collections: Use Option::map

Author: Ulrik Sverdrup

src/libcollections/vec.rs

@@ -1848,14 +1848,11 @@ impl<'a, T> Iterator for Drain<'a, T>
     #[inline]
     fn next(&mut self) -> Option<T>
     {
-        match self.iter.next() {
-            None => None,
-            Some(elt) => {
-                unsafe {
-                    Some(ptr::read(elt as *const _))
-                }
+        self.iter.next().map(|elt|
+            unsafe {
+                ptr::read(elt as *const _)
             }
-        }
+        )
     }
 
     fn size_hint(&self) -> (usize, Option<usize>)
@@ -1870,14 +1867,11 @@ impl<'a, T> DoubleEndedIterator for Drain<'a, T>
     #[inline]
     fn next_back(&mut self) -> Option<T>
     {
-        match self.iter.next_back() {
-            None => None,
-            Some(elt) => {
-                unsafe {
-                    Some(ptr::read(elt as *const _))
-                }
+        self.iter.next_back().map(|elt|
+            unsafe {
+                ptr::read(elt as *const _)
             }
-        }
+        )
     }
 }