From 30188d478e6ee08cd2635bda61f88cec3f832051 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sat, 13 Jul 2024 12:03:19 -0700
Subject: [PATCH] [board] Convert &BitBoard to BitBoard for several Board
 methods

I don't think passing by reference buys much for BitBoard. So simplify the
logic and borrowing semantics to make these easier to work with.
---
 board/src/board.rs | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/board/src/board.rs b/board/src/board.rs
index 15ae1e1..b1df95c 100644
--- a/board/src/board.rs
+++ b/board/src/board.rs
@@ -111,23 +111,26 @@ impl Board {
     /// A [`BitBoard`] representing the set of squares containing a piece. This
     /// set is the inverse of [`Board::empty_squares`].
     #[must_use]
-    pub fn occupied_squares(&self) -> &BitBoard {
+    pub fn occupied_squares(&self) -> BitBoard {
         self.pieces.all_pieces()
     }
 
     #[must_use]
-    pub fn friendly_pieces(&self) -> &BitBoard {
+    pub fn friendly_pieces_bitboard(&self) -> BitBoard {
         self.pieces.all_pieces_of_color(self.player_to_move)
     }
 
     #[must_use]
-    pub fn opposing_pieces(&self) -> &BitBoard {
+    pub fn opposing_pieces_bitboard(&self) -> BitBoard {
         self.pieces.all_pieces_of_color(self.player_to_move.other())
     }
 
     #[must_use]
-    pub fn all_pieces(&self) -> (&BitBoard, &BitBoard) {
-        (self.friendly_pieces(), self.opposing_pieces())
+    pub fn all_pieces(&self) -> (BitBoard, BitBoard) {
+        (
+            self.friendly_pieces_bitboard(),
+            self.opposing_pieces_bitboard(),
+        )
     }
 
     /// A [BitBoard] representing the set of squares containing a piece. This
@@ -166,8 +169,8 @@ impl Board {
         self.en_passant
     }
 
-    fn king_bitboard(&self, player: Color) -> &BitBoard {
-        self.pieces.bitboard_for_piece(&Piece::king(player))
+    fn king_bitboard(&self, player: Color) -> BitBoard {
+        self.pieces.bitboard_for_piece(Piece::king(player))
     }
 
     pub(crate) fn king_square(&self, player: Color) -> Square {
@@ -183,13 +186,13 @@ impl Board {
     }
 
     #[must_use]
-    pub fn bitboard_for_color(&self, color: Color) -> &BitBoard {
+    pub fn bitboard_for_color(&self, color: Color) -> BitBoard {
         self.pieces.bitboard_for_color(color)
     }
 
     #[must_use]
-    pub fn bitboard_for_piece(&self, piece: Piece) -> &BitBoard {
-        self.pieces.bitboard_for_piece(&piece)
+    pub fn bitboard_for_piece(&self, piece: Piece) -> BitBoard {
+        self.pieces.bitboard_for_piece(piece)
     }
 }