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use crate::{ConcurrentOption, states::*};
use core::{
mem::MaybeUninit,
ops::{Deref, DerefMut},
sync::atomic::Ordering,
};
impl<T> ConcurrentOption<T> {
/// Converts from `Option<T>` (or `&mut Option<T>`) to `Option<&mut T::Target>`.
///
/// Leaves the original `Option` in-place, creating a new one containing a mutable reference to
/// the inner type's [`Deref::Target`] type.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x: ConcurrentOption<String> = ConcurrentOption::some("hey".to_owned());
/// assert_eq!(x.exclusive_as_deref_mut().map(|x| {
/// x.make_ascii_uppercase();
/// x
/// }), Some("HEY".to_owned().as_mut_str()));
/// ```
pub fn exclusive_as_deref_mut(&mut self) -> Option<&mut <T as Deref>::Target>
where
T: DerefMut,
{
self.exclusive_as_mut().map(|x| x.deref_mut())
}
/// Converts from `&mut Option<T>` to `Option<&mut T>`.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::some(2);
/// match x.exclusive_as_mut() {
/// Some(v) => *v = 42,
/// None => {},
/// }
/// assert_eq!(unsafe { x.as_ref() }, Some(&42));
/// ```
pub fn exclusive_as_mut(&mut self) -> Option<&mut T> {
match self.state.load(Ordering::Relaxed) {
SOME => Some(unsafe { (*self.value.get()).assume_init_mut() }),
_ => None,
}
}
/// Takes the value out of the option, leaving a None in its place.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::some(42);
/// let y = x.exclusive_take();
/// assert_eq!(x, ConcurrentOption::none());
/// assert_eq!(y, Some(42));
///
/// let mut x: ConcurrentOption<u32> = ConcurrentOption::none();
/// let y = x.exclusive_take();
/// assert_eq!(x, ConcurrentOption::none());
/// assert_eq!(y, None);
/// ```
pub fn exclusive_take(&mut self) -> Option<T> {
match self.state.load(Ordering::Relaxed) {
SOME => {
self.state.store(NONE, Ordering::Relaxed);
let x = unsafe { &mut *self.value.get() };
Some(unsafe { x.assume_init_read() })
}
_ => None,
}
}
/// Takes the value out of the option, but only if the predicate evaluates to
/// `true` on a mutable reference to the value.
///
/// In other words, replaces `self` with None if the predicate returns `true`.
/// This method operates similar to [`ConcurrentOption::exclusive_take`] but conditional.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::some(42);
///
/// let prev = x.exclusive_take_if(|v| if *v == 42 {
/// *v += 1;
/// false
/// } else {
/// false
/// });
/// assert_eq!(x, ConcurrentOption::some(43));
/// assert_eq!(prev, None);
///
/// let prev = x.exclusive_take_if(|v| *v == 43);
/// assert_eq!(x, ConcurrentOption::none());
/// assert_eq!(prev, Some(43));
/// ```
pub fn exclusive_take_if<P>(&mut self, predicate: P) -> Option<T>
where
P: FnOnce(&mut T) -> bool,
{
match self.exclusive_as_mut().is_some_and(predicate) {
true => self.exclusive_take(),
false => None,
}
}
/// Returns a mutable iterator over the possibly contained value; yields
/// * the single element if the option is of Some variant;
/// * no elements otherwise.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::some(4);
/// match x.exclusive_iter_mut().next() {
/// Some(v) => *v = 42,
/// None => {},
/// }
/// assert_eq!(x, ConcurrentOption::some(42));
///
/// let mut x: ConcurrentOption<u32> = ConcurrentOption::none();
/// assert_eq!(x.exclusive_iter_mut().next(), None);
/// ```
pub fn exclusive_iter_mut(&mut self) -> crate::iter::IterMut<'_, T> {
let maybe = self.exclusive_as_mut();
crate::iter::IterMut { maybe }
}
/// Replaces the actual value in the option by the value given in parameter,
/// returning the old value if present,
/// leaving a Some in its place without de-initializing either one.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::some(2);
/// let old = x.exclusive_replace(5);
/// assert_eq!(x, ConcurrentOption::some(5));
/// assert_eq!(old, Some(2));
///
/// let mut x: ConcurrentOption<u32> = ConcurrentOption::none();
/// let old = x.exclusive_replace(3);
/// assert_eq!(x, ConcurrentOption::some(3));
/// assert_eq!(old, None);
/// ```
#[allow(clippy::panic, clippy::missing_panics_doc)]
pub fn exclusive_replace(&mut self, value: T) -> Option<T> {
match self.state.load(Ordering::Relaxed) {
SOME => {
self.state.store(RESERVED, Ordering::Relaxed);
let x = unsafe { (*self.value.get()).assume_init_mut() };
let old = core::mem::replace(x, value);
self.state.store(SOME, Ordering::Relaxed);
Some(old)
}
NONE => {
self.state.store(RESERVED, Ordering::Relaxed);
self.value = MaybeUninit::new(value).into();
self.state.store(SOME, Ordering::Relaxed);
None
}
_ => panic!("ConcurrentOption value is `replace`d while its value is being written."),
}
}
/// Inserts `value` into the option, then returns a mutable reference to it.
///
/// If the option already contains a value, the old value is dropped.
///
/// See also [`Option::get_or_insert`], which doesn't update the value if
/// the option already contains Some.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut opt: ConcurrentOption<_> = ConcurrentOption::none();
///
/// let val = opt.exclusive_insert(1);
/// assert_eq!(*val, 1);
/// assert_eq!(unsafe { opt.as_ref() }, Some(&1));
///
/// let val = opt.exclusive_insert(2);
/// assert_eq!(*val, 2);
/// *val = 3;
/// assert_eq!(opt.unwrap(), 3);
/// ```
#[allow(clippy::panic, clippy::missing_panics_doc)]
pub fn exclusive_insert(&mut self, value: T) -> &mut T {
match self.state.load(Ordering::Relaxed) {
SOME => {
self.state.store(RESERVED, Ordering::Relaxed);
let x = unsafe { (*self.value.get()).assume_init_mut() };
let _ = core::mem::replace(x, value);
self.state.store(SOME, Ordering::Relaxed);
}
NONE => {
self.state.store(RESERVED, Ordering::Relaxed);
self.value = MaybeUninit::new(value).into();
self.state.store(SOME, Ordering::Relaxed);
}
_ => panic!("ConcurrentOption value is `insert`ed while its value is being written."),
}
self.exclusive_as_mut().expect("should be some")
}
/// Inserts `value` into the option if it is None, then
/// returns a mutable reference to the contained value.
///
/// See also [`ConcurrentOption::insert`], which updates the value even if
/// the option already contains Some.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::none();
///
/// {
/// let y: &mut u32 = x.exclusive_get_or_insert(5);
/// assert_eq!(y, &5);
///
/// *y = 7;
/// }
///
/// assert_eq!(x, ConcurrentOption::some(7));
/// ```
pub fn exclusive_get_or_insert(&mut self, value: T) -> &mut T {
self.exclusive_get_or_insert_with(|| value)
}
/// Inserts a value computed from `f` into the option if it is None,
/// then returns a mutable reference to the contained value.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_option::*;
///
/// let mut x = ConcurrentOption::none();
///
/// {
/// let y: &mut u32 = x.exclusive_get_or_insert_with(|| 5);
/// assert_eq!(y, &5);
///
/// *y = 7;
/// }
///
/// assert_eq!(x, ConcurrentOption::some(7));
/// ```
#[allow(clippy::panic, clippy::missing_panics_doc)]
pub fn exclusive_get_or_insert_with<F>(&mut self, f: F) -> &mut T
where
F: FnOnce() -> T,
{
match self.state.load(Ordering::Relaxed) {
SOME => self.exclusive_as_mut().expect("is guaranteed to be some"),
NONE => {
self.state.store(RESERVED, Ordering::Relaxed);
self.value = MaybeUninit::new(f()).into();
self.state.store(SOME, Ordering::Relaxed);
self.exclusive_as_mut().expect("is guaranteed to be some")
}
_ => panic!(
"ConcurrentOption `get_or_insert_with` is called while its value is being written."
),
}
}
}