bundles/org.simantics.mapping/src/org/simantics/mapping/constraint/instructions/TripletPredicateQuery.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.mapping.constraint.instructions;
  13
  14 import gnu.trove.set.hash.TIntHashSet;
  15
  16 import java.util.ArrayList;
  17 import java.util.Collection;
  18 import java.util.Iterator;
  19
  20 import org.simantics.db.ReadGraph;
  21 import org.simantics.db.Resource;
  22 import org.simantics.db.Statement;
  23 import org.simantics.db.exception.DatabaseException;
  24 import org.simantics.layer0.Layer0;
  25
  26 public class TripletPredicateQuery extends TripletInstruction {
  27
  28         Resource predicate;
  29
  30         public TripletPredicateQuery(int variable0, int variable1, int variable2,
  31                         Resource predicate) {
  32                 super(variable0, variable1, variable2);
  33                 this.predicate = predicate;
  34         }
  35
  36         public TripletPredicateQuery(int variable0, int variable1, int variable2) {
  37                 super(variable0, variable1, variable2);
  38         }
  39
  40         @Override
  41         public Object query(ReadGraph g, Object[] bindings) throws DatabaseException {
  42                 Resource r0 = (Resource)bindings[variable0];
  43                 Resource r2 = (Resource)bindings[variable2];
  44                 Collection<Resource> result = new ArrayList<Resource>();
  45                 for(Statement stat :
  46                         predicate == null ?
  47                                 g.getStatements(r0, Layer0.getInstance(g).IsWeaklyRelatedTo) :
  48                                 g.getStatements(r0, predicate))
  49                         if(stat.getObject().equals(r2))
  50                                 result.add(stat.getPredicate());
  51                 if(result.isEmpty())
  52                         return IInstruction.FAILURE;
  53                 Iterator<Resource> it = result.iterator();
  54                 bindings[variable1] = it.next();
  55                 if(it.hasNext())
  56                         return it;
  57                 else
  58                         return null;
  59         }
  60
  61         @SuppressWarnings("unchecked")
  62         @Override
  63         public Object next(ReadGraph g, Object[] bindings, Object continuation) {
  64                 Iterator<Resource> it = (Iterator<Resource>)continuation;
  65                 if(it.hasNext()) {
  66                         bindings[variable1] = it.next();
  67                         if(it.hasNext())
  68                                 return it;
  69                         else
  70                                 return null;
  71                 }
  72                 else
  73                         return IInstruction.FAILURE;
  74         }
  75
  76         @Override
  77         public void collectVariables(TIntHashSet reads, TIntHashSet writes) {
  78                 super.collectVariables(reads, writes);
  79                 writes.add(variable1);
  80         }
  81
  82 }