itb_util.py 文件源码

def is_right_to_left(text):
    '''Check whether a text is right-to-left text or not

    :param text: The text to check
    :type text: string
    :rtype: boolean

    See: http://unicode.org/reports/tr9/#P2

    TR9> In each paragraph, find the first character of type L, AL, or R
    TR9> while skipping over any characters between an isolate initiator
    TR9> and its matching PDI or, if it has no matching PDI, the end of the
    TR9> paragraph

    Examples:

    >>> is_right_to_left('Hallo!')
    False

    >>> is_right_to_left('?')
    True

    >>> is_right_to_left('???')
    False

    >>> is_right_to_left('????')
    True

    >>> is_right_to_left('a????')
    False

    >>> is_right_to_left('?a?????')
    True
    '''
    skip = False
    for char in text:
        bidi_cat = unicodedata.bidirectional(char)
        if skip and bidi_cat != 'PDI':
            continue
        skip = False
        if bidi_cat in ('AL', 'R'):
            return True
        if bidi_cat == 'L':
            return False
        if bidi_cat in ('LRI', 'RLI', 'FSI'):
            skip = True
    return False