@spec parse(String.t(), Keyword.t()) :: {:ok, Date.t()} | {:error, Exception.t()}

Parses a locale-formatted date string.

Tries, in order: bare ISO-8601 (YYYY-MM-DD), then the locale's CLDR short/medium/long/full patterns for the requested calendar. The patterns encode the locale's preferred field order and any era markers — so the same input may parse to different dates under different locales by design.

Returns a Date.t/0 in the calendar identified by the :calendar option — Calendar.ISO for :gregorian (the default), Calendrical.Hebrew for :hebrew, Calendrical.Japanese for :japanese, and so on. Pass return_calendar: :iso to force the result into Gregorian regardless (useful for Date.Range, Ecto :date casts, or any consumer that requires ISO).

Arguments

• input is the raw user input string.

• options is a keyword list of options.

Options

• :locale — the locale to interpret the string under. Defaults to Localize.get_locale/0.

• :calendar — the CLDR calendar key (e.g. :gregorian, :buddhist, :islamic_civil, :japanese, :persian, :hebrew). Defaults to :gregorian. Drives both how the input is interpreted and what calendar the returned Date is in.

• :reference_date — the "today" anchor for two-digit-year pivoting. Defaults to Date.utc_today/0.

• :return_calendar — :native (default) returns the parsed date in whatever :calendar named. :iso forces Calendar.ISO. A calendar module (e.g. Calendrical.Persian) returns the date in that specific calendar.

Returns

• {:ok, Date.t()} on success.

• {:error, Calendrical.DateParseError.t()} when no pattern matched.

Examples

iex> Calendrical.Date.parse("2026-05-16", locale: :en)
{:ok, ~D[2026-05-16]}

iex> Calendrical.Date.parse("5/16/26", locale: :en)
{:ok, ~D[2026-05-16]}

iex> Calendrical.Date.parse("16.05.2026", locale: :de)
{:ok, ~D[2026-05-16]}

iex> Calendrical.Date.parse("2026-05-16", locale: :en, calendar: :hebrew)
{:ok, ~D[5786-09-29 Calendrical.Hebrew]}

iex> Calendrical.Date.parse("2026-05-16", locale: :en, calendar: :hebrew, return_calendar: :iso)
{:ok, ~D[2026-05-16]}

iex> Calendrical.Date.parse("Q2 2026", locale: :en)
{:ok, ~D[2026-04-01]}

iex> Calendrical.Date.parse("2nd quarter 2026", locale: :en)
{:ok, ~D[2026-04-01]}

iex> Calendrical.Date.parse("week 20 of 2026", locale: :en)
{:ok, ~D[2026-05-11]}

iex> Calendrical.Date.parse("Saturday, May 16, 2026", locale: :en)
{:ok, ~D[2026-05-16]}

@spec parse_range(String.t() | {String.t(), String.t()}, Keyword.t()) ::
  {:ok, Date.Range.t()} | {:error, Exception.t()}

Parses a locale-formatted date range.

Accepts either a single string (e.g. "May 5 – May 10, 2026") in which case the parser splits on the locale's CLDR intervalFormatFallback separator, or a 2-tuple {from_string, to_string} for two-input UIs that already have the endpoints split.

Each endpoint is parsed independently via parse/2. The result is a Date.Range.t/0 (Gregorian).

Arguments

• input is either a binary or a {from_binary, to_binary} tuple.

• options is a keyword list of options.

Options

Same as parse/2: :locale, :calendar, :reference_date. Plus:

• :allow_inverted — when true, an end-before-start range is returned as-is (Elixir's Date.range/3 builds a descending range). When false (the default), an inverted range is rejected with a Calendrical.DateRangeParseError.

Returns

• {:ok, Date.Range.t()} on success.

• {:error, Calendrical.DateParseError.t() | Calendrical.DateRangeParseError.t()} on failure.

Examples

iex> {:ok, range} = Calendrical.Date.parse_range({"2026-05-05", "2026-05-10"})
iex> {range.first, range.last}
{~D[2026-05-05], ~D[2026-05-10]}

iex> {:ok, range} = Calendrical.Date.parse_range("May 5, 2026 – May 10, 2026", locale: :en)
iex> {range.first, range.last}
{~D[2026-05-05], ~D[2026-05-10]}