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use std::marker::PhantomData;
use std::panic::UnwindSafe;
use std::ptr;
use super::ref_counted::RefCounted;
use super::{Ptr, Tag};
/// [`RawPtr`] is a raw pointer where the lifetime of the pointed-to instance is not managed.
///
/// [`RawPtr`] cannot be used to dereference the pointed-to instance unless it is converted into
/// [`Ptr`] through [`RawPtr::into_ptr`].
#[derive(Debug)]
pub struct RawPtr<'g, T> {
ptr: *const RefCounted<T>,
_phantom: PhantomData<&'g T>,
}
impl<'g, T> RawPtr<'g, T> {
/// Creates a null [`RawPtr`].
///
/// # Examples
///
/// ```
/// use sdd::RawPtr;
///
/// let ptr: RawPtr<usize> = RawPtr::null();
/// ```
#[inline]
#[must_use]
pub const fn null() -> Self {
Self {
ptr: ptr::null(),
_phantom: PhantomData,
}
}
/// Returns `true` if the [`RawPtr`] is null.
///
/// # Examples
///
/// ```
/// use sdd::RawPtr;
///
/// let ptr: RawPtr<usize> = RawPtr::null();
/// assert!(ptr.is_null());
/// ```
#[inline]
#[must_use]
pub fn is_null(&self) -> bool {
Tag::unset_tag(self.ptr).is_null()
}
/// Returns its [`Tag`].
///
/// # Examples
///
/// ```
/// use sdd::{RawPtr, Tag};
///
/// let ptr: RawPtr<usize> = RawPtr::null();
/// assert_eq!(ptr.tag(), Tag::None);
/// ```
#[inline]
#[must_use]
pub fn tag(&self) -> Tag {
Tag::into_tag(self.ptr)
}
/// Sets a [`Tag`], overwriting the existing [`Tag`].
///
/// Returns the previous tag value.
///
/// # Examples
///
/// ```
/// use sdd::{RawPtr, Tag};
///
/// let mut ptr: RawPtr<usize> = RawPtr::null();
/// assert_eq!(ptr.set_tag(Tag::Both), Tag::None);
/// assert_eq!(ptr.tag(), Tag::Both);
/// ```
#[inline]
pub fn set_tag(&mut self, tag: Tag) -> Tag {
let old_tag = Tag::into_tag(self.ptr);
self.ptr = Tag::update_tag(self.ptr, tag);
old_tag
}
/// Clears its [`Tag`].
///
/// Returns the previous tag value.
///
/// # Examples
///
/// ```
/// use sdd::{RawPtr, Tag};
///
/// let mut ptr: RawPtr<usize> = RawPtr::null().with_tag(Tag::Both);
/// assert_eq!(ptr.unset_tag(), Tag::Both);
/// ```
#[inline]
pub fn unset_tag(&mut self) -> Tag {
let old_tag = Tag::into_tag(self.ptr);
self.ptr = Tag::unset_tag(self.ptr);
old_tag
}
/// Returns a copy of `self` with a [`Tag`] set.
///
/// # Examples
///
/// ```
/// use sdd::{RawPtr, Tag};
///
/// let mut ptr: RawPtr<usize> = RawPtr::null();
/// assert_eq!(ptr.tag(), Tag::None);
///
/// let ptr_with_tag = ptr.with_tag(Tag::First);
/// assert_eq!(ptr_with_tag.tag(), Tag::First);
/// ```
#[inline]
#[must_use]
pub fn with_tag(self, tag: Tag) -> Self {
Self::from(Tag::update_tag(self.ptr, tag))
}
/// Returns a copy of `self` with its [`Tag`] erased.
///
/// # Examples
///
/// ```
/// use sdd::{Ptr, RawPtr, Tag};
///
/// let mut ptr: RawPtr<usize> = RawPtr::null();
/// ptr.set_tag(Tag::Second);
/// assert_eq!(ptr.tag(), Tag::Second);
///
/// let ptr_without_tag = ptr.without_tag();
/// assert_eq!(ptr_without_tag.tag(), Tag::None);
/// ```
#[inline]
#[must_use]
pub fn without_tag(self) -> Self {
Self::from(Tag::unset_tag(self.ptr))
}
/// Converts itself into a [`Ptr`] to dereference the instance.
///
/// # Safety
///
/// The pointed-to instance must be valid for the lifetime `'g`.
///
/// # Examples
///
/// ```
/// use sdd::Owned;
///
/// let owned: Owned<usize> = Owned::new(83);
/// let ptr = owned.into_raw();
/// assert_eq!(unsafe { ptr.into_ptr().as_ref() }, Some(&83));
/// drop(unsafe { Owned::from_raw(ptr) });
/// ```
#[inline]
#[must_use]
pub const unsafe fn into_ptr(self) -> Ptr<'g, T> {
Ptr::from(self.ptr)
}
/// Creates a new [`RawPtr`] from a [`RefCounted`] pointer.
#[inline]
pub(super) const fn from(ptr: *const RefCounted<T>) -> Self {
Self {
ptr,
_phantom: PhantomData,
}
}
/// Returns a pointer to the [`RefCounted`], including tag bits.
#[inline]
pub(super) const fn underlying_ptr(self) -> *const RefCounted<T> {
self.ptr
}
}
impl<T> Clone for RawPtr<'_, T> {
#[inline]
fn clone(&self) -> Self {
*self
}
}
impl<T> Copy for RawPtr<'_, T> {}
impl<T> Default for RawPtr<'_, T> {
#[inline]
fn default() -> Self {
Self::null()
}
}
impl<T> Eq for RawPtr<'_, T> {}
impl<T> PartialEq for RawPtr<'_, T> {
#[inline]
fn eq(&self, other: &Self) -> bool {
self.ptr == other.ptr
}
}
impl<T: UnwindSafe> UnwindSafe for RawPtr<'_, T> {}