src/libcore/bool.rs

   1 //! impl bool {}
   2
   3 #[cfg(not(bootstrap))]
   4 #[lang = "bool"]
   5 impl bool {
   6     /// Returns `Some(t)` if the `bool` is `true`, or `None` otherwise.
   7     ///
   8     /// # Examples
   9     ///
  10     /// ```
  11     /// #![feature(bool_to_option)]
  12     ///
  13     /// assert_eq!(false.then(0), None);
  14     /// assert_eq!(true.then(0), Some(0));
  15     /// ```
  16     #[unstable(feature = "bool_to_option", issue = "64260")]
  17     #[inline]
  18     pub fn then<T>(self, t: T) -> Option<T> {
  19         if self {
  20             Some(t)
  21         } else {
  22             None
  23         }
  24     }
  25
  26     /// Returns `Some(f())` if the `bool` is `true`, or `None` otherwise.
  27     ///
  28     /// # Examples
  29     ///
  30     /// ```
  31     /// #![feature(bool_to_option)]
  32     ///
  33     /// assert_eq!(false.then_with(|| 0), None);
  34     /// assert_eq!(true.then_with(|| 0), Some(0));
  35     /// ```
  36     #[unstable(feature = "bool_to_option", issue = "64260")]
  37     #[inline]
  38     pub fn then_with<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
  39         if self {
  40             Some(f())
  41         } else {
  42             None
  43         }
  44     }
  45 }