shakmaty

A Rust library for chess move generation

Features

• Generate legal moves:

  use shakmaty::{Chess, Position};
  
  let pos = Chess::default();
  let legals = pos.legal_moves();
  assert_eq!(legals.len(), 20);

• Play moves:

  use shakmaty::{Square, Move, Role};
  
  // 1. e4
  let pos = pos.play(&Move::Normal {
      role: Role::Pawn,
      from: Square::E2,
      to: Square::E4,
      capture: None,
      promotion: None,
  })?;

• Detect game end conditions: pos.is_checkmate(), pos.is_stalemate(), pos.is_insufficient_material(), pos.outcome().

• Read and write FENs, SANs and UCIs.

• Supports all Lichess variants: Standard chess, Chess960, Antichess, Atomic, King of the Hill, Three-Check, Crazyhouse, Racing Kings and Horde. Provides vocabulary to implement other variants.

• Bitboards and compact fixed shift magic attack tables.

• Probe Syzygy tablebases with shakmaty-syzygy.

Documentation

Read the documentation

Benchmarks

Simple perft of the initial position. No hashtables. i7-6850K CPU @ 3.60GHz.

perft	4	5
shakmaty 0.16.0	1.0 ms	24.1 ms
jordanbray/chess 3.1.1	0.8 ms	18.6 ms
Stockfish 8 (x86-64-bmi2)	4 ms	33 ms

It should be noted that Stockfish is not optimized for perft speed and also maintains additional data structures for evaluation. Newer versions of Stockfish put even less emphasis on this.

Changelog

• 0.19.0
  • Update arrayvec to 0.7.x. MoveList is now using const generics.
  • Derive Hash for Move, Outcome, and Fen.
  • Eliminate unsafe usage where no longer required for performance. Justify remaining cases.
• 0.18.0
  • Remove f32, f64, u128, and i128 conversions.
  • Use std::num::TryFromIntError.
  • Functions now return MoveList instead of using it as an out parameter. Return value optimization by hand is no longer required.
  • Introduce ByColor, used as Material and ByColor<RemainingChecks>.
  • Introduce PlayError.
  • Renamed variants module to variant. Now gated behind a non-default feature variant.
• 0.17.2
  • Parse Uci::to_move() where king captures unmoved rook.
• 0.17.1
  • Also reject checker aligned with king and en passant square with PositionErrorKinds::IMPOSSIBLE_CHECK.
• 0.17.0
  • Introduce CastlingMode, now required for FromSetup::from_setup(..., mode), the VariantPosition analogon, Fen::position(mode), and exposed by Castles::mode().
  • Uci::from_move() now takes the mode as context instead of the position. Give pos.castles().mode() for the old behavior.
  • Add Uci::from_standard().
  • Rework PositionError. The original error kinds are available as PositionError::kinds(). There are now methods to safely ignore particular errors.
  • Reject setups with impossible (i.e., too much) material with the new PositionErrorKinds::IMPOSSIBLE_MATERIAL. Can be ignored using PositionError::ignore_impossible_material() for the previous behavior.
  • Reject setups with multiple aligned sliding checkers with the new PositionErrorKinds::IMPOSSIBLE_CHECK.
  • Rename BAD_CASTLING_RIGHTS to INVALID_CASTLING_RIGHTS.
  • Remove IllegalMoveError. In the context of UCI validation, replace with IllegalUciError. Position::play() instead returns the original position as the error.
  • Change fullmoves from u32 to NonZeroU32 everywhere.
  • Remove public Castles::from_setup().
  • Remove Square::with_rank_of().
  • Remove Giveaway in favor of Antichess (where players start without castling rights).
  • Fix swap_turn() if en passant square exists. Would always fail, now discards the en passant square.
  • Add Move::to_uci() convenience method.
  • Add CastlingSide::{king,rook}_to_file().
  • Add Variant::distinguishes_promoted().
  • Add Variant::uci() and Variant::from_uci().
  • Future proof error types (remove some implemented traits and available constructors).
• 0.16.4
  • Fix insufficient material detection with same-color bishops on both sides.
  • Document limitations of Position::is_irreversible(). Moves that cede en passant are now considered irreversible.
• 0.16.3
  • Implement From<Role> for nonzero integer types.
  • Performance: Remove internal BB_BETWEEN table and compute it from rays at runtime, to improve cache efficiency.
  • Support Miri.
• 0.16.2
  • Fix Racing Kings game end detection: Black cannot catch up if their own pieces block the goal.
  • Pawn drops in Crazyhouse are now considered zeroing.
• 0.16.1
  • Fix (impossible) Crazyhouse insufficient material.
  • Fix (impossible) castling rights of exploded king in Atomic chess.
• 0.16.0
  • Update arrayvec to 0.5.x, which comes with significant performance improvements.
  • The default Giveaway position now has castling rights.
• 0.15.3
  • Follow FICS rules in Atomic castling edge cases.
  • Use #[repr(align)] enum and reverse_bits() stabilized in Rust 1.37.
• 0.15.2
  • In Horde chess, allow double pawn moves from the first rank.
  • Added {Square,Bitboard}::{flip_anti_diagonal,rotate_90,rotate_180,rotate_270}().
• 0.15.1
  • FEN parser was expecting ~ before promoted pieces, but it should be after.
• 0.15.0
  • Moved Position::from_setup() to a seperate new trait FromSetup.
  • Square and file/rank index calculations are now performed with u32 and i32, which is more performant than using the narrower types u8 and i8. The types are still #[repr(u8)].
  • Renamed Square::combine() to Square::with_rank_of().
  • Added Fen::from_setup().
  • Added FenOpts::scid() for Scid/Lichess compatible FEN formatting. Of course the parser also accepts these formats.
  • Added variant::Variant and VariantPosition for runtime selected chess variants. Limited to the built in variants.
  • Added {Material,MaterialSide}::is_empty().
• 0.14.1
  • TryFrom now available on stable.
• 0.14.0
  • SanPlus::from_move() no longer requires the move to be legal, which was an undocumented requirement. The new SanPlus::from_move_and_play_unchecked() is closest to the previous behavior.
  • Added San::disambiguate() and SanSuffix::from_position().
  • Implement TryFrom for various types on nightly.
  • Implement Add, AddAssign, Sub, SubAssign for Material and MaterialSide.
  • Added CastlingSide::from_{king|queen}_side().
  • Use u32 for depth argument of perft().
• 0.13.1
  • Performance improvements on nightly (aligned Move enum).
• 0.13.0
  • Replaced SanPlus::check and SanPlus::checkmate with san::Suffix enum.
  • Renamed {Rank,File}::rotate() to flip_diagonal().
  • Renamed Bitboard::flip() to toggle().
  • Added Square::coords().
  • Added Bitboard::flip_{vertical,horizontal,diagonal}().
  • Added Position::promotion_moves().
  • Derive Hash on Board, FenOpts, San, SanPlus, Suffix, Color, Role, Piece, RemainingChecks, CastlingSide, and Uci.
  • Minimum Rust version 1.31.0.
• 0.12.0
  • Setup::halfmove_clock() is now Setup::halfmoves().
  • New conversions: f32::from(file), f64::from(rank).
  • Replace Pockets and Pocket by more general Material and MaterialSide. Note that their Display and FromStr implementations differ.
  • Unify naming of error types.
• 0.11.2
  • Fix Atomic insufficient material: KQN can mate.
• 0.11.1
  • Fix Chess960 should not allow a-side castling over a blocking h-side rook.
• 0.11.0
  • Outcome is now Copy.
  • Position::castling_uncovers_rank_attack() is no longer public.
• 0.10.0
  • Add File, Rank. These are now returned by Square::{file, rank}. Square::from_coords(file, rank) takes the new types and is no longer fallible.
  • Bitboard is now IntoIterator instead of Iterator itself. Methods Bitboard::{first, last, count, is_empty} remain.
  • Bitboard::{add, flip, discard, with, without} are now generic over Into<Bitboard>. Alternative methods *_all have been removed.
  • Bitboard::relative_shift(color, shift: u8) now takes u32.
  • shakmaty::CarryRippler is now shakmaty::bitboard::CarryRippler.
  • Add new methods: Bitboard::{pop_front, pop_back, is_disjoint, is_subset, is_superset}.
  • Add Position::has_insufficient_material(color).
• 0.9.0
  • Remove uci, chess960_uci, san and san_plus that were deprecated in 0.8.1.
  • Rename *::from_bytes() to *::from_ascii().
  • Take small copy types by value: Piece::char(), CastlingSide::*.
  • Add Castles::has(color, side).
  • fen::{board_fen, epd, fen} are now shortcuts for formatting with default options.
  • Minimum rust version 1.27.0 (i128 conversions again, fused iterators again, Option::filter(), dyn Trait).
  • Eliminate many uses of unsafe, including TrustedLen impls, at minor cost.
• 0.8.1
  • Make Role discriminants public.
  • Put San, SanPlus and Uci constructors on San, SanPlus and Uci respectively.
• 0.8.0
  • Revert fused iterators and u128. Minimum Rust version back to 1.23.0.
  • Change Role discriminants. Now starting with Pawn = 1.
  • Performance improvements (~12% faster perft).
  • Switch benchmarks to criterion.rs.
• 0.7.2
  • Add Outcome.winner().
• 0.7.1
  • Minimum Rust version 1.26.0 (fused iterators, u128 conversions).
• 0.7.0
  • Reintroduce the remaining Lichess variants: Crazyhouse, KingOfTheHill, ThreeCheck, Horde, RacingKings.
  • Expose Position.castles() and replace Position.is_chess960() with Position.castles().is_chess960().
  • Fix insufficient material: KNvK was not given as drawn due to a typo.
  • Fix insufficient material in Atomic: Two knights of different colors are not safe.
  • Let Pockets.count() and Pocket.count() return usize.
• 0.6.7
  • Giveaway starting position should have no castling rights.
• 0.6.6
  • Fix missing king promotions in Giveaway.
• 0.6.5
  • Validate color of missing king in atomic chess.
  • Clear move buffers before generating variant moves.
• 0.6.4
  • Reintroduce Giveaway and Atomic chess variants.
• 0.6.3
  • New method Move.is_zeroing().
• 0.6.2
  • Make unit error types (InvalidSquareName, InvalidUci, InvalidSan) completely public.
  • Documentation, coding style and debugging tweaks.
• 0.6.1
  • Expose attacks::bishop_mask and attacks::rook_mask.
  • Eliminate almost all unchecked indexing.
• 0.6.0
  • Split impl From<Move> for Uci into uci() and chess960_uci().
  • Fix display of pawn drops.
  • Move generating methods clear the move buffer (and therefor no longer panic on too full buffers).
  • Added Position.is_chess960(), Bitboard.without_all(), Role.upper_char(), Board.stepper().
• 0.5.1
  • Fix Uci::to_move() for en passant moves. Thanks zxqfl.
• 0.5.0
  • Use u64 instead of usize for perft().
  • Export error type InvalidSquareName.
  • New methods: CastlingSide.is_{queen|king}_side(), San.matches(), Move.is_capture(), Move.is_promotion(), Move.castling_side(), Position.is_check().
  • Derive Ord and PartialOrd for Role.
  • Support running benchmarks on stable.
• 0.4.2
  • Fix build error on beta due to the new nightly option_filter feature.
  • Fix unterminated code block in documentation.
• 0.4.1
  • Fix build error due to the new nightly option_filter feature.
• 0.4.0
  • Rename Color::from_bool() to Color::from_white(), add Color::from_black().
  • Add Move::role(), Move::is_en_passant() and Move::is_castle().
  • Add Position::en_passant_moves() and Position::capture_moves().
  • Implement BitXor<bool> for Color.
  • Implement FusedIterator and TrustedLen on Bitboard.
• 0.3.0
  • Switch to #[repr(i8)] for Square. Implement all lossless integer conversions From<Square>.
  • Add Square::flip_horizontal(), flip_vertical() and flip_diagonal().
  • Efficiently implement CarryRippler::last() by @nvzqz.
  • Eliminate some unchecked indexing by @nvzqz.
  • Faster ASCII case conversions and tests by @nvzqz.
• 0.2.0
  • Square is now a #[repr(u8)] enum.
  • Use bitflags for PositionError.
  • Rename RemainingChecks::subtract() to decrement().
  • Add Position::swap_turn().
• 0.1.0
  • First release with support for stable Rust.

License

Shakmaty is licensed under the GPL-3.0 (or any later version at your option). See the COPYING file for the full license text.