"""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):

    """a tag store for full relation definitions :

         (subject type, relation type, object type, tagged)

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

    This class associates a single tag to each key.

    """

    def __init__(self):

        self._tagdefs = {}

    def __repr__(self):

        return repr(self._tagdefs)

    # dict compat

    def __getitem__(self, key):

        return self.get(*key)

    __contains__ = __getitem__

    def _get_keys(self, rtype, tagged, stype, otype):

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

        keys = [(rtype, tagged, '*', '*'),

                (rtype, tagged, '*', otype),

                (rtype, tagged, stype, '*'),

                (rtype, tagged, stype, otype)]

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

            keys.remove((rtype, tagged, '*', '*'))

            if stype == '*':

                keys.remove((rtype, tagged, '*', otype))

            if otype == '*':

                keys.remove((rtype, tagged, stype, '*'))

        return keys

    def tag_attribute(self, tag, stype, attr):

        self._tagdefs[(str(attr), 'subject', str(stype), '*')] = tag

    def tag_relation(self, tag, relation, tagged):

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

        stype, rtype, otype = relation

        self._tagdefs[(str(rtype), tagged, str(stype), str(otype))] = tag

    def del_rtag(self, relation, tagged):

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

        stype, rtype, otype = relation

        del self._tagdefs[(str(rtype), tagged, str(stype), str(otype))]

    def get(self, rtype, tagged, stype='*', otype='*'):

        for key in reversed(self._get_keys(rtype, tagged, stype, otype)):

            try:

                return self._tagdefs[key]

            except KeyError:

                continue

        return None

    def etype_get(self, etype, rtype, tagged, ttype='*'):

        if tagged == 'subject':

            return self.get(rtype, tagged, etype, ttype)

        return self.get(rtype, tagged, ttype, etype)

class RelationTagsSet(RelationTags):

    """This class associates a set of tags to each key."""

    def tag_relation(self, tag, relation, tagged):

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

        stype, rtype, otype = relation

        rtags = self._tagdefs.setdefault((rtype, tagged, stype, otype), set())

        rtags.add(tag)

    def get(self, rtype, tagged, stype='*', otype='*'):

        rtags = set()

        for key in self._get_keys(rtype, tagged, stype, otype):

            try:

                rtags.update(self._tagdefs[key])

            except KeyError:

                continue

        return rtags