cm-pgn/src/Pgn.js

Module for parsing and rendering of PGNs (Portable Game Notation)

/**
 * Author and copyright: Stefan Haack (https://shaack.com)
 * Repository: https://github.com/shaack/cm-pgn
 * License: MIT, see file 'LICENSE'
 */
import {Header, TAGS} from "./Header.js"
import {History} from "./History.js"

export class Pgn {

    constructor(pgnString = "", props = {}) {
        // only the header?
        const lastHeaderElement = pgnString.trim().slice(-1) === "]" ? pgnString.length : pgnString.lastIndexOf("]\n\n") + 1
        const headerString = pgnString.substring(0, lastHeaderElement)
        const historyString = pgnString.substring(lastHeaderElement)
        this.props = {
            sloppy: false,
            chess960: false,
            ...props
        }
        this.header = new Header(headerString)
        const variant = this.header.tags[TAGS.Variant]
        if (variant &&
            (variant.toLowerCase() === "chess960" ||
                variant.toLowerCase() === "freestyle" ||
                variant.toLowerCase() === "fischerandom")) {
            this.props.chess960 = true
        }
        if (this.header.tags[TAGS.SetUp] === "1" && this.header.tags[TAGS.FEN]) {
            this.history = new History(historyString, {
                setUpFen: this.header.tags[TAGS.FEN],
                sloppy: this.props.sloppy,
                chess960: this.props.chess960
            })
        } else {
            this.history = new History(historyString, {sloppy: this.props.sloppy, chess960: this.props.chess960})
        }
    }

    wrap(str, maxLength) {
        // Tokenize such that {...} comments stay atomic; wrap must never
        // insert a line break inside a comment, otherwise round-tripping
        // a comment that already contains whitespace becomes unstable.
        const tokens = []
        let i = 0
        while (i < str.length) {
            const ch = str[i]
            if (ch === " " || ch === "\n" || ch === "\t") {
                i++
                continue
            }
            if (ch === "{") {
                const end = str.indexOf("}", i)
                if (end === -1) {
                    tokens.push(str.substring(i))
                    break
                }
                tokens.push(str.substring(i, end + 1))
                i = end + 1
            } else {
                let j = i
                while (j < str.length && str[j] !== " " && str[j] !== "\n" && str[j] !== "\t" && str[j] !== "{") {
                    j++
                }
                tokens.push(str.substring(i, j))
                i = j
            }
        }
        const lines = []
        let line = ""
        for (const tok of tokens) {
            if (line.length === 0) {
                line = tok
            } else if (line.length + 1 + tok.length <= maxLength) {
                line += " " + tok
            } else {
                lines.push(line)
                line = tok
            }
        }
        if (line.length > 0) {
            lines.push(line)
        }
        return lines.join("\n")
    }

    render(renderHeader = true, renderComments = true, renderNags = true) {
        const header = renderHeader ? (this.header.render() + "\n") : ""
        let history = this.history.render(renderComments, renderNags)
        if (this.header.tags[TAGS.Result]) {
            history += " " + this.header.tags[TAGS.Result]
        }
        return header + this.wrap(history, 80)
    }

}