"""
babel.lists
~~~~~~~~~~~
Locale dependent formatting of lists.
The default locale for the functions in this module is determined by the
following environment variables, in that order:
* ``LC_ALL``, and
* ``LANG``
:copyright: (c) 2015-2023 by the Babel Team.
:license: BSD, see LICENSE for more details.
"""
from __future__ import annotations
from collections.abc import Sequence
from typing import TYPE_CHECKING
from babel.core import Locale, default_locale
if TYPE_CHECKING:
from typing_extensions import Literal
DEFAULT_LOCALE = default_locale()
def format_list(lst: Sequence[str],
style: Literal['standard', 'standard-short', 'or', 'or-short', 'unit', 'unit-short', 'unit-narrow'] = 'standard',
locale: Locale | str | None = DEFAULT_LOCALE) -> str:
"""
Format the items in `lst` as a list.
>>> format_list(['apples', 'oranges', 'pears'], locale='en')
u'apples, oranges, and pears'
>>> format_list(['apples', 'oranges', 'pears'], locale='zh')
u'apples\u3001oranges\u548cpears'
>>> format_list(['omena', 'peruna', 'aplari'], style='or', locale='fi')
u'omena, peruna tai aplari'
These styles are defined, but not all are necessarily available in all locales.
The following text is verbatim from the Unicode TR35-49 spec [1].
* standard:
A typical 'and' list for arbitrary placeholders.
eg. "January, February, and March"
* standard-short:
A short version of a 'and' list, suitable for use with short or abbreviated placeholder values.
eg. "Jan., Feb., and Mar."
* or:
A typical 'or' list for arbitrary placeholders.
eg. "January, February, or March"
* or-short:
A short version of an 'or' list.
eg. "Jan., Feb., or Mar."
* unit:
A list suitable for wide units.
eg. "3 feet, 7 inches"
* unit-short:
A list suitable for short units
eg. "3 ft, 7 in"
* unit-narrow:
A list suitable for narrow units, where space on the screen is very limited.
eg. "3′ 7″"
[1]: https://www.unicode.org/reports/tr35/tr35-49/tr35-general.html#ListPatterns
:param lst: a sequence of items to format in to a list
:param style: the style to format the list with. See above for description.
:param locale: the locale
"""
locale = Locale.parse(locale)
if not lst:
return ''
if len(lst) == 1:
return lst[0]
if style not in locale.list_patterns:
raise ValueError(
f'Locale {locale} does not support list formatting style {style!r} '
f'(supported are {sorted(locale.list_patterns)})'
)
patterns = locale.list_patterns[style]
if len(lst) == 2:
return patterns['2'].format(*lst)
result = patterns['start'].format(lst[0], lst[1])
for elem in lst[2:-1]:
result = patterns['middle'].format(result, elem)
result = patterns['end'].format(result, lst[-1])
return result
