defmodule Cldr.DateTime do
@moduledoc """
Provides localization and formatting of a `DateTime`
struct or any map with the keys `:year`, `:month`,
`:day`, `:calendar`, `:hour`, `:minute`, `:second` and optionally `:microsecond`.
`Cldr.DateTime` provides support for the built-in calendar
`Calendar.ISO` or any calendars defined with
[ex_cldr_calendars](https://hex.pm/packages/ex_cldr_calendars)
CLDR provides standard format strings for `DateTime` which
are reresented by the names `:short`, `:medium`, `:long`
and `:full`. This allows for locale-independent
formatting since each locale will define the underlying
format string as appropriate.
"""
alias Cldr.DateTime.Format
alias Cldr.LanguageTag
@style_types [:short, :medium, :long, :full]
@default_type :medium
defmodule Styles do
@moduledoc false
defstruct Module.get_attribute(Cldr.DateTime, :style_types)
end
@doc """
Formats a DateTime according to a format string
as defined in CLDR and described in [TR35](http://unicode.org/reports/tr35/tr35-dates.html)
## Arguments
* `datetime` is a `%DateTime{}` `or %NaiveDateTime{}`struct or any map that contains the keys
`:year`, `:month`, `:day`, `:calendar`. `:hour`, `:minute` and `:second` with optional
`:microsecond`.
* `backend` is any module that includes `use Cldr` and therefore
is a `Cldr` backend module. The default is `Cldr.default_backend/0`.
* `options` is a keyword list of options for formatting.
## Options
* `format:` `:short` | `:medium` | `:long` | `:full` or a format string or
any of the keys returned by `Cldr.DateTime.Format.date_time_available_formats/0`.
The default is `:medium`
* `locale` is any valid locale name returned by `Cldr.known_locale_names/0`
or a `Cldr.LanguageTag` struct. The default is `Cldr.get_locale/0`
* `number_system:` a number system into which the formatted date digits should
be transliterated
* `era: :variant` will use a variant for the era is one is available in the locale.
In the "en" for example, the locale `era: :variant` will return "BCE" instead of "BC".
* `period: :variant` will use a variant for the time period and flexible time period if
one is available in the locale. For example, in the "en" locale `period: :variant` will
return "pm" instead of "PM"
## Returns
* `{:ok, formatted_datetime}` or
* `{:error, reason}`
## Examples
iex> {:ok, datetime} = DateTime.from_naive(~N[2000-01-01 23:59:59.0], "Etc/UTC")
iex> Cldr.DateTime.to_string datetime
{:ok, "Jan 1, 2000, 11:59:59 PM"}
iex> Cldr.DateTime.to_string datetime, MyApp.Cldr, locale: "en"
{:ok, "Jan 1, 2000, 11:59:59 PM"}
iex> Cldr.DateTime.to_string datetime, MyApp.Cldr, format: :long, locale: "en"
{:ok, "January 1, 2000 at 11:59:59 PM UTC"}
iex> Cldr.DateTime.to_string datetime, MyApp.Cldr, format: :hms, locale: "en"
{:ok, "11:59:59 PM"}
iex> Cldr.DateTime.to_string datetime, MyApp.Cldr, format: :full, locale: "en"
{:ok, "Saturday, January 1, 2000 at 11:59:59 PM GMT"}
iex> Cldr.DateTime.to_string datetime, MyApp.Cldr, format: :full, locale: "fr"
{:ok, "samedi 1 janvier 2000 à 23:59:59 UTC"}
"""
@spec to_string(map, Cldr.backend() | Keyword.t(), Keyword.t()) ::
{:ok, String.t()} | {:error, {module, String.t()}}
def to_string(datetime, backend \\ Cldr.Date.default_backend(), options \\ [])
def to_string(%{calendar: Calendar.ISO} = datetime, backend, options) do
%{datetime | calendar: Cldr.Calendar.Gregorian}
|> to_string(backend, options)
end
def to_string(datetime, options, []) when is_list(options) do
{locale, backend} = Cldr.locale_and_backend_from(options)
options = Keyword.put_new(options, :locale, locale)
to_string(datetime, backend, options)
end
def to_string(%{calendar: calendar} = datetime, backend, options)
when is_atom(backend) and is_list(options) do
options = normalize_options(backend, options)
format_backend = Module.concat(backend, DateTime.Formatter)
number_system = Keyword.get(options, :number_system)
with {:ok, locale} <- Cldr.validate_locale(options[:locale], backend),
{:ok, cldr_calendar} <- type_from_calendar(calendar),
{:ok, _} <- Cldr.Number.validate_number_system(locale, number_system, backend),
{:ok, format_string} <- format_string(options[:format], locale, cldr_calendar, backend),
{:ok, formatted} <- format_backend.format(datetime, format_string, locale, options) do
{:ok, formatted}
end
rescue
e in [Cldr.DateTime.UnresolvedFormat] ->
{:error, {e.__struct__, e.message}}
end
def to_string(datetime, _backend, _options) do
error_return(datetime, [:year, :month, :day, :hour, :minute, :second, :calendar])
end
defp normalize_options(backend, []) do
{locale, _backend} = Cldr.locale_and_backend_from(nil, backend)
number_system = Cldr.Number.System.number_system_from_locale(locale, backend)
[locale: locale, number_system: number_system, format: @default_type]
end
defp normalize_options(backend, options) do
{locale, _backend} = Cldr.locale_and_backend_from(options[:locale], backend)
format = options[:format] || options[:style] || @default_type
locale_number_system = Cldr.Number.System.number_system_from_locale(locale, backend)
number_system = Keyword.get(options, :number_system, locale_number_system)
options
|> Keyword.put(:locale, locale)
|> Keyword.put(:format, format)
|> Keyword.delete(:style)
|> Keyword.put_new(:number_system, number_system)
end
@doc false
# Returns the CLDR calendar type for a calendar
def type_from_calendar(Cldr.Calendar.Gregorian = calendar) do
{:ok, calendar.cldr_calendar_type()}
end
def type_from_calendar(calendar) do
with {:ok, calendar} <- Cldr.Calendar.validate_calendar(calendar) do
{:ok, calendar.cldr_calendar_type()}
end
end
@doc """
Formats a DateTime according to a format string
as defined in CLDR and described in [TR35](http://unicode.org/reports/tr35/tr35-dates.html)
returning a formatted string or raising on error.
## Arguments
* `datetime` is a `%DateTime{}` `or %NaiveDateTime{}`struct or any map that contains the keys
`:year`, `:month`, `:day`, `:calendar`. `:hour`, `:minute` and `:second` with optional
`:microsecond`.
* `backend` is any module that includes `use Cldr` and therefore
is a `Cldr` backend module. The default is `Cldr.default_backend/0`.
* `options` is a keyword list of options for formatting.
## Options
* `format:` `:short` | `:medium` | `:long` | `:full` or a format string or
any of the keys returned by `Cldr.DateTime.available_format_names` or a format string.
The default is `:medium`
* `locale` is any valid locale name returned by `Cldr.known_locale_names/0`
or a `Cldr.LanguageTag` struct. The default is `Cldr.get_locale/0`
* `number_system:` a number system into which the formatted date digits should
be transliterated
* `era: :variant` will use a variant for the era is one is available in the locale.
In the "en" for example, the locale `era: :variant` will return "BCE" instead of "BC".
* `period: :variant` will use a variant for the time period and flexible time period if
one is available in the locale. For example, in the "en" locale `period: :variant` will
return "pm" instead of "PM"
## Returns
* `formatted_datetime` or
* raises an exception
## Examples
iex> {:ok, datetime} = DateTime.from_naive(~N[2000-01-01 23:59:59.0], "Etc/UTC")
iex> Cldr.DateTime.to_string! datetime, MyApp.Cldr, locale: "en"
"Jan 1, 2000, 11:59:59 PM"
iex> Cldr.DateTime.to_string! datetime, MyApp.Cldr, format: :long, locale: "en"
"January 1, 2000 at 11:59:59 PM UTC"
iex> Cldr.DateTime.to_string! datetime, MyApp.Cldr, format: :full, locale: "en"
"Saturday, January 1, 2000 at 11:59:59 PM GMT"
iex> Cldr.DateTime.to_string! datetime, MyApp.Cldr, format: :full, locale: "fr"
"samedi 1 janvier 2000 à 23:59:59 UTC"
"""
@spec to_string!(map, Cldr.backend() | Keyword.t(), Keyword.t()) :: String.t() | no_return
def to_string!(datetime, backend \\ Cldr.Date.default_backend(), options \\ [])
def to_string!(datetime, backend, options) do
case to_string(datetime, backend, options) do
{:ok, string} -> string
{:error, {exception, message}} -> raise exception, message
end
end
# Standard format
defp format_string(style, %LanguageTag{cldr_locale_name: locale_name}, cldr_calendar, backend)
when style in @style_types do
with {:ok, styles} <- Format.date_time_formats(locale_name, cldr_calendar, backend) do
{:ok, Map.get(styles, style)}
end
end
# Look up for the format in :available_formats
defp format_string(style, %LanguageTag{cldr_locale_name: locale_name}, cldr_calendar, backend)
when is_atom(style) do
with {:ok, styles} <-
Format.date_time_available_formats(locale_name, cldr_calendar, backend),
format_string <- Map.get(styles, style) do
if format_string do
{:ok, format_string}
else
{:error,
{Cldr.DateTime.InvalidStyle,
"Invalid datetime style #{inspect(style)}. " <>
"The valid styles are #{inspect(styles)}."}}
end
end
end
# Format with a number system
defp format_string(%{number_system: number_system, format: style}, locale, calendar, backend) do
{:ok, format_string} = format_string(style, locale, calendar, backend)
{:ok, %{number_system: number_system, format: format_string}}
end
# Straight up format string
defp format_string(format_string, _locale, _calendar, _backend)
when is_binary(format_string) do
{:ok, format_string}
end
defp error_return(map, requirements) do
requirements =
requirements
|> Enum.map(&inspect/1)
|> Cldr.DateTime.Formatter.join_requirements()
{:error,
{ArgumentError,
"Invalid DateTime. DateTime is a map that contains at least #{requirements}. " <>
"Found: #{inspect(map)}"}}
end
end
