From a6b98abb95e36a52d75f51ba93c568d2b0533302 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Mon, 15 Jan 2024 17:17:34 -0800
Subject: [PATCH] [board] Create a bitboard! macro and BitBoardBuilder
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The Builder enables cleanly building a BitBoard out of squares.
The macro lets you create a BitBoard from a simple list of coordinates:

bitboard!(A1, B2, C3, D4, …)
---
 board/src/bitboard/bitboard.rs | 21 +++++++++++++++++++++
 board/src/bitboard/mod.rs      | 11 ++++++++++-
 board/src/lib.rs               |  1 +
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/board/src/bitboard/bitboard.rs b/board/src/bitboard/bitboard.rs
index 0ccc713..60d4f22 100644
--- a/board/src/bitboard/bitboard.rs
+++ b/board/src/bitboard/bitboard.rs
@@ -188,6 +188,27 @@ impl Not for &BitBoard {
     }
 }
 
+pub struct BitBoardBuilder(BitBoard);
+
+impl BitBoardBuilder {
+    pub const fn empty() -> BitBoardBuilder {
+        BitBoardBuilder(BitBoard::empty())
+    }
+
+    pub fn new(bits: u64) -> BitBoardBuilder {
+        BitBoardBuilder(BitBoard::new(bits))
+    }
+
+    pub fn square(mut self, square: Square) -> BitBoardBuilder {
+        self.0.set_square(square);
+        self
+    }
+
+    pub fn build(&self) -> BitBoard {
+        self.0
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/board/src/bitboard/mod.rs b/board/src/bitboard/mod.rs
index 6093fa8..238f6ac 100644
--- a/board/src/bitboard/mod.rs
+++ b/board/src/bitboard/mod.rs
@@ -4,4 +4,13 @@ mod library;
 mod shifts;
 
 pub(crate) use bit_scanner::{LeadingBitScanner, TrailingBitScanner};
-pub(crate) use bitboard::BitBoard;
+pub(crate) use bitboard::{BitBoard, BitBoardBuilder};
+
+#[macro_export]
+macro_rules! bitboard {
+    ($($sq:ident),*) => {
+        $crate::bitboard::BitBoardBuilder::empty()
+            $(.square($crate::Square::$sq))*
+            .build()
+    };
+}
diff --git a/board/src/lib.rs b/board/src/lib.rs
index 03b5c96..cea348e 100644
--- a/board/src/lib.rs
+++ b/board/src/lib.rs
@@ -1,5 +1,6 @@
 // Eryn Wells <eryn@erynwells.me>
 
+#[macro_use]
 mod bitboard;
 mod display;
 mod moves;