1 /*******************************************************************************
2 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
4 * All rights reserved. This program and the accompanying materials
5 * are made available under the terms of the Eclipse Public License v1.0
6 * which accompanies this distribution, and is available at
7 * http://www.eclipse.org/legal/epl-v10.html
10 * VTT Technical Research Centre of Finland - initial API and implementation
11 *******************************************************************************/
12 package org.simantics.db.layer0.genericrelation.combinators;
14 import java.util.ArrayList;
15 import java.util.Collection;
16 import java.util.List;
18 import org.simantics.db.ReadGraph;
19 import org.simantics.db.exception.DatabaseException;
20 import org.simantics.db.layer0.adapter.GenericRelation;
21 import org.simantics.db.layer0.genericrelation.AbstractRelation;
22 import org.simantics.utils.datastructures.Pair;
25 * Takes the intersection of multiple relations.
27 public class Intersection extends AbstractRelation {
29 GenericRelation realizable = null;
30 Collection<GenericRelation> constraints;
32 public Intersection(Collection<GenericRelation> relations) {
33 for(GenericRelation relation : relations)
34 if(realizable == null && relation.isRealizable()) {
35 realizable = relation;
38 constraints.add(relation);
41 public Intersection(GenericRelation realizable, Collection<GenericRelation> constraints) {
42 assert(realizable.isRealizable());
43 this.realizable = realizable;
44 this.constraints = constraints;
48 public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {
49 if(!realizable.contains(g, tuple))
51 for(GenericRelation relation : constraints)
52 if(!relation.contains(g, tuple))
58 public boolean isRealizable() {
59 return realizable != null;
63 public List<Object[]> realize(ReadGraph g) throws DatabaseException {
64 ArrayList<Object[]> result = new ArrayList<Object[]>();
66 for(Object[] tuple : realizable.realize(g)) {
67 for(GenericRelation constraint : constraints)
68 if(!constraint.contains(g, tuple))
75 // TODO optimize select
78 public GenericRelation selectByRelation(String bindingPattern,
79 GenericRelation constraint) {
80 if(realizable != null)
81 return new Intersection(realizable.selectByRelation(bindingPattern, constraint),
84 return super.selectByRelation(bindingPattern, constraint);
88 public Pair<String, String>[] getFields() {
89 if(realizable != null)
90 return realizable.getFields();
91 for(GenericRelation relation : constraints)
92 return relation.getFields();