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"""Translation helper functions."""
import functools
import gettext as gettext_module
import os
import re
import sys
import warnings
from collections import OrderedDict
from threading import local
from django.apps import apps
from django.conf import settings
from django.conf.locale import LANG_INFO
from django.core.exceptions import AppRegistryNotReady
from django.core.signals import setting_changed
from django.dispatch import receiver
from django.utils.safestring import SafeData, mark_safe
from django.utils.translation import LANGUAGE_SESSION_KEY
# Translations are cached in a dictionary for every language.
# The active translations are stored by threadid to make them thread local.
_translations = {}
_active = local()
# The default translation is based on the settings file.
_default = None
# magic gettext number to separate context from message
# Format of Accept-Language header values. From RFC 2616, section 14.4 and 3.9
# and RFC 3066, section 2.1
accept_language_re = re.compile(r'''
([A-Za-z]{1,8}(?:-[A-Za-z0-9]{1,8})*|\*) # "en", "en-au", "x-y-z", "es-419", "*"
(?:\s*;\s*q=(0(?:\.\d{,3})?|1(?:\.0{,3})?))? # Optional "q=1.00", "q=0.8"
(?:\s*,\s*|$) # Multiple accepts per header.
''', re.VERBOSE)
language_code_re = re.compile(
language_code_prefix_re = re.compile(r'^/(\w+([@-]\w+)?)(/|$)')
def reset_cache(**kwargs):
Reset global state when LANGUAGES setting has been changed, as some
languages should no longer be accepted.
if kwargs['setting'] in ('LANGUAGES', 'LANGUAGE_CODE'):
def to_locale(language):
"""Turn a language name (en-us) into a locale name (en_US)."""
language = language.lower()
parts = language.split('-')
country = parts[1]
except IndexError:
return language
# A language with > 2 characters after the dash only has its first
# character after the dash capitalized; e.g. sr-latn becomes sr_Latn.
# A language with 2 characters after the dash has both characters
# capitalized; e.g. en-us becomes en_US.
parts[1] = country.title() if len(country) > 2 else country.upper()
return parts[0] + '_' + '-'.join(parts[1:])
def to_language(locale):
"""Turn a locale name (en_US) into a language name (en-us)."""
p = locale.find('_')
if p >= 0:
return locale[:p].lower() + '-' + locale[p + 1:].lower()
return locale.lower()
class DjangoTranslation(gettext_module.GNUTranslations):
Set up the GNUTranslations context with regard to output charset.
This translation object will be constructed out of multiple GNUTranslations
objects by merging their catalogs. It will construct an object for the
requested language and add a fallback to the default language, if it's
different from the requested language.
domain = 'django'
def __init__(self, language, domain=None, localedirs=None):
"""Create a GNUTranslations() using many locale directories"""
if domain is not None:
self.domain = domain
self.__language = language
self.__to_language = to_language(language)
self.__locale = to_locale(language)
self._catalog = None
# If a language doesn't have a catalog, use the Germanic default for
# pluralization: anything except one is pluralized.
self.plural = lambda n: int(n != 1)
if self.domain == 'django':
if localedirs is not None:
# A module-level cache is used for caching 'django' translations
warnings.warn("localedirs is ignored when domain is 'django'.", RuntimeWarning)
localedirs = None
if localedirs:
for localedir in localedirs:
translation = self._new_gnu_trans(localedir)
if self.__language == settings.LANGUAGE_CODE and self.domain == 'django' and self._catalog is None:
# default lang should have at least one translation file available.
raise IOError("No translation files found for default language %s." % settings.LANGUAGE_CODE)
if self._catalog is None:
# No catalogs found for this language, set an empty catalog.
self._catalog = {}
def __repr__(self):
return "<DjangoTranslation lang:%s>" % self.__language
def _new_gnu_trans(self, localedir, use_null_fallback=True):
Return a mergeable gettext.GNUTranslations instance.
A convenience wrapper. By default gettext uses 'fallback=False'.
Using param `use_null_fallback` to avoid confusion with any other
references to 'fallback'.
return gettext_module.translation(
def _init_translation_catalog(self):
"""Create a base catalog using global django translations."""
settingsfile = sys.modules[settings.__module__].__file__
localedir = os.path.join(os.path.dirname(settingsfile), 'locale')
translation = self._new_gnu_trans(localedir)
def _add_installed_apps_translations(self):
"""Merge translations from each installed app."""
app_configs = reversed(list(apps.get_app_configs()))
except AppRegistryNotReady:
raise AppRegistryNotReady(
"The translation infrastructure cannot be initialized before the "
"apps registry is ready. Check that you don't make non-lazy "
"gettext calls at import time.")
for app_config in app_configs:
localedir = os.path.join(app_config.path, 'locale')
if os.path.exists(localedir):
translation = self._new_gnu_trans(localedir)
def _add_local_translations(self):
"""Merge translations defined in LOCALE_PATHS."""
for localedir in reversed(settings.LOCALE_PATHS):
translation = self._new_gnu_trans(localedir)
def _add_fallback(self, localedirs=None):
"""Set the GNUTranslations() fallback with the default language."""
# Don't set a fallback for the default language or any English variant
# (as it's empty, so it'll ALWAYS fall back to the default language)
if self.__language == settings.LANGUAGE_CODE or self.__language.startswith('en'):
if self.domain == 'django':
# Get from cache
default_translation = translation(settings.LANGUAGE_CODE)
default_translation = DjangoTranslation(
settings.LANGUAGE_CODE, domain=self.domain, localedirs=localedirs
def merge(self, other):
"""Merge another translation into this catalog."""
if not getattr(other, '_catalog', None):
return # NullTranslations() has no _catalog
if self._catalog is None:
# Take plural and _info from first catalog found (generally Django's).
self.plural = other.plural
self._info = other._info.copy()
self._catalog = other._catalog.copy()
if other._fallback:
def language(self):
"""Return the translation language."""
return self.__language
def to_language(self):
"""Return the translation language name."""
return self.__to_language
def translation(language):
Return a translation object in the default 'django' domain.
global _translations
if language not in _translations:
_translations[language] = DjangoTranslation(language)
return _translations[language]
def activate(language):
Fetch the translation object for a given language and install it as the
current translation object for the current thread.
if not language:
_active.value = translation(language)
def deactivate():
Uninstall the active translation object so that further _() calls resolve
to the default translation object.
if hasattr(_active, "value"):
del _active.value
def deactivate_all():
Make the active translation object a NullTranslations() instance. This is
useful when we want delayed translations to appear as the original string
for some reason.
_active.value = gettext_module.NullTranslations()
_active.value.to_language = lambda *args: None
def get_language():
"""Return the currently selected language."""
t = getattr(_active, "value", None)
if t is not None:
return t.to_language()
except AttributeError:
# If we don't have a real translation object, assume it's the default language.
return settings.LANGUAGE_CODE
def get_language_bidi():
Return selected language's BiDi layout.
* False = left-to-right layout
* True = right-to-left layout
lang = get_language()
if lang is None:
return False
base_lang = get_language().split('-')[0]
return base_lang in settings.LANGUAGES_BIDI
def catalog():
Return the current active catalog for further processing.
This can be used if you need to modify the catalog or want to access the
whole message catalog instead of just translating one string.
global _default
t = getattr(_active, "value", None)
if t is not None:
return t
if _default is None:
_default = translation(settings.LANGUAGE_CODE)
return _default
def gettext(message):
Translate the 'message' string. It uses the current thread to find the
translation object to use. If no current translation is activated, the
message will be run through the default translation object.
global _default
eol_message = message.replace('\r\n', '\n').replace('\r', '\n')
if eol_message:
_default = _default or translation(settings.LANGUAGE_CODE)
translation_object = getattr(_active, "value", _default)
result = translation_object.gettext(eol_message)
# Return an empty value of the corresponding type if an empty message
# is given, instead of metadata, which is the default gettext behavior.
result = type(message)('')
if isinstance(message, SafeData):
return mark_safe(result)
return result
def pgettext(context, message):
msg_with_ctxt = "%s%s%s" % (context, CONTEXT_SEPARATOR, message)
result = gettext(msg_with_ctxt)
# Translation not found
result = message
elif isinstance(message, SafeData):
result = mark_safe(result)
return result
def gettext_noop(message):
Mark strings for translation but don't translate them now. This can be
used to store strings in global variables that should stay in the base
language (because they might be used externally) and will be translated
return message
def do_ntranslate(singular, plural, number, translation_function):
global _default
t = getattr(_active, "value", None)
if t is not None:
return getattr(t, translation_function)(singular, plural, number)
if _default is None:
_default = translation(settings.LANGUAGE_CODE)
return getattr(_default, translation_function)(singular, plural, number)
def ngettext(singular, plural, number):
Return a string of the translation of either the singular or plural,
based on the number.
return do_ntranslate(singular, plural, number, 'ngettext')
def npgettext(context, singular, plural, number):
msgs_with_ctxt = ("%s%s%s" % (context, CONTEXT_SEPARATOR, singular),
"%s%s%s" % (context, CONTEXT_SEPARATOR, plural),
result = ngettext(*msgs_with_ctxt)
# Translation not found
result = ngettext(singular, plural, number)
return result
def all_locale_paths():
Return a list of paths to user-provides languages files.
globalpath = os.path.join(
os.path.dirname(sys.modules[settings.__module__].__file__), 'locale')
app_paths = []
for app_config in apps.get_app_configs():
locale_path = os.path.join(app_config.path, 'locale')
if os.path.exists(locale_path):
return [globalpath] + list(settings.LOCALE_PATHS) + app_paths
def check_for_language(lang_code):
Check whether there is a global language file for the given language
code. This is used to decide whether a user-provided language is
lru_cache should have a maxsize to prevent from memory exhaustion attacks,
as the provided language codes are taken from the HTTP request. See also
# First, a quick check to make sure lang_code is well-formed (#21458)
if lang_code is None or not
return False
return any(
gettext_module.find('django', path, [to_locale(lang_code)]) is not None
for path in all_locale_paths()
def get_languages():
Cache of settings.LANGUAGES in an OrderedDict for easy lookups by key.
return OrderedDict(settings.LANGUAGES)
def get_supported_language_variant(lang_code, strict=False):
Return the language code that's listed in supported languages, possibly
selecting a more generic variant. Raise LookupError if nothing is found.
If `strict` is False (the default), look for a country-specific variant
when neither the language code nor its generic variant is found.
lru_cache should have a maxsize to prevent from memory exhaustion attacks,
as the provided language codes are taken from the HTTP request. See also
if lang_code:
# If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
possible_lang_codes = [lang_code]
except KeyError:
generic_lang_code = lang_code.split('-')[0]
supported_lang_codes = get_languages()
for code in possible_lang_codes:
if code in supported_lang_codes and check_for_language(code):
return code
if not strict:
# if fr-fr is not supported, try fr-ca.
for supported_code in supported_lang_codes:
if supported_code.startswith(generic_lang_code + '-'):
return supported_code
raise LookupError(lang_code)
def get_language_from_path(path, strict=False):
Return the language code if there's a valid language code found in `path`.
If `strict` is False (the default), look for a country-specific variant
when neither the language code nor its generic variant is found.
regex_match = language_code_prefix_re.match(path)
if not regex_match:
return None
lang_code =
return get_supported_language_variant(lang_code, strict=strict)
except LookupError:
return None
def get_language_from_request(request, check_path=False):
Analyze the request to find what language the user wants the system to
show. Only languages listed in settings.LANGUAGES are taken into account.
If the user requests a sublanguage where we have a main language, we send
out the main language.
If check_path is True, the URL path prefix will be checked for a language
code, otherwise this is skipped for backwards compatibility.
if check_path:
lang_code = get_language_from_path(request.path_info)
if lang_code is not None:
return lang_code
supported_lang_codes = get_languages()
if hasattr(request, 'session'):
lang_code = request.session.get(LANGUAGE_SESSION_KEY)
if lang_code in supported_lang_codes and lang_code is not None and check_for_language(lang_code):
return lang_code
lang_code = request.COOKIES.get(settings.LANGUAGE_COOKIE_NAME)
return get_supported_language_variant(lang_code)
except LookupError:
accept = request.META.get('HTTP_ACCEPT_LANGUAGE', '')
for accept_lang, unused in parse_accept_lang_header(accept):
if accept_lang == '*':
if not
return get_supported_language_variant(accept_lang)
except LookupError:
return get_supported_language_variant(settings.LANGUAGE_CODE)
except LookupError:
return settings.LANGUAGE_CODE
def parse_accept_lang_header(lang_string):
Parse the lang_string, which is the body of an HTTP Accept-Language
header, and return a tuple of (lang, q-value), ordered by 'q' values.
Return an empty tuple if there are any format errors in lang_string.
result = []
pieces = accept_language_re.split(lang_string.lower())
if pieces[-1]:
return ()
for i in range(0, len(pieces) - 1, 3):
first, lang, priority = pieces[i:i + 3]
if first:
return ()
if priority:
priority = float(priority)
priority = 1.0
result.append((lang, priority))
result.sort(key=lambda k: k[1], reverse=True)
return tuple(result)