basabuuka_prototyp/venv/lib/python3.5/site-packages/dns/grange.py

# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license

# Copyright (C) 2012-2017 Nominum, Inc.
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# provided that the above copyright notice and this permission notice
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"""DNS GENERATE range conversion."""

import dns

def from_text(text):
    """Convert the text form of a range in a ``$GENERATE`` statement to an
    integer.

    *text*, a ``str``, the textual range in ``$GENERATE`` form.

    Returns a tuple of three ``int`` values ``(start, stop, step)``.
    """

    # TODO, figure out the bounds on start, stop and step.
    step = 1
    cur = ''
    state = 0
    # state   0 1 2 3 4
    #         x - y / z

    if text and text[0] == '-':
        raise dns.exception.SyntaxError("Start cannot be a negative number")

    for c in text:
        if c == '-' and state == 0:
            start = int(cur)
            cur = ''
            state = 2
        elif c == '/':
            stop = int(cur)
            cur = ''
            state = 4
        elif c.isdigit():
            cur += c
        else:
            raise dns.exception.SyntaxError("Could not parse %s" % (c))

    if state in (1, 3):
        raise dns.exception.SyntaxError()

    if state == 2:
        stop = int(cur)

    if state == 4:
        step = int(cur)

    assert step >= 1
    assert start >= 0
    assert start <= stop
    # TODO, can start == stop?

    return (start, stop, step)