close #511810: bad rql generated when looking for vocabulary for a relation on an entity which doesn't exist (yet)
technical details:
* add a graph of linked variables in the RRQLExpression instance
* modify rql rewriter to remove relations where an unexistant
variable and or a variable linked to an unexistant variable is used.
* activate this feature in Entity.unrelated_rql if the entity doesn't exists yet
"""map standard cubicweb schema to xml vocabularies
:organization: Logilab
:copyright: 2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
from yams import xy
xy.register_prefix('http://purl.org/dc/elements/1.1/', 'dc')
xy.register_prefix('http://xmlns.com/foaf/0.1/', 'foaf')
xy.register_prefix('http://usefulinc.com/ns/doap#', 'doap')
xy.add_equivalence('creation_date', 'dc:date')
xy.add_equivalence('created_by', 'dc:creator')
xy.add_equivalence('description', 'dc:description')
xy.add_equivalence('CWUser', 'foaf:Person')
xy.add_equivalence('CWUser login', 'dc:title')
xy.add_equivalence('CWUser surname', 'foaf:Person foaf:name')