut_reference = (T::__get(this) as *mut T).as_mut()?;
Some(Pin::new_unchecked(mut_reference))
}
}
pub fn pin_mut(&mut self) -> Pin<&mut T> {
match self.as_mut() {
Some(target) => target,
None => panic!("called pin_mut on a null SharedPtr<{}>", T::__NAME),
}
}
}
unsafe impl<T> Send for SharedPtr<T> where T: Send + Sync + SharedPtrTarget {}
unsafe impl<T> Sync for SharedPtr<T> where T: Send + Sync + SharedPtrTarget {}
impl<T> Clone for SharedPtr<T>
where
T: SharedPtrTarget,
{
fn clone(&self) -> Self {
let mut shared_ptr = MaybeUninit::<SharedPtr<T>>::uninit();
let new = shared_ptr.as_mut_ptr().cast();
let this = self as *const Self as *mut c_void;
unsafe {
T::__clone(this, new);
shared_ptr.assume_init()
}
}
}
impl<T> Drop for SharedPtr<T>
where
T: SharedPtrTarget,
{
fn drop(&mut self) {
let this = self as *mut Self as *mut c_void;
unsafe { T::__drop(this) }
}
}
impl<T> Deref for SharedPtr<T>
where
T: SharedPtrTarget,
{
type Target = T;
fn deref(&self) -> &Self::Target {
match self.as_ref() {
Some(target) => target,
None => panic!("called deref on a null SharedPtr<{}>", T::__NAME),
}
}
}
impl<T> DerefMut for SharedPtr<T>
where
T: SharedPtrTarget + Unpin,
{
fn deref_mut(&mut self) -> &mut Self::Target {
match self.as_mut() {
Some(target) => Pin::into_inner(target),
None => panic!("called deref_mut on a null SharedPtr<{}>", T::__NAME),
}
}
}
impl<T> Debug for SharedPtr<T>
where
T: Debug + SharedPtrTarget,
{
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
match self.as_ref() {
None => formatter.write_str("nullptr"),
Some(value) => Debug::fmt(value, formatter),
}
}
}
impl<T> Display for SharedPtr<T>
where
T: Display + SharedPtrTarget,
{
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
match self.as_ref() {
None => formatter.write_str("nullptr"),
Some(value) => Display::fmt(value, formatter),
}
}
}
pub unsafe trait SharedPtrTarget {
#[doc(hidden)]
const __NAME: &'static dyn Display;
#[doc(hidden)]
unsafe fn __null(new: *mut c_void);
#[doc(hidden)]
unsafe fn __new(value: Self, new: *mut c_void)
where
Self: Sized,
{
let _ = value;
let _ = new;
unreachable!()
}
#[doc(hidden)]
unsafe fn __clone(this: *const c_void, new: *mut c_void);
#[doc(hidden)]
unsafe fn __get(this: *const c_void) -> *const Self;
#[doc(hidden)]
unsafe fn __drop(this: *mut c_void);
}