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use super::Possible;
use core::{hint, mem};
impl<T> Possible<T> {
/// Takes the value out of the option, leaving a [`Possible::Void`] in its place.
///
/// # Examples
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Some(2);
/// let y = x.take();
/// assert_eq!(x, Possible::Void);
/// assert_eq!(y, Possible::Some(2));
///
/// let mut x: Possible<u32> = Possible::None;
/// let y = x.take();
/// assert_eq!(x, Possible::Void);
/// assert_eq!(y, Possible::None);
/// ```
#[inline]
pub fn take(&mut self) -> Possible<T> {
mem::take(self)
}
/// Inserts `value` into the `Possible` then returns a mutable reference to it.
///
/// If the `Possible` already contains a value, the old value is dropped.
///
/// See also [`Possible::get_or_insert`], which doesn't update the value if
/// the option already contains [`Possible::Some`].
///
/// # Example
///
/// ```
/// use possible::Possible;
///
/// let mut opt = Possible::None;
/// let val = opt.insert(1);
/// assert_eq!(*val, 1);
/// assert_eq!(opt.unwrap(), 1);
/// let val = opt.insert(2);
/// assert_eq!(*val, 2);
/// *val = 3;
/// assert_eq!(opt.unwrap(), 3);
/// ```
#[must_use = "if you intended to set a value, consider assignment instead"]
#[inline]
pub fn insert(&mut self, value: T) -> &mut T {
*self = Possible::Some(value);
match self {
Possible::Some(v) => v,
// SAFETY: the code above just filled the option
Possible::None | Possible::Void => unsafe { hint::unreachable_unchecked() },
}
}
/// Inserts `value` into the `Possible` if it is [`Possible::None`] or
/// [`Possible::Void`], then returns a mutable reference to the contained value.
///
/// See also [`Possible::insert`], which updates the value even if
/// the `Possible` already contains [`Some`].
///
/// # Examples
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::None;
///
/// {
/// let y: &mut u32 = x.get_or_insert(5);
/// assert_eq!(y, &5);
///
/// *y = 7;
/// }
///
/// assert_eq!(x, Possible::Some(7));
/// ```
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Void;
///
/// {
/// let y: &mut u32 = x.get_or_insert(3);
/// assert_eq!(y, &3);
///
/// *y = 4;
/// }
///
/// assert_eq!(x, Possible::Some(4));
/// ```
#[inline]
pub fn get_or_insert(&mut self, value: T) -> &mut T {
self.get_or_insert_with(|| value)
}
/// Inserts the default value into the option if it is [`Possible::None`] or
/// or [`Possible::Void`], then returns a mutable reference to the contained value.
///
/// # Examples
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::None;
///
/// {
/// let y: &mut u32 = x.get_or_insert_default();
/// assert_eq!(y, &0);
///
/// *y = 7;
/// }
///
/// assert_eq!(x, Possible::Some(7));
/// ```
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Void;
///
/// {
/// let y: &mut u32 = x.get_or_insert_default();
/// assert_eq!(y, &0);
///
/// *y = 4;
/// }
///
/// assert_eq!(x, Possible::Some(4));
/// ```
#[inline]
pub fn get_or_insert_default(&mut self) -> &mut T
where
T: Default,
{
self.get_or_insert_with(Default::default)
}
/// Inserts a value computed from `f` into the `Possible` if it is [`Possible::None`]
/// or [`Possible::Void`] then returns a mutable reference to the contained value.
///
/// # Examples
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::None;
///
/// {
/// let y: &mut u32 = x.get_or_insert_with(|| 5);
/// assert_eq!(y, &5);
///
/// *y = 7;
/// }
///
/// assert_eq!(x, Possible::Some(7));
/// ```
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Void;
///
/// {
/// let y: &mut u32 = x.get_or_insert_with(|| 3);
/// assert_eq!(y, &3);
///
/// *y = 4;
/// }
///
/// assert_eq!(x, Possible::Some(4));
/// ```
#[inline]
pub fn get_or_insert_with<F: FnOnce() -> T>(&mut self, f: F) -> &mut T {
if let Possible::None | Possible::Void = *self {
*self = Possible::Some(f());
}
match self {
Possible::Some(v) => v,
// SAFETY: a `Possible::None` or a `Possible::Void` variant for `self`
// would have been replaced by a `Some` variant in the code above.
Possible::None | Possible::Void => unsafe { hint::unreachable_unchecked() },
}
}
/// 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 deinitializing either one.
///
/// # Examples
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Some(2);
/// let old = x.replace(5);
/// assert_eq!(x, Possible::Some(5));
/// assert_eq!(old, Possible::Some(2));
/// ```
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::None;
/// let old = x.replace(3);
/// assert_eq!(x, Possible::Some(3));
/// assert_eq!(old, Possible::None);
/// ```
///
/// ```
/// use possible::Possible;
///
/// let mut x = Possible::Void;
/// let old = x.replace(7);
/// assert_eq!(x, Possible::Some(7));
/// assert_eq!(old, Possible::Void);
/// ```
#[inline]
pub fn replace(&mut self, value: T) -> Possible<T> {
mem::replace(self, Possible::Some(value))
}
}