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Start to implement a Position struct
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,244 @@ | ||
| use std::str::FromStr; | ||
|
|
||
| use crate::{Bitboard, CastleRights, Color, Error, File, Piece, Rank, Square}; | ||
|
|
||
| #[derive(Debug, Clone)] | ||
| pub struct Position { | ||
| pieces: [Bitboard; Piece::NUM_PIECES], | ||
| color_combined: [Bitboard; Color::NUM_COLORS], | ||
| side_to_move: Color, | ||
| castle_rights: [CastleRights; Color::NUM_COLORS], | ||
| en_passant: Option<Square>, | ||
| halfmove_clock: u8, | ||
| } | ||
|
|
||
| impl Position { | ||
| #[must_use] | ||
| pub fn piece_on(&self, sq: Square) -> Option<Piece> { | ||
| Piece::ALL | ||
| .into_iter() | ||
| .find(|&piece| self.pieces[piece.as_index()] & sq != Bitboard::EMPTY) | ||
| } | ||
|
|
||
| #[must_use] | ||
| pub fn color_on(&self, sq: Square) -> Option<Color> { | ||
| Color::ALL | ||
| .into_iter() | ||
| .find(|&color| self.color_combined[color.as_index()] & sq != Bitboard::EMPTY) | ||
| } | ||
|
|
||
| pub const STARTING_POSITION_FEN: &str = | ||
| "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"; | ||
| } | ||
|
|
||
| impl Default for Position { | ||
| fn default() -> Self { | ||
| Position::from_str(Position::STARTING_POSITION_FEN).unwrap() | ||
| } | ||
| } | ||
|
|
||
| impl FromStr for Position { | ||
| type Err = Error; | ||
|
|
||
| fn from_str(value: &str) -> Result<Self, Self::Err> { | ||
| let mut board = [None; Square::NUM_SQUARES]; | ||
| let invalid_fen = || Error::InvalidFen(value.to_string()); | ||
|
|
||
| let tokens: Vec<&str> = value.split(' ').collect(); | ||
| if tokens.len() < 4 { | ||
| return Err(invalid_fen()); | ||
| } | ||
|
|
||
| let pieces = tokens[0]; | ||
| let side = tokens[1]; | ||
| let castles = tokens[2]; | ||
| let ep = tokens[3]; | ||
| let halfmove = tokens[4]; | ||
| let mut cur_rank = Rank::R8; | ||
| let mut cur_file = File::A; | ||
|
|
||
| for x in pieces.chars() { | ||
| match x { | ||
| '/' => { | ||
| cur_rank = cur_rank | ||
| .down() | ||
| .ok_or_else(|| Error::InvalidFen(value.to_string()))?; | ||
| cur_file = File::A; | ||
| } | ||
| '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' => { | ||
| cur_file = File::new( | ||
| u8::try_from(cur_file.0 as usize + (x as usize) - ('0' as usize)) | ||
| .map_err(|_| invalid_fen())? | ||
| % 8, | ||
| ) | ||
| .map_err(|_| invalid_fen())?; | ||
| } | ||
| x => { | ||
| let (piece, color) = match x { | ||
| 'r' => (Piece::Rook, Color::Black), | ||
| 'R' => (Piece::Rook, Color::White), | ||
| 'n' => (Piece::Knight, Color::Black), | ||
| 'N' => (Piece::Knight, Color::White), | ||
| 'b' => (Piece::Bishop, Color::Black), | ||
| 'B' => (Piece::Bishop, Color::White), | ||
| 'q' => (Piece::Queen, Color::Black), | ||
| 'Q' => (Piece::Queen, Color::White), | ||
| 'k' => (Piece::King, Color::Black), | ||
| 'K' => (Piece::King, Color::White), | ||
| 'p' => (Piece::Pawn, Color::Black), | ||
| 'P' => (Piece::Pawn, Color::White), | ||
| _ => { | ||
| return Err(invalid_fen()); | ||
| } | ||
| }; | ||
| board[Square::make_square(cur_rank, cur_file).as_index()] = | ||
| Some((piece, color)); | ||
| cur_file = cur_file.right().unwrap_or(File::A); | ||
| } | ||
| } | ||
| } | ||
| let side_to_move = match side { | ||
| "w" | "W" => Color::White, | ||
| "b" | "B" => Color::Black, | ||
| _ => { | ||
| return Err(invalid_fen()); | ||
| } | ||
| }; | ||
|
|
||
| let mut castle_rights = [CastleRights::None; Color::NUM_COLORS]; | ||
| if castles.contains('K') && castles.contains('Q') { | ||
| castle_rights[Color::White.as_index()] = CastleRights::Both; | ||
| } else if castles.contains('K') { | ||
| castle_rights[Color::White.as_index()] = CastleRights::KingSide; | ||
| } else if castles.contains('Q') { | ||
| castle_rights[Color::White.as_index()] = CastleRights::QueenSide; | ||
| } | ||
|
|
||
| if castles.contains('k') && castles.contains('q') { | ||
| castle_rights[Color::Black.as_index()] = CastleRights::Both; | ||
| } else if castles.contains('k') { | ||
| castle_rights[Color::Black.as_index()] = CastleRights::KingSide; | ||
| } else if castles.contains('q') { | ||
| castle_rights[Color::Black.as_index()] = CastleRights::QueenSide; | ||
| } | ||
|
|
||
| let ep_square = Square::from_str(ep).ok(); | ||
|
|
||
| let halfmove_clock = halfmove.parse::<u8>().map_err(|_| invalid_fen())?; | ||
|
|
||
| let mut pieces = [Bitboard(0); Piece::NUM_PIECES]; | ||
| let mut color_combined = [Bitboard(0); Color::NUM_COLORS]; | ||
| for (&piece, sq) in board.iter().zip(Square::ALL_SQUARES) { | ||
| if let Some((piece, color)) = piece { | ||
| pieces[piece.as_index()] |= sq; | ||
| color_combined[color.as_index()] |= sq; | ||
| } | ||
| } | ||
|
|
||
| Ok(Position { | ||
| pieces, | ||
| color_combined, | ||
| side_to_move, | ||
| castle_rights, | ||
| en_passant: ep_square, | ||
| halfmove_clock, | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| impl std::fmt::Display for Position { | ||
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { | ||
| for rank in Rank::ALL.into_iter().rev() { | ||
| let mut empty = 0; | ||
| for file in File::ALL { | ||
| let sq = Square::make_square(rank, file); | ||
| match self.piece_on(sq) { | ||
| None => empty += 1, | ||
| Some(piece) => { | ||
| if empty > 0 { | ||
| write!(f, "{empty}")?; | ||
| empty = 0; | ||
| } | ||
| let color = self.color_on(sq).unwrap(); | ||
| let c = piece.as_char(); | ||
| write!( | ||
| f, | ||
| "{}", | ||
| if color == Color::Black { | ||
| c.to_ascii_lowercase() | ||
| } else { | ||
| c | ||
| } | ||
| )?; | ||
| } | ||
| } | ||
| } | ||
| if empty > 0 { | ||
| write!(f, "{empty}")?; | ||
| } | ||
| if rank != Rank::R1 { | ||
| write!(f, "/")?; | ||
| } | ||
| } | ||
|
|
||
| write!(f, " {} ", self.side_to_move)?; | ||
|
|
||
| match self.castle_rights { | ||
| [CastleRights::None, CastleRights::None] => write!(f, "-")?, | ||
| [white, black] => { | ||
| match white { | ||
| CastleRights::KingSide => write!(f, "K")?, | ||
| CastleRights::QueenSide => write!(f, "Q")?, | ||
| CastleRights::Both => write!(f, "KQ")?, | ||
| CastleRights::None => {} | ||
| } | ||
|
|
||
| match black { | ||
| CastleRights::KingSide => write!(f, "k")?, | ||
| CastleRights::QueenSide => write!(f, "q")?, | ||
| CastleRights::Both => write!(f, "kq")?, | ||
| CastleRights::None => {} | ||
| } | ||
| } | ||
| } | ||
|
|
||
| if let Some(ep) = self.en_passant { | ||
| write!(f, " {ep}")?; | ||
| } else { | ||
| write!(f, " -")?; | ||
| } | ||
|
|
||
| write!(f, " {}", self.halfmove_clock)?; | ||
| write!(f, " 1") // Full move clock, not stored here so just write 1 to be FEN-compliant. | ||
| } | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use super::*; | ||
|
|
||
| #[test] | ||
| fn test_from_str() { | ||
| for fen in [ | ||
| "2n1k3/8/8/8/8/8/8/2N1K3 w - - 0 1", | ||
| "5B2/6P1/1p6/8/1N6/kP6/2K5/8 w - - 0 1", | ||
| "6R1/P2k4/r7/5N1P/r7/p7/7K/8 w - - 0 1", | ||
| "7K/8/k1P5/7p/8/8/8/8 w - - 0 1", | ||
| "7k/8/8/8/8/8/8/7K w - - 0 1", | ||
| "8/5k2/3p4/1pPPp2p/pP2Pp1P/P4P1K/8/8 b - b6 99 1", | ||
| "8/8/7p/3KNN1k/2p4p/8/3P2p1/8 w - - 0 1", | ||
| "r4rk1/1pp2ppp/3b4/3P4/3p4/3B4/1PP2PPP/R4RK1 b - - 0 1", | ||
| "rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b - - 1 1", | ||
| "rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 1", | ||
| "rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b Kkq - 1 1", | ||
| "rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R w kq - 10 1", | ||
| "rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 1", | ||
| "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1", | ||
| "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1", | ||
| ] { | ||
| let pos = Position::from_str(fen).unwrap(); | ||
| assert_eq!(pos.to_string(), fen); | ||
| println!("{pos}"); | ||
| } | ||
| } | ||
| } |
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