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