pgn-reader

A fast non-allocating and streaming reader for 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 (besides a single fixed-size buffer). 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 std::io; use pgn_reader::{Visitor, Skip, BufferedReader, SanPlus};

struct MoveCounter { moves: usize, }

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

impl Visitor for MoveCounter { type Result = usize;

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

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

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

fn end_game(&mut self) -> Self::Result {
    self.moves
}

}

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

let mut reader = BufferedReader::new_cursor(&pgn[..]);

let mut counter = MoveCounter::new();
let moves = reader.read_game(&mut counter)?;

assert_eq!(moves, Some(4));
Ok(())

} ```

Documentation

Read the documentation

Benchmarks (v0.12.0)

Run with lichessdbstandardrated2018-10.pgn (24,784,600 games, 52,750 MB uncompressed) on an SSD (Samsung 850), Intel i7-6850K CPU @ 3.60 GHz:

Benchmark | Time | Throughput --- | --- | --- examples/stats.rs | 111.9s | 471.4 MB/s examples/validate.rs | 237.1s | 222.5 MB/s examples/parallel_validate.rs | 148.6s | 355.0 MB/s scoutfish make | 269.2s | 196.0 MB/s grep -F "[Event " -c | 39.2s | 1345.7 MB/s

examples/stats.rs with compressed files:

Compression | File size | Time | Throughput --- | --- | --- | --- none | 52,750 MB | 111.9s | 471.4 MB/s bz2 | 6,226 MB | 1263.1s | 4.9 MB/s xz | 6,989 MB | 495.9s | 14.1 MB/s gz | 10,627 MB | 335.7s | 31.7 MB/s lz4 | 16,428 MB | 180.0s | 91.3 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.