library/core/src/bool.rs

   1 //! impl bool {}
   2
   3 #[lang = "bool"]
   4 impl bool {
   5     /// Returns `Some(t)` if the `bool` is [`true`](../std/keyword.true.html),
   6     /// or `None` otherwise.
   7     ///
   8     /// # Examples
   9     ///
  10     /// ```
  11     /// #![feature(bool_to_option)]
  12     ///
  13     /// assert_eq!(false.then_some(0), None);
  14     /// assert_eq!(true.then_some(0), Some(0));
  15     /// ```
  16     #[unstable(feature = "bool_to_option", issue = "80967")]
  17     #[inline]
  18     pub fn then_some<T>(self, t: T) -> Option<T> {
  19         if self { Some(t) } else { None }
  20     }
  21
  22     /// Returns `Some(f())` if the `bool` is [`true`](../std/keyword.true.html),
  23     /// or `None` otherwise.
  24     ///
  25     /// # Examples
  26     ///
  27     /// ```
  28     /// assert_eq!(false.then(|| 0), None);
  29     /// assert_eq!(true.then(|| 0), Some(0));
  30     /// ```
  31     #[stable(feature = "lazy_bool_to_option", since = "1.50.0")]
  32     #[inline]
  33     pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
  34         if self { Some(f()) } else { None }
  35     }
  36 }