diff options
| -rw-r--r-- | library/core/src/option.rs | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/library/core/src/option.rs b/library/core/src/option.rs index 1020e655579..becb6330997 100644 --- a/library/core/src/option.rs +++ b/library/core/src/option.rs @@ -1698,6 +1698,41 @@ impl<T> Option<T> { mem::replace(self, 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 [`Option::take`] but conditional. + /// + /// # Examples + /// + /// ``` + /// #![feature(option_take_if)] + /// + /// let mut x = Some(42); + /// + /// let prev = x.take_if(|v| if *v == 42 { + /// *v += 1; + /// false + /// } else { + /// false + /// }); + /// assert_eq!(x, Some(43)); + /// assert_eq!(prev, None); + /// + /// let prev = x.take_if(|v| *v == 43); + /// assert_eq!(x, None); + /// assert_eq!(prev, Some(43)); + /// ``` + #[inline] + #[unstable(feature = "option_take_if", issue = "98934")] + pub fn take_if<P>(&mut self, predicate: P) -> Option<T> + where + P: FnOnce(&mut T) -> bool, + { + if self.as_mut().map_or(false, predicate) { self.take() } else { None } + } + /// 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. |