simplify Bounds

src/flow/binary/bounds.rs

@@ -28,6 +28,30 @@ impl<A: Clone> Bounds<A> {
         }
     }
 
+    fn orderedl(
+        l: &Option<A>,
+        r: &A,
+        comparator: &impl Comparator<A>,
+    ) -> Result<(), BoundsError<A>> {
+        if let Some(l) = &l {
+            Self::ordered(l, r, comparator)
+        } else {
+            Err(BoundsError::OverflowL(r.clone()))
+        }
+    }
+
+    fn orderedr(
+        l: &A,
+        r: &Option<A>,
+        comparator: &impl Comparator<A>,
+    ) -> Result<(), BoundsError<A>> {
+        if let Some(r) = &r {
+            Self::ordered(l, r, comparator)
+        } else {
+            Err(BoundsError::OverflowR(l.clone()))
+        }
+    }
+
     fn new(
         l: Option<A>,
         r: Option<A>,
@@ -56,23 +80,15 @@ impl<A: Clone> Bounds<A> {
         key: &A,
         comparator: &impl Comparator<A>,
     ) -> Result<Self, BoundsError<A>> {
-        if let Some(lr) = &l.r {
+        Self::orderedl(&l.r, key, comparator)?;
-            Self::ordered(lr, key, comparator)?
+        Self::orderedr(key, &r.l, comparator)?;
-        } else {
-            Err(BoundsError::OverflowL(key.clone()))?
-        }
-        if let Some(rl) = &r.l {
-            Self::ordered(key, rl, comparator)?
-        } else {
-            Err(BoundsError::OverflowR(key.clone()))?
-        }
         Self::new(l.l, r.r, comparator)
     }
 
     fn equal_bound(l: &Option<A>, r: &Option<A>, comparator: &impl Comparator<A>) -> bool {
         match (l, r) {
             (None, None) => true,
-            (Some(kl), Some(kr)) => matches!(comparator.compare(kl, kr), Comparison::E),
+            (Some(kl), Some(kr)) => comparator.equal(kl, kr),
             _ => false,
         }
     }

src/flow/comparator.rs

@@ -17,6 +17,10 @@ pub enum Comparison {
 /// ```
 pub trait Comparator<A> {
     fn compare(&self, kl: &A, kr: &A) -> Comparison;
+
+    fn equal(&self, kl: &A, kr: &A) -> bool {
+        matches!(self.compare(kl, kr), Comparison::E)
+    }
 }
 
 /// Implementation of a [Comparator] relying on [`Ord`].