library/core/src/bool.rs

   1 //! impl bool {}
   2
   3 #[lang = "bool"]
   4 impl bool {
   5     /// Returns `Some(t)` if the `bool` is `true`, or `None` otherwise.
   6     ///
   7     /// # Examples
   8     ///
   9     /// ```
  10     /// #![feature(bool_to_option)]
  11     ///
  12     /// assert_eq!(false.then_some(0), None);
  13     /// assert_eq!(true.then_some(0), Some(0));
  14     /// ```
  15     #[unstable(feature = "bool_to_option", issue = "64260")]
  16     #[inline]
  17     pub fn then_some<T>(self, t: T) -> Option<T> {
  18         if self { Some(t) } else { None }
  19     }
  20
  21     /// Returns `Some(f())` if the `bool` is `true`, or `None` otherwise.
  22     ///
  23     /// # Examples
  24     ///
  25     /// ```
  26     /// #![feature(bool_to_option)]
  27     ///
  28     /// assert_eq!(false.then(|| 0), None);
  29     /// assert_eq!(true.then(|| 0), Some(0));
  30     /// ```
  31     #[unstable(feature = "bool_to_option", issue = "64260")]
  32     #[inline]
  33     pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
  34         if self { Some(f()) } else { None }
  35     }
  36 }