AoC Day 5 in Python: the power of regex

ip.py

#! /usr/bin/env python
import sys
import re

ABBA_REGEX = re.compile(r'(.)(?!\1)(.)\2\1')
ABA_REGEX = re.compile(r'(?=(.)(?!\1)(.)\1)')

def contains_abba(s):
    return ABBA_REGEX.search(s) is not None

def supports_tls(line):
    split = re.split(r'[\[\]]', line)
    for i in range(1, len(split), 2):
        if contains_abba(split[i]):
            return False
    for i in range(0, len(split), 2):
        if contains_abba(split[i]):
            return True
    return False

def supports_ssl(line):
    split = re.split(r'[\[\]]', line)
    abas = set()
    babs = set()
    for i, s in enumerate(split):
        for m in re.finditer(ABA_REGEX, split[i]):
            if i % 2 == 0:
                aba = m.group(1) + m.group(2)
                if aba in babs:
                    return True
                abas.add(aba)
            else:
                bab = m.group(2) + m.group(1)
                if bab in abas:
                    return True
                babs.add(bab)
    return False

if __name__ == '__main__':
    with open(sys.argv[1]) as f:
        count_tls = 0
        count_ssl = 0
        for line in f:
            if supports_tls(line.strip()):
                count_tls += 1
            if supports_ssl(line.strip()):
                count_ssl += 1
    print("TLS count: {}".format(count_tls))
    print("SSL count: {}".format(count_ssl))