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
    }

    static createGrammar() {
        return /** @type {P<UnknownKeysEntity>} */(
            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")
        )
    }
}