# Django 4.1.8.dev20230308103347 ドキュメント

# django.utils.translation のソースコード

    """
    Internationalization support.
    """
    from contextlib import ContextDecorator
    from decimal import ROUND_UP, Decimal

    from django.utils.autoreload import autoreload_started, file_changed
    from django.utils.functional import lazy
    from django.utils.regex_helper import _lazy_re_compile

    __all__ = [
        "activate",
        "deactivate",
        "override",
        "deactivate_all",
        "get_language",
        "get_language_from_request",
        "get_language_info",
        "get_language_bidi",
        "check_for_language",
        "to_language",
        "to_locale",
        "templatize",
        "gettext",
        "gettext_lazy",
        "gettext_noop",
        "ngettext",
        "ngettext_lazy",
        "pgettext",
        "pgettext_lazy",
        "npgettext",
        "npgettext_lazy",
    ]

    class TranslatorCommentWarning(SyntaxWarning):
        pass

    # Here be dragons, so a short explanation of the logic won't hurt:
    # We are trying to solve two problems: (1) access settings, in particular
    # settings.USE_I18N, as late as possible, so that modules can be imported
    # without having to first configure Django, and (2) if some other code creates
    # a reference to one of these functions, don't break that reference when we
    # replace the functions with their real counterparts (once we do access the
    # settings).

    class Trans:
        """
        The purpose of this class is to store the actual translation function upon
        receiving the first call to that function. After this is done, changes to
        USE_I18N will have no effect to which function is served upon request. If
        your tests rely on changing USE_I18N, you can delete all the functions
        from _trans.__dict__.

        Note that storing the function with setattr will have a noticeable
        performance effect, as access to the function goes the normal path,
        instead of using __getattr__.
        """

        def __getattr__(self, real_name):
            from django.conf import settings

            if settings.USE_I18N:
                from django.utils.translation import trans_real as trans
                from django.utils.translation.reloader import (
                    translation_file_changed,
                    watch_for_translation_changes,
                )

                autoreload_started.connect(
                    watch_for_translation_changes, dispatch_uid="translation_file_changed"
                )
                file_changed.connect(
                    translation_file_changed, dispatch_uid="translation_file_changed"
                )
            else:
                from django.utils.translation import trans_null as trans
            setattr(self, real_name, getattr(trans, real_name))
            return getattr(trans, real_name)

    _trans = Trans()

    # The Trans class is no more needed, so remove it from the namespace.
    del Trans

    def gettext_noop(message):
        return _trans.gettext_noop(message)

    def gettext(message):
        return _trans.gettext(message)

    def ngettext(singular, plural, number):
        return _trans.ngettext(singular, plural, number)

    def pgettext(context, message):
        return _trans.pgettext(context, message)

    def npgettext(context, singular, plural, number):
        return _trans.npgettext(context, singular, plural, number)

    gettext_lazy = lazy(gettext, str)
    pgettext_lazy = lazy(pgettext, str)

    def lazy_number(func, resultclass, number=None, **kwargs):
        if isinstance(number, int):
            kwargs["number"] = number
            proxy = lazy(func, resultclass)(**kwargs)
        else:
            original_kwargs = kwargs.copy()

            class NumberAwareString(resultclass):
                def __bool__(self):
                    return bool(kwargs["singular"])

                def _get_number_value(self, values):
                    try:
                        return values[number]
                    except KeyError:
                        raise KeyError(
                            "Your dictionary lacks key '%s'. Please provide "
                            "it, because it is required to determine whether "
                            "string is singular or plural." % number
                        )

                def _translate(self, number_value):
                    kwargs["number"] = number_value
                    return func(**kwargs)

                def format(self, *args, **kwargs):
                    number_value = (
                        self._get_number_value(kwargs) if kwargs and number else args[0]
                    )
                    return self._translate(number_value).format(*args, **kwargs)

                def __mod__(self, rhs):
                    if isinstance(rhs, dict) and number:
                        number_value = self._get_number_value(rhs)
                    else:
                        number_value = rhs
                    translated = self._translate(number_value)
                    try:
                        translated = translated % rhs
                    except TypeError:
                        # String doesn't contain a placeholder for the number.
                        pass
                    return translated

            proxy = lazy(lambda **kwargs: NumberAwareString(), NumberAwareString)(**kwargs)
            proxy.__reduce__ = lambda: (
                _lazy_number_unpickle,
                (func, resultclass, number, original_kwargs),
            )
        return proxy

    def _lazy_number_unpickle(func, resultclass, number, kwargs):
        return lazy_number(func, resultclass, number=number, **kwargs)

    def ngettext_lazy(singular, plural, number=None):
        return lazy_number(ngettext, str, singular=singular, plural=plural, number=number)

    def npgettext_lazy(context, singular, plural, number=None):
        return lazy_number(
            npgettext, str, context=context, singular=singular, plural=plural, number=number
        )

    def activate(language):
        return _trans.activate(language)

    def deactivate():
        return _trans.deactivate()

    class override(ContextDecorator):
        def __init__(self, language, deactivate=False):
            self.language = language
            self.deactivate = deactivate

        def __enter__(self):
            self.old_language = get_language()
            if self.language is not None:
                activate(self.language)
            else:
                deactivate_all()

        def __exit__(self, exc_type, exc_value, traceback):
            if self.old_language is None:
                deactivate_all()
            elif self.deactivate:
                deactivate()
            else:
                activate(self.old_language)

    def get_language():
        return _trans.get_language()

    def get_language_bidi():
        return _trans.get_language_bidi()

    def check_for_language(lang_code):
        return _trans.check_for_language(lang_code)

    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()
        else:
            return locale.lower()

    def to_locale(language):
        """Turn a language name (en-us) into a locale name (en_US)."""
        lang, _, country = language.lower().partition("-")
        if not country:
            return language[:3].lower() + language[3:]
        # 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.
        country, _, tail = country.partition("-")
        country = country.title() if len(country) > 2 else country.upper()
        if tail:
            country += "-" + tail
        return lang + "_" + country

    def get_language_from_request(request, check_path=False):
        return _trans.get_language_from_request(request, check_path)

    def get_language_from_path(path):
        return _trans.get_language_from_path(path)

    def get_supported_language_variant(lang_code, *, strict=False):
        return _trans.get_supported_language_variant(lang_code, strict)

    def templatize(src, **kwargs):
        from .template import templatize

        return templatize(src, **kwargs)

    def deactivate_all():
        return _trans.deactivate_all()

    def get_language_info(lang_code):
        from django.conf.locale import LANG_INFO

        try:
            lang_info = LANG_INFO[lang_code]
            if "fallback" in lang_info and "name" not in lang_info:
                info = get_language_info(lang_info["fallback"][0])
            else:
                info = lang_info
        except KeyError:
            if "-" not in lang_code:
                raise KeyError("Unknown language code %s." % lang_code)
            generic_lang_code = lang_code.split("-")[0]
            try:
                info = LANG_INFO[generic_lang_code]
            except KeyError:
                raise KeyError(
                    "Unknown language code %s and %s." % (lang_code, generic_lang_code)
                )

        if info:
            info["name_translated"] = gettext_lazy(info["name"])
        return info

    trim_whitespace_re = _lazy_re_compile(r"\s*\n\s*")

    def trim_whitespace(s):
        return trim_whitespace_re.sub(" ", s.strip())

    def round_away_from_one(value):
        return int(Decimal(value - 1).quantize(Decimal("0"), rounding=ROUND_UP)) + 1