Add naive king move generation

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod board;
+pub mod movegen;
 pub mod utils;

src/movegen/king.rs

@@ -0,0 +1,225 @@
+use crate::board::{Bitboard, CastleRights, Color, Direction, File, Square};
+
+/// Compute a king's movement. No castling moves included
+#[allow(unused)]
+pub fn king_moves(square: Square) -> Bitboard {
+    let board = square.into_bitboard();
+
+    Direction::iter_royalty()
+        .map(|dir| dir.move_board(board))
+        .fold(Bitboard::EMPTY, |lhs, rhs| lhs | rhs)
+}
+
+/// Compute a king's castling moves, given its [Color] and [CastleRights].
+#[allow(unused)]
+pub fn king_castling_moves(color: Color, castle_rights: CastleRights) -> Bitboard {
+    let rank = color.first_rank();
+
+    let king_side_square = Square::new(File::G, rank);
+    let queen_side_square = Square::new(File::C, rank);
+
+    match castle_rights {
+        CastleRights::NoSide => Bitboard::EMPTY,
+        CastleRights::KingSide => king_side_square.into_bitboard(),
+        CastleRights::QueenSide => queen_side_square.into_bitboard(),
+        CastleRights::BothSides => king_side_square | queen_side_square,
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn moves_first_rank() {
+        assert_eq!(king_moves(Square::A1), Square::A2 | Square::B1 | Square::B2);
+        assert_eq!(
+            king_moves(Square::B1),
+            Square::A1 | Square::A2 | Square::B2 | Square::C1 | Square::C2
+        );
+        assert_eq!(
+            king_moves(Square::C1),
+            Square::B1 | Square::B2 | Square::C2 | Square::D1 | Square::D2
+        );
+        assert_eq!(
+            king_moves(Square::D1),
+            Square::C1 | Square::C2 | Square::D2 | Square::E1 | Square::E2
+        );
+        assert_eq!(
+            king_moves(Square::E1),
+            Square::D1 | Square::D2 | Square::E2 | Square::F1 | Square::F2
+        );
+        assert_eq!(
+            king_moves(Square::F1),
+            Square::E1 | Square::E2 | Square::F2 | Square::G1 | Square::G2
+        );
+        assert_eq!(
+            king_moves(Square::G1),
+            Square::F1 | Square::F2 | Square::G2 | Square::H1 | Square::H2
+        );
+        assert_eq!(king_moves(Square::H1), Square::G1 | Square::G2 | Square::H2);
+    }
+
+    #[test]
+    fn moves_last_rank() {
+        assert_eq!(king_moves(Square::A8), Square::A7 | Square::B8 | Square::B7);
+        assert_eq!(
+            king_moves(Square::B8),
+            Square::A8 | Square::A7 | Square::B7 | Square::C8 | Square::C7
+        );
+        assert_eq!(
+            king_moves(Square::C8),
+            Square::B8 | Square::B7 | Square::C7 | Square::D8 | Square::D7
+        );
+        assert_eq!(
+            king_moves(Square::D8),
+            Square::C8 | Square::C7 | Square::D7 | Square::E8 | Square::E7
+        );
+        assert_eq!(
+            king_moves(Square::E8),
+            Square::D8 | Square::D7 | Square::E7 | Square::F8 | Square::F7
+        );
+        assert_eq!(
+            king_moves(Square::F8),
+            Square::E8 | Square::E7 | Square::F7 | Square::G8 | Square::G7
+        );
+        assert_eq!(
+            king_moves(Square::G8),
+            Square::F8 | Square::F7 | Square::G7 | Square::H8 | Square::H7
+        );
+        assert_eq!(king_moves(Square::H8), Square::G8 | Square::G7 | Square::H7);
+    }
+
+    #[test]
+    fn moves_first_file() {
+        assert_eq!(king_moves(Square::A1), Square::A2 | Square::B1 | Square::B2);
+        assert_eq!(
+            king_moves(Square::A2),
+            Square::A1 | Square::A3 | Square::B1 | Square::B2 | Square::B3
+        );
+        assert_eq!(
+            king_moves(Square::A3),
+            Square::A2 | Square::A4 | Square::B2 | Square::B3 | Square::B4
+        );
+        assert_eq!(
+            king_moves(Square::A4),
+            Square::A3 | Square::A5 | Square::B3 | Square::B4 | Square::B5
+        );
+        assert_eq!(
+            king_moves(Square::A5),
+            Square::A4 | Square::A6 | Square::B4 | Square::B5 | Square::B6
+        );
+        assert_eq!(
+            king_moves(Square::A6),
+            Square::A5 | Square::A7 | Square::B5 | Square::B6 | Square::B7
+        );
+        assert_eq!(
+            king_moves(Square::A7),
+            Square::A6 | Square::A8 | Square::B6 | Square::B7 | Square::B8
+        );
+        assert_eq!(king_moves(Square::A8), Square::A7 | Square::B7 | Square::B8);
+    }
+
+    #[test]
+    fn moves_last_file() {
+        assert_eq!(king_moves(Square::H1), Square::H2 | Square::G1 | Square::G2);
+        assert_eq!(
+            king_moves(Square::H2),
+            Square::H1 | Square::H3 | Square::G1 | Square::G2 | Square::G3
+        );
+        assert_eq!(
+            king_moves(Square::H3),
+            Square::H2 | Square::H4 | Square::G2 | Square::G3 | Square::G4
+        );
+        assert_eq!(
+            king_moves(Square::H4),
+            Square::H3 | Square::H5 | Square::G3 | Square::G4 | Square::G5
+        );
+        assert_eq!(
+            king_moves(Square::H5),
+            Square::H4 | Square::H6 | Square::G4 | Square::G5 | Square::G6
+        );
+        assert_eq!(
+            king_moves(Square::H6),
+            Square::H5 | Square::H7 | Square::G5 | Square::G6 | Square::G7
+        );
+        assert_eq!(
+            king_moves(Square::H7),
+            Square::H6 | Square::H8 | Square::G6 | Square::G7 | Square::G8
+        );
+        assert_eq!(king_moves(Square::H8), Square::H7 | Square::G7 | Square::G8);
+    }
+
+    #[test]
+    fn moves_middle() {
+        assert_eq!(
+            king_moves(Square::D4),
+            Square::C3
+                | Square::C4
+                | Square::C5
+                | Square::D3
+                | Square::D5
+                | Square::E3
+                | Square::E4
+                | Square::E5
+        );
+        assert_eq!(
+            king_moves(Square::D5),
+            Square::C4
+                | Square::C5
+                | Square::C6
+                | Square::D4
+                | Square::D6
+                | Square::E4
+                | Square::E5
+                | Square::E6
+        );
+        assert_eq!(
+            king_moves(Square::E5),
+            Square::D4
+                | Square::D5
+                | Square::D6
+                | Square::E4
+                | Square::E6
+                | Square::F4
+                | Square::F5
+                | Square::F6
+        );
+    }
+
+    #[test]
+    fn castling_moves() {
+        assert_eq!(
+            king_castling_moves(Color::White, CastleRights::NoSide),
+            Bitboard::EMPTY
+        );
+        assert_eq!(
+            king_castling_moves(Color::Black, CastleRights::NoSide),
+            Bitboard::EMPTY
+        );
+        assert_eq!(
+            king_castling_moves(Color::White, CastleRights::KingSide),
+            Square::G1.into_bitboard()
+        );
+        assert_eq!(
+            king_castling_moves(Color::Black, CastleRights::KingSide),
+            Square::G8.into_bitboard()
+        );
+        assert_eq!(
+            king_castling_moves(Color::White, CastleRights::QueenSide),
+            Square::C1.into_bitboard()
+        );
+        assert_eq!(
+            king_castling_moves(Color::Black, CastleRights::QueenSide),
+            Square::C8.into_bitboard()
+        );
+        assert_eq!(
+            king_castling_moves(Color::White, CastleRights::BothSides),
+            Square::C1 | Square::G1
+        );
+        assert_eq!(
+            king_castling_moves(Color::Black, CastleRights::BothSides),
+            Square::C8 | Square::G8
+        );
+    }
+}

src/movegen/mod.rs

@@ -0,0 +1,2 @@
+// Move generation implementation details
+mod king;