oslo.i18n/oslo_i18n/_gettextutils.py

# Copyright 2012 Red Hat, Inc.
# Copyright 2013 IBM Corp.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""gettextutils provides a wrapper around gettext for OpenStack projects"""

import copy
import gettext
import locale
import os
from typing import Any, Literal, overload
from collections.abc import Iterable

from oslo_i18n import _factory
from oslo_i18n import _locale

__all__ = [
    'install',
    'get_available_languages',
]


def install(domain: str) -> None:
    """Install a _() function using the given translation domain.

    Given a translation domain, install a _() function using gettext's
    install() function.

    The main difference from gettext.install() is that we allow
    overriding the default localedir (e.g. /usr/share/locale) using
    a translation-domain-specific environment variable (e.g.
    NOVA_LOCALEDIR).

    :param domain: the translation domain
    """
    import builtins

    tf = _factory.TranslatorFactory(domain)
    builtins.__dict__['_'] = tf.primary


_AVAILABLE_LANGUAGES: dict[str, list[str]] = {}
# Copied from Babel so anyone using aliases that were previously provided by
# the Babel implementation of get_available_languages continues to work. These
# are not recommended for use in new code.
_BABEL_ALIASES = {
    'ar': 'ar_SY',
    'bg': 'bg_BG',
    'bs': 'bs_BA',
    'ca': 'ca_ES',
    'cs': 'cs_CZ',
    'da': 'da_DK',
    'de': 'de_DE',
    'el': 'el_GR',
    'en': 'en_US',
    'es': 'es_ES',
    'et': 'et_EE',
    'fa': 'fa_IR',
    'fi': 'fi_FI',
    'fr': 'fr_FR',
    'gl': 'gl_ES',
    'he': 'he_IL',
    'hu': 'hu_HU',
    'id': 'id_ID',
    'is': 'is_IS',
    'it': 'it_IT',
    'ja': 'ja_JP',
    'km': 'km_KH',
    'ko': 'ko_KR',
    'lt': 'lt_LT',
    'lv': 'lv_LV',
    'mk': 'mk_MK',
    'nl': 'nl_NL',
    'nn': 'nn_NO',
    'no': 'nb_NO',
    'pl': 'pl_PL',
    'pt': 'pt_PT',
    'ro': 'ro_RO',
    'ru': 'ru_RU',
    'sk': 'sk_SK',
    'sl': 'sl_SI',
    'sv': 'sv_SE',
    'th': 'th_TH',
    'tr': 'tr_TR',
    'uk': 'uk_UA',
}


def get_available_languages(domain: str) -> list[str]:
    """Lists the available languages for the given translation domain.

    :param domain: the domain to get languages for
    """
    if domain in _AVAILABLE_LANGUAGES:
        return copy.copy(_AVAILABLE_LANGUAGES[domain])

    localedir = os.environ.get(_locale.get_locale_dir_variable_name(domain))

    def find(x: str) -> str | None:
        return gettext.find(domain, localedir=localedir, languages=[x])

    # NOTE(mrodden): en_US should always be available (and first in case
    # order matters) since our in-line message strings are en_US
    language_list = ['en_US']
    locale_identifiers = set(locale.windows_locale.values())
    language_list.extend(
        language for language in locale_identifiers if find(language)
    )
    language_list.extend(
        alias for alias, _ in _BABEL_ALIASES.items() if find(alias)
    )

    _AVAILABLE_LANGUAGES[domain] = language_list
    return copy.copy(language_list)


_original_find = gettext.find
_FIND_CACHE: dict[
    tuple[str, str | None, tuple[str, ...] | None, bool | int], Any
] = {}


@overload
def cached_find(
    domain: str,
    localedir: str | None = None,
    languages: Iterable[str] | None = None,
    all: Literal[False] = False,
) -> str | None: ...


@overload
def cached_find(
    domain: str,
    localedir: str | None = None,
    languages: Iterable[str] | None = None,
    *,
    all: Literal[True],
) -> list[str]: ...


@overload
def cached_find(
    domain: str,
    localedir: str | None,
    languages: Iterable[str] | None,
    all: Literal[True],
) -> list[str]: ...


@overload
def cached_find(
    domain: str,
    localedir: str | None = None,
    languages: Iterable[str] | None = None,
    all: bool = False,
) -> Any: ...


def cached_find(
    domain: str,
    localedir: str | None = None,
    languages: Iterable[str] | None = None,
    all: bool = False,
) -> Any:
    """A version of gettext.find using a cache.

    gettext.find looks for mo files on the disk using os.path.exists. Those
    don't tend to change over time, but the system calls pile up with a
    long-running service. This caches the result so that we return the same mo
    files, and only call find once per domain.
    """
    key = (
        domain,
        localedir,
        tuple(languages) if languages is not None else None,
        all,
    )
    if key in _FIND_CACHE:
        return _FIND_CACHE[key]
    result = _original_find(domain, localedir, languages, all)
    _FIND_CACHE[key] = result
    return result


gettext.find = cached_find  # type: ignore[assignment]