trans_real.py 文件源码

def get_supported_language_variant(lang_code, strict=False):
    """
    Returns the language-code that's listed in supported languages, possibly
    selecting a more generic variant. Raises LookupError if nothing found.

    If `strict` is False (the default), the function will look for an alternative
    country-specific variant when the currently checked is not 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
    <https://www.djangoproject.com/weblog/2007/oct/26/security-fix/>.
    """
    if lang_code:
        # If 'fr-ca' is not supported, try special fallback or language-only 'fr'.
        possible_lang_codes = [lang_code]
        try:
            possible_lang_codes.extend(LANG_INFO[lang_code]['fallback'])
        except KeyError:
            pass
        generic_lang_code = lang_code.split('-')[0]
        possible_lang_codes.append(generic_lang_code)
        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)