bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/Union.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   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
   8  *
   9  * Contributors:
  10  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.layer0.genericrelation.combinators;
  13
  14 import java.util.ArrayList;
  15 import java.util.Collection;
  16 import java.util.List;
  17
  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;
  23
  24 /**
  25  * Takes the union of multiple relations. Does not remove duplicates.
  26  */
  27 public class Union extends AbstractRelation {
  28
  29         Collection<GenericRelation> relations;
  30
  31         public Union(Collection<GenericRelation> relations) {
  32                 this.relations = relations;
  33         }
  34
  35         @Override
  36         public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {
  37                 for(GenericRelation relation : relations)
  38                         if(relation.contains(g, tuple))
  39                                 return true;
  40                 return false;
  41         }
  42
  43         @Override
  44         public boolean isRealizable() {
  45                 for(GenericRelation relation : relations)
  46                         if(!relation.isRealizable())
  47                                 return false;
  48                 return true;
  49         }
  50
  51         @Override
  52         public List<Object[]> realize(ReadGraph g) throws DatabaseException {
  53                 ArrayList<List<Object[]>> results = new ArrayList<List<Object[]>>(relations.size());
  54                 for(GenericRelation relation : relations)
  55                         results.add(relation.realize(g));
  56                 int size = 0;
  57                 for(List<Object[]> part : results)
  58                         size += part.size();
  59                 ArrayList<Object[]> result = new ArrayList<Object[]>(size);
  60                 for(List<Object[]> part : results)
  61                         result.addAll(part);
  62                 return result;
  63         }
  64
  65         @Override
  66         public GenericRelation selectByRelation(String bindingPattern, GenericRelation constraint) {
  67                 ArrayList<GenericRelation> semijoinRelations = new ArrayList<GenericRelation>(relations.size());
  68                 for(GenericRelation relation : relations)
  69                         semijoinRelations.add(relation.selectByRelation(bindingPattern, constraint));
  70                 return new Union(semijoinRelations);
  71         }
  72
  73         @Override
  74         public GenericRelation select(String bindingPattern, Object[] constants) {
  75                 ArrayList<GenericRelation> selectedRelations = new ArrayList<GenericRelation>(relations.size());
  76                 for(GenericRelation relation : relations)
  77                         selectedRelations.add(relation.select(bindingPattern, constants));
  78                 return new Union(selectedRelations);
  79         }
  80
  81         @Override
  82         public Pair<String, String>[] getFields() {
  83                 for(GenericRelation relation : relations)
  84                         return relation.getFields();
  85                 return null;
  86         }
  87
  88 }