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

⏲️ Cron Quartz and Cron UNIX expression parser

import {
	DIGIT,
	END,
	NOT_WHITESPACE,
	START,
	WHITESPACE,
	allow,
	exists,
	group,
	join,
	notCaptureNext,
	or,
	quantity,
	range,
	set,
} from "functional-expression";
import { fieldRegExp } from "./fieldRegExp.js";
import { paddedRegExp } from "./paddedRegExp.js";
import { valueOrListRegExp } from "./valueOrListRegExp.js";
import { valueRangeOrListRegExp } from "./valueRangeOrListRegExp.js";
/**
 * Regular expression to test for valid cron expressions.
 *
 * @category Regular Expression
 * @remarks
 * -   We allow 0 or more whitespace before and after the expression.
 * -   Negative lookahead to avoid impossible matches:
 * 	-   30 or 31 of February (Any combination like 30,31; 30-31; 30-30; etc.)
 * 	-   31 of February, April, Jun, September or November (also any combination).
 * -   Then we start capturing each field in a named group (separated with any
 * amount of whitespace):
 * 	-   `minute`: Digits from `0` to `59` (including padded like `05`).
 * 	-   `hour`: Digits from `0` to `23` (also including padded).
 * 	-   `dayOfMonth`: Digits from `0` to `31` (also including padded).
 * 	-   `month`: Digits from `1` to `12` (also including padded, and 3 letter
 * aliases like `oct`).
 * 	-   `dayOfWeek`: Digits from `0` to `6` (all padded, and also including 3
 * letter aliases like `fri`).
 * @example
 * ```typescript
 * new RegExp(cronRegExp).test("* * * * *"); // true
 * new RegExp(cronRegExp).test("nope"); // false
 * new RegExp(cronRegExp).test("* * 31 2 *"); // false
 * new RegExp(cronRegExp).test("* * 31 feb,4,6 *"); // false
 * new RegExp(cronRegExp).test("* * 31 feb,mar *"); // true
 * new RegExp(cronRegExp).test("1 2 3 4 5"); // true
 * ```
 */
export const cronRegExp = join(
	START,
	allow(WHITESPACE),
	notCaptureNext(
		quantity(2)(group(exists(NOT_WHITESPACE), exists(WHITESPACE))),
		group(
			or(
				group(
					valueRangeOrListRegExp(join(3, set(0, 1))),
					exists(WHITESPACE),
					valueRangeOrListRegExp(group(or(paddedRegExp(2), "feb"))),
				),
				group(
					valueRangeOrListRegExp(31),
					exists(WHITESPACE),
					valueOrListRegExp(
						group(
							or(
								paddedRegExp(set(2, 4, 6, 9)),
								11,
								"feb",
								"apr",
								"jun",
								"sep",
								"nov",
							),
						),
					),
				),
			),
		),
		exists(WHITESPACE),
		exists(NOT_WHITESPACE),
	),
	fieldRegExp(
		"minute",
		group(or(paddedRegExp(DIGIT), join(set(range(1)(5)), DIGIT))),
	),
	exists(WHITESPACE),
	fieldRegExp(
		"hour",
		group(or(paddedRegExp(DIGIT), join(1, DIGIT), join(2, range(0)(3)))),
	),
	exists(WHITESPACE),
	fieldRegExp(
		"dayOfMonth",
		group(
			or(
				paddedRegExp(set(range(1)(9))),
				join(set(1, 2), DIGIT),
				join(3, set(0, 1)),
			),
		),
	),
	exists(WHITESPACE),
	fieldRegExp(
		"month",
		group(
			or(
				"jan",
				"feb",
				"mar",
				"apr",
				"may",
				"jun",
				"jul",
				"aug",
				"sep",
				"oct",
				"nov",
				"dec",
				paddedRegExp(set(range(1)(9))),
				join(1, set(range(0)(2))),
			),
		),
	),
	exists(WHITESPACE),
	fieldRegExp(
		"dayOfWeek",
		group(
			or(
				"sun",
				"mon",
				"tue",
				"wed",
				"thu",
				"fri",
				"sat",
				paddedRegExp(set(range(0)(6))),
			),
		),
	),
	allow(WHITESPACE),
	END,
);