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

   1 /*******************************************************************************\r
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
   3  * in Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  *\r
   9  * Contributors:\r
  10  *     VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 package org.simantics.db.layer0.genericrelation.combinators;\r
  13 \r
  14 import java.util.ArrayList;\r
  15 import java.util.Collection;\r
  16 import java.util.List;\r
  17 \r
  18 import org.simantics.db.ReadGraph;\r
  19 import org.simantics.db.exception.DatabaseException;\r
  20 import org.simantics.db.layer0.adapter.GenericRelation;\r
  21 import org.simantics.db.layer0.genericrelation.AbstractRelation;\r
  22 import org.simantics.utils.datastructures.Pair;\r
  23 \r
  24 /**\r
  25  * Takes the union of multiple relations. Does not remove duplicates.\r
  26  */\r
  27 public class Union extends AbstractRelation {\r
  28 \r
  29         Collection<GenericRelation> relations;\r
  30         \r
  31         public Union(Collection<GenericRelation> relations) {\r
  32                 this.relations = relations;\r
  33         }\r
  34 \r
  35         @Override\r
  36         public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {\r
  37                 for(GenericRelation relation : relations)\r
  38                         if(relation.contains(g, tuple))\r
  39                                 return true;\r
  40                 return false;\r
  41         }\r
  42 \r
  43         @Override\r
  44         public boolean isRealizable() {\r
  45                 for(GenericRelation relation : relations)\r
  46                         if(!relation.isRealizable())\r
  47                                 return false;\r
  48                 return true;\r
  49         }\r
  50 \r
  51         @Override\r
  52         public List<Object[]> realize(ReadGraph g) throws DatabaseException {\r
  53                 ArrayList<List<Object[]>> results = new ArrayList<List<Object[]>>(relations.size());            \r
  54                 for(GenericRelation relation : relations)\r
  55                         results.add(relation.realize(g));\r
  56                 int size = 0;\r
  57                 for(List<Object[]> part : results)\r
  58                         size += part.size();\r
  59                 ArrayList<Object[]> result = new ArrayList<Object[]>(size);\r
  60                 for(List<Object[]> part : results)\r
  61                         result.addAll(part);\r
  62                 return result;\r
  63         }\r
  64         \r
  65         @Override\r
  66         public GenericRelation selectByRelation(String bindingPattern, GenericRelation constraint) {\r
  67                 ArrayList<GenericRelation> semijoinRelations = new ArrayList<GenericRelation>(relations.size()); \r
  68                 for(GenericRelation relation : relations)\r
  69                         semijoinRelations.add(relation.selectByRelation(bindingPattern, constraint));\r
  70                 return new Union(semijoinRelations);\r
  71         }\r
  72         \r
  73         @Override\r
  74         public GenericRelation select(String bindingPattern, Object[] constants) {\r
  75                 ArrayList<GenericRelation> selectedRelations = new ArrayList<GenericRelation>(relations.size()); \r
  76                 for(GenericRelation relation : relations)\r
  77                         selectedRelations.add(relation.select(bindingPattern, constants));\r
  78                 return new Union(selectedRelations);\r
  79         }\r
  80 \r
  81         @Override\r
  82         public Pair<String, String>[] getFields() {\r
  83                 for(GenericRelation relation : relations)\r
  84                         return relation.getFields();\r
  85                 return null;\r
  86         }\r
  87 \r
  88 }\r