cm-pgn
Parser for PGNs (Portable Game Notation)
This is as ES6 Module for parsing and rendering of PGNs (Portable Game Notation).
The API is similar to history() of chess.js, but this module supports variations, nags and comments in the pgn.
We used the nice grammar file from PgnViewerJS of mliebelt to create the parser.
Install
npm install cm-pgn
Usage
Use the Pgn class as JS Module:
<script type="module">
import {Pgn} from "./PATH/TO/cm-pgn/src/Pgn.js"
// parse pgn
const pgn = new Pgn(`[Site "Berlin"]
[Date "1989.07.02"]
[White "Haack, Stefan"]
[Black "Maier, Karsten"]
1. e4 e5 (e6) 2. Nf3 $1 {Great move!} Nc6 *`)
</script>Pgn constructor
constructor(pgnString = "", props = {})
if you set { sloppy: true } in props, some non-standard move notations
will be accepted. See also .move(move, options) from chess.js.
Data structure
The pgn has a pgn.header and a pgn.history.
pgn.header
The header holds the PGN header elements in the key value object tags.
pgn.header.tags = {
Site: "Berlin",
Date: "1989.07.02",
White: "Haack, Stefan",
Black: "Maier, Karsten"
}pgn.history
The moves are stored in an array. Every element of that array has the following structure
pgn.history.moves[i] = {
color: "w", // the moving color
fen: "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1", // the fen after that move
flags: "b", // the flags, like described below
from: "e2", // the square from
next: {color: "b", from: "e7", to: "e6", flags: "n", piece: "p", /*…*/}, // a pointer to the next move
piece: "p", // the piece type
ply: 1, // the ply number
previous: undefined, // a pointer to the previous move
san: "e4", // the move in SAN notation
to: "e4", // the square to
variation: (4) [{/*…*/}, {/*…*/}, {/*…*/}, {/*…*/}], // a pointer to the begin of the current variation
variations: [] // all variations starting with that move
}pgn.history.moves[i].flags
- 'n' - a non-capture
- 'b' - a pawn push of two squares
- 'e' - an en passant capture
- 'c' - a standard capture
- 'p' - a promotion
- 'k' - kingside castling
- 'q' - queenside castling
pgn.history.moves[i].piece
- 'p' - pawn
- 'n' - knight
- 'b' - bishop
- 'r' - root
- 'q' - queen
- 'k' - king
Examples
const history = pgn.history
assert.equal(4, history.moves.length)
assert.equal(history.moves[0].san, "e4")
assert.equal(history.moves[1].variations.length, 1)
assert.equal(history.moves[1].variations[0][0].san, "e6")
assert.equal(history.moves[2].nag, "$1")
assert.equal(history.moves[2].commentAfter, "Great move!")
assert.equal(history.moves[2].fen, "rnbqkbnr/pppp1ppp/8/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2")
assert.equal(history.moves[3].from, "b8")
assert.equal(history.moves[3].to, "c6")
assert.equal(history.moves[3].san, "Nc6")
assert.equal(history.moves[3].previous.san, "Nf3")
assert.equal(history.moves[3].previous.next.san, "Nc6")Development
This module uses PEG.js for parser generation. The parser (pgnParser.js)
in src/cm-pgn/parser/ is generated from the grammar file src/grammar/pgn.pegjs.
To recreate the parser after modification of src/grammar/pgn.pegjs, run bin/generate-parser.sh.