Refactoring largest_by_key

Author: ejmount

src/k_smallest.rs

@@ -1,5 +1,5 @@
 use alloc::vec::Vec;
-use core::cmp::{Ordering, Reverse};
+use core::cmp::Ordering;
 
 /// Consumes a given iterator, returning the minimum elements in **ascending** order.
 pub(crate) fn k_smallest_general<I, F>(mut iter: I, k: usize, mut comparator: F) -> Vec<I::Item>
@@ -95,9 +95,10 @@ where
     move |a, b| cmp(b, a)
 }
 
-pub(crate) fn reverse_key<T, K, F>(f: F) -> impl Fn(&T) -> Reverse<K>
+pub(crate) fn key_to_cmp<T, K, F>(key: F) -> impl Fn(&T, &T) -> Ordering
 where
     F: Fn(&T) -> K,
+    K: Ord,
 {
-    move |a| Reverse(f(a))
+    move |a, b| key(a).cmp(&key(b))
 }

src/lib.rs

@@ -2990,7 +2990,7 @@ pub trait Itertools: Iterator {
         Self: Sized,
         F: Fn(&Self::Item, &Self::Item) -> Ordering,
     {
-        crate::k_smallest::k_smallest_general(self, k, cmp).into_iter()
+        k_smallest::k_smallest_general(self, k, cmp).into_iter()
     }
 
     /// Return the elements producing the k smallest outputs of the provided function
@@ -3005,7 +3005,7 @@ pub trait Itertools: Iterator {
         F: Fn(&Self::Item) -> K,
         K: Ord,
     {
-        self.k_smallest_by(k, |a, b| key(a).cmp(&key(b)))
+        self.k_smallest_by(k, k_smallest::key_to_cmp(key))
     }
 
     /// Sort the k largest elements into a new iterator, in descending order.
@@ -3052,8 +3052,7 @@ pub trait Itertools: Iterator {
         F: Fn(&Self::Item) -> K,
         K: Ord,
     {
-        let key = crate::k_smallest::reverse_key(key);
-        self.k_smallest_by_key(k, key)
+        self.k_largest_by(k, k_smallest::key_to_cmp(key))
     }
 
     /// Collect all iterator elements into one of two