From 8261b0c06b854ca6ca8818e1281b915583d7e4e2 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sun, 17 Jul 2022 20:39:47 +0200
Subject: [PATCH] Add 'Bitboard::count'

---
 src/board/bitboard/mod.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/board/bitboard/mod.rs b/src/board/bitboard/mod.rs
index 524cf33..d2c8921 100644
--- a/src/board/bitboard/mod.rs
+++ b/src/board/bitboard/mod.rs
@@ -37,6 +37,12 @@ impl Bitboard {
         Bitboard(0b00000000_11111111_00000000_00000000_00000000_00000000_00000000_00000000),
         Bitboard(0b11111111_00000000_00000000_00000000_00000000_00000000_00000000_00000000),
     ];
+
+    /// Count the number of pieces in the [Bitboard].
+    #[inline(always)]
+    pub fn count(self) -> u32 {
+        self.0.count_ones()
+    }
 }
 
 impl Default for Bitboard {
@@ -170,6 +176,13 @@ mod test {
     use super::*;
     use crate::board::square::*;
 
+    #[test]
+    fn count() {
+        assert_eq!(Bitboard::EMPTY.count(), 0);
+        assert_eq!(Bitboard::FILES[0].count(), 8);
+        assert_eq!(Bitboard::ALL.count(), 64);
+    }
+
     #[test]
     fn iter() {
         assert_eq!(Bitboard::EMPTY.into_iter().collect::<Vec<_>>(), Vec::new());