pretty print ip sets

ipsets.py

#!/usr/bin/env python

import sys
import subprocess
import json

def range_string(start, end):
    if start != end:
        return '%s-%s' % (start, end)
    else:
        return str(start)

ipsets = {} 
in_set = False
in_members = False

set_name = ""

in_range = False
port_start = 0
port_end = 0


p = subprocess.Popen(['ipset', 'list'],stdout=subprocess.PIPE)

while True:
    line = p.stdout.readline()
    if line != b'':
        line = line.strip()
        if line == '':
            if in_members and in_range:
                ipsets[set_name]['Members'].append(range_string(port_start, port_end))
            in_set = False
            in_members = False
            in_range = False
            continue
        if not in_set:
            k,v = line.split(":", 1)
            if k == 'Name':
                in_set = True
                set_name = v.strip()
                ipsets[set_name] = {}
        else:
            if not in_members:
                k,v = line.split(":", 1)
                if k == 'Members':
                    in_members = True
                    ipsets[set_name]['Members'] = []
                else:
                    ipsets[set_name][k.strip()] = v.strip()
            else:
                v = line.strip()
                try:
                    v = int(v)
                    if not in_range:
                        in_range = True
                        port_start = port_end = v
                    elif v == (port_end + 1):
                        port_end = v
                    else:
                        ipsets[set_name]['Members'].append(range_string(port_start, port_end))
                        port_start = port_end = v
                except ValueError:
                    if in_range:
                        in_range = False
                        ipsets[set_name]['Members'].append(range_string(port_start, port_end))
                    ipsets[set_name]['Members'].append(v)
    else:
        if in_members and in_range:
            ipsets[set_name]['Members'].append(range_string(port_start, port_end))
        break



name_width   = max(30, 3 + len(max(ipsets, key=len)))
type_width   = max(15, 3 + len(max([ipsets[s]['Type'] for s in ipsets], key=len)))
member_width = max(30, 3 + len(max((x for y in [ipsets[s]['Members'] for s in ipsets] for x in y), key=len)))


def print_set_line(n, t, m):
    print '{name:<{name_w}}{type:<{type_w}}{members:<{member_w:}}'.format(
        name=n,    name_w=name_width,
        type=t,    type_w=type_width,
        members=m, member_w=member_width
        )
    
print_set_line("Name", "Type", "Members")
print '_' * (name_width + type_width + member_width)
for name in sorted(ipsets):
    type    = ipsets[name]['Type']
    members = ipsets[name]['Members']
    print_set_line(name, type, (members[0] if members else ''))
    if len(members) > 1:
        for member in members[1:]:
            print_set_line('', '', member)

... I'm not a seasoned python programmer, this can probably be simpler/better...