Python `str.ljust` and `str.rjust` for CJK characters mixed with ASCII characters string.

cjkjust.py

__all__ = [
    'cjkljust',
    'cjkrjust',
    'cjkcenter',
]

import unicodedata

#def cjklen(string):
#    return sum(2 if unicodedata.east_asian_width(char) in 'FW' else 1
#               for char in string)


def count_cjk_chars(string):
    return sum(unicodedata.east_asian_width(char) in 'FW' for char in string)


def cjkljust(string, width, fillbyte=' '):
    """
    >>> cjkljust('hello', 10, '*')
    'hello*****'
    >>> cjkljust('你好world', 10, '*')
    '你好world*'
    >>> cjkljust('你好world', 1, '*')
    '你好world'
    """
    #return string.ljust(len(string) + width - cjklen(string), fillbyte)
    return string.ljust(width - count_cjk_chars(string), fillbyte)


def cjkrjust(string, width, fillbyte=' '):
    #return string.rjust(len(string) + width - cjklen(string), fillbyte)
    return string.rjust(width - count_cjk_chars(string), fillbyte)


def cjkcenter(string, width, fillbyte=' '):
    return string.center(width - count_cjk_chars(string), fillbyte)