formal-language/grammar

import Children from '../ast/Children.js';
import rmap from '../ast/rmap.js';

import _children_next_lazy from './_children_next_lazy.js';

/**
 * Table-driven predictive lazy parsing.
 *
 * @param {Object} eof - The end-of-file symbol.
 * @param {Map} productions - The ll1 productions.
 * @param {Map} table - The symbol table.
 * @param {Array} rule - The production rule in use.
 * @param {Tape} tape - The tape from which to read the symbols from.
 * @param {String} nonterminal - The nonterminal that produced `rule`.
 * @param {String} production - The production that corresponds to `rule`.
 * @returns {Object} The root node of the parsed tree.
 */
export default function _parse_lazy(
    eof,
    productions,
    table,
    rule,
    tape,
    nonterminal,
    production,
) {
    const shallow_materialize = async (expected) =>
        _children_next_lazy(eof, productions, table, tape, expected);

    const iterator = rmap(shallow_materialize, rule)[Symbol.asyncIterator]();

    return {
        type: 'node',
        nonterminal,
        production,
        children: new Children(iterator, rule.length),
    };
}