def __repr__(self):
        return "<Requirements({})>".format(self.filename.name or "")
def _patternrootsanddirs(kindpats):
    """Returns roots and directories corresponding to each pattern.

    This calculates the roots and directories exactly matching the patterns and
    returns a tuple of (roots, dirs) for each. It does not return other
    directories which may also need to be considered, like the parent
    directories.
    """
    r = []
    d = []
    for kind, pat, source in kindpats:
        if kind == "glob":  # find the non-glob prefix
            root = []
            for p in pat.split("/"):
                if "[" in p or "{" in p or "*" in p or "?" in p:
                    break
                root.append(p)
            r.append("/".join(root))
        elif kind in ("relpath", "path"):
            if pat == ".":
                pat = ""
            r.append(pat)
        elif kind in ("rootfilesin",):
            if pat == ".":
                pat = ""
            d.append(pat)
        else:  # relglob, re, relre
            r.append("")
    return r, d