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use crate::bitboard::{BitBoard, EMPTY}; use crate::castle_rights::CastleRights; use crate::chess_move::ChessMove; use crate::color::{Color, ALL_COLORS, NUM_COLORS}; use crate::file::File; use crate::magic::{ between, get_adjacent_files, get_bishop_rays, get_castle_moves, get_file, get_king_moves, get_knight_moves, get_pawn_attacks, get_pawn_dest_double_moves, get_pawn_source_double_moves, get_rank, get_rook_rays, }; use crate::movegen::*; use crate::piece::{Piece, ALL_PIECES, NUM_PIECES}; use crate::rank::Rank; use crate::square::Square; use crate::zobrist::Zobrist; use std::mem; /// A representation of a chess board. That's why you're here, right? #[derive(Copy, Clone, PartialEq, Debug)] pub struct Board { pieces: [BitBoard; NUM_PIECES], color_combined: [BitBoard; NUM_COLORS], combined: BitBoard, side_to_move: Color, castle_rights: [CastleRights; NUM_COLORS], pinned: BitBoard, checkers: BitBoard, hash: u64, en_passant: Option<Square>, } /// What is the status of this game? #[derive(Copy, Clone, PartialEq, PartialOrd, Debug)] pub enum BoardStatus { Ongoing, Stalemate, Checkmate, } /// Construct the initial position. impl Default for Board { fn default() -> Board { Board::from_fen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1".to_owned()) .expect("Valid FEN") } } impl Board { /// Construct a new `Board` that is completely empty. /// Note: This does NOT give you the initial position. Just a blank slate. fn new() -> Board { Board { pieces: [EMPTY; NUM_PIECES], color_combined: [EMPTY; NUM_COLORS], combined: EMPTY, side_to_move: Color::White, castle_rights: [CastleRights::NoRights; NUM_COLORS], pinned: EMPTY, checkers: EMPTY, hash: 0, en_passant: None, } } /// Construct a board from a FEN string. /// /// ``` /// use chess::Board; /// /// let init_position = Board::from_fen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1".to_owned()).expect("Valid FEN"); /// assert_eq!(init_position, Board::default()); /// ``` pub fn from_fen(fen: String) -> Option<Board> { let mut cur_rank = Rank::Eighth; let mut cur_file = File::A; let mut board: Board = Board::new(); let tokens: Vec<&str> = fen.split(' ').collect(); if tokens.len() != 6 { return None; } let pieces = tokens[0]; let side = tokens[1]; let castles = tokens[2]; let ep = tokens[3]; //let irreversable_moves = tokens[4]; //let total_moves = tokens[5]; for x in pieces.chars() { match x { '/' => { cur_rank = cur_rank.down(); cur_file = File::A; } '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' => { cur_file = File::from_index(cur_file.to_index() + (x as usize) - ('0' as usize)); } 'r' => { board.xor(Piece::Rook, BitBoard::set(cur_rank, cur_file), Color::Black); cur_file = cur_file.right(); } 'R' => { board.xor(Piece::Rook, BitBoard::set(cur_rank, cur_file), Color::White); cur_file = cur_file.right(); } 'n' => { board.xor( Piece::Knight, BitBoard::set(cur_rank, cur_file), Color::Black, ); cur_file = cur_file.right(); } 'N' => { board.xor( Piece::Knight, BitBoard::set(cur_rank, cur_file), Color::White, ); cur_file = cur_file.right(); } 'b' => { board.xor( Piece::Bishop, BitBoard::set(cur_rank, cur_file), Color::Black, ); cur_file = cur_file.right(); } 'B' => { board.xor( Piece::Bishop, BitBoard::set(cur_rank, cur_file), Color::White, ); cur_file = cur_file.right(); } 'p' => { board.xor(Piece::Pawn, BitBoard::set(cur_rank, cur_file), Color::Black); cur_file = cur_file.right(); } 'P' => { board.xor(Piece::Pawn, BitBoard::set(cur_rank, cur_file), Color::White); cur_file = cur_file.right(); } 'q' => { board.xor( Piece::Queen, BitBoard::set(cur_rank, cur_file), Color::Black, ); cur_file = cur_file.right(); } 'Q' => { board.xor( Piece::Queen, BitBoard::set(cur_rank, cur_file), Color::White, ); cur_file = cur_file.right(); } 'k' => { board.xor(Piece::King, BitBoard::set(cur_rank, cur_file), Color::Black); cur_file = cur_file.right(); } 'K' => { board.xor(Piece::King, BitBoard::set(cur_rank, cur_file), Color::White); cur_file = cur_file.right(); } _ => { panic!(); } } } match side { "w" | "W" => board.side_to_move = Color::White, "b" | "B" => { board.side_to_move = Color::Black; board.hash ^= Zobrist::color(); } _ => panic!(), } if castles.contains("K") && castles.contains("Q") { board.castle_rights[Color::White.to_index()] = CastleRights::Both; } else if castles.contains("K") { board.castle_rights[Color::White.to_index()] = CastleRights::KingSide; } else if castles.contains("Q") { board.castle_rights[Color::White.to_index()] = CastleRights::QueenSide; } else { board.castle_rights[Color::White.to_index()] = CastleRights::NoRights; } if castles.contains("k") && castles.contains("q") { board.castle_rights[Color::Black.to_index()] = CastleRights::Both; } else if castles.contains("k") { board.castle_rights[Color::Black.to_index()] = CastleRights::KingSide; } else if castles.contains("q") { board.castle_rights[Color::Black.to_index()] = CastleRights::QueenSide; } else { board.castle_rights[Color::Black.to_index()] = CastleRights::NoRights; } let color = board.side_to_move; match Square::from_string(ep.to_owned()) { None => {} Some(sq) => { board.side_to_move = !board.side_to_move; board.set_ep(sq.ubackward(color)); board.side_to_move = !board.side_to_move; } }; board.update_pin_info(); if board.is_sane() { Some(board) } else { None } } #[deprecated( since = "3.0.0", note = "please use the MoveGen structure instead. It is faster and more idiomatic." )] pub fn enumerate_moves(&self, moves: &mut [ChessMove; 256]) -> usize { let movegen = MoveGen::new_legal(self); let mut size = 0; for m in movegen { moves[size] = m; size += 1; } size } /// Is this game Ongoing, is it Stalemate, or is it Checkmate? /// /// ``` /// use chess::{Board, BoardStatus, Square, Rank, File, ChessMove}; /// /// let mut board = Board::default(); /// /// assert_eq!(board.status(), BoardStatus::Ongoing); /// /// board = board.make_move_new(ChessMove::new(Square::make_square(Rank::Second, File::E), /// Square::make_square(Rank::Fourth, File::E), /// None)); /// /// assert_eq!(board.status(), BoardStatus::Ongoing); /// /// board = board.make_move_new(ChessMove::new(Square::make_square(Rank::Seventh, File::F), /// Square::make_square(Rank::Sixth, File::F), /// None)); /// /// assert_eq!(board.status(), BoardStatus::Ongoing); /// /// board = board.make_move_new(ChessMove::new(Square::make_square(Rank::Second, File::D), /// Square::make_square(Rank::Fourth, File::D), /// None)); /// /// assert_eq!(board.status(), BoardStatus::Ongoing); /// /// board = board.make_move_new(ChessMove::new(Square::make_square(Rank::Seventh, File::G), /// Square::make_square(Rank::Fifth, File::G), /// None)); /// /// assert_eq!(board.status(), BoardStatus::Ongoing); /// /// board = board.make_move_new(ChessMove::new(Square::make_square(Rank::First, File::D), /// Square::make_square(Rank::Fifth, File::H), /// None)); /// /// assert_eq!(board.status(), BoardStatus::Checkmate); /// ``` pub fn status(&self) -> BoardStatus { let moves = MoveGen::new_legal(&self).len(); match moves { 0 => { if self.checkers == EMPTY { BoardStatus::Stalemate } else { BoardStatus::Checkmate } } _ => BoardStatus::Ongoing, } } /// Grab the "combined" `BitBoard`. This is a `BitBoard` with every piece. /// /// ``` /// use chess::{Board, BitBoard, Rank, get_rank}; /// /// let board = Board::default(); /// /// let combined_should_be = get_rank(Rank::First) | /// get_rank(Rank::Second) | /// get_rank(Rank::Seventh) | /// get_rank(Rank::Eighth); /// /// assert_eq!(*board.combined(), combined_should_be); /// ``` pub fn combined(&self) -> &BitBoard { &self.combined } /// Grab the "color combined" `BitBoard`. This is a `BitBoard` with every piece of a particular /// color. /// /// ``` /// use chess::{Board, BitBoard, Rank, get_rank, Color}; /// /// let board = Board::default(); /// /// let white_pieces = get_rank(Rank::First) | /// get_rank(Rank::Second); /// /// let black_pieces = get_rank(Rank::Seventh) | /// get_rank(Rank::Eighth); /// /// assert_eq!(*board.color_combined(Color::White), white_pieces); /// assert_eq!(*board.color_combined(Color::Black), black_pieces); /// ``` pub fn color_combined(&self, color: Color) -> &BitBoard { unsafe { self.color_combined.get_unchecked(color.to_index()) } } /// Give me the `Square` the `color` king is on. /// /// ``` /// use chess::{Board, Square, Color, Rank, File}; /// /// let board = Board::default(); /// /// assert_eq!(board.king_square(Color::White), Square::make_square(Rank::First, File::E)); /// assert_eq!(board.king_square(Color::Black), Square::make_square(Rank::Eighth, File::E)); /// ``` pub fn king_square(&self, color: Color) -> Square { (self.pieces(Piece::King) & self.color_combined(color)).to_square() } /// Grab the "pieces" `BitBoard`. This is a `BitBoard` with every piece of a particular type. /// /// ``` /// use chess::{Board, BitBoard, Piece, Square, Rank, File}; /// /// // The rooks should be in each corner of the board /// let rooks = BitBoard::from_square(Square::make_square(Rank::First, File::A)) | /// BitBoard::from_square(Square::make_square(Rank::First, File::H)) | /// BitBoard::from_square(Square::make_square(Rank::Eighth, File::A)) | /// BitBoard::from_square(Square::make_square(Rank::Eighth, File::H)); /// /// let board = Board::default(); /// /// assert_eq!(*board.pieces(Piece::Rook), rooks); /// ``` pub fn pieces(&self, piece: Piece) -> &BitBoard { unsafe { self.pieces.get_unchecked(piece.to_index()) } } /// Grab the `CastleRights` for a particular side. /// /// ``` /// use chess::{Board, Square, Rank, File, CastleRights, Color, ChessMove}; /// /// let move1 = ChessMove::new(Square::make_square(Rank::Second, File::A), /// Square::make_square(Rank::Fourth, File::A), /// None); /// /// let move2 = ChessMove::new(Square::make_square(Rank::Seventh, File::E), /// Square::make_square(Rank::Fifth, File::E), /// None); /// /// let move3 = ChessMove::new(Square::make_square(Rank::First, File::A), /// Square::make_square(Rank::Second, File::A), /// None); /// /// let move4 = ChessMove::new(Square::make_square(Rank::Eighth, File::E), /// Square::make_square(Rank::Seventh, File::E), /// None); /// /// let mut board = Board::default(); /// /// assert_eq!(board.castle_rights(Color::White), CastleRights::Both); /// assert_eq!(board.castle_rights(Color::Black), CastleRights::Both); /// /// board = board.make_move_new(move1) /// .make_move_new(move2) /// .make_move_new(move3) /// .make_move_new(move4); /// /// assert_eq!(board.castle_rights(Color::White), CastleRights::KingSide); /// assert_eq!(board.castle_rights(Color::Black), CastleRights::NoRights); /// ``` pub fn castle_rights(&self, color: Color) -> CastleRights { unsafe { *self.castle_rights.get_unchecked(color.to_index()) } } /// Add castle rights for a particular side. Note: this can create an invalid position. pub fn add_castle_rights(&mut self, color: Color, add: CastleRights) { unsafe { *self.castle_rights.get_unchecked_mut(color.to_index()) = self.castle_rights(color).add(add); } } /// Remove castle rights for a particular side. /// /// ``` /// use chess::{Board, CastleRights, Color}; /// /// let mut board = Board::default(); /// assert_eq!(board.castle_rights(Color::White), CastleRights::Both); /// /// board.remove_castle_rights(Color::White, CastleRights::KingSide); /// assert_eq!(board.castle_rights(Color::White), CastleRights::QueenSide); /// ``` pub fn remove_castle_rights(&mut self, color: Color, remove: CastleRights) { unsafe { *self.castle_rights.get_unchecked_mut(color.to_index()) = self.castle_rights(color).remove(remove); } } /// Who's turn is it? /// /// ``` /// use chess::{Board, Color}; /// /// let mut board = Board::default(); /// assert_eq!(board.side_to_move(), Color::White); /// ``` pub fn side_to_move(&self) -> Color { self.side_to_move } /// Grab my `CastleRights`. /// /// ``` /// use chess::{Board, Color, CastleRights}; /// /// let mut board = Board::default(); /// board.remove_castle_rights(Color::White, CastleRights::KingSide); /// board.remove_castle_rights(Color::Black, CastleRights::QueenSide); /// /// assert_eq!(board.my_castle_rights(), board.castle_rights(Color::White)); /// ``` pub fn my_castle_rights(&self) -> CastleRights { self.castle_rights(self.side_to_move()) } /// Add to my `CastleRights`. Note: This can make the position invalid. pub fn add_my_castle_rights(&mut self, add: CastleRights) { let color = self.side_to_move(); self.add_castle_rights(color, add); } /// Remove some of my `CastleRights`. /// /// ``` /// use chess::{Board, CastleRights}; /// /// let mut board = Board::default(); /// assert_eq!(board.my_castle_rights(), CastleRights::Both); /// /// board.remove_my_castle_rights(CastleRights::KingSide); /// assert_eq!(board.my_castle_rights(), CastleRights::QueenSide); /// ``` pub fn remove_my_castle_rights(&mut self, remove: CastleRights) { let color = self.side_to_move(); self.remove_castle_rights(color, remove); } /// My opponents `CastleRights`. /// /// ``` /// use chess::{Board, Color, CastleRights}; /// /// let mut board = Board::default(); /// board.remove_castle_rights(Color::White, CastleRights::KingSide); /// board.remove_castle_rights(Color::Black, CastleRights::QueenSide); /// /// assert_eq!(board.their_castle_rights(), board.castle_rights(Color::Black)); /// ``` pub fn their_castle_rights(&self) -> CastleRights { self.castle_rights(!self.side_to_move()) } /// Add to my opponents `CastleRights`. Note: This can make the position invalid. pub fn add_their_castle_rights(&mut self, add: CastleRights) { let color = !self.side_to_move(); self.add_castle_rights(color, add) } /// Remove some of my opponents `CastleRights`. /// /// ``` /// use chess::{Board, CastleRights}; /// /// let mut board = Board::default(); /// assert_eq!(board.their_castle_rights(), CastleRights::Both); /// /// board.remove_their_castle_rights(CastleRights::KingSide); /// assert_eq!(board.their_castle_rights(), CastleRights::QueenSide); /// ``` pub fn remove_their_castle_rights(&mut self, remove: CastleRights) { let color = !self.side_to_move(); self.remove_castle_rights(color, remove); } /// Add or remove a piece from the bitboards in this struct. fn xor(&mut self, piece: Piece, bb: BitBoard, color: Color) { unsafe { *self.pieces.get_unchecked_mut(piece.to_index()) ^= bb; *self.color_combined.get_unchecked_mut(color.to_index()) ^= bb; self.combined ^= bb; self.hash ^= Zobrist::piece(piece, bb.to_square(), color); } } /// For a chess UI: set a piece on a particular square. /// /// ``` /// use chess::{Board, Piece, Color, Square, Rank, File}; /// /// let board = Board::default(); /// /// let new_board = board.set_piece(Piece::Queen, /// Color::White, /// Square::make_square(Rank::Fourth, File::E)) /// .expect("Valid Position"); /// /// assert_eq!(new_board.pieces(Piece::Queen).count(), 3); /// ``` pub fn set_piece(&self, piece: Piece, color: Color, square: Square) -> Option<Board> { let mut result = *self; let square_bb = BitBoard::from_square(square); match self.piece_on(square) { None => result.xor(piece, square_bb, color), Some(x) => { // remove x from the bitboard if self.color_combined(Color::White) & square_bb == square_bb { result.xor(x, square_bb, Color::White); } else { result.xor(x, square_bb, Color::Black); } // add piece to the bitboard result.xor(piece, square_bb, color); } } // If setting this piece down leaves my opponent in check, and it's my move, then the // position is not a valid chess board result.side_to_move = !result.side_to_move; result.update_pin_info(); if result.checkers != EMPTY { return None; } // undo our damage result.side_to_move = !result.side_to_move; result.update_pin_info(); Some(result) } /// For a chess UI: clear a particular square. /// /// ``` /// use chess::{Board, Square, Rank, File, Piece}; /// /// let board = Board::default(); /// /// let new_board = board.clear_square(Square::make_square(Rank::First, File::A)) /// .expect("Valid Position"); /// /// assert_eq!(new_board.pieces(Piece::Rook).count(), 3); /// ``` pub fn clear_square(&self, square: Square) -> Option<Board> { let mut result = *self; let square_bb = BitBoard::from_square(square); match self.piece_on(square) { None => {} Some(x) => { // remove x from the bitboard if self.color_combined(Color::White) & square_bb == square_bb { result.xor(x, square_bb, Color::White); } else { result.xor(x, square_bb, Color::Black); } } } // If setting this piece down leaves my opponent in check, and it's my move, then the // position is not a valid chess board result.side_to_move = !result.side_to_move; result.update_pin_info(); if result.checkers != EMPTY { return None; } // undo our damage result.side_to_move = !result.side_to_move; result.update_pin_info(); Some(result) } /// Switch the color of the player without actually making a move. Returns None if the current /// player is in check. /// /// Note that this erases the en-passant information, so applying this function twice does not /// always give the same result back. /// /// ``` /// use chess::{Board, Color}; /// /// let board = Board::default(); /// /// assert_eq!(board.side_to_move(), Color::White); /// /// let new_board = board.null_move().expect("Valid Position"); /// /// assert_eq!(new_board.side_to_move(), Color::Black); /// ``` pub fn null_move(&self) -> Option<Board> { if self.checkers != EMPTY { None } else { let mut result = *self; result.side_to_move = !result.side_to_move; result.hash ^= Zobrist::color(); result.remove_ep(); result.update_pin_info(); Some(result) } } /// Does this board "make sense"? /// Do all the pieces make sense, do the bitboards combine correctly, etc? /// This is for sanity checking. /// /// ``` /// use chess::{Board, Color, Piece, Square, Rank, File}; /// /// let board = Board::default(); /// /// assert_eq!(board.is_sane(), true); /// /// // Remove the king /// let bad_board = board.clear_square(Square::make_square(Rank::First, File::E)).expect("Valid Position"); /// assert_eq!(bad_board.is_sane(), false); /// ``` pub fn is_sane(&self) -> bool { // make sure there is no square with multiple pieces on it for x in ALL_PIECES.iter() { for y in ALL_PIECES.iter() { if *x != *y { if self.pieces(*x) & self.pieces(*y) != EMPTY { return false; } } } } // make sure the colors don't overlap, either if self.color_combined(Color::White) & self.color_combined(Color::Black) != EMPTY { return false; } // grab all the pieces by OR'ing together each piece() BitBoard let combined = ALL_PIECES .iter() .fold(EMPTY, |cur, next| cur | self.pieces(*next)); // make sure that's equal to the combined bitboard if combined != *self.combined() { return false; } // make sure there is exactly one white king if (self.pieces(Piece::King) & self.color_combined(Color::White)).popcnt() != 1 { return false; } // make sure there is exactly one black king if (self.pieces(Piece::King) & self.color_combined(Color::Black)).popcnt() != 1 { return false; } // make sure the en_passant square has a pawn on it of the right color match self.en_passant { None => {} Some(x) => { if self.pieces(Piece::Pawn) & self.color_combined(!self.side_to_move) & BitBoard::from_square(x) == EMPTY { return false; } } } // make sure my opponent is not currently in check (because that would be illegal) let mut board_copy = *self; board_copy.side_to_move = !board_copy.side_to_move; board_copy.update_pin_info(); if board_copy.checkers != EMPTY { return false; } // for each color, verify that, if they have castle rights, that they haven't moved their // rooks or king for color in ALL_COLORS.iter() { // get the castle rights let castle_rights = self.castle_rights(*color); // the castle rights object will tell us which rooks shouldn't have moved yet. // verify there are rooks on all those squares if castle_rights.unmoved_rooks(*color) & self.pieces(Piece::Rook) & self.color_combined(*color) != castle_rights.unmoved_rooks(*color) { return false; } // if we have castle rights, make sure we have a king on the (E, {1,8}) square, // depending on the color if castle_rights != CastleRights::NoRights { if self.pieces(Piece::King) & self.color_combined(*color) != get_file(File::E) & get_rank(color.to_my_backrank()) { return false; } } } // we must make sure the kings aren't touching if get_king_moves(self.king_square(Color::White)) & self.pieces(Piece::King) != EMPTY { return false; } // it checks out return true; } /// Get a hash of the board. pub fn get_hash(&self) -> u64 { self.hash ^ if let Some(ep) = self.en_passant { Zobrist::en_passant(ep.get_file(), !self.side_to_move) } else { 0 } ^ Zobrist::castles( self.castle_rights[self.side_to_move.to_index()], self.side_to_move, ) ^ Zobrist::castles( self.castle_rights[(!self.side_to_move).to_index()], !self.side_to_move, ) } /// Get a pawn hash of the board (a hash that only changes on color change and pawn moves). pub fn get_pawn_hash(&self) -> u64 { 0 } /// What piece is on a particular `Square`? Is there even one? /// /// ``` /// use chess::{Board, Piece, Square, Rank, File}; /// /// let board = Board::default(); /// /// let sq1 = Square::make_square(Rank::First, File::A); /// let sq2 = Square::make_square(Rank::Fourth, File::D); /// /// assert_eq!(board.piece_on(sq1), Some(Piece::Rook)); /// assert_eq!(board.piece_on(sq2), None); /// ``` pub fn piece_on(&self, square: Square) -> Option<Piece> { let opp = BitBoard::from_square(square); if self.combined() & opp == EMPTY { None } else { //naiive algorithm /* for p in ALL_PIECES { if self.pieces(*p) & opp { return p; } } */ if (self.pieces(Piece::Pawn) ^ self.pieces(Piece::Knight) ^ self.pieces(Piece::Bishop)) & opp != EMPTY { if self.pieces(Piece::Pawn) & opp != EMPTY { Some(Piece::Pawn) } else if self.pieces(Piece::Knight) & opp != EMPTY { Some(Piece::Knight) } else { Some(Piece::Bishop) } } else { if self.pieces(Piece::Rook) & opp != EMPTY { Some(Piece::Rook) } else if self.pieces(Piece::Queen) & opp != EMPTY { Some(Piece::Queen) } else { Some(Piece::King) } } } } /// What color piece is on a particular square? pub fn color_on(&self, square: Square) -> Option<Color> { if (self.color_combined(Color::White) & BitBoard::from_square(square)) != EMPTY { Some(Color::White) } else if (self.color_combined(Color::Black) & BitBoard::from_square(square)) != EMPTY { Some(Color::Black) } else { None } } /// Unset the en_passant square. fn remove_ep(&mut self) { self.en_passant = None; } /// Give me the en_passant square, if it exists. /// /// ``` /// use chess::{Board, ChessMove, Square, Rank, File}; /// /// let move1 = ChessMove::new(Square::make_square(Rank::Second, File::D), /// Square::make_square(Rank::Fourth, File::D), /// None); /// /// let move2 = ChessMove::new(Square::make_square(Rank::Seventh, File::H), /// Square::make_square(Rank::Fifth, File::H), /// None); /// /// let move3 = ChessMove::new(Square::make_square(Rank::Fourth, File::D), /// Square::make_square(Rank::Fifth, File::D), /// None); /// /// let move4 = ChessMove::new(Square::make_square(Rank::Seventh, File::E), /// Square::make_square(Rank::Fifth, File::E), /// None); /// /// let board = Board::default().make_move_new(move1) /// .make_move_new(move2) /// .make_move_new(move3) /// .make_move_new(move4); /// /// assert_eq!(board.en_passant(), Some(Square::make_square(Rank::Fifth, File::E))); /// ``` pub fn en_passant(self) -> Option<Square> { self.en_passant } /// Set the en_passant square. Note: This must only be called when self.en_passant is already /// None. fn set_ep(&mut self, sq: Square) { // Only set self.en_passant if the pawn can actually be captured next move. if get_adjacent_files(sq.get_file()) & get_rank(sq.get_rank()) & self.pieces(Piece::Pawn) & self.color_combined(!self.side_to_move) != EMPTY { self.en_passant = Some(sq); } } /// Is a particular move legal? This function is very slow, but will work on unsanitized /// input. /// /// ``` /// use chess::{Board, ChessMove, Square, Rank, File}; /// /// let move1 = ChessMove::new(Square::make_square(Rank::Second, File::E), /// Square::make_square(Rank::Fourth, File::E), /// None); /// /// let move2 = ChessMove::new(Square::make_square(Rank::Second, File::E), /// Square::make_square(Rank::Fifth, File::E), /// None); /// /// let board = Board::default(); /// /// assert_eq!(board.legal(move1), true); /// assert_eq!(board.legal(move2), false); pub fn legal(&self, m: ChessMove) -> bool { MoveGen::new_legal(&self).find(|x| *x == m).is_some() } /// Make a chess move onto a new board. /// /// panic!() if king is captured. /// /// ``` /// use chess::{Board, ChessMove, Square, Rank, File, Color}; /// /// let m = ChessMove::new(Square::make_square(Rank::Second, File::D), /// Square::make_square(Rank::Fourth, File::D), /// None); /// /// let board = Board::default(); /// assert_eq!(board.make_move_new(m).side_to_move(), Color::Black); /// ``` pub fn make_move_new(&self, m: ChessMove) -> Board { let mut result = unsafe { mem::uninitialized() }; self.make_move(m, &mut result); result } /// Make a chess move onto an already allocated `Board`. /// /// panic!() if king is captured. /// /// ``` /// use chess::{Board, ChessMove, Square, Rank, File, Color}; /// /// let m = ChessMove::new(Square::make_square(Rank::Second, File::D), /// Square::make_square(Rank::Fourth, File::D), /// None); /// /// let board = Board::default(); /// let mut result = Board::default(); /// board.make_move(m, &mut result); /// assert_eq!(result.side_to_move(), Color::Black); /// ``` pub fn make_move(&self, m: ChessMove, result: &mut Board) { *result = *self; result.remove_ep(); result.checkers = EMPTY; result.pinned = EMPTY; let source = m.get_source(); let dest = m.get_dest(); let source_bb = BitBoard::from_square(source); let dest_bb = BitBoard::from_square(dest); let move_bb = source_bb ^ dest_bb; let moved = self.piece_on(source).unwrap(); result.xor(moved, source_bb, self.side_to_move); result.xor(moved, dest_bb, self.side_to_move); if let Some(captured) = self.piece_on(dest) { result.xor(captured, dest_bb, !self.side_to_move); } result.remove_their_castle_rights(CastleRights::square_to_castle_rights( !self.side_to_move, dest, )); result.remove_my_castle_rights(CastleRights::square_to_castle_rights( self.side_to_move, source, )); let opp_king = result.pieces(Piece::King) & result.color_combined(!result.side_to_move); let castles = moved == Piece::King && (move_bb & get_castle_moves()) == move_bb; let ksq = opp_king.to_square(); const CASTLE_ROOK_START: [File; 8] = [ File::A, File::A, File::A, File::A, File::H, File::H, File::H, File::H, ]; const CASTLE_ROOK_END: [File; 8] = [ File::D, File::D, File::D, File::D, File::F, File::F, File::F, File::F, ]; if moved == Piece::Knight { result.checkers ^= get_knight_moves(ksq) & dest_bb; } else if moved == Piece::Pawn { if let Some(Piece::Knight) = m.get_promotion() { result.xor(Piece::Pawn, dest_bb, self.side_to_move); result.xor(Piece::Knight, dest_bb, self.side_to_move); result.checkers ^= get_knight_moves(ksq) & dest_bb; } else if let Some(promotion) = m.get_promotion() { result.xor(Piece::Pawn, dest_bb, self.side_to_move); result.xor(promotion, dest_bb, self.side_to_move); } else if (source_bb & get_pawn_source_double_moves()) != EMPTY && (dest_bb & get_pawn_dest_double_moves()) != EMPTY { result.set_ep(dest); result.checkers ^= get_pawn_attacks(ksq, !result.side_to_move, dest_bb); } else if Some(dest.ubackward(self.side_to_move)) == self.en_passant { result.xor( Piece::Pawn, BitBoard::from_square(dest.ubackward(self.side_to_move)), !self.side_to_move, ); result.checkers ^= get_pawn_attacks(ksq, !result.side_to_move, dest_bb); } else { result.checkers ^= get_pawn_attacks(ksq, !result.side_to_move, dest_bb); } } else if castles { let my_backrank = self.side_to_move.to_my_backrank(); let index = dest.get_file().to_index(); let start = BitBoard::set(my_backrank, unsafe { *CASTLE_ROOK_START.get_unchecked(index) }); let end = BitBoard::set(my_backrank, unsafe { *CASTLE_ROOK_END.get_unchecked(index) }); result.xor(Piece::Rook, start, self.side_to_move); result.xor(Piece::Rook, end, self.side_to_move); } // now, lets see if we're in check or pinned let attackers = result.color_combined(result.side_to_move) & ((get_bishop_rays(ksq) & (result.pieces(Piece::Bishop) | result.pieces(Piece::Queen))) | (get_rook_rays(ksq) & (result.pieces(Piece::Rook) | result.pieces(Piece::Queen)))); for sq in attackers { let between = between(sq, ksq) & result.combined(); if between == EMPTY { result.checkers ^= BitBoard::from_square(sq); } else if between.popcnt() == 1 { result.pinned ^= between; } } result.side_to_move = !result.side_to_move; result.hash ^= Zobrist::color(); } /// Update the pin information. fn update_pin_info(&mut self) { self.pinned = EMPTY; self.checkers = EMPTY; let ksq = (self.pieces(Piece::King) & self.color_combined(self.side_to_move)).to_square(); let pinners = self.color_combined(!self.side_to_move) & ((get_bishop_rays(ksq) & (self.pieces(Piece::Bishop) | self.pieces(Piece::Queen))) | (get_rook_rays(ksq) & (self.pieces(Piece::Rook) | self.pieces(Piece::Queen)))); for sq in pinners { let between = between(sq, ksq) & self.combined(); if between == EMPTY { self.checkers ^= BitBoard::from_square(sq); } else if between.popcnt() == 1 { self.pinned ^= between; } } self.checkers ^= get_knight_moves(ksq) & self.color_combined(!self.side_to_move) & self.pieces(Piece::Knight); self.checkers ^= get_pawn_attacks( ksq, self.side_to_move, self.color_combined(!self.side_to_move) & self.pieces(Piece::Pawn), ); } /// Give me the `BitBoard` of my pinned pieces. pub fn pinned(&self) -> &BitBoard { &self.pinned } /// Give me the `Bitboard` of the pieces putting me in check. pub fn checkers(&self) -> &BitBoard { &self.checkers } } #[test] fn test_null_move_en_passant() { let start = Board::from_fen("rnbqkbnr/pppp2pp/8/4pP2/8/8/PPPP1PPP/RNBQKBNR w KQkq e6 0 0".into()) .unwrap(); let expected = Board::from_fen("rnbqkbnr/pppp2pp/8/4pP2/8/8/PPPP1PPP/RNBQKBNR b KQkq - 0 0".into()) .unwrap(); assert_eq!(start.null_move().unwrap(), expected); }