From 620701057d461fee657407e849d563cbe5d838a3 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sun, 21 Jan 2024 09:14:02 -0800
Subject: [PATCH] [board] Rehash BitBoard's std::ops implementations

Implement bitwise AND and OR for all permutations of BitBoard and &BitBoard.
Refer to the std::ops traits by fully-qualified path rather than requiring the
module to import those traits to implement them.

Implement bitwise AND and OR assignment (&= and |=) for BitBoard and &BitBoard.

Implement XOR and XOR assignment for BitBoards.
---
 board/src/bitboard/bitboard.rs | 71 ++++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 16 deletions(-)

diff --git a/board/src/bitboard/bitboard.rs b/board/src/bitboard/bitboard.rs
index 070f43f..6480e99 100644
--- a/board/src/bitboard/bitboard.rs
+++ b/board/src/bitboard/bitboard.rs
@@ -4,7 +4,7 @@ use super::library::{library, FILES, RANKS};
 use super::LeadingBitScanner;
 use crate::{square::Direction, Square};
 use std::fmt;
-use std::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, Not};
+use std::ops::Not;
 
 #[derive(Clone, Copy, Eq, Hash, PartialEq)]
 pub(crate) struct BitBoard(pub(super) u64);
@@ -156,39 +156,49 @@ impl fmt::Debug for BitBoard {
 }
 
 macro_rules! infix_op {
+    ($trait_type:ident, $func_name:ident, $type:ty) => {
+        infix_op!($trait_type, $func_name, $type, $type);
+        infix_op!($trait_type, $func_name, $type, &$type);
+        infix_op!($trait_type, $func_name, &$type, $type);
+        infix_op!($trait_type, $func_name, &$type, &$type);
+    };
     ($trait_type:ident, $func_name:ident, $left_type:ty, $right_type:ty) => {
-        impl $trait_type<$right_type> for $left_type {
+        impl std::ops::$trait_type<$right_type> for $left_type {
             type Output = BitBoard;
 
             #[inline]
             fn $func_name(self, rhs: $right_type) -> Self::Output {
-                BitBoard($trait_type::$func_name(self.0, rhs.0))
+                BitBoard(std::ops::$trait_type::$func_name(self.0, rhs.0))
             }
         }
     };
 }
 
 macro_rules! assign_op {
-    ($trait_type:ident, $func_name:ident, $left_type:ty) => {
-        impl $trait_type for $left_type {
+    ($trait_type:ident, $func_name:ident, $type:ty) => {
+        impl std::ops::$trait_type for $type {
             #[inline]
-            fn $func_name(&mut self, rhs: Self) {
-                $trait_type::$func_name(&mut self.0, rhs.0)
+            fn $func_name(&mut self, rhs: $type) {
+                std::ops::$trait_type::$func_name(&mut self.0, rhs.0)
+            }
+        }
+
+        impl std::ops::$trait_type<&$type> for $type {
+            #[inline]
+            fn $func_name(&mut self, rhs: &$type) {
+                std::ops::$trait_type::$func_name(&mut self.0, rhs.0)
             }
         }
     };
 }
 
-infix_op!(BitAnd, bitand, BitBoard, BitBoard);
-infix_op!(BitAnd, bitand, BitBoard, &BitBoard);
-infix_op!(BitAnd, bitand, &BitBoard, &BitBoard);
+infix_op!(BitAnd, bitand, BitBoard);
+infix_op!(BitOr, bitor, BitBoard);
+infix_op!(BitXor, bitxor, BitBoard);
 
 assign_op!(BitAndAssign, bitand_assign, BitBoard);
 assign_op!(BitOrAssign, bitor_assign, BitBoard);
-
-infix_op!(BitOr, bitor, BitBoard, BitBoard);
-infix_op!(BitOr, bitor, BitBoard, &BitBoard);
-infix_op!(BitOr, bitor, &BitBoard, &BitBoard);
+assign_op!(BitXorAssign, bitxor_assign, BitBoard);
 
 impl Not for BitBoard {
     type Output = BitBoard;
@@ -232,13 +242,12 @@ impl BitBoardBuilder {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Square;
+    use crate::{bitboard, Square};
 
     #[test]
     fn display_and_debug() {
         let bb = BitBoard::file(0) | BitBoard::file(3) | BitBoard::rank(7) | BitBoard::rank(4);
         println!("{}", &bb);
-        println!("{:?}", &bb);
     }
 
     #[test]
@@ -302,4 +311,34 @@ mod tests {
             assert_eq!(a, b);
         }
     }
+
+    #[test]
+    fn xor() {
+        let a = bitboard![C5, G7];
+        let b = bitboard![B5, G7, H3];
+
+        assert_eq!(a ^ b, bitboard![B5, C5, H3]);
+        assert_eq!(a ^ BitBoard::empty(), a);
+        assert_eq!(BitBoard::empty() ^ BitBoard::empty(), BitBoard::empty());
+    }
+
+    #[test]
+    fn bitand_assign() {
+        let mut a = bitboard![C5, G7];
+        let b = bitboard![B5, G7, H3];
+
+        a &= b;
+
+        assert_eq!(a, bitboard![G7]);
+    }
+
+    #[test]
+    fn bitor_assign() {
+        let mut a = bitboard![C5, G7];
+        let b = bitboard![B5, G7, H3];
+
+        a |= b;
+
+        assert_eq!(a, bitboard![B5, C5, G7, H3]);
+    }
 }