[bitboard] Move everything in board::bitboard to the bitboard crate

bitboard/src/bitboard.rs

@@ -0,0 +1,352 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use crate::library::{library, FILES, RANKS};
+use crate::LeadingBitScanner;
+use chess_core::{Direction, Square};
+use std::fmt;
+use std::ops::Not;
+
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+pub(crate) struct BitBoard(pub(super) u64);
+
+macro_rules! moves_getter {
+    ($getter_name:ident) => {
+        pub fn $getter_name(sq: Square) -> BitBoard {
+            library().$getter_name(sq)
+        }
+    };
+}
+
+impl BitBoard {
+    pub const fn empty() -> BitBoard {
+        BitBoard(0)
+    }
+
+    pub fn new(bits: u64) -> BitBoard {
+        BitBoard(bits)
+    }
+
+    pub fn rank(rank: usize) -> BitBoard {
+        assert!(rank < 8);
+        RANKS[rank]
+    }
+
+    pub fn file(file: usize) -> BitBoard {
+        assert!(file < 8);
+        FILES[file]
+    }
+
+    pub fn ray(sq: Square, dir: Direction) -> BitBoard {
+        library().ray(sq, dir)
+    }
+
+    moves_getter!(knight_moves);
+    moves_getter!(bishop_moves);
+    moves_getter!(rook_moves);
+    moves_getter!(queen_moves);
+    moves_getter!(king_moves);
+}
+
+impl BitBoard {
+    pub fn is_empty(&self) -> bool {
+        self.0 == 0
+    }
+
+    pub fn is_set(self, sq: Square) -> bool {
+        let square_bitboard: BitBoard = sq.into();
+        !(self & square_bitboard).is_empty()
+    }
+
+    pub fn set_square(&mut self, sq: Square) {
+        let sq_bb: BitBoard = sq.into();
+        *self |= sq_bb
+    }
+
+    pub fn clear_square(&mut self, sq: Square) {
+        let sq_bb: BitBoard = sq.into();
+        *self &= !sq_bb
+    }
+}
+
+impl BitBoard {
+    /// Return an Iterator over the occupied squares, starting from the leading
+    /// (most-significant bit) end of the field.
+    pub(crate) fn occupied_squares(&self) -> impl Iterator<Item = Square> {
+        LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
+    }
+
+    /// Return an Iterator over the occupied squares, starting from the trailing
+    /// (least-significant bit) end of the field.
+    pub(crate) fn occupied_squares_trailing(&self) -> impl Iterator<Item = Square> {
+        LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
+    }
+}
+
+impl Default for BitBoard {
+    fn default() -> Self {
+        BitBoard::empty()
+    }
+}
+
+impl From<Square> for BitBoard {
+    fn from(value: Square) -> Self {
+        BitBoard(1 << value as u64)
+    }
+}
+
+impl FromIterator<Square> for BitBoard {
+    fn from_iter<T: IntoIterator<Item = Square>>(iter: T) -> Self {
+        let mut builder = BitBoardBuilder::empty();
+
+        for sq in iter {
+            builder = builder.square(sq)
+        }
+
+        builder.build()
+    }
+}
+
+impl fmt::Binary for BitBoard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Delegate to u64's implementation of Binary.
+        fmt::Binary::fmt(&self.0, f)
+    }
+}
+
+impl fmt::LowerHex for BitBoard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Delegate to u64's implementation of LowerHex.
+        fmt::LowerHex::fmt(&self.0, f)
+    }
+}
+
+impl fmt::UpperHex for BitBoard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Delegate to u64's implementation of UpperHex.
+        fmt::UpperHex::fmt(&self.0, f)
+    }
+}
+
+impl fmt::Display for BitBoard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let binary_ranks = format!("{:064b}", self.0)
+            .chars()
+            .rev()
+            .map(|c| String::from(c))
+            .collect::<Vec<String>>();
+
+        let mut ranks_written = 0;
+        for rank in binary_ranks.chunks(8).rev() {
+            let joined_rank = rank.join(" ");
+            write!(f, "{}", joined_rank)?;
+
+            ranks_written += 1;
+            if ranks_written < 8 {
+                write!(f, "\n")?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl fmt::Debug for BitBoard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        write!(f, "BitBoard({:064b})", self.0)
+    }
+}
+
+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, $right_type:ty) => {
+        impl std::ops::$trait_type<$right_type> for $left_type {
+            type Output = BitBoard;
+
+            #[inline]
+            fn $func_name(self, rhs: $right_type) -> Self::Output {
+                BitBoard(std::ops::$trait_type::$func_name(self.0, rhs.0))
+            }
+        }
+    };
+}
+
+macro_rules! assign_op {
+    ($trait_type:ident, $func_name:ident, $type:ty) => {
+        impl std::ops::$trait_type for $type {
+            #[inline]
+            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);
+infix_op!(BitOr, bitor, BitBoard);
+infix_op!(BitXor, bitxor, BitBoard);
+
+assign_op!(BitAndAssign, bitand_assign, BitBoard);
+assign_op!(BitOrAssign, bitor_assign, BitBoard);
+assign_op!(BitXorAssign, bitxor_assign, BitBoard);
+
+impl Not for BitBoard {
+    type Output = BitBoard;
+
+    #[inline]
+    fn not(self) -> Self::Output {
+        BitBoard(!self.0)
+    }
+}
+
+impl Not for &BitBoard {
+    type Output = BitBoard;
+
+    #[inline]
+    fn not(self) -> Self::Output {
+        BitBoard(!self.0)
+    }
+}
+
+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::*;
+    use crate::bitboard;
+    use chess_core::Square;
+
+    #[test]
+    fn display_and_debug() {
+        let bb = BitBoard::file(0) | BitBoard::file(3) | BitBoard::rank(7) | BitBoard::rank(4);
+        println!("{}", &bb);
+    }
+
+    #[test]
+    fn rank() {
+        assert_eq!(BitBoard::rank(0).0, 0xFF, "Rank 1");
+        assert_eq!(BitBoard::rank(1).0, 0xFF00, "Rank 2");
+        assert_eq!(BitBoard::rank(2).0, 0xFF0000, "Rank 3");
+        assert_eq!(BitBoard::rank(3).0, 0xFF000000, "Rank 4");
+        assert_eq!(BitBoard::rank(4).0, 0xFF00000000, "Rank 5");
+        assert_eq!(BitBoard::rank(5).0, 0xFF0000000000, "Rank 6");
+        assert_eq!(BitBoard::rank(6).0, 0xFF000000000000, "Rank 7");
+        assert_eq!(BitBoard::rank(7).0, 0xFF00000000000000, "Rank 8");
+    }
+
+    #[test]
+    fn is_empty() {
+        assert!(BitBoard(0).is_empty());
+        assert!(!BitBoard(0xFF).is_empty());
+    }
+
+    #[test]
+    fn has_piece_at() {
+        let bb = BitBoard(0b1001100);
+        assert!(bb.is_set(Square::C1));
+        assert!(!bb.is_set(Square::B1));
+    }
+
+    #[test]
+    fn set_square() {
+        let sq = Square::E4;
+        let mut bb = BitBoard(0b1001100);
+        bb.set_square(sq);
+        assert!(bb.is_set(sq));
+    }
+
+    #[test]
+    fn clear_square() {
+        let sq = Square::A3;
+        let mut bb = BitBoard(0b1001100);
+        bb.clear_square(sq);
+        assert!(!bb.is_set(sq));
+    }
+
+    #[test]
+    fn single_rank_occupancy() {
+        let bb = BitBoard(0b01010100);
+        let expected_squares = [Square::G1, Square::E1, Square::C1];
+        for (a, b) in bb.occupied_squares().zip(expected_squares.iter().cloned()) {
+            assert_eq!(a, b);
+        }
+    }
+
+    #[test]
+    fn occupancy_spot_check() {
+        let bb =
+            BitBoard(0b10000000_00000000_00100000_00000100_00000000_00000000_00010000_00001000);
+
+        let expected_squares = [Square::H8, Square::F6, Square::C5, Square::E2, Square::D1];
+
+        for (a, b) in bb.occupied_squares().zip(expected_squares.iter().cloned()) {
+            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]);
+    }
+
+    #[test]
+    fn from_square() {
+        assert_eq!(BitBoard::from(Square::A1), BitBoard(0b1));
+        assert_eq!(BitBoard::from(Square::H8), BitBoard(1 << 63));
+    }
+}