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