From c6e799f7224c25cada830da0f2734d15eb58a409 Mon Sep 17 00:00:00 2001 From: Eryn Wells Date: Sat, 6 Jan 2024 20:06:54 -0800 Subject: [PATCH] [board] Implement bishop::ClassicalMoveGenerator Implement a bishop move generator using the "classical" approach. This approach walks each ray to find blockers and then masks out friendly pieces. This is not efficient compared to other approaches, but it's much easier to implement. --- board/src/moves/bishop.rs | 167 ++++++++++++++++++++++++++++++ board/src/moves/mod.rs | 1 + board/src/moves/move_generator.rs | 6 +- 3 files changed, 173 insertions(+), 1 deletion(-) create mode 100644 board/src/moves/bishop.rs diff --git a/board/src/moves/bishop.rs b/board/src/moves/bishop.rs new file mode 100644 index 0000000..40c5bea --- /dev/null +++ b/board/src/moves/bishop.rs @@ -0,0 +1,167 @@ +// Eryn Wells + +use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet}; +use crate::{ + bitboard::BitBoard, + piece::{Color, Piece, PlacedPiece}, + square::Direction, + Move, Position, +}; + +move_generator_declaration!(ClassicalMoveGenerator); + +impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> { + fn piece(color: Color) -> Piece { + Piece::bishop(color) + } + + fn move_set_for_piece(position: &Position, placed_piece: PlacedPiece) -> MoveSet { + let piece = placed_piece.piece(); + let color = piece.color(); + let square = placed_piece.square(); + + let blockers = position.occupied_squares(); + let empty_squares = !blockers; + let friendly_pieces = position.bitboard_for_color(color); + let opposing_pieces = position.bitboard_for_color(color.other()); + + let mut all_moves = BitBoard::empty(); + + macro_rules! update_moves_with_ray { + ($direction:ident, $occupied_squares:tt) => { + let ray = BitBoard::ray(square, Direction::$direction); + if let Some(first_occupied_square) = + BitBoard::$occupied_squares(&(ray & blockers)).next() + { + let remainder = BitBoard::ray(first_occupied_square, Direction::$direction); + let attack_ray = ray & !remainder; + all_moves |= attack_ray; + } else { + all_moves |= ray; + } + }; + } + + update_moves_with_ray!(NorthEast, occupied_squares_trailing); + update_moves_with_ray!(NorthWest, occupied_squares_trailing); + update_moves_with_ray!(SouthEast, occupied_squares); + update_moves_with_ray!(SouthWest, occupied_squares); + + let quiet_moves_bb = all_moves & (empty_squares | !friendly_pieces); + let capture_moves_bb = all_moves & opposing_pieces; + + let map_to_move = |sq| Move::new(piece, square, sq); + let quiet_moves = quiet_moves_bb.occupied_squares().map(map_to_move); + let capture_moves = capture_moves_bb.occupied_squares().map(map_to_move); + + MoveSet::new(placed_piece) + .quiet_moves(quiet_moves_bb, quiet_moves) + .capture_moves(capture_moves_bb, capture_moves) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::{ + bitboard::BitBoard, + piece::{Color, Piece}, + position::DiagramFormatter, + Position, Square, + }; + + #[test] + fn classical_single_bishop_bitboard() { + let mut pos = Position::empty(); + [(Piece::bishop(Color::White), Square::A1)] + .into_iter() + .for_each(|(p, sq)| { + pos.place_piece(p, sq) + .expect(&format!("Unable to place {:?} on {}", &p, &sq)) + }); + + let generator = ClassicalMoveGenerator::new(&pos, Color::White); + + assert_eq!( + generator.bitboard(), + BitBoard::new( + 0b10000000_01000000_00100000_00010000_00001000_00000100_00000010_00000000 + ) + ); + } + + /// Test that a bishop can move up to, but not onto, a friendly piece. + #[test] + fn classical_single_bishop_with_same_color_blocker_bitboard() { + let mut pos = Position::empty(); + [ + (Piece::bishop(Color::White), Square::A1), + (Piece::knight(Color::White), Square::E5), + ] + .into_iter() + .for_each(|(p, sq)| { + pos.place_piece(p, sq) + .expect(&format!("Unable to place {} on {}", p, sq)) + }); + + println!("{}", DiagramFormatter::new(&pos)); + + let generator = ClassicalMoveGenerator::new(&pos, Color::White); + + assert_eq!( + generator.bitboard(), + BitBoard::new( + 0b00000000_00000000_00000000_00000000_00001000_00000100_00000010_00000000 + ) + ); + } + + /// Test that a rook can move up to, and then capture, an enemy piece. + #[test] + fn classical_single_bishop_with_opposing_color_blocker_bitboard() { + let mut pos = Position::empty(); + [ + (Piece::bishop(Color::White), Square::A1), + (Piece::knight(Color::Black), Square::C3), + ] + .into_iter() + .for_each(|(p, sq)| { + pos.place_piece(p, sq) + .expect(&format!("Unable to place {} on {}", p, sq)) + }); + + let generator = ClassicalMoveGenerator::new(&pos, Color::White); + + assert_eq!( + generator.bitboard(), + BitBoard::new( + 0b00000000_00000000_00000000_00000000_00000000_00000100_00000010_00000000 + ) + ); + } + + #[test] + fn classical_single_bishop_in_center() { + let mut pos = Position::empty(); + [(Piece::bishop(Color::White), Square::E4)] + .into_iter() + .for_each(|(p, sq)| { + pos.place_piece(p, sq) + .expect(&format!("Unable to place {} on {}", p, sq)) + }); + + println!("{}", DiagramFormatter::new(&pos)); + + let generator = ClassicalMoveGenerator::new(&pos, Color::White); + let bitboard = generator.bitboard(); + let expected = BitBoard::new( + 0b00000001_10000010_01000100_00101000_00000000_00101000_01000100_10000010, + ); + + assert_eq!( + bitboard, expected, + "actual:\n{}\nexpected:\n{}", + bitboard, expected + ); + } +} diff --git a/board/src/moves/mod.rs b/board/src/moves/mod.rs index 75db67c..b13ae12 100644 --- a/board/src/moves/mod.rs +++ b/board/src/moves/mod.rs @@ -1,5 +1,6 @@ // Eryn Wells +mod bishop; mod king; mod knight; mod r#move; diff --git a/board/src/moves/move_generator.rs b/board/src/moves/move_generator.rs index 6816b93..62cb5ea 100644 --- a/board/src/moves/move_generator.rs +++ b/board/src/moves/move_generator.rs @@ -1,7 +1,8 @@ // Eryn Wells use super::{ - king::KingMoveGenerator, knight::KnightMoveGenerator, pawn::PawnMoveGenerator, + bishop::ClassicalMoveGenerator as BishopMoveGenerator, king::KingMoveGenerator, + knight::KnightMoveGenerator, pawn::PawnMoveGenerator, rook::ClassicalMoveGenerator as RookMoveGenerator, Move, }; use crate::piece::Color; @@ -10,6 +11,7 @@ use crate::Position; pub struct Moves<'pos> { pawn_moves: PawnMoveGenerator<'pos>, knight_moves: KnightMoveGenerator<'pos>, + bishop_moves: BishopMoveGenerator<'pos>, rook_moves: RookMoveGenerator<'pos>, king_moves: KingMoveGenerator<'pos>, } @@ -19,6 +21,7 @@ impl<'a> Moves<'a> { Moves { pawn_moves: PawnMoveGenerator::new(position, color), knight_moves: KnightMoveGenerator::new(position, color), + bishop_moves: BishopMoveGenerator::new(position, color), rook_moves: RookMoveGenerator::new(position, color), king_moves: KingMoveGenerator::new(position, color), } @@ -28,6 +31,7 @@ impl<'a> Moves<'a> { self.pawn_moves .iter() .chain(self.knight_moves.iter()) + .chain(self.bishop_moves.iter()) .chain(self.rook_moves.iter()) .chain(self.king_moves.iter()) .cloned()