Add Iterator::find_map

1 files changed, 32 insertions, 0 deletions

diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs
index 31f77f92435..f039d1730eb 100644
--- a/src/libcore/iter/iterator.rs
+++ b/src/libcore/iter/iterator.rs
@@ -1745,6 +1745,38 @@ pub trait Iterator {
         }).break_value()
     }
 
+    /// Applies function to the elements of iterator and returns
+    /// the first non-none result.
+    ///
+    /// `iter.find_map(f)` is equivalent to `iter.filter_map(f).next()`.
+    ///
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(iterator_find_map)]
+    /// let a = ["lol", "NaN", "2", "5"];
+    ///
+    /// let mut first_number = a.iter().find_map(|s| s.parse().ok());
+    ///
+    /// assert_eq!(first_number, Some(2));
+    /// ```
+    #[inline]
+    #[unstable(feature = "iterator_find_map",
+               reason = "unstable new API",
+               issue = "49602")]
+    fn find_map<B, F>(&mut self, mut f: F) -> Option<B> where
+        Self: Sized,
+        F: FnMut(Self::Item) -> Option<B>,
+    {
+        self.try_for_each(move |x| {
+            match f(x) {
+                Some(x) => LoopState::Break(x),
+                None => LoopState::Continue(()),
+            }
+        }).break_value()
+    }
+
     /// Searches for an element in an iterator, returning its index.
     ///
     /// `position()` takes a closure that returns `true` or `false`. It applies