From 88cdc71db6fa0839ea12b135b4acbb0d0d70067e Mon Sep 17 00:00:00 2001
From: GrayJack <gr41.j4ck@gmail.com>
Date: Mon, 25 Nov 2024 19:47:05 -0300
Subject: [PATCH] feat: Specialize `ExactSizeIterator::len` when possible

---
 Cargo.toml |  1 +
 src/lib.rs | 16 ++++++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index d56223b..6e13a17 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ license = "MIT"
 keywords = ["no_std", "bitset", "set"]
 categories = ["data-structures", "no-std"]
 edition = "2021"
+exclude = ["/.fleet", "/.github", "/.idea", "/.vscode"]
 
 [package.metadata.docs.rs]
 all-features = true
diff --git a/src/lib.rs b/src/lib.rs
index a3a4ec9..41205f4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1069,7 +1069,7 @@ impl<T: PrimInt, const N: usize> Iterator for Drain<'_, T, N> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let len = self.inner.count_ones() as usize;
+        let len = self.inner.len();
         (len, Some(len))
     }
 }
@@ -1131,7 +1131,7 @@ impl<T: PrimInt, const N: usize> Iterator for IntoIter<T, N> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let len = self.0.count_ones() as usize;
+        let len = self.0.len();
         (len, Some(len))
     }
 }
@@ -1155,7 +1155,11 @@ impl<T: PrimInt, const N: usize> DoubleEndedIterator for IntoIter<T, N> {
 }
 
 impl<T: PrimInt, const N: usize> FusedIterator for IntoIter<T, N> {}
-impl<T: PrimInt, const N: usize> ExactSizeIterator for IntoIter<T, N> {}
+impl<T: PrimInt, const N: usize> ExactSizeIterator for IntoIter<T, N> {
+    fn len(&self) -> usize {
+        self.0.len()
+    }
+}
 
 /// An iterator over the items of a `BitSet`.
 ///
@@ -1236,7 +1240,11 @@ impl<T: PrimInt, const N: usize> DoubleEndedIterator for Iter<'_, T, N> {
 }
 
 impl<T: PrimInt, const N: usize> FusedIterator for Iter<'_, T, N> {}
-impl<T: PrimInt, const N: usize> ExactSizeIterator for Iter<'_, T, N> {}
+impl<T: PrimInt, const N: usize> ExactSizeIterator for Iter<'_, T, N> {
+    fn len(&self) -> usize {
+        self.borrow.len() - self.passed_count
+    }
+}
 
 /// A lazy iterator producing elements in the difference of `BitSet`s.
 ///