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//! Additional common utilities
use core::fmt::Display;
use crate::*;
#[cfg(test)]
mod tests;
/// Parses a UCI move into a [`Move`].
///
/// This differs from [`Move`]'s [`FromStr`](core::str::FromStr) implementation in that
/// it converts the standard UCI castling notation to the king-captures-rook
/// notation that `cozy-chess` uses (e.g. `e1g1` parses as `e1h1`).
///
/// # Examples
///
/// ```
/// # use cozy_chess::*;
/// # use cozy_chess::util::*;
/// let board: Board = "rnbqkb1r/ppp2ppp/4pn2/3p4/8/5NP1/PPPPPPBP/RNBQK2R w KQkq - 0 4"
/// .parse().unwrap();
/// assert_eq!(
/// parse_uci_move(&board, "e1g1").unwrap(),
/// "e1h1".parse::<Move>().unwrap()
/// );
/// ```
pub fn parse_uci_move(board: &Board, mv: &str) -> Result<Move, MoveParseError> {
let mut mv: Move = mv.parse()?;
let first_rank = Rank::First.relative_to(board.side_to_move());
let uci_castle_start = Square::new(File::E, first_rank);
let uci_castle_short = Square::new(File::G, first_rank);
let uci_castle_long = Square::new(File::C, first_rank);
let rights = board.castle_rights(board.side_to_move());
if board.king(board.side_to_move()) == mv.from && mv.from == uci_castle_start {
if mv.to == uci_castle_short {
if let Some(rook_file) = rights.short {
mv.to = Square::new(rook_file, first_rank);
}
}
if mv.to == uci_castle_long {
if let Some(rook_file) = rights.long {
mv.to = Square::new(rook_file, first_rank);
}
}
}
Ok(mv)
}
/// Returns an object that allows printing a [`Move`] in UCI format.
///
/// This differs from [`Move`]'s [`Display`] implementation in that
/// it converts the king-captures-rook notation that `cozy-chess`
/// uses to standard UCI castling (e.g. `e1h1` displays as `e1g1`).
///
/// # Examples
///
/// ```
/// # use cozy_chess::*;
/// # use cozy_chess::util::*;
/// let board: Board = "rnbqkb1r/ppp2ppp/4pn2/3p4/8/5NP1/PPPPPPBP/RNBQK2R w KQkq - 0 4"
/// .parse().unwrap();
/// let castle: Move = "e1h1".parse().unwrap();
/// assert_eq!(format!("{}", display_uci_move(&board, castle)), "e1g1");
/// ```
pub fn display_uci_move(board: &Board, mv: Move) -> impl core::fmt::Display {
let mut mv = mv;
let first_rank = Rank::First.relative_to(board.side_to_move());
let rights = board.castle_rights(board.side_to_move());
let frc_castle_short = rights.short.map(|f| Square::new(f, first_rank));
let frc_castle_long = rights.long.map(|f| Square::new(f, first_rank));
if board.king(board.side_to_move()) == mv.from {
if Some(mv.to) == frc_castle_short {
mv.to = Square::new(File::G, first_rank);
}
if Some(mv.to) == frc_castle_long {
mv.to = Square::new(File::C, first_rank);
}
}
mv
}
/// Parses a Standard Algebraic Notation move into a [`Move`].
///
/// Canonical SAN is guaranteed to parse correctly, but non-canonical SAN may or may not parse.
/// The returned move is always legal.
///
/// # Examples
///
/// ```
/// # use cozy_chess::*;
/// # use cozy_chess::util::*;
/// let board: Board = "3k2n1/7P/Q3p3/4BPp1/Q1Q4q/8/5B2/R3K2R w KQ g6 0 1"
/// .parse().unwrap();
/// let mv: Move = "h7g8r".parse().unwrap();
/// assert_eq!(parse_san_move(&board, "hxg8=R").unwrap(), mv);
/// let mv: Move = "e1a1".parse().unwrap();
/// assert_eq!(parse_san_move(&board, "O-O-O+").unwrap(), mv);
/// let mv: Move = "e5d4".parse().unwrap();
/// assert_eq!(parse_san_move(&board, "Bd4").unwrap(), mv);
/// ```
pub fn parse_san_move(board: &Board, mv: &str) -> Result<Move, MoveParseError> {
// SAN is easier to parse backwards
let mut chars = mv.chars().rev().peekable();
// Ignore check/checkmate character, we don't need it
chars.next_if(|&c| c == '+' || c == '#');
let dst;
let src_rank: Option<Rank>;
let src_file: Option<File>;
let piece;
let promotion;
if chars.next_if_eq(&'O').is_some() {
// Castles
chars.next_if_eq(&'-').ok_or(MoveParseError)?;
chars.next_if_eq(&'O').ok_or(MoveParseError)?;
let rook_file = if chars.next_if_eq(&'-').is_some() {
chars.next_if_eq(&'O').ok_or(MoveParseError)?;
board.castle_rights(board.side_to_move()).long
} else {
board.castle_rights(board.side_to_move()).short
};
dst = Square::new(
rook_file.ok_or(MoveParseError)?,
board.king(board.side_to_move()).rank(),
);
piece = Piece::King;
src_file = None;
src_rank = None;
promotion = None;
} else {
// Non-castles
promotion = chars
.peek()
.filter(|&c| c.is_ascii_uppercase())
.and_then(|&c| c.to_ascii_lowercase().try_into().ok());
if promotion.is_some() {
// Consume promotion character
chars.next();
// Consume optional '='
chars.next_if_eq(&'=');
}
// Destination square
let dst_rank = chars
.next()
.and_then(|c| c.try_into().ok())
.ok_or(MoveParseError)?;
let dst_file = chars
.next()
.and_then(|c| c.try_into().ok())
.ok_or(MoveParseError)?;
dst = Square::new(dst_file, dst_rank);
// Consume optional captures
chars.next_if_eq(&'x');
// Source square
src_rank = chars.peek().and_then(|&c| c.try_into().ok());
if src_rank.is_some() {
chars.next();
}
src_file = chars.peek().and_then(|&c| c.try_into().ok());
if src_file.is_some() {
chars.next();
}
// Piece
piece = chars.next().map_or(Ok(Piece::Pawn), |c| {
c.is_ascii_uppercase()
.then_some(c.to_ascii_lowercase())
.ok_or(MoveParseError)?
.try_into()
.map_err(|_| MoveParseError)
})?;
}
if chars.next().is_some() {
// too many characters
return Err(MoveParseError);
}
let mut src_mask = board.colored_pieces(board.side_to_move(), piece);
if let Some(src_rank) = src_rank {
src_mask &= src_rank.bitboard();
}
if let Some(src_file) = src_file {
src_mask &= src_file.bitboard();
}
let mut mv = None;
board.generate_moves_for(src_mask, |mut mvs| {
mvs.to &= dst.bitboard();
for m in mvs {
if m.promotion != promotion {
continue;
}
if mv.is_some() {
// ambiguous; error out
mv = None;
return true;
}
mv = Some(m);
}
false
});
mv.ok_or(MoveParseError)
}
/// Returns an object that allows printing a [`Move`] in Standard Algebraic Notation.
///
/// # Panics
/// This is guaranteed to panic if the move is illegal.
///
/// # Examples
///
/// ```
/// # use cozy_chess::*;
/// # use cozy_chess::util::*;
/// let board: Board = "3k2n1/7P/Q3p3/4BPp1/Q1Q4q/8/5B2/R3K2R w KQ g6 0 1"
/// .parse().unwrap();
/// let mv: Move = "h7g8r".parse().unwrap();
/// assert_eq!(format!("{}", display_san_move(&board, mv)), "hxg8=R+");
/// let mv: Move = "e1a1".parse().unwrap();
/// assert_eq!(format!("{}", display_san_move(&board, mv)), "O-O-O+");
/// let mv: Move = "e5d4".parse().unwrap();
/// assert_eq!(format!("{}", display_san_move(&board, mv)), "Bd4");
/// ```
pub fn display_san_move(board: &Board, mv: Move) -> impl Display {
let mut after_board = board.clone();
after_board.play(mv);
let check = !after_board.checkers().is_empty();
let checkmate = check && !after_board.generate_moves(|_| true);
let piece = board.piece_on(mv.from).unwrap();
let captures = board.occupied().len() > after_board.occupied().len();
let first_rank = Rank::First.relative_to(board.side_to_move());
let rights = board.castle_rights(board.side_to_move());
let castle_short = rights.short.map(|f| Square::new(f, first_rank));
let castle_long = rights.long.map(|f| Square::new(f, first_rank));
if piece == Piece::King && Some(mv.to) == castle_short || Some(mv.to) == castle_long {
return SanDisplay {
piece: None,
from_file: None,
from_rank: None,
captures,
to_sq: mv.to,
promotion: None,
check,
checkmate,
long_castles: Some(mv.to) == castle_long,
short_castles: Some(mv.to) == castle_short,
};
}
let mut file_disambiguates = true;
let mut rank_disambiguates = true;
let mut ambiguous = false;
board.generate_moves_for(board.colored_pieces(board.side_to_move(), piece), |mvs| {
if mvs.from != mv.from && mvs.to.has(mv.to) {
ambiguous = true;
if mvs.from.file() == mv.from.file() {
file_disambiguates = false;
}
if mvs.from.rank() == mv.from.rank() {
rank_disambiguates = false;
}
}
false
});
if piece == Piece::Pawn && captures {
ambiguous = true;
}
let (from_file, from_rank) = match (ambiguous, file_disambiguates, rank_disambiguates) {
(false, _, _) => (None, None),
(true, true, _) => (Some(mv.from.file()), None),
(true, false, false) => (Some(mv.from.file()), Some(mv.from.rank())),
(true, false, true) => (None, Some(mv.from.rank())),
};
SanDisplay {
piece: (piece != Piece::Pawn).then_some(piece),
from_file,
from_rank,
captures,
to_sq: mv.to,
promotion: mv.promotion,
check,
checkmate,
long_castles: false,
short_castles: false,
}
}
struct SanDisplay {
piece: Option<Piece>,
from_file: Option<File>,
from_rank: Option<Rank>,
captures: bool,
to_sq: Square,
promotion: Option<Piece>,
check: bool,
checkmate: bool,
long_castles: bool,
short_castles: bool,
}
impl Display for SanDisplay {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
if self.long_castles {
write!(f, "O-O-O")?;
} else if self.short_castles {
write!(f, "O-O")?;
} else {
if let Some(piece) = self.piece {
write!(f, "{}", char::to_ascii_uppercase(&piece.into()))?;
}
if let Some(file) = self.from_file {
write!(f, "{file}")?;
}
if let Some(rank) = self.from_rank {
write!(f, "{rank}")?;
}
if self.captures {
write!(f, "x")?;
}
write!(f, "{}", self.to_sq)?;
if let Some(promo) = self.promotion {
write!(f, "={}", char::to_ascii_uppercase(&promo.into()))?;
}
}
if self.checkmate {
write!(f, "#")?;
} else if self.check {
write!(f, "+")?;
}
Ok(())
}
}