def _parse_tags(tagstring):
    """
    Parses tag input, with multiple word input being activated and
    delineated by commas and double quotes. Quotes take precedence, so
    they may contain commas.

    Returns a sorted list of unique tag names.

    Ported from Jonathan Buchanan's `django-tagging
    <http://django-tagging.googlecode.com/>`_
    """
    if not tagstring:
        return []

    tagstring = force_text(tagstring)

    # Special case - if there are no commas or double quotes in the
    # input, we don't *do* a recall... I mean, we know we only need to
    # split on spaces.
    if ',' not in tagstring and '"' not in tagstring:
        words = list(set(split_strip(tagstring, ' ')))
        words.sort()
        return words

    words = []
    buffer = []
    # Defer splitting of non-quoted sections until we know if there are
    # any unquoted commas.
    to_be_split = []
    saw_loose_comma = False
    open_quote = False
    i = iter(tagstring)
    try:
        while True:
            c = six.next(i)
            if c == '"':
                if buffer:
                    to_be_split.append(''.join(buffer))
                    buffer = []
                # Find the matching quote
                open_quote = True
                c = six.next(i)
                while c != '"':
                    buffer.append(c)
                    c = six.next(i)
                if buffer:
                    word = ''.join(buffer).strip()
                    if word:
                        words.append(word)
                    buffer = []
                open_quote = False
            else:
                if not saw_loose_comma and c == ',':
                    saw_loose_comma = True
                buffer.append(c)
    except StopIteration:
        # If we were parsing an open quote which was never closed treat
        # the buffer as unquoted.
        if buffer:
            if open_quote and ',' in buffer:
                saw_loose_comma = True
            to_be_split.append(''.join(buffer))
    if to_be_split:
        if saw_loose_comma:
            delimiter = ','
        else:
            delimiter = ' '
        for chunk in to_be_split:
            words.extend(split_strip(chunk, delimiter))
    words = list(set(words))
    words.sort()
    return words
dataset/ETHPy150Open alex/django-taggit/taggit/utils.py/_parse_tags/original