"""relation tags store

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

"""

__docformat__ = "restructuredtext en"

class RelationTags(object):

    """RelationTags instances are a tag store for full relation definitions :

         (subject type, relation type, object type, role)

    allowing to set tags using wildcard (eg '*') as subject type / object type

    if `use_set` is True, a set of tags is associated to each key, and you

    should use rtags / etype_rtags / add_rtag api. Otherwise, a single tag is

    associated to each key, and you should use rtag / etype_rtag / set_rtag api.

    """

    def __init__(self, use_set=False):

        self.use_set = use_set

        self._tagdefs = {}

        assert not self.use_set

        assert role in ('subject', 'object'), role

        assert not self.use_set

            try:

                return self._tagdefs[key]

            except KeyError:

                continue

        return None

        if role == 'subject':

        assert self.use_set

        assert role in ('subject', 'object'), role

        rtags.add(tag)

        assert self.use_set

        rtags = set()

            try:

                rtags.update(self._tagdefs[key])

            except KeyError:

                continue

        return rtags

        if role == 'subject':

        assert role in ('subject', 'object'), role

        if stype == '*' or otype == '*':

            if stype == '*':

            if otype == '*':

        return keys

    # dict compat

    def __getitem__(self, key):

        if isinstance(key, basestring):

            key = (key,)

        return self.rtags(*key)

    __contains__ = __getitem__