todo.parse-repeat

export function parseRepeat(text: string, due: string | null, today: string): Recurrence | null

import { parseRepeat } from "#fune/todo.parse-repeat@^1";

import { addDays } from "./dates_add_days.ts";  ← from dates.add-days ^1.0.0 · built alongside by fune
import { dayOfWeek } from "./dates_day_of_week.ts";  ← from dates.day-of-week ^1.0.0 · built alongside by fune
import { type Recurrence } from "./todo_item.ts";  ← from todo.item ^1.0.0 · built alongside by fune
import { parseDatePhrase } from "./todo_parse_date_phrase.ts";  ← from todo.parse-date-phrase ^1.0.0 · built alongside by fune
import { parseQuickAdd } from "./todo_parse_quick_add.ts";  ← from todo.parse-quick-add ^1.0.0 · built alongside by fune

function lowerAscii(text: string): string {
  return text.replace(/[A-Z]/g, (c) => c.toLowerCase());
}

/**
 * A Repeat box: an "every ..." phrase exactly as todo.parse-quick-add reads
 * it, then optionally a date phrase for the start. Anything else, words left
 * over included, is null. The series starts on the typed date, else on
 * `due`, else where quick-add would start it; for "every <weekday>" and
 * "every weekday" the start moves forward to the first day the pattern
 * allows. The anchor is that first date.
 */
export function parseRepeat(text: string, due: string | null, today: string): Recurrence | null {
  // addDays(x, 0) is the date check: it throws dates.add-days's message.
  addDays(today, 0);
  if (due !== null) addDays(due, 0);
  const words = text.split(/[ \t\n\r\v\f]+/).filter((w) => w !== "");
  if (words.length < 2 || lowerAscii(words[0]) !== "every") return null;

  // The repeat is 2 words ("every week") or 3 ("every 2 weeks"); no 2-word
  // form starts a 3-word one, so the first that parses as a bare repeat wins.
  let repeat: Recurrence | null = null;
  let length = 0;
  for (const n of [2, 3]) {
    if (n > words.length) break;
    const draft = parseQuickAdd(words.slice(0, n).join(" "), today);
    if (draft.recurrence !== null && draft.title === "") {
      repeat = draft.recurrence;
      length = n;
      break;
    }
  }
  if (repeat === null) return null;

  let start = due;
  if (words.length > length) {
    start = parseDatePhrase(words.slice(length).join(" "), today);
    if (start === null) return null;
  }
  if (start === null) return repeat;

  if (repeat.frequency === "weekdays") {
    const day = dayOfWeek(start);
    if (day >= 6) start = addDays(start, 8 - day);
  } else if (repeat.frequency === "weekly" && length === 2 && parseDatePhrase(words[1], today) !== null) {
    // "every monday": quick-add anchored it on the next Monday, so that
    // anchor's weekday is the one the series keeps.
    start = addDays(start, (dayOfWeek(repeat.anchor) - dayOfWeek(start) + 7) % 7);
  }
  return { ...repeat, anchor: start };
}

Install

fune build

With that line in your source, in a TypeScript project (language typescript in fune.project), fune build resolves it and its 5 dependencies, pins them in fune.lock, downloads only the TypeScript package of each, and builds the code above into your project’s .fune/build, one readable file per capability with a header linking back here. Or pin a range in fune.project and build in one step:

fune add todo.parse-repeat

The manifest, vectors and README with only the TypeScript implementation. Install it without the registry with fune add ./todo.parse-repeat-1.0.0-typescript.fune, or fetch it from a terminal with fune pull todo.parse-repeat@1.0.0:typescript.

The whole function, every language, is one file too: todo.parse-repeat-1.0.0.fune, 16,279 bytes, sha256 efdd5ec36a56dc62104de85dc0453a6b348ac1d515dc1f5a5e1f6b7a9c048043. It installs into a project of any language.

// fune: before todo.parse-repeat

// fune: after todo.parse-repeat

// fune: replace dates.add-days in todo.parse-repeat
// fune: replace dates.day-of-week in todo.parse-repeat
// fune: replace todo.item in todo.parse-repeat
// fune: replace todo.parse-date-phrase in todo.parse-repeat
// fune: replace todo.parse-quick-add in todo.parse-repeat

// fune: step todo.parse-repeat after <n|label>

More from the author

## What it reads

The whole box must be one `every ...` phrase, then optionally a start date:

- **The repeat** is todo.parse-quick-add's grammar, exactly (the capability calls it rather than keeping a copy): `every day`, `every weekday`, `every week`, `every monday` (any weekday name), `every month`, `every year`, `every other week`, `every 3 days`, `every ten years` (1 to 999). Case-insensitive, ASCII whitespace between words. - **The start date**, if any, is whatever todo.parse-date-phrase reads as a whole: `tomorrow`, `on fri`, `next week`, `2026-10-15`. - **Anything else is null**: words left over (`every week please`), a date first (`tomorrow every week`), `weekly` on its own (a title word to quick-add), an empty box, `every 1000 days`. A form shows its own "try every week" message for null.

## Where the series starts

The anchor is the series' first date, and so the todo's due date from then on (todo.item refuses a due date before the anchor).

1. The date typed in the box, if there is one. 2. Otherwise `due`, the todo's due date. 3. Otherwise quick-add's choice: today; for `every weekday` today if it is Monday to Friday, else next Monday; for `every <weekday>` the next such day strictly after today.

Then, for steps 1 and 2, the start moves forward to the first day the pattern allows: `every monday` on a todo due Wednesday 30 September starts Monday 5 October (quick-add, by contrast, lets a date phrase in the same line win and repeats weekly on Wednesdays; in a Repeat box the weekday is the point), and `every weekday` from a Saturday starts the Monday after. A start already on an allowed day stays: `every friday` due Friday 2 October starts that day.

Month ends and leap days are left to todo.next-occurrence: `every month` from 31 January is anchored on the 31st, so it falls on each month's last day.

## Errors

Only a malformed or impossible `today` or `due` throws, with dates.add-days's message (`"28/09/2026" is not an ISO date`). Text that is not a repeat is null, never an error.

Files