Source code for aioxmpp.i18n
########################################################################
# File name: i18n.py
# This file is part of: aioxmpp
#
# LICENSE
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this program. If not, see
# <http://www.gnu.org/licenses/>.
#
########################################################################
"""
:mod:`~aioxmpp.i18n` -- Helper functions for localizing text
############################################################
This module provides facilities to faciliate the internationalization of
applications using :mod:`aioxmpp`.
.. autoclass:: LocalizingFormatter
.. autoclass:: LocalizableString
Shorthand functions
===================
.. autofunction:: _
.. autofunction:: ngettext
"""
import numbers
import string
from datetime import datetime, timedelta, date, time
import babel
import babel.dates
import babel.numbers
import tzlocal
[docs]class LocalizingFormatter(string.Formatter):
"""
This is an alternative implementation on top of
:class:`string.Formatter`. It is designed to work well with :mod:`babel`,
which also means that some things work differently when compared with the
default :class:`string.Formatter`.
Most notably, all objects from :mod:`datetime` are handled without using
their :meth:`__format__` method. Depending on their type, they are
forwarded to the respective formatting method in :mod:`babel.dates`.
+----------------------------+------------------------------------+-----------------+
|Type |Babel function |Timezone support |
+============================+====================================+=================+
|:class:`~datetime.datetime` |:func:`babel.dates.format_datetime` |yes |
+----------------------------+------------------------------------+-----------------+
|:class:`~datetime.timedelta`|:func:`babel.dates.format_timedelta`|no |
+----------------------------+------------------------------------+-----------------+
|:class:`~datetime.date` |:func:`babel.dates.format_date` |no |
+----------------------------+------------------------------------+-----------------+
|:class:`~datetime.time` |:func:`babel.dates.format_time` |no |
+----------------------------+------------------------------------+-----------------+
If the format specification is empty, the default format as babel defines
it is used.
In addition to date and time formatting, numbers which use the ``n`` format
type are also formatted with babel. If the format specificaton is empty
(except for the trailing ``n``), :func:`babel.numbers.format_number` is
used. Otherwise, the remainder of the format specification is passed as
format to :func:`babel.numbers.format_decimal`.
Examples::
>>> import pytz, babel, datetime, aioxmpp.i18n
>>> tz = pytz.timezone("Europe/Berlin")
>>> dt = datetime.datetime(year=2015, 5, 5, 15, 55, 55, tzinfo=tz)
>>> fmt = aioxmpp.i18n.LocalizingFormatter(locale=babel.Locale("en_GB"))
>>> fmt.format("{}", dt)
'5 May 2015 15:55:55'
>>> fmt.format("{:full}", dt)
'Tuesday, 5 May 2015 15:55:55 GMT+00:00'
>>> fmt.format("{:##.###n}, 120.3)
>>> fmt.format("{:##.###n}", 12.3)
'12.3'
>>> fmt.format("{:##.###;-(#)n}", -1.234)
'-(1.234)'
>>> fmt.format("{:n}", -10000)
'-10,000'
"""
def __init__(self, locale=None, tzinfo=None):
super().__init__()
self.locale = locale if locale is not None else babel.default_locale()
self.tzinfo = tzinfo if tzinfo is not None else tzlocal.get_localzone()
def format_field(self, value, format_spec, locale=None, tzinfo=None):
if tzinfo is None:
tzinfo = self.tzinfo
if locale is None:
locale = self.locale
if isinstance(value, datetime):
if value.tzinfo is not None:
value = tzinfo.normalize(value)
if format_spec:
return babel.dates.format_datetime(value,
locale=locale,
format=format_spec)
else:
return babel.dates.format_datetime(value,
locale=locale)
elif isinstance(value, timedelta):
if format_spec:
return babel.dates.format_timedelta(value,
locale=locale,
format=format_spec)
else:
return babel.dates.format_timedelta(value,
locale=locale)
elif isinstance(value, date):
if format_spec:
return babel.dates.format_date(value,
locale=locale,
format=format_spec)
else:
return babel.dates.format_date(value,
locale=locale)
elif isinstance(value, time):
if format_spec:
return babel.dates.format_time(value,
locale=locale,
format=format_spec)
else:
return babel.dates.format_time(value,
locale=locale)
elif isinstance(value, numbers.Real) and format_spec.endswith("n"):
if len(format_spec) > 1:
return babel.numbers.format_decimal(value,
format=format_spec[:-1],
locale=locale)
else:
return babel.numbers.format_number(value, locale=locale)
else:
return super().format_field(value, format_spec)
def convert_field(self, value, conversion, locale=None, tzinfo=None):
if conversion != "s":
return super().convert_field(value, conversion)
if locale is None:
locale = self.locale
if tzinfo is None:
tzinfo = self.tzinfo
if isinstance(value, datetime):
return babel.dates.format_datetime(
tzinfo.normalize(value),
locale=locale)
elif isinstance(value, timedelta):
return babel.dates.format_timedelta(value, locale=locale)
elif isinstance(value, date):
return babel.dates.format_date(value, locale=locale)
elif isinstance(value, time):
return babel.dates.format_time(
value,
locale=locale)
return super().convert_field(value, conversion)
[docs]class LocalizableString:
"""
This class can be used for lazily translated localizable strings.
`singular` must be a :class:`str`. If `plural` is not set, the string will
be localized using `gettext`; otherwise, `ngettext` will be used. The
detailed process on localizing a string is described in the documentation
of :meth:`localize`.
Localizable strings compare equal if their `singular`, `plural` and
`number_index` values all match. The :func:`str` of a localizable string is
its singular string. The :func:`repr` depends on whether `plural` is set
and refers to the usage of :func:`_` and :func:`ngettext`.
The arguments are stored in attributes named like the
arguments. :class:`LocalizableString` instances are immutable and
hashable.
Examples::
>>> import aioxmpp.i18n, pytz, babel, gettext
>>> fmt = aioxmpp.i18n.LocalizingFormatter()
>>> translator = gettext.NullTranslations()
>>> s1 = aioxmpp.i18n.LocalizableString(
... "{count} thing",
... "{count} things", "count")
>>> s1.localize(fmt, translator, count=1)
'1 thing'
>>> s1.localize(fmt, translator, count=10)
'10 things'
.. automethod:: localize
"""
__slots__ = ("_singular", "_plural", "_number_index")
def __init__(self, singular, plural=None, number_index=None):
if plural is None and number_index is not None:
raise ValueError("plural is required if number_index is given")
self._singular = singular
self._plural = plural
if plural is not None:
if number_index is None:
number_index = "0"
self._number_index = str(number_index)
else:
self._number_index = None
@property
def singular(self):
return self._singular
@property
def plural(self):
return self._plural
@property
def number_index(self):
return self._number_index
def __eq__(self, other):
if not isinstance(other, LocalizableString):
return NotImplemented
return (self.singular == other.singular and
self.plural == other.plural and
self.number_index == other.number_index)
def __ne__(self, other):
return not (self == other)
def __hash__(self):
return hash((self._singular, self._plural, self._number_index))
[docs] def localize(self, formatter, translator, *args, **kwargs):
"""
Localize and format the string using the given `formatter` and
`translator`. The remaining args are passed to the
:meth:`~LocalizingFormatter.format` method of the `formatter`.
The `translator` must be an object supporting the
:class:`gettext.NullTranslations` interface.
If :attr:`plural` is not :data:`None`, the number which will be passed
to the `ngettext` method of `translator` is first extracted from the
`args` or `kwargs`, depending on :attr:`number_index`. The whole
semantics of all three are described in
:meth:`string.Formatter.get_field`, which is used by this method
(:attr:`number_index` is passed as `field_name`).
The value returned by :meth:`~string.Formatter.get_field` is then used
as third argument to `ngettext`, while the others are sourced from
:attr:`singular` and :attr:`plural`.
If :attr:`plural` is :data:`None`, the `gettext` method of `translator`
is used with :attr:`singular` as its only argument.
After the translation step, the `formatter` is used with the translated
string and `args` and `kwargs` to obtain a formatted version of the
string which is then returned.
All of this works best when using a :class:`LocalizingFormatter`.
"""
if self.plural is not None:
n, _ = formatter.get_field(self.number_index, args, kwargs)
translated = translator.ngettext(self.singular,
self.plural,
n)
else:
translated = translator.gettext(self.singular)
return formatter.vformat(translated, args, kwargs)
def __str__(self):
return self.singular
def __repr__(self):
if self.plural is not None:
return "ngettext({!r}, {!r}, {!r})".format(
self.singular,
self.plural,
self.number_index
)
return "_({!r})".format(self.singular)
[docs]def _(s):
"""
Return a new singular :class:`LocalizableString` using `s` as singular
form.
"""
return LocalizableString(s)
[docs]def ngettext(singular, plural, number_index):
"""
Return a new plural :class:`LocalizableString` with the given arguments;
these are passed to the constructor of :class:`LocalizableString`.
"""
return LocalizableString(singular, plural, number_index)