pgn-reader

A fast non-allocating reader chess games in PGN notation, as a Rust library.

Introduction

Reader parses games and calls methods of a user provided Visitor. Implementing custom visitors allows for maximum flexibility:

• The reader itself does not allocate. The visitor can decide if and how to represent games in memory.
• The reader does not validate move legality. This allows implementing support for custom chess variants, or delaying move validation.
• The visitor can signal to the reader that it does not care about a game or variation.

Example

A visitor that counts the number of syntactically valid moves in the mainline of each game.

```rust extern crate pgn_reader;

use pgn_reader::{Visitor, Skip, Reader, San};

struct MoveCounter { moves: usize, }

impl MoveCounter { fn new() -> MoveCounter { MoveCounter { moves: 0 } } }

impl<'pgn> Visitor<'pgn> for MoveCounter { type Result = usize;

fn begin_game(&mut self) {
    self.moves = 0;
}

fn san(&mut self, _san: San) {
    self.moves += 1;
}

fn begin_variation(&mut self) -> Skip {
    Skip(true) // stay in the mainline
}

fn end_game(&mut self, _game: &'pgn [u8]) -> Self::Result {
    self.moves
}

}

fn main() { let pgn = b"1. e4 e5 2. Nf3 (2. f4) { game paused due to bad weather } 2... Nf6 *";

let mut counter = MoveCounter::new();
let reader = Reader::new(&mut counter, pgn);

let moves: usize = reader.into_iter().sum();
assert_eq!(moves, 4);

} ```

Documentation

Read the documentation

Bechmarks

Run with lichessdbstandardrated2014-07.pgn (1,048,440 games, 1000 MB uncompressed) on an SSD, Intel i7-5500U CPU @ 2.40GHz.

Benchmark | Time | Throughput --- | --- | --- examples/stats.rs | 4.0s | 249.4 MB/s examples/validate.rs | 10.2s | 98.0 MB/s examples/lichess4545.rs | 1.6s | 625.0 MB/s scoutfish make | 10.9s | 96.1 MB/s grep -F "[Event " -c | 1.1s | 909.1 MB/s

License

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