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[board] Implement danger squares for the current player

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This concept comes from [1]. Danger squares are the squares a king cannot move to
because it would permit the opposing player to capture the king on their next
turn.

[1]: https://peterellisjones.com/posts/generating-legal-chess-moves-efficiently/
This commit is contained in:
Eryn Wells 2024-01-28 00:25:53 -08:00
parent 654e4094d9
commit 164fe94bc0
6 changed files with 190 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

139
board/src/sight.rs
View file

@ -1,42 +1,56 @@
// Eryn Wells <eryn@erynwells.me>
use crate::position::piece_sets::PieceBitBoards;
use crate::Position;
use chessfriend_bitboard::BitBoard;
use chessfriend_core::{Color, Direction, PlacedPiece, Shape};
use chessfriend_core::{Color, Direction, Piece, PlacedPiece, Shape, Square};
pub(crate) trait SightExt {
fn sight_in_position(&self, position: &Position) -> BitBoard;
fn sight(&self, pieces: &PieceBitBoards, en_passant_square: Option<Square>) -> BitBoard;
fn white_pawn_sight_in_position(&self, position: &Position) -> BitBoard;
fn black_pawn_sight_in_position(&self, position: &Position) -> BitBoard;
fn knight_sight_in_position(&self, position: &Position) -> BitBoard;
fn bishop_sight_in_position(&self, position: &Position) -> BitBoard;
fn rook_sight_in_position(&self, position: &Position) -> BitBoard;
fn queen_sight_in_position(&self, position: &Position) -> BitBoard;
fn king_sight_in_position(&self, position: &Position) -> BitBoard;
fn white_pawn_sight(
&self,
pieces: &PieceBitBoards,
en_passant_square: Option<Square>,
) -> BitBoard;
fn black_pawn_sight(
&self,
pieces: &PieceBitBoards,
en_passant_square: Option<Square>,
) -> BitBoard;
fn knight_sight(&self, pieces: &PieceBitBoards) -> BitBoard;
fn bishop_sight(&self, pieces: &PieceBitBoards) -> BitBoard;
fn rook_sight(&self, pieces: &PieceBitBoards) -> BitBoard;
fn queen_sight(&self, pieces: &PieceBitBoards) -> BitBoard;
fn king_sight(&self, pieces: &PieceBitBoards) -> BitBoard;
}
impl SightExt for PlacedPiece {
fn sight_in_position(&self, position: &Position) -> BitBoard {
fn sight(&self, pieces: &PieceBitBoards, en_passant_square: Option<Square>) -> BitBoard {
match self.shape() {
Shape::Pawn => match self.color() {
Color::White => self.white_pawn_sight_in_position(position),
Color::Black => self.black_pawn_sight_in_position(position),
Color::White => self.white_pawn_sight(pieces, en_passant_square),
Color::Black => self.black_pawn_sight(pieces, en_passant_square),
},
Shape::Knight => self.knight_sight_in_position(position),
Shape::Bishop => self.bishop_sight_in_position(position),
Shape::Rook => self.rook_sight_in_position(position),
Shape::Queen => self.queen_sight_in_position(position),
Shape::King => self.king_sight_in_position(position),
Shape::Knight => self.knight_sight(pieces),
Shape::Bishop => self.bishop_sight(pieces),
Shape::Rook => self.rook_sight(pieces),
Shape::Queen => self.queen_sight(pieces),
Shape::King => self.king_sight(pieces),
}
}
fn white_pawn_sight_in_position(&self, position: &Position) -> BitBoard {
fn white_pawn_sight(
&self,
pieces: &PieceBitBoards,
en_passant_square: Option<Square>,
) -> BitBoard {
let opponent = self.color().other();
let pawn: BitBoard = self.square().into();
let pawn = pawn.shift_north_west_one() | pawn.shift_north_east_one();
let mut possible_squares = position.empty_squares() | position.opposing_pieces();
if let Some(en_passant) = position.en_passant_square() {
let mut possible_squares = pieces.empty_squares() | pieces.all_pieces_of_color(opponent);
if let Some(en_passant) = en_passant_square {
let en_passant_bitboard: BitBoard = en_passant.into();
possible_squares |= en_passant_bitboard;
}
@ -44,28 +58,34 @@ impl SightExt for PlacedPiece {
pawn & possible_squares
}
fn black_pawn_sight_in_position(&self, position: &Position) -> BitBoard {
fn black_pawn_sight(
&self,
pieces: &PieceBitBoards,
en_passant_square: Option<Square>,
) -> BitBoard {
let opponent = self.color().other();
let pawn: BitBoard = self.square().into();
let pawn = pawn.shift_south_west_one() | pawn.shift_south_east_one();
let mut possible_squares = position.empty_squares() | position.opposing_pieces();
if let Some(en_passant) = position.en_passant_square() {
let mut possible_squares = pieces.empty_squares() | pieces.all_pieces_of_color(opponent);
if let Some(en_passant) = en_passant_square {
possible_squares |= &en_passant.into();
}
pawn & possible_squares
}
fn knight_sight_in_position(&self, position: &Position) -> BitBoard {
BitBoard::knight_moves(self.square()) & !position.friendly_pieces()
fn knight_sight(&self, pieces: &PieceBitBoards) -> BitBoard {
BitBoard::knight_moves(self.square()) & !pieces.all_pieces_of_color(self.color())
}
fn bishop_sight_in_position(&self, position: &Position) -> BitBoard {
fn bishop_sight(&self, pieces: &PieceBitBoards) -> BitBoard {
let square = self.square();
let mut sight = BitBoard::empty();
let blockers = position.occupied_squares();
let blockers = pieces.all_pieces();
macro_rules! update_moves_with_ray {
($direction:ident, $occupied_squares:tt) => {
@ -87,15 +107,16 @@ impl SightExt for PlacedPiece {
update_moves_with_ray!(SouthEast, occupied_squares);
update_moves_with_ray!(SouthWest, occupied_squares);
sight
let friendly_pieces = pieces.all_pieces_of_color(self.color());
sight & !friendly_pieces
}
fn rook_sight_in_position(&self, position: &Position) -> BitBoard {
fn rook_sight(&self, pieces: &PieceBitBoards) -> BitBoard {
let square = self.square();
let mut sight = BitBoard::empty();
let blockers = position.occupied_squares();
let blockers = pieces.all_pieces();
macro_rules! update_moves_with_ray {
($direction:ident, $occupied_squares:tt) => {
@ -117,15 +138,16 @@ impl SightExt for PlacedPiece {
update_moves_with_ray!(South, occupied_squares);
update_moves_with_ray!(West, occupied_squares);
sight
let friendly_pieces = pieces.all_pieces_of_color(self.color());
sight & !friendly_pieces
}
fn queen_sight_in_position(&self, position: &Position) -> BitBoard {
fn queen_sight(&self, pieces: &PieceBitBoards) -> BitBoard {
let square = self.square();
let mut sight = BitBoard::empty();
let blockers = position.occupied_squares();
let blockers = pieces.all_pieces();
macro_rules! update_moves_with_ray {
($direction:ident, $occupied_squares:tt) => {
@ -151,11 +173,12 @@ impl SightExt for PlacedPiece {
update_moves_with_ray!(SouthWest, occupied_squares);
update_moves_with_ray!(West, occupied_squares);
sight
let friendly_pieces = pieces.all_pieces_of_color(self.color());
sight & !friendly_pieces
}
fn king_sight_in_position(&self, position: &Position) -> BitBoard {
BitBoard::king_moves(self.square()) & !position.friendly_pieces()
fn king_sight(&self, pieces: &PieceBitBoards) -> BitBoard {
BitBoard::king_moves(self.square()) & !pieces.all_pieces_of_color(self.color())
}
}
@ -166,8 +189,8 @@ mod tests {
#[test]
fn $test_name() {
let pos = $position;
let pp = $piece;
let sight = pp.sight_in_position(&pos);
let piece = $piece;
let sight = pos.sight_of_piece(&piece);
assert_eq!(sight, $bitboard);
}
@ -178,7 +201,7 @@ mod tests {
}
mod pawn {
use crate::{sight::SightExt, test_position};
use crate::test_position;
use chessfriend_bitboard::{bitboard, BitBoard};
use chessfriend_core::{piece, Square};
@ -202,8 +225,8 @@ mod tests {
White Pawn on E4,
);
let pp = piece!(White Pawn on E4);
let sight = pp.sight_in_position(&pos);
let piece = piece!(White Pawn on E4);
let sight = pos.sight_of_piece(&piece);
assert_eq!(sight, BitBoard::empty());
}
@ -216,8 +239,8 @@ mod tests {
White Pawn on E4,
);
let pp = piece!(White Pawn on E4);
let sight = pp.sight_in_position(&pos);
let piece = piece!(White Pawn on E4);
let sight = pos.sight_of_piece(&piece);
assert_eq!(sight, bitboard!(D5));
}
@ -229,8 +252,8 @@ mod tests {
Black Pawn on D5,
);
pos.test_set_en_passant_square(Square::D6);
let pp = piece!(White Pawn on E5);
let sight = pp.sight_in_position(&pos);
let piece = piece!(White Pawn on E5);
let sight = pos.sight_of_piece(&piece);
assert_eq!(sight, bitboard!(D6, F6));
}
@ -238,7 +261,6 @@ mod tests {
#[macro_use]
mod knight {
use crate::sight::SightExt;
use chessfriend_bitboard::bitboard;
use chessfriend_core::piece;
@ -250,7 +272,6 @@ mod tests {
}
mod bishop {
use crate::sight::SightExt;
use chessfriend_bitboard::bitboard;
use chessfriend_core::piece;
@ -262,7 +283,7 @@ mod tests {
}
mod rook {
use crate::sight::SightExt;
use crate::test_position;
use chessfriend_bitboard::bitboard;
use chessfriend_core::piece;
@ -271,5 +292,27 @@ mod tests {
piece!(White Rook on G3),
bitboard!(G1, G2, G4, G5, G6, G7, G8, A3, B3, C3, D3, E3, F3, H3)
);
sight_test!(
e4_rook_with_e1_white_king_e7_black_king,
test_position![
White Rook on E4,
White King on E1,
Black King on E7,
],
piece!(White Rook on E4),
bitboard!(A4, B4, C4, D4, F4, G4, H4, E2, E3, E5, E6, E7)
);
}
mod king {
use chessfriend_bitboard::bitboard;
use chessfriend_core::piece;
sight_test!(
e1_king,
piece!(White King on E1),
bitboard![D1, D2, E2, F2, F1]
);
}
}