python titlecase filter for jinja

titlecase.py

# modified from https://gist.github.com/bsmithgall/372de43205804a2279c9
SMALL_WORDS = re.compile(r'^(a|an|and|as|at|but|by|en|etc|for|if|in|nor|of|on|or|per|the|to|vs?\.?|via)$', re.I)
SPACE_SPLIT = re.compile(r'[\t ]')
# taken from http://stackoverflow.com/a/267405
CAP_WORDS = re.compile(r'^M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$')
PUNC_REGEX = re.compile(r'[{}]'.format(re.escape(string.punctuation)))
# taken from python-titlecase: https://github.com/ppannuto/python-titlecase/blob/master/titlecase/__init__.py#L27
UC_INITIALS = re.compile(r'^(?:[A-Z]{1}\.{1}|[A-Z]{1}\.{1}[A-Z]{1})+$', re.I)

def better_title(string):
    '''drop in replacement for jinja default title filter

    modified from https://gist.github.com/bsmithgall/372de43205804a2279c9
    '''
    rv = []
    for word in re.split(SPACE_SPLIT, string):
        _cleaned_word = PUNC_REGEX.sub('', word)
        if re.match(UC_INITIALS, word):
            rv.append(word.upper())
        elif re.match(SMALL_WORDS, _cleaned_word.strip()):
            rv.append(word.lower())
        elif word.startswith('('):
            new_string = '('
            new_string += better_title(word.lstrip('('))
            rv.append(new_string)
        elif re.match(CAP_WORDS, _cleaned_word):
            rv.append(word.upper())
        else:
            rv.append(word[0].upper() + word[1:].lower())

    return ' '.join(rv)