209f5402f2
git-svn-id: svn://svn.cy55.de/Zope3/src/loops/trunk@2264 fd906abe-77d9-0310-91a1-e0d9ade77398
117 lines
4.4 KiB
Python
117 lines
4.4 KiB
Python
#
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# Copyright (c) 2008 Helmut Merz helmutm@cy55.de
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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"""
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Constraint definitions for restricting concepts and predicates available
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for assignment as children or as concepts to resources.
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Constraints may be used to build up an ontology, in the sense of a
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ruleset that governs the possible relationships between objects.
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$Id$
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"""
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from zope.interface import Interface, Attribute
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from zope import interface, component, schema
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from loops.concept import Concept
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from loops.interfaces import IConceptSchema
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from loops.util import _
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class IConstraint(Interface):
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""" A constraint is an adapter for concepts and resources and
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provides information on which relations are allowed for its
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client object.
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When the client object is a concept the constraint checks
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parent relations, if it is a resource it checks concept
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relations. In order to check for allowed child relations
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on a concept only you may specify a relation type of ``child``
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as an additional argument for the method calls.
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"""
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client = Attribute('Object that will be checked for allowed relations.')
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def isRelationAllowed(concept, predicate, relationType=None):
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""" Return True if this constraint allows the assignment of a
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relation to the client object specified by the target concept
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and the predicate given.
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"""
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def getAllowedPredicates(relationType=None):
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""" Return a sequence of concepts of type ``predicate`` that
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may be used for assigning concepts to the client object.
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"""
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def getAllowedConcepts(predicate, candidates=None, relationType=None):
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""" Return an iterable of concepts that - according to this
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constraint - may be assigned to the client object via the
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predicate given.
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If given, use candidates as a list of concepts from
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which to select the allowed targets.
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"""
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class IStaticConstraint(IConceptSchema, IConstraint):
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""" Provides a statically assigned contstraint setting.
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Typically used as a concept adapter for a persistent constraint
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that allows editing of predicates, target types and cardinality
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of allowed relationships.
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"""
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relationType = schema.Choice(
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title=_(u'Relation type'),
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description=_(u'Select the type of the relation for '
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'which this constraint should be checked, '
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'"default" meaning parent relations for concepts '
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'and resource/concept relations for resources.'),
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values=('default', 'child'),
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default='default',
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required=True,)
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predicates = schema.List(
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title=_(u'Predicates'),
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description=_(u'Select the predicates that this '
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'constraint should allow.'),
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value_type=schema.Choice(
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title=_(u'Predicate'),
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source='loops.predicateSource'),
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required=False,)
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types = schema.List(
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title=_(u'Target types'),
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description=_(u'Select the types of the objects '
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'that this constraints should allow.'),
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value_type=schema.Choice(
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title=_(u'Type'),
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source='loops.conceptTypeSource'),
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required=False,)
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cardinality = schema.Choice(
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title=_(u'Cardinality'),
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description=_(u'Select an entry that represents the '
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'allowed number of assigned items as specified '
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'by this constraint.'),
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values=('0,*', '0,1', '1,*', '1,1'),
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default='0,*',
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required=True,)
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