introduce the Comparable trait for btree internals

Author: conradludgate

library/alloc/src/collections/btree/navigate.rs

@@ -1,4 +1,4 @@
-use core::borrow::Borrow;
+use core::cmp::Comparable;
 use core::ops::RangeBounds;
 use core::{hint, ptr};
 
@@ -267,7 +267,7 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
     ) -> LeafRange<BorrowType, K, V>
     where
         Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
         R: RangeBounds<Q>,
     {
         match self.search_tree_for_bifurcation(&range) {
@@ -316,7 +316,7 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>
     pub(super) fn range_search<Q, R>(self, range: R) -> LeafRange<marker::Immut<'a>, K, V>
     where
         Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
         R: RangeBounds<Q>,
     {
         // SAFETY: our borrow type is immutable.
@@ -342,7 +342,7 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::ValMut<'a>, K, V, marker::LeafOrInternal>
     pub(super) fn range_search<Q, R>(self, range: R) -> LeafRange<marker::ValMut<'a>, K, V>
     where
         Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
         R: RangeBounds<Q>,
     {
         unsafe { self.find_leaf_edges_spanning_range(range) }
@@ -746,8 +746,7 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         mut bound: SearchBound<&Q>,
     ) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>
     where
-        Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
     {
         let mut node = self;
         loop {
@@ -769,8 +768,7 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         mut bound: SearchBound<&Q>,
     ) -> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::Edge>
     where
-        Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
     {
         let mut node = self;
         loop {

library/alloc/src/collections/btree/search.rs

@@ -1,5 +1,4 @@
-use core::borrow::Borrow;
-use core::cmp::Ordering;
+use core::cmp::{Comparable, Ordering};
 use core::ops::{Bound, RangeBounds};
 
 use SearchBound::*;
@@ -51,8 +50,7 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         key: &Q,
     ) -> SearchResult<BorrowType, K, V, marker::LeafOrInternal, marker::Leaf>
     where
-        Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
     {
         loop {
             self = match self.search_node(key) {
@@ -95,7 +93,7 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
     >
     where
         Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
         R: RangeBounds<Q>,
     {
         // Determine if map or set is being searched
@@ -161,8 +159,8 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         bound: SearchBound<&'r Q>,
     ) -> (Handle<Self, marker::Edge>, SearchBound<&'r Q>)
     where
-        Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        Q: ?Sized,
+        K: Comparable<Q>,
     {
         let (edge_idx, bound) = self.find_lower_bound_index(bound);
         let edge = unsafe { Handle::new_edge(self, edge_idx) };
@@ -175,8 +173,8 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         bound: SearchBound<&'r Q>,
     ) -> (Handle<Self, marker::Edge>, SearchBound<&'r Q>)
     where
-        Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        Q: ?Sized,
+        K: Comparable<Q>,
     {
         let (edge_idx, bound) = unsafe { self.find_upper_bound_index(bound, 0) };
         let edge = unsafe { Handle::new_edge(self, edge_idx) };
@@ -197,8 +195,7 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
         key: &Q,
     ) -> SearchResult<BorrowType, K, V, Type, Type>
     where
-        Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
     {
         match unsafe { self.find_key_index(key, 0) } {
             IndexResult::KV(idx) => Found(unsafe { Handle::new_kv(self, idx) }),
@@ -216,17 +213,16 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
     /// `start_index` must be a valid edge index for the node.
     unsafe fn find_key_index<Q: ?Sized>(&self, key: &Q, start_index: usize) -> IndexResult
     where
-        Q: Ord,
-        K: Borrow<Q>,
+        K: Comparable<Q>,
     {
         let node = self.reborrow();
         let keys = node.keys();
         debug_assert!(start_index <= keys.len());
         for (offset, k) in unsafe { keys.get_unchecked(start_index..) }.iter().enumerate() {
-            match key.cmp(k.borrow()) {
-                Ordering::Greater => {}
+            match k.compare(key) {
+                Ordering::Less => {}
                 Ordering::Equal => return IndexResult::KV(start_index + offset),
-                Ordering::Less => return IndexResult::Edge(start_index + offset),
+                Ordering::Greater => return IndexResult::Edge(start_index + offset),
             }
         }
         IndexResult::Edge(keys.len())
@@ -242,8 +238,8 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
         bound: SearchBound<&'r Q>,
     ) -> (usize, SearchBound<&'r Q>)
     where
-        Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        Q: ?Sized,
+        K: Comparable<Q>,
     {
         match bound {
             Included(key) => match unsafe { self.find_key_index(key, 0) } {
@@ -270,8 +266,8 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
         start_index: usize,
     ) -> (usize, SearchBound<&'r Q>)
     where
-        Q: ?Sized + Ord,
-        K: Borrow<Q>,
+        Q: ?Sized,
+        K: Comparable<Q>,
     {
         match bound {
             Included(key) => match unsafe { self.find_key_index(key, start_index) } {

library/alloc/src/lib.rs

@@ -107,6 +107,7 @@
 #![feature(char_max_len)]
 #![feature(clone_to_uninit)]
 #![feature(coerce_unsized)]
+#![feature(comparable_trait)]
 #![feature(const_default)]
 #![feature(const_eval_select)]
 #![feature(const_heap)]

library/alloctests/lib.rs

@@ -20,6 +20,7 @@
 #![feature(assert_matches)]
 #![feature(char_internals)]
 #![feature(char_max_len)]
+#![feature(comparable_trait)]
 #![feature(core_intrinsics)]
 #![feature(exact_size_is_empty)]
 #![feature(extend_one)]