Struct Position 

pub struct Position { /* private fields */ }

Chess position, including the board, turn, rights, and counters.

Size:

• board: 9 * 8 = 72 bytes
• turn: 1 byte (really 1 bit)
• castle rights: 2 bytes (really 2 bits)
• en passant square: 1 bytes (really 65 options)
• reversible move counter: 4 bytes (modeled as u32, really 1 byte would be enough)
• round counter: 4 bytes (value >=1, u16 or even u8 should be enough, who has 65536 rounds in a game of chess?)

Unpacked, this amounts to 88 bytes (Rust 1.91). Packed it is 84 bytes.

https://lichess.org/@/revoof/blog/adapting-nnue-pytorchs-binary-position-format-for-lichess/cpeeAMeY shows that about 18.7 bytes is enough

Besides size, a goal is also to stick these into SQLite3 (or DuckDB), and make something similar to Chess Query Language (with a less weird syntax…) efficently implementable.

The contents can be split in:

• board
• rights: turn + castle + en passant
• counters

Implementations

impl Position

pub fn from_fen(fen: &str) -> Result<Self>

impl Position

pub fn apparent_fen(&self) -> String

pub fn fen(&self) -> String

pub fn chess_fen(&self) -> Option<String>

pub fn shredder_fen(&self) -> String

pub fn transposition_fen(&self) -> String

impl Position

pub fn resolve_uci(self, mode: Mode, moves: &[Move]) -> Vec<Move>

pub fn resolve_uci_san(self, mode: Mode, moves: &[Move]) -> Vec<String>

impl Position

pub fn id(self) -> Id

pub const fn standard_id(self) -> Id

pub const fn polyglot_id(self) -> Id

pub const fn transposition_id(self, basis: &Basis) -> Id

pub const fn apparent_id(self, basis: &Basis) -> Id

impl Position

Position Move API.

pub fn legal_moves(&self) -> Vec<Move>

pub fn legal_castle_moves(&self) -> Vec<Move>

pub fn pseudo_piece_moves(&self) -> Vec<Move>

pub fn legal_king_moves(&self) -> Vec<Move>

pub fn can_castle(&self, side: Side) -> Option<Move>

impl Position

pub fn new(parts: Parts) -> Result<Self>

impl Position

pub const fn start() -> Position

pub const fn freestyle(i: Scharnagl) -> Position

impl Position

pub const fn board(&self) -> Board

pub const fn turn(&self) -> Player

pub const fn castles(&self) -> Castles

pub const fn en_passant(&self) -> Option<EnPassant>

pub const fn reversible(&self) -> u32

pub const fn round(&self) -> NonZeroU32

pub const fn checkers(&self) -> Bitboard

pub const fn is_check(&self) -> bool

impl Position

pub fn capture_moves(&self) -> Vec<Move>

pub fn castle_side_moves(&self, side: Side) -> Vec<Move>

pub fn castle_moves(&self) -> Vec<Move>

impl Position

pub const fn parts(self) -> Parts

pub fn first_ply(&self) -> usize

Trait Implementations

impl Clone for Position

fn clone(&self) -> Position

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Position

impl Debug for Position

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

Formats the value using the given formatter.

impl Eq for Position

impl From<Position> for Game

fn from(position: Position) -> Self

Converts to this type from the input type.

impl From<Position> for Parts

fn from(position: Position) -> Self

Converts to this type from the input type.

impl Ord for Position

fn cmp(&self, other: &Position) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Position

fn eq(&self, other: &Position) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Position

fn partial_cmp(&self, other: &Position) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Position