Pleco

Pleco is a Chess Library, containing the building blocks of the chess engine Stockfish, re-written entirely in Rust.

This project is split into two crates, pleco (the library you are currently in), which contains the library functionality, and pleco_engine, which contains the UCI (Universal Chess Interface) compatible Engine & AI.

The overall goal of pleco is to recreate the Stockfish engine in rust, for comparison and educational purposes. As such, the majority of the algorithms used here are a direct port of Stockfish's, and the credit for the majority of the code go directly to the maintainers and authors of Stockfish.

• Documentation
• crates.io

For the chess engine implemented using this library provided by pleco, see pleco_engine.

Features

Some of the features pleco implements:

• Bitboard Representation of Piece Locations:
• Ability for concurrent Board State access, for use by parallel searchers
• Full Move-generation Capabilities, including generation of pseudo-legal moves
• Statically computed lookup-tables (including Magic Bitboards)
• Zobrist Hashing
• A Transposition Table: lightning fast lookup table storing information for a board
• Pre-implemented searchers, some of which using rayon.rs for easy parallelism

Use

To use Pleco inside your own Rust projects, Pleco.rs is available as a library on crates.io. Pleco runs on all three distributions (nightly, beta, stable) of rust.

Basic Usage

Setting up a board position is extremely simple.

use pleco::{Board,Player,PieceType};

let board = Board::start_pos();
assert_eq!(board.count_piece(Player::White,PieceType::P), 8);
assert_eq!(&board.fen(),"rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");

Creating a board from a Position

A Board can be created with any valid chess position using a valid FEN (Forsyth-Edwards Notation) String. Check out the Wikipedia article for more information on FEN Strings and their format.

let board: Board = Board::from_fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2").unwrap();

Applying and Generating Moves

Moves are represented with a BitMove structure. They must be generated by a Board object directly, to be considered a valid move. Using Board::generate_moves() will generate all legal BitMoves of the current position for the current player.

use pleco::{Board,BitMove};

let mut board = Board::start_pos(); // create a board of the starting position
let moves = board.generate_moves(); // generate all possible legal moves
board.apply_move(moves[0]);
assert_eq!(board.moves_played(), 1);

We can ask the Board to apply a move to itself from a string. This string must follow the format of a standard UCI Move, in the format [src_sq][dst_sq][promo]. E.g., moving a piece from A1 to B3 would have a uci string of "a1b3", while promoting a pawn would look something like "e7e81". If the board is supplied a UCI move that is either incorrectly formatted or illegal, false shall be returned.

let mut board = Board::start_pos(); // create a board of the starting position
let success = board.apply_uci_move("e7e8q"); // apply a move where piece on e7 -> eq, promotes to queen
assert!(!success); // Wrong, not a valid move for the starting position

Undoing Moves

We can revert to the previous chessboard state with a simple Board::undo_move():

let mut board = Board::start_pos();
board.apply_uci_move("e2e4"); // A very good starting move, might I say
assert_eq!(board.moves_played(),1);
board.undo_move();
assert_eq!(board.moves_played(),0);

Features

If on nightly rust, the feature "nightly" is available. This enables some nightly optimizations and speed improvements.

Usage is as easy as updating your cargo.toml to include:

[dependencies]
pleco = {version = "*", features = ["nightly"]}

Contributing

Any and all contributions are welcome! Open up a PR to contribute some improvements. Look at the Issues tab to see what needs some help.

License

Pleco is distributed under the terms of the MIT license. See LICENSE-MIT for details. Opening a pull requests is assumed to signal agreement with these licensing terms.