bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/SelectByRelation.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 gnu.trove.list.array.TIntArrayList;\r
  15 \r
  16 import java.util.ArrayList;\r
  17 import java.util.List;\r
  18 \r
  19 import org.simantics.db.ReadGraph;\r
  20 import org.simantics.db.exception.DatabaseException;\r
  21 import org.simantics.db.layer0.adapter.GenericRelation;\r
  22 import org.simantics.db.layer0.genericrelation.AbstractRelation;\r
  23 import org.simantics.utils.datastructures.Pair;\r
  24 \r
  25 \r
  26 public class SelectByRelation extends AbstractRelation {\r
  27         \r
  28         GenericRelation base;\r
  29         int baseLength;\r
  30         String bindingPattern;\r
  31         int[] boundPositions;\r
  32         GenericRelation constraint;\r
  33         \r
  34         public SelectByRelation(GenericRelation base, String bindingPattern, GenericRelation constraint) {\r
  35                 super();\r
  36                 this.base = base;\r
  37                 this.bindingPattern = bindingPattern;\r
  38                 TIntArrayList boundPositionArray = new TIntArrayList();\r
  39                 baseLength = bindingPattern.length();\r
  40                 for(int i=0;i<baseLength;++i)\r
  41                         if(bindingPattern.charAt(i) == 'b') \r
  42                                 boundPositionArray.add(i);\r
  43                 boundPositions = boundPositionArray.toArray();\r
  44                 this.constraint = constraint;\r
  45         }\r
  46         \r
  47         private Object[] map(Object[] tuple) {\r
  48                 Object[] result = new Object[boundPositions.length];\r
  49                 for(int i=0;i<result.length;++i)\r
  50                         result[i] = tuple[boundPositions[i]];\r
  51                 return result;\r
  52         }\r
  53         \r
  54         @Override\r
  55         public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {\r
  56                 assert tuple.length == baseLength;\r
  57                 return base.contains(g, tuple) && constraint.contains(g, map(tuple));\r
  58         }\r
  59         @Override\r
  60         public Pair<String, String>[] getFields() {\r
  61                 return base.getFields();\r
  62         }\r
  63         @Override\r
  64         public boolean isRealizable() {\r
  65                 return base.isRealizable();\r
  66         }\r
  67         @Override\r
  68         public GenericRelation select(String bindingPattern, Object[] constants) {\r
  69                 return new SelectByRelation(base.select(bindingPattern, constants), bindingPattern, constraint);\r
  70         }\r
  71         @Override\r
  72         public List<Object[]> realize(ReadGraph g) throws DatabaseException {\r
  73                 ArrayList<Object[]> result = new ArrayList<Object[]>();\r
  74                 for(Object[] tuple : base.realize(g))\r
  75                         if(constraint.contains(g, map(tuple)))\r
  76                                 result.add(tuple);\r
  77                 return result;\r
  78         }\r
  79 \r
  80 }\r