Struct pleco::board::Board

pub struct Board {
    pub magic_helper: &'static MAGIC_HELPER,
    // some fields omitted
}

Represents a ChessBoard through a Board.

Board contains everything that needs to be known about the current state of the Game. It is used by both Engines and Players / Bots alike.

Ideally, the Engine contains the original Representation of a board (owns the board), and utilizes [Board::shallow_clone()] to share this representaion with Players.

Examples

use pleco::Board;

fn main() {
    let mut chessboard = Board::default();

    let moves = chessboard.generate_moves();
    chessboard.apply_move(moves[0]);

    let b2 = chessboard.shallow_clone(); // boards allow for easy cloning
    assert_eq!(chessboard.moves_played(), b2.moves_played());
}

BitBoard Representation

For the majority of the struct, the board utilizes [BitBoard]s, which is a u64 where each bit represents an occupied location, and each bit index represents a certain square (as in bit 0 is Square A1, bit 1 is B1, etc.). Indexes increase first horizontally by File, and then by Rank. See BitBoards article ChessWiki for more information.

The exact mapping from each square to bits is below,

8 | 56 57 58 59 60 61 62 63
7 | 48 49 50 51 52 53 54 55
6 | 40 41 42 43 44 45 46 47
5 | 32 33 34 35 36 37 38 39
4 | 24 25 26 27 28 29 30 31
3 | 16 17 18 19 20 21 22 23
2 | 8  9  10 11 12 13 14 15
1 | 0  1  2  3  4  5  6  7
  -------------------------
     a  b  c  d  e  f  g  h

Fields

magic_helper: &'static MAGIC_HELPER

Reference to the pre-computed lookup tables.

Methods

impl Board

fn default() -> Board

Constructs a board from the starting position

Examples

use pleco::{Board,Player};

let chessboard = Board::default();
assert_eq!(chessboard.count_pieces_player(Player::White),16);

fn shallow_clone(&self) -> Board

Constructs a shallow clone of the Board.

Contains only the information necessary to apply future moves, more specifically does not clone the moves list, and sets depth to zero. Intended for an Engine or main thread to share the board to users wanting to search.

Safety

After this method has called, [Board::undo_move()] cannot be called immediately after. Undoing moves can only be done once a move has been played, and cannot be called more times than moves have been played since calling [Board::shallow_clone()].

Examples

use pleco::Board;

let mut chessboard = Board::default();
let moves = chessboard.generate_moves(); // generate all possible legal moves
chessboard.apply_move(moves[0]); // apply first move

assert_eq!(chessboard.moves_played(), 1);

let board_clone = chessboard.shallow_clone();
assert_eq!(chessboard.moves_played(), board_clone.moves_played());

assert_ne!(chessboard.depth(),board_clone.depth()); // different depths

fn parallel_clone(&self) -> Board

Constructs a parallel clone of the Board.

Similar to [Board::shallow_clone()], but keeps the current search depth the same. Should be used when implementing a searcher, and want to search a list of moves in parallel with different threads.

Safety

After this method has called, [Board::undo_move()] cannot be called immediately after. Undoing moves can only be done once a move has been played, and cannot be called more times than moves have been played since calling [Board::parallel_clone()].

Examples

use pleco::Board;

let mut chessboard = Board::default();
let moves = chessboard.generate_moves(); // generate all possible legal moves
chessboard.apply_move(moves[0]);
assert_eq!(chessboard.moves_played(), 1);

let board_clone = chessboard.parallel_clone();
assert_eq!(chessboard.moves_played(), board_clone.moves_played());

assert_eq!(chessboard.depth(),board_clone.depth()); // different depths

unsafe fn deep_clone(&self) -> Board

Returns an exact clone of the current board.

Safety

This method is unsafe as it can give the impression of owning and operating a board structure, rather than just being provided shallow clones.

fn new_from_fen(fen: &str) -> Board

Constructs a board from a FEN String.

FEN stands for Forsyth-Edwards Notation, and is a way of representing a board through a string of characters. More information can be found on the ChessWiki.

Examples

use pleco::Board;

let board = Board::new_from_fen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
assert_eq!(board.count_all_pieces(),32);

Panics

The FEN string must be valid, or else the method will panic.

There is a possibility of the FEN string representing an unvalid position, with no panics resulting. The Constructed Board may have some Undefined Behavior as a result. It is up to the user to give a valid FEN string.

fn get_fen(&self) -> String

Creates a FEN String of the Given Board.

FEN stands for Forsyth-Edwards Notation, and is a way of representing a board through a string of characters. More information can be found on the ChessWiki.

Examples

use pleco::Board;

let board = Board::default();
assert_eq!(board.get_fen(),"rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");

impl Board

fn apply_move(&mut self, bit_move: BitMove)

Applies a move to the Board.

Safety

The passed in [BitMove] must be

Panics

The supplied BitMove must be both a valid move for that position, as well as a valid [BitMove], Otherwise, a panic will occur. Valid BitMoves can be generated with [Board::generate_moves()], which guarantees that only Legal moves will be created.

fn apply_uci_move(&mut self, uci_move: &str) -> bool

Applies a UCI move to the board. If the move is a valid string representing a UCI move, then true will be returned & the move will be applied. Otherwise, false is returned and the board isn't changed.

Examples

use pleco::Board;

let mut board = Board::default();
let success = board.apply_uci_move("e2e4");

assert!(success);

fn undo_move(&mut self)

Un-does the previously applied move, allowing the Board to return to it's most recently held state.

Panics

Cannot be done if after a [Board::shallow_clone()] or [Board::parallel_clone()] has been done and no subsequent moves have been played.

Examples

use pleco::Board;

let mut chessboard = Board::default();

let moves = chessboard.generate_moves();
chessboard.apply_move(moves[0]);

let mut board_clone = chessboard.shallow_clone();

chessboard.undo_move(); // works, chessboard existed before the move was played
board_clone.undo_move(); // error: board_clone was created after the move was applied

unsafe fn apply_null_move(&mut self)

Apply a "Null Move" to the board, essentially swapping the current turn of the board without moving any pieces.

Safety

This method should only be used for special evaluation purposes, as it does not give an accurate or legal state of the chess board.

Unsafe as it allows for Null Moves to be applied in states of check, which is never a valid state of a chess game.

Panics

Panics if the Board is currently in check.

Examples

use pleco::board::*;

let mut chessboard = Board::default();
let board_clone = chessboard.shallow_clone();

unsafe { chessboard.apply_null_move(); }

assert_ne!(chessboard.depth(), board_clone.depth());

unsafe fn undo_null_move(&mut self)

Undo a "Null Move" to the Board, returning to the previous state.

Safety

This method should only be used if it can be guaranteed that the last played move from the current state is a Null-Move. Otherwise, a panic will occur.

Examples

use pleco::board::*;

let mut chessboard = Board::default();
let board_clone = chessboard.shallow_clone();

unsafe { chessboard.apply_null_move(); }

assert_ne!(chessboard.ply(), board_clone.ply());

unsafe { chessboard.undo_null_move(); }

assert_eq!(chessboard.moves_played(), board_clone.moves_played());
assert_eq!(chessboard.get_fen(), board_clone.get_fen());

fn generate_moves(&self) -> Vec<BitMove>

Get a List of legal [BitMove]s for the player whose turn it is to move.

This method already takes into account if the Board is currently in check, and will return legal moves only.

# Examples

use pleco::board::*;

let chessboard = Board::default();
let moves = chessboard.generate_moves();

println!("There are {} possible legal moves.", moves.len());

fn generate_pseudolegal_moves(&self) -> Vec<BitMove>

Get a List of all PseudoLegal [BitMove]s for the player whose turn it is to move. Works exactly the same as [Board::generate_moves()], but doesn't guarantee that all the moves are legal for the current position. Moves need to be checked with a [Board::legal_move(move)] in order to be certain of a legal move.

fn generate_moves_of_type(&self, gen_type: GenTypes) -> Vec<BitMove>

Get a List of legal [BitMove]s for the player whose turn it is to move or a certain type.

This method already takes into account if the Board is currently in check, and will return legal moves only. If a non-ALL GenType is supplied, only a subset of the total moves will be given.

Panics

Panics if given [GenTypes::QuietChecks] while the current board is in check

Examples

use pleco::board::*;
use pleco::templates::GenTypes;

let chessboard = Board::default();
let capturing_moves = chessboard.generate_moves_of_type(GenTypes::Captures);

assert_eq!(capturing_moves.len(), 0); // no possible captures for the starting position

fn generate_pseudolegal_moves_of_type(&self, gen_type: GenTypes) -> Vec<BitMove>

Get a List of all PseudoLegal [BitMove]s for the player whose turn it is to move. Works exactly the same as [Board::generate_moves()], but doesn't guarantee that all the moves are legal for the current position. Moves need to be checked with a [Board::legal_move(move)] in order to be certain of a legal move.

This method already takes into account if the Board is currently in check. If a non-ALL GenType is supplied, only a subset of the total moves will be given.

Panics

Panics if given [GenTypes::QuietChecks] while the current board is in check

impl Board

fn turn(&self) -> Player

Get the Player whose turn it is to move.

Examples

use pleco::{Board,Player};

let chessboard = Board::default();
assert_eq!(chessboard.turn(), Player::White);

fn zobrist(&self) -> u64

Return the Zobrist Hash.

fn moves_played(&self) -> u16

Get the total number of moves played.

Examples

use pleco::Board;

let mut chessboard = Board::default();
assert_eq!(chessboard.moves_played(), 0);

let moves = chessboard.generate_moves();
chessboard.apply_move(moves[0]);
assert_eq!(chessboard.moves_played(), 1);

fn depth(&self) -> u16

Get the current depth (half moves from a [Board::shallow_clone()].

fn rule_50(&self) -> i16

Get the number of half-moves since a Pawn Push, castle, or capture.

fn piece_captured_last_turn(&self) -> Option<Piece>

Return the Piece, if any, that was last captured.

fn magic_helper(&self) -> &'static MagicHelper

Get a reference to the MagicHelper pre-computed BitBoards.

fn ply(&self) -> u16

Get the current ply of the board.

fn ep_square(&self) -> SQ

Get the current square of en_passant.

If the current en-passant square is none, it should return 64.

impl Board

fn get_occupied(&self) -> BitBoard

Gets the BitBoard of all pieces.

Examples

use pleco::Board;

let chessboard = Board::default();
assert_eq!(chessboard.get_occupied(), 0xFFFF00000000FFFF);

fn get_occupied_player(&self, player: Player) -> BitBoard

Get the BitBoard of the squares occupied by the given player.

Examples

use pleco::{Board,Player};

let chessboard = Board::default();
assert_eq!(chessboard.get_occupied_player(Player::White), 0x000000000000FFFF);

fn occupied_white(&self) -> BitBoard

Returns a Bitboard consisting of only the squares occupied by the White Player.

fn occupied_black(&self) -> BitBoard

Returns a BitBoard consisting of only the squares occupied by the Black Player.

fn piece_bb(&self, player: Player, piece: Piece) -> BitBoard

Returns BitBoard of a single player and that one type of piece.

Examples

use pleco::Board;
use pleco::{Player,Piece};

let chessboard = Board::default();
assert_eq!(chessboard.piece_bb(Player::White,Piece::P), 0x000000000000FF00);

fn sliding_piece_bb(&self, player: Player) -> BitBoard

Returns the BitBoard of the Queens and Rooks of a given player.

Examples

use pleco::{Board,Player};
use pleco::bit_twiddles::*;

let chessboard = Board::default();
assert_eq!(popcount64(chessboard.sliding_piece_bb(Player::White)), 3);

fn diagonal_piece_bb(&self, player: Player) -> BitBoard

Returns the BitBoard of the Queens and Bishops of a given player.

Examples

use pleco::{Board,Player};
use pleco::bit_twiddles::*;

let chessboard = Board::default();
assert_eq!(popcount64(chessboard.diagonal_piece_bb(Player::White)), 3);

fn piece_bb_both_players(&self, piece: Piece) -> BitBoard

Returns the combined BitBoard of both players for a given piece.

Examples

use pleco::{Board,Piece};

let chessboard = Board::default();
assert_eq!(chessboard.piece_bb_both_players(Piece::P), 0x00FF00000000FF00);

fn piece_two_bb_both_players(&self, piece: Piece, piece2: Piece) -> BitBoard

Returns the combined BitBoard of both players for two pieces.

Examples

use pleco::{Board,Piece};
use pleco::bit_twiddles::*;

let chessboard = Board::default();
assert_eq!(popcount64(chessboard.piece_two_bb_both_players(Piece::Q,Piece::K)), 4);

fn piece_two_bb(&self, piece: Piece, piece2: Piece, player: Player) -> BitBoard

fn count_piece(&self, player: Player, piece: Piece) -> u8

Get the total number of pieces of the given piece and player.

Examples

use pleco::{Board,Player,Piece};

let chessboard = Board::default();
assert_eq!(chessboard.count_piece(Player::White, Piece::P), 8);

fn count_pieces_player(&self, player: Player) -> u8

Get the total number of pieces a given player has.

Examples

use pleco::{Board,Player,Piece};
use pleco::bit_twiddles::*;

let chessboard = Board::default();
assert_eq!(chessboard.count_pieces_player(Player::White), 16);

fn count_all_pieces(&self) -> u8

Get the total number of pieces on the board.

Examples

use pleco::{Board,Player,Piece};
use pleco::bit_twiddles::*;

let chessboard = Board::default();
assert_eq!(chessboard.count_all_pieces(), 32);

fn piece_at_bb(&self, src_bit: BitBoard, player: Player) -> Option<Piece>

Returns the piece (if any) at the given BitBoard for a given player.

Safety

Number of bits must be equal to 1, or else a panic will occur.

fn piece_at_bb_all(&self, src_bit: BitBoard) -> Option<Piece>

Returns the piece (if any) at the given BitBoard for either player.

Safety

Number of bits must be equal to 1, or else a panic will occur.

fn piece_at_sq(&self, sq: SQ) -> Option<Piece>

Returns the Piece, if any, at the square.

fn color_of_sq(&self, sq: SQ) -> Option<Player>

Returns the Player, if any, occupying the square.

fn player_at_sq(&self, s: SQ) -> Option<Player>

Returns the player, if any, at the square.

fn king_sq(&self, player: Player) -> SQ

Returns the square of the King for a given player

fn pinned_pieces(&self, player: Player) -> BitBoard

Returns the pinned pieces of the given player.

Pinned is defined as pinned to the same players king

fn all_pinned_pieces(&self, player: Player) -> BitBoard

Returns the pinned pieces for a given players king. Can contain piece of from both players, but all are garunteed to be pinned to the given player's king.

fn pinning_pieces(&self, player: Player) -> BitBoard

Returns the pinning pieces of a given player. e.g, pieces that are pinning a piece to the opponent's king.

fn can_castle(&self, player: Player, castle_type: CastleType) -> bool

Return if a player has the possibility of castling for a given CastleType.

fn castle_impeded(&self, castle_type: CastleType) -> bool

Check if the castle path is impeded for the current player.

fn castling_rook_square(&self, castle_type: CastleType) -> SQ

Square of the Rook that is involved with the current player's castle.

fn last_move(&self) -> Option<BitMove>

Return the last move played, if any.

fn has_castled(&self, player: Player) -> bool

Returns if the current player has castled ever.

fn piece_last_captured(&self) -> Option<Piece>

Return if the piece (if any) that was captured last move.

impl Board

fn in_check(&self) -> bool

Return if current side to move is in check

fn checkmate(&self) -> bool

Return if the current side to move is in check_mate.

This method can be computationally expensive, do not use outside of Engines.

fn stalemate(&self) -> bool

Return if the current side to move is in stalemate.

This method can be computationally expensive, do not use outside of Engines.

fn checkers(&self) -> BitBoard

Return the BitBoard of Checks on the current player's king.

fn discovered_check_candidates(&self) -> BitBoard

Returns the BitBoard of pieces the current side can move to discover check.

fn pieces_pinned(&self, player: Player) -> BitBoard

Gets the Pinned pieces for the given player.

fn attackers_to(&self, sq: SQ, occupied: BitBoard) -> BitBoard

Returns a BitBoard of possible attacks / defends to a square with a given occupancy.

impl Board

fn legal_move(&self, m: BitMove) -> bool

Tests if a given move is legal.

fn gives_check(&self, m: BitMove) -> bool

Returns if a move will give check to the opposing player's King.

fn moved_piece(&self, m: BitMove) -> Piece

Returns the piece that was moved from a given BitMove.

fn captured_piece(&self, m: BitMove) -> Option<Piece>

Returns the piece that was captured, if any from a given BitMove.

impl Board

fn pretty_string(&self) -> String

Returns a prettified String of the current board, for Quick Display.

Capital Letters represent White pieces, while lower case represents Black pieces.

fn get_arc_strong_count(&self) -> usize

Return the current ARC count of the board's BoardState

fn print_debug_info(&self)

Get Debug Information.

fn pretty_print(&self)

Prints a prettified representation of the board.

fn fancy_print(&self)

Print the board alongside useful information.

Mostly for Debugging useage.

fn is_okay(&self) -> bool

Trait Implementations

impl Display for Board

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.