ueblueprint/js/entity/UnknownKeysEntity.js

import P from "parsernostrum"
import Grammar from "../serialization/Grammar.js"
import IEntity from "./IEntity.js"

export default class UnknownKeysEntity extends IEntity {

    static grammar = this.createGrammar()

    static {
        IEntity.unknownEntity = this
    }

    /** @returns {P<UnknownKeysEntity>} */
    static createGrammar() {
        return P.seq(
            // Lookbehind
            P.reg(new RegExp(`(${Grammar.Regex.Path.source}|${Grammar.Regex.Symbol.source}\\s*)?\\(\\s*`), 1),
            P.seq(Grammar.attributeName, Grammar.equalSeparation).map(([attribute, equal]) => attribute)
                .chain(attributeName =>
                    this.unknownEntityGrammar.map(attributeValue =>
                        values => values[attributeName] = attributeValue
                    )
                )
                .sepBy(Grammar.commaSeparation),
            P.reg(/\s*(?:,\s*)?\)/),
        ).map(([lookbehind, attributes, _2]) => {
            lookbehind ??= ""
            let values = {}
            if (lookbehind.length) {
                values.lookbehind = lookbehind
            }
            attributes.forEach(attributeSetter => attributeSetter(values))
            return new this(values)
        }).label("UnknownKeysEntity")
    }
}