@lou.codes/cron/dist/parse.js

⏲️ Cron Quartz and Cron UNIX expression parser

import { entriesToObject, length, objectToEntries } from "@lou.codes/iterables";
import { build } from "functional-expression";
import { cronRegExp } from "./cronRegExp.js";
import { normalizeAliases } from "./normalizeAliases.js";
import { parseFieldTuplesMap } from "./parseFieldTuplesMap.js";
/**
 * Parses a cron expression into an object representation.
 *
 * @category Cron String
 * @example
 * ```typescript
 * parse("* * * * *"); // { minute: "*", hour: "*", dayOfMonth: "*", month: "*", dayOfWeek: "*" }
 * parse("* * 13 10 *"); // { minute: "*", hour: "*", dayOfMonth: 13, month: 10, dayOfWeek: "*" }
 * parse("5 * 10,11,13 1-10 *"); // { minute: 5, hour: "*", dayOfMonth: [10, 11, 13], month: { from: 1, to: 10 }, dayOfWeek: "*" }
 * parse("* * 31 2 *"); // undefined
 * parse("nope"); // undefined
 * ```
 * @see {@link parseFieldTuplesMap}
 * @see {@link normalizeAliases}
 *
 * @param expression Cron expression to be parsed.
 * @returns Object representing that expression or `undefined` if expression is
 * invalid.
 */
export const parse = expression => {
	const entries = parseFieldTuplesMap(
		objectToEntries(
			build("iu")(cronRegExp).exec(normalizeAliases(expression))
				?.groups ?? {},
		),
	);
	return length(entries) === 0 ? undefined : entriesToObject(entries);
};