cpython/Lib/_pyrepl/utils.py

import re
import unicodedata
import functools

ANSI_ESCAPE_SEQUENCE = re.compile(r"\x1b\[[ -@]*[A-~]")


@functools.cache
def str_width(c: str) -> int:
    if ord(c) < 128:
        return 1
    w = unicodedata.east_asian_width(c)
    if w in ('N', 'Na', 'H', 'A'):
        return 1
    return 2


def wlen(s: str) -> int:
    length = sum(str_width(i) for i in s)
    # remove lengths of any escape sequences
    sequence = ANSI_ESCAPE_SEQUENCE.findall(s)
    return length - sum(len(i) for i in sequence)