diff --git a/src/libcore/result.rs b/src/libcore/result.rs index 9cb42124e00bf..3d34f62006785 100644 --- a/src/libcore/result.rs +++ b/src/libcore/result.rs @@ -792,6 +792,44 @@ impl Result { } } +impl Result { + /// Returns the contained value or a default + /// + /// Consumes the `self` argument then, if `Ok`, returns the contained + /// value, otherwise if `Err`, returns the default value for that + /// type. + /// + /// # Examples + /// + /// Convert a string to an integer, turning poorly-formed strings + /// into 0 (the default value for integers). [`parse`] converts + /// a string to any other type that implements [`FromStr`], returning an + /// `Err` on error. + /// + /// ``` + /// #![feature(result_unwrap_or_default)] + /// + /// let good_year_from_input = "1909"; + /// let bad_year_from_input = "190blarg"; + /// let good_year = good_year_from_input.parse().unwrap_or_default(); + /// let bad_year = bad_year_from_input.parse().unwrap_or_default(); + /// + /// assert_eq!(1909, good_year); + /// assert_eq!(0, bad_year); + /// + /// [`parse`]: ../../std/primitive.str.html#method.parse + /// [`FromStr`]: ../../std/str/trait.FromStr.html + /// ``` + #[inline] + #[unstable(feature = "result_unwrap_or_default", issue = "0")] + pub fn unwrap_or_default(self) -> T { + match self { + Ok(x) => x, + Err(_) => Default::default(), + } + } +} + // This is a separate function to reduce the code size of the methods #[inline(never)] #[cold] diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs index 590bf478aa723..cdbc214731806 100644 --- a/src/libcoretest/lib.rs +++ b/src/libcoretest/lib.rs @@ -34,6 +34,7 @@ #![feature(unique)] #![feature(iter_max_by)] #![feature(iter_min_by)] +#![feature(result_unwrap_or_default)] extern crate core; extern crate test; diff --git a/src/libcoretest/result.rs b/src/libcoretest/result.rs index 6e9f653dcd8ac..bc2cd8bbfc651 100644 --- a/src/libcoretest/result.rs +++ b/src/libcoretest/result.rs @@ -183,3 +183,9 @@ pub fn test_iter_mut() { } assert_eq!(err, Err("error")); } + +#[test] +pub fn test_unwrap_or_default() { + assert_eq!(op1().unwrap_or_default(), 666); + assert_eq!(op2().unwrap_or_default(), 0); +}