regex.py

def is_match(text, pattern):
    assert text != None
    assert pattern != None
    assert isinstance(text, str)
    assert isinstance(pattern, str)

    T, P = len(text), len(pattern)

    def _is_match(ti, pi):
        if pi == P:
            return ti == T

        # . *
        first_char_match = ti != T and (text[ti] == pattern[pi] or pattern[pi] == ".")
        if P - pi >= 2:
            if pattern[pi + 1] == "*":
                return _is_match(ti, pi + 2) or (
                    first_char_match and _is_match(ti + 1, pi)
                )
            elif pattern[pi + 1] == "+":
                return first_char_match and (
                    _is_match(ti + 1, pi) or _is_match(ti + 1, pi + 2)
                )

        return first_char_match and _is_match(ti + 1, pi + 1)

    return _is_match(0, 0)


print(is_match("axyzb", "++"))


from itertools import permutations

n = 1543
p = permutations(list(str(n)))
for i in range(2):
    print(next(p))