convert_base.py

import functools
import string

from test_framework import generic_test


def convert_base(num_as_string: str, b1: int, b2: int) -> str:
    def construct_from_base(num_as_int, base):
        return ('' if num_as_int == 0 else
                construct_from_base(num_as_int // base, base) +
                string.hexdigits[num_as_int % base].upper())

    is_negative = num_as_string[0] == '-'
    num_as_int = functools.reduce(
        lambda x, c: x * b1 + string.hexdigits.index(c.lower()),
        num_as_string[is_negative:], 0)
    return ('-' if is_negative else '') + ('0' if num_as_int == 0 else
                                           construct_from_base(num_as_int, b2))


if __name__ == '__main__':
    exit(
        generic_test.generic_test_main('convert_base.py', 'convert_base.tsv',
                                       convert_base))