skiplist: extract equivalent mod to a crate

crossbeam-skiplist/Cargo.toml

@@ -30,6 +30,7 @@ alloc = ["crossbeam-epoch/alloc"]
 [dependencies]
 crossbeam-epoch = { version = "0.9.17", path = "../crossbeam-epoch", default-features = false }
 crossbeam-utils = { version = "0.8.18", path = "../crossbeam-utils", default-features = false }
+equivalent-flipped = "0.1"
 
 [dev-dependencies]
 rand = "0.8"

crossbeam-skiplist/src/equivalent.rs

@@ -3,52 +3,4 @@
 
 //! Traits for key comparison in maps.
 
-use core::{borrow::Borrow, cmp::Ordering};
-
-/// Key equivalence trait.
-///
-/// This trait allows hash table lookup to be customized. It has one blanket
-/// implementation that uses the regular solution with `Borrow` and `Eq`, just
-/// like `HashMap` does, so that you can pass `&str` to lookup into a map with
-/// `String` keys and so on.
-///
-/// # Contract
-///
-/// The implementor **must** hash like `Q`, if it is hashable.
-pub trait Equivalent<Q: ?Sized> {
-    /// Compare self to `key` and return `true` if they are equal.
-    fn equivalent(&self, key: &Q) -> bool;
-}
-
-impl<K: ?Sized, Q: ?Sized> Equivalent<Q> for K
-where
-    K: Borrow<Q>,
-    Q: Eq,
-{
-    #[inline]
-    fn equivalent(&self, key: &Q) -> bool {
-        PartialEq::eq(self.borrow(), key)
-    }
-}
-
-/// Key ordering trait.
-///
-/// This trait allows ordered map lookup to be customized. It has one blanket
-/// implementation that uses the regular solution with `Borrow` and `Ord`, just
-/// like `BTreeMap` does, so that you can pass `&str` to lookup into a map with
-/// `String` keys and so on.
-pub trait Comparable<Q: ?Sized>: Equivalent<Q> {
-    /// Compare self to `key` and return their ordering.
-    fn compare(&self, key: &Q) -> Ordering;
-}
-
-impl<K: ?Sized, Q: ?Sized> Comparable<Q> for K
-where
-    K: Borrow<Q>,
-    Q: Ord,
-{
-    #[inline]
-    fn compare(&self, key: &Q) -> Ordering {
-        Ord::cmp(self.borrow(), key)
-    }
-}
+pub use equivalent_flipped::*;