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Add the put family of methods to Option<T> #25149

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Add the put family of methods to Option<T> #25149

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73 changes: 73 additions & 0 deletions src/libcore/option.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -685,6 +685,79 @@ impl<T> Option<T> {
mem::replace(self, None)
}

/// Puts a value into the option, returning a reference to it.
///
/// # Examples
///
/// ```
/// let mut x = None;
/// {
/// let y: &mut i32 = x.put(5);
/// assert_eq!(*y, 5);
/// *y = 10;
/// }
/// assert_eq!(x, Some(10));
/// ```
#[inline]
#[unstable(feature = "rust1", since = "1.0.0")]
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master is now 1.1, so if this is accepted, this would need to be fixed

pub fn put(&mut self, val: T) -> &mut T {
*self = Some(val);
self.as_mut().unwrap()
}

/// Puts a value into the option if it is empty, returning a reference to
/// the contents of the option.
///
/// # Examples
///
/// ```
/// let mut x = None;
/// {
/// let y: &mut i32 = x.or_put(5);
/// assert_eq!(*y, 5);
/// *y = 10;
/// }
/// {
/// let z: &mut i32 = x.or_put(15);
/// assert_eq!(*z, 10);
/// *z = 20;
/// }
/// assert_eq!(x, Some(20));
/// ```
#[inline]
#[unstable(feature = "rust1", since = "1.0.0")]
pub fn or_put(&mut self, val: T) -> &mut T {
self.or_else_put(|| val)
}

/// Puts a value computed from a closure into the option if it is empty,
/// returning a reference to the contents of the option.
///
/// # Examples
///
/// ```
/// let mut x = None;
/// {
/// let y: &mut i32 = x.or_else_put(|| 5);
/// assert_eq!(*y, 5);
/// *y = 10;
/// }
/// {
/// let z: &mut i32 = x.or_else_put(|| 15);
/// assert_eq!(*z, 10);
/// *z = 20;
/// }
/// assert_eq!(x, Some(20));
/// ```
#[inline]
#[unstable(feature = "rust1", since = "1.0.0")]
pub fn or_else_put<F: FnOnce() -> T>(&mut self, f: F) -> &mut T {
match *self {
Some(ref mut inner) => inner,
None => self.put(f()),
}
}

/// Converts from `Option<T>` to `&[T]` (without copying)
#[inline]
#[unstable(feature = "as_slice", since = "unsure of the utility here")]
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