Function _cmpkey

numpy/_utils/_pep440.py:436–486

(epoch, release, pre, post, dev, local)

def _cmpkey(epoch, release, pre, post, dev, local):
    # When we compare a release version, we want to compare it with all of the
    # trailing zeros removed. So we'll use a reverse the list, drop all the now
    # leading zeros until we come to something non-zero, then take the rest,
    # re-reverse it back into the correct order, and make it a tuple and use
    # that for our sorting key.
    release = tuple(
        reversed(list(
            itertools.dropwhile(
                lambda x: x == 0,
                reversed(release),
            )
        ))
    )

    # We need to "trick" the sorting algorithm to put 1.0.dev0 before 1.0a0.
    # We'll do this by abusing the pre-segment, but we _only_ want to do this
    # if there is no pre- or a post-segment. If we have one of those, then
    # the normal sorting rules will handle this case correctly.
    if pre is None and post is None and dev is not None:
        pre = -Infinity
    # Versions without a pre-release (except as noted above) should sort after
    # those with one.
    elif pre is None:
        pre = Infinity

    # Versions without a post-segment should sort before those with one.
    if post is None:
        post = -Infinity

    # Versions without a development segment should sort after those with one.
    if dev is None:
        dev = Infinity

    if local is None:
        # Versions without a local segment should sort before those with one.
        local = -Infinity
    else:
        # Versions with a local segment need that segment parsed to implement
        # the sorting rules in PEP440.
        # - Alphanumeric segments sort before numeric segments
        # - Alphanumeric segments sort lexicographically
        # - Numeric segments sort numerically
        # - Shorter versions sort before longer versions when the prefixes
        #   match exactly
        local = tuple(
            (i, "") if isinstance(i, int) else (-Infinity, i)
            for i in local
        )

    return epoch, release, pre, post, dev, local