Hostrange expansion

[Peter Otten]

Sam Giraffe wrote:

> I need some help in expanding a hostrange as in: h[1-100].domain.com
> should get expanded into a list containing h1.domain.com to
> h100.domain.com. Is there a library that can do this for me? I also need
> to valid the range before I expand it, i.e., h[1*100].domain.com should
> not be accept, or other formats should not be accepted.

To get you started:

import re
import itertools

def to_range(s, sep="-"):
    """
    >>> to_range("9-11")
    ['9', '10', '11']
    """
    lo, hi = s.split(sep)
    return [str(i) for i in range(int(lo), int(hi)+1)]

def explode(s):
    """
    >>> list(explode("h[3-5].com"))
    ['h3.com', 'h4.com', 'h5.com']
    """
    parts = re.compile(r"(\[\d+-\d+\])").split(s)
    parts[0::2] = [[p] for p in parts[0::2]]
    parts[1::2] = [to_range(p[1:-1]) for p in parts[1::2]]
    return ("".join(p) for p in itertools.product(*parts))

if __name__ == "__main__":
    dom = "h[1-3]x[9-11].com"
    print(dom)
    for name in explode(dom):
        print("    {}".format(name))