whenparse

Parse natural-language dates and times — in English and Russian — into jiff types. One direct dependency, no regex, deterministic.

whenparse turns strings like next friday 8pm, через 2 недели, 15 March 2026, Q3 2025, or 2ч30м into a typed When: a date, a zoned datetime, a range, or a duration.

Why

Explicit anchor. Every parse takes a now: &Zoned you supply, so results are deterministic and testable — no hidden clock.
Bilingual. English and Russian share one grammar; you get both without a flag.
Ranges are first-class. next week, March, and Q3 resolve to a real [start, end) range instead of a lossy point.
Small. One direct dependency (jiff). Hand-rolled scanner and grammar, no regex.

Install

[dependencies]
whenparse = "0.1"
jiff = "0.2"

Usage

use jiff::Zoned;
use whenparse::{parse, parse_with, Dialect, Options, When};

let now = Zoned::now();

// Default options: automatic language, international date order.
if let Ok(When::DateTime(z)) = parse_with("next friday 8pm", &now) {
    println!("{z}");
}

// Russian, ranges, and durations go through the same call.
assert!(matches!(parse_with("через 2 недели", &now), Ok(When::Date(_))));
assert!(matches!(parse_with("Q3 2025", &now), Ok(When::Range { .. })));
assert!(matches!(parse_with("2ч30м", &now), Ok(When::Duration(_))));

// Tune the dialect (US month/day order and "next Friday" semantics).
let opts = Options { dialect: Dialect::Us, ..Options::default() };
let _ = parse("3/15/2026", &now, opts); // -> 2026-03-15

Output

pub enum When {
    Date(jiff::civil::Date),
    DateTime(jiff::Zoned),
    Range { start: jiff::Zoned, end: jiff::Zoned },
    Duration(jiff::Span),
}

What it understands

Class	English	Russian
Named days	`today`, `tomorrow`, `yesterday`	`сегодня`, `завтра`, `послезавтра`
Offsets	`in 3 days`, `2 weeks ago`, `in an hour`	`через 3 дня`, `неделю назад`, `через час`
Weekdays	`next friday`, `last monday`, `this thursday`	`в следующую пятницу`, `в прошлый вторник`
Periods → `Range`	`this` / `next` / `last` `week` \| `month` \| `year`	`на следующей неделе`, `в этом месяце`
Absolute	`15 March 2026`, `March 15`, `3/15/2026`, `15.03.2026`	`15 марта 2026`, `15.03.2026`
Months / quarters → `Range`	`March`, `Q3`, `Q3 2025`	`март`
Clock	`8pm`, `8:30`, `noon`, `at 8`	`в 17:00`, `в 8 вечера`, `в полдень`
Combined	`tomorrow at 5pm`, `next friday 8pm`	`завтра в 17:00`
Durations → `Duration`	`3 hours 20 minutes`, `2h30m`	`3 часа 20 минут`, `2ч30м`

ISO 8601 input (2026-03-15, 2026-03-15T14:30:00[America/New_York]) passes straight through to jiff.

Options

lang: Auto (default), En, or Ru.
dialect: Intl (default; day/month/year) or Us (month/day/year; next Friday means the coming Friday). Ambiguous numeric dates auto-correct when only one ordering is valid.
week_start: the first day of the week for period ranges (default Monday).

Not in scope (v0.1)

Time zones by name or abbreviation, recurrence (every monday), holidays, and spelled-out fractions (half an hour). ISO datetimes are delegated to jiff.

License

Licensed under either of MIT or Apache-2.0 at your option.

whenparse 0.1.0