orx_concurrent_option/with_order.rs
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use crate::{states::*, ConcurrentOption};
use core::{ops::Deref, sync::atomic::Ordering};
impl<T> ConcurrentOption<T> {
/// Loads and returns the concurrent state of the option with the given `order`.
///
/// # Examples
///
/// ```
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::some(2);
/// assert_eq!(x.state(Ordering::Relaxed), State::Some);
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::none();
/// assert_eq!(x.state(Ordering::SeqCst), State::None);
/// ```
pub fn state(&self, order: Ordering) -> State {
State::new(self.state.load(order))
}
/// Returns `true` if the option is a Some variant.
///
/// # Examples
///
/// ```
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::some(2);
/// assert_eq!(x.is_some(), true);
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::none();
/// assert_eq!(x.is_some(), false);
/// ```
#[inline]
pub fn is_some_with_order(&self, order: Ordering) -> bool {
self.state.load(order) == SOME
}
/// Returns `true` if the option is a None variant.
///
/// # Examples
///
/// ```
/// use orx_concurrent_option::*;
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::some(2);
/// assert_eq!(x.is_none(), false);
///
/// let x: ConcurrentOption<u32> = ConcurrentOption::none();
/// assert_eq!(x.is_none(), true);
/// ```
#[inline]
pub fn is_none_with_order(&self, order: Ordering) -> bool {
self.state.load(order) != SOME
}
/// Converts from `&Option<T>` to `Option<&T>`.
///
/// Depending on requirement of the use case, `Relaxed`, `Acquire` or `SeqCst` can be used as the `order`.
///
/// # Safety
///
/// Note that creating a valid reference part of this method is thread safe.
///
/// The method is `unsafe` due to the returned reference to the underlying value.
///
/// * It is safe to use this method if the returned reference is discarded (miri would still complain).
/// * It is also safe to use this method if the caller is able to guarantee that there exist
/// no concurrent writes while holding onto this reference.
/// * One such case is using `as_ref` together with `initialize_when_none` method.
/// This is perfectly safe since the value will be written only once,
/// and `as_ref` returns a valid reference only after the value is initialized.
/// * Otherwise, it will lead to an **Undefined Behavior** due to data race.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// let x = ConcurrentOption::some(3.to_string());
/// assert_eq!(unsafe { x.as_ref_with_order(Ordering::Relaxed) }, Some(&3.to_string()));
///
/// _ = x.take();
/// assert_eq!(unsafe { x.as_ref_with_order(Ordering::Acquire) }, None);
/// ```
pub unsafe fn as_ref_with_order(&self, order: Ordering) -> Option<&T> {
match self.state.load(order) {
SOME => {
let x = &*self.value.get();
Some(x.assume_init_ref())
}
_ => None,
}
}
/// Converts from `Option<T>` (or `&Option<T>`) to `Option<&T::Target>`.
///
/// Leaves the original Option in-place, creating a new one with a reference
/// to the original one, additionally coercing the contents via [`Deref`].
///
/// Depending on requirement of the use case, `Relaxed`, `Acquire` or `SeqCst` can be used as the `order`.
///
/// # Safety
///
/// Note that creating a valid reference part of this method is thread safe.
///
/// The method is `unsafe` due to the returned reference to the underlying value.
///
/// * It is safe to use this method if the returned reference is discarded (miri would still complain).
/// * It is also safe to use this method if the caller is able to guarantee that there exist
/// no concurrent writes while holding onto this reference.
/// * One such case is using `as_ref` together with `initialize_when_none` method.
/// This is perfectly safe since the value will be written only once,
/// and `as_ref` returns a valid reference only after the value is initialized.
/// * Otherwise, it will lead to an **Undefined Behavior** due to data race.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// unsafe
/// {
/// let x: ConcurrentOption<String> = ConcurrentOption::some("hey".to_owned());
/// assert_eq!(x.as_deref_with_order(Ordering::Acquire), Some("hey"));
///
/// let x: ConcurrentOption<String> = ConcurrentOption::none();
/// assert_eq!(x.as_deref_with_order(Ordering::SeqCst), None);
/// }
/// ```
pub unsafe fn as_deref_with_order(&self, order: Ordering) -> Option<&<T as Deref>::Target>
where
T: Deref,
{
match self.state.load(order) {
SOME => {
let x = &*self.value.get();
Some(x.assume_init_ref())
}
_ => None,
}
}
/// Returns an iterator over the possibly contained value; yields
/// * the single element if the option is of Some variant;
/// * no elements otherwise.
///
/// Depending on requirement of the use case, `Relaxed`, `Acquire` or `SeqCst` can be used as the `order`.
///
/// # Safety
///
/// Note that creating a valid reference part of this method is thread safe.
///
/// The method is `unsafe` due to the returned reference to the underlying value.
///
/// * It is safe to use this method if the returned reference is discarded (miri would still complain).
/// * It is also safe to use this method if the caller is able to guarantee that there exist
/// no concurrent writes while holding onto this reference.
/// * One such case is using `as_ref` together with `initialize_when_none` method.
/// This is perfectly safe since the value will be written only once,
/// and `as_ref` returns a valid reference only after the value is initialized.
/// * Otherwise, it will lead to an **Undefined Behavior** due to data race.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// fn validate<'a>(mut iter: impl ExactSizeIterator<Item = &'a String>) {
/// assert_eq!(iter.len(), 0);
/// assert!(iter.next().is_none());
/// assert!(iter.next().is_none());
/// }
///
/// let x = ConcurrentOption::<String>::none();
/// unsafe
/// {
/// validate(x.iter_with_order(Ordering::SeqCst));
/// validate(x.iter_with_order(Ordering::Relaxed).rev());
/// validate((&x).into_iter());
/// }
/// ```
pub unsafe fn iter_with_order(&self, order: Ordering) -> crate::iter::Iter<'_, T> {
let maybe = unsafe { self.as_ref_with_order(order) };
crate::iter::Iter { maybe }
}
/// Clones the concurrent option with the desired `order` into an Option.
///
/// Note that the `Clone` trait implementation clones the concurrent option with the default ordering.
///
/// You may use `clone_with_order` in order to clone with the desired ordering.
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// let mut x = ConcurrentOption::some(42);
/// let y = x.clone_with_order(Ordering::SeqCst);
/// assert_eq!(x.take(), y);
/// ```
pub fn clone_with_order(&self, order: Ordering) -> Option<T>
where
T: Clone,
{
unsafe { self.as_ref_with_order(order) }.cloned()
}
/// Returns whether or not self is equal to the `other` with the desired `order`.
///
/// Note that the `PartialEq` trait implementation checks equality with the default ordering.
///
/// You may use `eq_with_order` in order to check equality with the desired ordering.
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::sync::atomic::Ordering;
///
/// let x = ConcurrentOption::some(3);
/// let y = ConcurrentOption::some(7);
/// let z = ConcurrentOption::<i32>::none();
///
/// let o = Ordering::SeqCst;
///
/// assert!(x.eq_with_order(&x, o));
/// assert!(!x.eq_with_order(&y, o));
/// assert!(!x.eq_with_order(&z, o));
///
/// assert!(!z.eq_with_order(&x, o));
/// assert!(!z.eq_with_order(&y, o));
/// assert!(z.eq_with_order(&z, o));
/// ```
pub fn eq_with_order(&self, other: &Self, order: Ordering) -> bool
where
T: PartialEq,
{
match (unsafe { self.as_ref_with_order(order) }, unsafe {
other.as_ref_with_order(order)
}) {
(None, None) => true,
(Some(x), Some(y)) => x.eq(y),
_ => false,
}
}
/// Returns an ordering between `self` and `other` with the desired `order`.
///
/// Note that the `PartialOrd` trait implementation checks equality with the default ordering.
///
/// You may use `partial_cmp_with_order` in order to check equality with the desired ordering.
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::cmp::Ordering::*;
///
/// let x = ConcurrentOption::some(3);
/// let y = ConcurrentOption::some(7);
/// let z = ConcurrentOption::<i32>::none();
///
/// let ord = core::sync::atomic::Ordering::SeqCst;
///
/// assert_eq!(x.partial_cmp_with_order(&x, ord), Some(Equal));
/// assert_eq!(x.partial_cmp_with_order(&y, ord), Some(Less));
/// assert_eq!(x.partial_cmp_with_order(&z, ord), Some(Greater));
///
/// assert_eq!(y.partial_cmp_with_order(&x, ord), Some(Greater));
/// assert_eq!(y.partial_cmp_with_order(&y, ord), Some(Equal));
/// assert_eq!(y.partial_cmp_with_order(&z, ord), Some(Greater));
///
/// assert_eq!(z.partial_cmp_with_order(&x, ord), Some(Less));
/// assert_eq!(z.partial_cmp_with_order(&y, ord), Some(Less));
/// assert_eq!(z.partial_cmp_with_order(&z, ord), Some(Equal));
/// ```
pub fn partial_cmp_with_order(
&self,
other: &Self,
order: Ordering,
) -> Option<core::cmp::Ordering>
where
T: PartialOrd,
{
use core::cmp::Ordering::*;
match (unsafe { self.as_ref_with_order(order) }, unsafe {
other.as_ref_with_order(order)
}) {
(Some(l), Some(r)) => l.partial_cmp(r),
(Some(_), None) => Some(Greater),
(None, Some(_)) => Some(Less),
(None, None) => Some(Equal),
}
}
/// Returns an ordering between `self` and `other` with the desired `order`.
///
/// Note that the `Ord` trait implementation checks equality with the default ordering.
///
/// You may use `cmp_with_order` in order to check equality with the desired ordering.
///
/// ```rust
/// use orx_concurrent_option::*;
/// use core::cmp::Ordering::*;
///
/// let x = ConcurrentOption::some(3);
/// let y = ConcurrentOption::some(7);
/// let z = ConcurrentOption::<i32>::none();
///
/// let ord = core::sync::atomic::Ordering::SeqCst;
///
/// assert_eq!(x.cmp_with_order(&x, ord), Equal);
/// assert_eq!(x.cmp_with_order(&y, ord), Less);
/// assert_eq!(x.cmp_with_order(&z, ord), Greater);
///
/// assert_eq!(y.cmp_with_order(&x, ord), Greater);
/// assert_eq!(y.cmp_with_order(&y, ord), Equal);
/// assert_eq!(y.cmp_with_order(&z, ord), Greater);
///
/// assert_eq!(z.cmp_with_order(&x, ord), Less);
/// assert_eq!(z.cmp_with_order(&y, ord), Less);
/// assert_eq!(z.cmp_with_order(&z, ord), Equal);
/// ```
pub fn cmp_with_order(&self, other: &Self, order: Ordering) -> core::cmp::Ordering
where
T: Ord,
{
use core::cmp::Ordering::*;
match (unsafe { self.as_ref_with_order(order) }, unsafe {
other.as_ref_with_order(order)
}) {
(Some(l), Some(r)) => l.cmp(r),
(Some(_), None) => Greater,
(None, Some(_)) => Less,
(None, None) => Equal,
}
}
}