version.py 文件源码

def _sort_key(self):
        """Return a key for sorting SemanticVersion's on."""
        # key things:
        # - final is after rc's, so we make that a/b/rc/z
        # - dev==None is after all other devs, so we use sys.maxsize there.
        # - unqualified dev releases come before any pre-releases.
        # So we do:
        # (major, minor, patch) - gets the major grouping.
        # (0|1) unqualified dev flag
        # (a/b/rc/z) - release segment grouping
        # pre-release level
        # dev count, maxsize for releases.
        rc_lookup = {'a': 'a', 'b': 'b', 'rc': 'rc', None: 'z'}
        if self._dev_count and not self._prerelease_type:
            uq_dev = 0
        else:
            uq_dev = 1
        return (
            self._major, self._minor, self._patch,
            uq_dev,
            rc_lookup[self._prerelease_type], self._prerelease,
            self._dev_count or sys.maxsize)