__init__.py 文件源码

def normalize_language_tag(tag):
    """Return a list of normalized combinations for a `BCP 47` language tag.

    Example:

    >>> from docutils.utils import normalize_language_tag
    >>> normalize_language_tag('de_AT-1901')
    ['de-at-1901', 'de-at', 'de-1901', 'de']
    >>> normalize_language_tag('de-CH-x_altquot')
    ['de-ch-x-altquot', 'de-ch', 'de-x-altquot', 'de']

    """
    # normalize:
    tag = tag.lower().replace('-','_')
    # split (except singletons, which mark the following tag as non-standard):
    tag = re.sub(r'_([a-zA-Z0-9])_', r'_\1-', tag)
    subtags = [subtag for subtag in tag.split('_')]
    base_tag = [subtags.pop(0)]
    # find all combinations of subtags
    taglist = []
    for n in range(len(subtags), 0, -1):
        for tags in unique_combinations(subtags, n):
            taglist.append('-'.join(base_tag+tags))
    taglist += base_tag
    return taglist