[position] Move castle evaluation code to its own submodule of position

Move the tests too.
This commit is contained in:
Eryn Wells 2025-05-19 16:59:13 -07:00
parent 54ac88aaf7
commit 97552302cb
3 changed files with 278 additions and 272 deletions

View file

@ -1,9 +1,11 @@
// Eryn Wells <eryn@erynwells.me>
mod castle;
mod make_move;
mod position;
pub use {
castle::CastleEvaluationError,
make_move::{MakeMoveError, ValidateMove},
position::{CastleEvaluationError, Position},
position::Position,
};

View file

@ -0,0 +1,241 @@
// Eryn Wells <eryn@erynwells.me>
use crate::Position;
use chessfriend_core::{Color, Piece, Square, Wing};
use thiserror::Error;
#[derive(Clone, Copy, Debug, Error, Eq, PartialEq)]
pub enum CastleEvaluationError {
#[error("{color} does not have the right to castle {wing}")]
NoRights { color: Color, wing: Wing },
#[error("no king")]
NoKing,
#[error("no rook")]
NoRook,
#[error("castling path is not clear")]
ObstructingPieces,
#[error("opposing pieces check castling path")]
CheckingPieces,
}
impl Position {
/// Evaluates whether the active color can castle toward the given wing of the board in the
/// current position.
///
/// ## Errors
///
/// Returns an error indicating why the active color cannot castle.
pub fn active_color_can_castle(&self, wing: Wing) -> Result<(), CastleEvaluationError> {
// TODO: Cache this result. It's expensive!
let active_color = self.board.active_color;
if !self
.board
.castling_rights
.color_has_right(active_color, wing)
{
return Err(CastleEvaluationError::NoRights {
color: active_color,
wing,
});
}
let parameters = self.board.castling_parameters(wing);
if self.castling_king(parameters.origin.king).is_none() {
return Err(CastleEvaluationError::NoKing);
}
if self.castling_rook(parameters.origin.rook).is_none() {
return Err(CastleEvaluationError::NoRook);
}
// All squares must be clear.
let has_obstructing_pieces = (self.board.occupancy() & parameters.clear).is_populated();
if has_obstructing_pieces {
return Err(CastleEvaluationError::ObstructingPieces);
}
// King cannot pass through check.
let opposing_sight = self.opposing_sight();
let opposing_pieces_can_see_castling_path =
(parameters.check & opposing_sight).is_populated();
if opposing_pieces_can_see_castling_path {
return Err(CastleEvaluationError::CheckingPieces);
}
Ok(())
}
pub(crate) fn castling_king(&self, square: Square) -> Option<Piece> {
self.get_piece(square).and_then(|piece| {
if piece.color == self.board.active_color && piece.is_king() {
Some(piece)
} else {
None
}
})
}
pub(crate) fn castling_rook(&self, square: Square) -> Option<Piece> {
self.get_piece(square).and_then(|piece| {
if piece.color == self.board.active_color && piece.is_rook() {
Some(piece)
} else {
None
}
})
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_position;
use chessfriend_core::{piece, Color, Wing};
#[test]
fn king_on_starting_square_can_castle() {
let pos = test_position!(
White King on E1,
White Rook on A1,
White Rook on H1
);
let rights = pos.board.castling_rights;
assert!(rights.color_has_right(Color::White, Wing::KingSide));
assert!(rights.color_has_right(Color::White, Wing::QueenSide));
}
#[test]
fn king_for_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
];
let kingside_parameters = pos.board.castling_parameters(Wing::KingSide);
assert_eq!(
pos.castling_king(kingside_parameters.origin.king),
Some(piece!(White King))
);
let queenside_parameters = pos.board.castling_parameters(Wing::QueenSide);
assert_eq!(
pos.castling_king(queenside_parameters.origin.king),
Some(piece!(White King))
);
}
#[test]
fn rook_for_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
];
let kingside_parameters = pos.board.castling_parameters(Wing::KingSide);
assert_eq!(
pos.castling_rook(kingside_parameters.origin.rook),
Some(piece!(White Rook))
);
let pos = test_position![
White King on E1,
White Rook on A1,
];
let queenside_parameters = pos.board.castling_parameters(Wing::QueenSide);
assert_eq!(
pos.castling_rook(queenside_parameters.origin.rook),
Some(piece!(White Rook))
);
}
#[test]
fn white_can_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
];
assert_eq!(pos.active_color_can_castle(Wing::KingSide), Ok(()));
assert_eq!(pos.active_color_can_castle(Wing::QueenSide), Ok(()));
}
#[test]
fn white_cannot_castle_missing_king() {
let pos = test_position![
White King on E2,
White Rook on H1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::NoKing)
);
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::NoKing)
);
}
#[test]
fn white_cannot_castle_missing_rook() {
let pos = test_position![
White King on E1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::NoRook)
);
let pos = test_position![
White King on E1,
White Rook on H1,
];
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::NoRook)
);
}
#[test]
fn white_cannot_castle_obstructing_piece() {
let pos = test_position![
White King on E1,
White Bishop on F1,
White Rook on H1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::ObstructingPieces)
);
assert_eq!(pos.active_color_can_castle(Wing::QueenSide), Ok(()));
}
#[test]
fn white_cannot_castle_checking_pieces() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
Black Queen on C6,
];
assert_eq!(pos.active_color_can_castle(Wing::KingSide), Ok(()));
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::CheckingPieces)
);
}
}

View file

@ -113,91 +113,6 @@ impl Position {
}
}
#[derive(Clone, Copy, Debug, Error, Eq, PartialEq)]
pub enum CastleEvaluationError {
#[error("{color} does not have the right to castle {wing}")]
NoRights { color: Color, wing: Wing },
#[error("no king")]
NoKing,
#[error("no rook")]
NoRook,
#[error("castling path is not clear")]
ObstructingPieces,
#[error("opposing pieces check castling path")]
CheckingPieces,
}
impl Position {
/// Evaluates whether the active color can castle toward the given wing of the board in the
/// current position.
///
/// ## Errors
///
/// Returns an error indicating why the active color cannot castle.
pub fn active_color_can_castle(&self, wing: Wing) -> Result<(), CastleEvaluationError> {
// TODO: Cache this result. It's expensive!
let active_color = self.board.active_color;
if !self
.board
.castling_rights
.color_has_right(active_color, wing)
{
return Err(CastleEvaluationError::NoRights {
color: active_color,
wing,
});
}
let parameters = self.board.castling_parameters(wing);
if self.castling_king(parameters.origin.king).is_none() {
return Err(CastleEvaluationError::NoKing);
}
if self.castling_rook(parameters.origin.rook).is_none() {
return Err(CastleEvaluationError::NoRook);
}
// All squares must be clear.
let has_obstructing_pieces = (self.board.occupancy() & parameters.clear).is_populated();
if has_obstructing_pieces {
return Err(CastleEvaluationError::ObstructingPieces);
}
// King cannot pass through check.
let opposing_sight = self.opposing_sight();
let opposing_pieces_can_see_castling_path =
(parameters.check & opposing_sight).is_populated();
if opposing_pieces_can_see_castling_path {
return Err(CastleEvaluationError::CheckingPieces);
}
Ok(())
}
fn castling_king(&self, square: Square) -> Option<Piece> {
self.get_piece(square).and_then(|piece| {
if piece.color == self.board.active_color && piece.is_king() {
Some(piece)
} else {
None
}
})
}
fn castling_rook(&self, square: Square) -> Option<Piece> {
self.get_piece(square).and_then(|piece| {
if piece.color == self.board.active_color && piece.is_rook() {
Some(piece)
} else {
None
}
})
}
}
/*
impl Position {
pub fn moves(&self) -> &Moves {
@ -242,28 +157,6 @@ impl Position {
self.board.en_passant().map(EnPassant::target_square)
}
fn _sight_of_player(&self, player: Color, board: &Board) -> BitBoard {
let en_passant_target_square = self._en_passant_target_square();
Shape::ALL
.iter()
.filter_map(|&shape| {
let piece = Piece::new(player, shape);
let bitboard = board.bitboard_for_piece(piece);
if !bitboard.is_empty() {
Some((piece, bitboard))
} else {
None
}
})
.flat_map(|(piece, bitboard)| {
bitboard.occupied_squares().map(move |square| {
PlacedPiece::new(piece, square).sight(board, en_passant_target_square)
})
})
.fold(BitBoard::empty(), |acc, sight| acc | sight)
}
pub(crate) fn moves_for_piece(&self, piece: &PlacedPiece) -> Option<&MoveSet> {
self.moves().moves_for_piece(piece)
}
@ -378,43 +271,31 @@ mod tests {
assert_eq!(pos.board.get_piece(Square::A8), Some(piece!(Black Rook)));
}
#[test]
fn king_is_in_check() {
let pos = position![
White King on E1,
Black Rook on E8,
];
assert!(pos.is_king_in_check());
}
// #[test]
// fn king_is_in_check() {
// let pos = position![
// White King on E1,
// Black Rook on E8,
// ];
// assert!(pos.is_king_in_check());
// }
#[test]
fn king_is_not_in_check() {
let pos = position![
White King on F1,
Black Rook on E8,
];
assert!(!pos.is_king_in_check());
}
// #[test]
// fn king_is_not_in_check() {
// let pos = position![
// White King on F1,
// Black Rook on E8,
// ];
// assert!(!pos.is_king_in_check());
// }
#[test]
fn king_not_on_starting_square_cannot_castle() {
let pos = test_position!(White King on E4);
assert!(!pos.player_can_castle(Color::White, Castle::KingSide));
assert!(!pos.player_can_castle(Color::White, Castle::QueenSide));
}
#[test]
fn king_on_starting_square_can_castle() {
let pos = test_position!(
White King on E1,
White Rook on A1,
White Rook on H1
);
let rights = pos.board.castling_rights;
assert!(rights.color_has_right(Color::White, Wing::KingSide));
assert!(rights.color_has_right(Color::White, Wing::QueenSide));
}
// #[test]
// fn king_not_on_starting_square_cannot_castle() {
// let pos = test_position!(White King on E4);
// let rights = pos.board.castling_rights;
// assert!(!rights.color_has_right(Color::White, Castle::KingSide));
// assert!(!rights.color_has_right(Color::White, Castle::QueenSide));
// }
#[test]
fn friendly_sight() {
@ -437,134 +318,16 @@ mod tests {
assert_eq!(sight, bitboard![A7 B7 C7 D7 F7 G7 H7 E8 E6 E5 E4]);
}
#[test]
fn king_for_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
];
// #[test]
// fn danger_squares() {
// let pos = test_position!(Black, [
// White King on E1,
// Black King on E7,
// White Rook on E4,
// ]);
let kingside_parameters = pos.board.castling_parameters(Wing::KingSide);
assert_eq!(
pos.castling_king(kingside_parameters.origin.king),
Some(piece!(White King))
);
let queenside_parameters = pos.board.castling_parameters(Wing::QueenSide);
assert_eq!(
pos.castling_king(queenside_parameters.origin.king),
Some(piece!(White King))
);
}
#[test]
fn rook_for_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
];
let kingside_parameters = pos.board.castling_parameters(Wing::KingSide);
assert_eq!(
pos.castling_rook(kingside_parameters.origin.rook),
Some(piece!(White Rook))
);
let pos = test_position![
White King on E1,
White Rook on A1,
];
let queenside_parameters = pos.board.castling_parameters(Wing::QueenSide);
assert_eq!(
pos.castling_rook(queenside_parameters.origin.rook),
Some(piece!(White Rook))
);
}
#[test]
fn white_can_castle() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
];
assert_eq!(pos.active_color_can_castle(Wing::KingSide), Ok(()));
assert_eq!(pos.active_color_can_castle(Wing::QueenSide), Ok(()));
}
#[test]
fn white_cannot_castle_missing_king() {
let pos = test_position![
White King on E2,
White Rook on H1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::NoKing)
);
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::NoKing)
);
}
#[test]
fn white_cannot_castle_missing_rook() {
let pos = test_position![
White King on E1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::NoRook)
);
let pos = test_position![
White King on E1,
White Rook on H1,
];
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::NoRook)
);
}
#[test]
fn white_cannot_castle_obstructing_piece() {
let pos = test_position![
White King on E1,
White Bishop on F1,
White Rook on H1,
White Rook on A1,
];
assert_eq!(
pos.active_color_can_castle(Wing::KingSide),
Err(CastleEvaluationError::ObstructingPieces)
);
assert_eq!(pos.active_color_can_castle(Wing::QueenSide), Ok(()));
}
#[test]
fn white_cannot_castle_checking_pieces() {
let pos = test_position![
White King on E1,
White Rook on H1,
White Rook on A1,
Black Queen on C6,
];
assert_eq!(pos.active_color_can_castle(Wing::KingSide), Ok(()));
assert_eq!(
pos.active_color_can_castle(Wing::QueenSide),
Err(CastleEvaluationError::CheckingPieces)
);
}
// let danger_squares = pos.king_danger(Color::Black);
// let expected = bitboard![D1 F1 D2 E2 F2 E3 A4 B4 C4 D4 F4 G4 H4 E5 E6 E7 E8];
// assert_eq_bitboards!(danger_squares, expected);
// }
}