Compare pairs with `slice::windows`

2 files changed, 9 insertions, 8 deletions

diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs
index 4035ad6b77c..ac21586c0b8 100644
--- a/src/libcore/iter/iterator.rs
+++ b/src/libcore/iter/iterator.rs
@@ -2655,7 +2655,10 @@ pub trait Iterator {
         };
 
         while let Some(curr) = self.next() {
-            if compare(&last, &curr).map(|o| o == Ordering::Greater).unwrap_or(true) {
+            if compare(&last, &curr)
+                .map(|o| o == Ordering::Greater)
+                .unwrap_or(true)
+            {
                 return false;
             }
             last = curr;
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index 9c82aca9ab2..11ce8115d30 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -2293,13 +2293,11 @@ impl<T> [T] {
     where
         F: FnMut(&T, &T) -> Option<Ordering>
     {
-        let len = self.len();
-        if len <= 1 {
-            return true;
-        }
-
-        for i in 1..len {
-            if compare(&self[i - 1], &self[i]).map(|o| o == Ordering::Greater).unwrap_or(true) {
+        for pair in self.windows(2) {
+            if compare(&pair[0], &pair[1])
+                .map(|o| o == Ordering::Greater)
+                .unwrap_or(true)
+            {
                 return false;
             }
         }