bundles/org.simantics.mapping/src/org/simantics/mapping/constraint/instructions/TripletObjectQuery.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.Collection;
  17 import java.util.Iterator;
  18
  19 import org.simantics.db.ReadGraph;
  20 import org.simantics.db.Resource;
  21 import org.simantics.db.exception.DatabaseException;
  22
  23 public class TripletObjectQuery extends TripletInstruction {
  24
  25         public TripletObjectQuery(int variable0, int variable1, int variable2) {
  26                 super(variable0, variable1, variable2);
  27         }
  28
  29         @Override
  30         public Object query(ReadGraph g, Object[] bindings) throws DatabaseException {
  31                 Resource r0 = (Resource)bindings[variable0];
  32                 Resource r1 = (Resource)bindings[variable1];
  33                 Collection<Resource> result = g.getObjects(r0, r1);
  34                 if(result.isEmpty())
  35                         return IInstruction.FAILURE;
  36                 Iterator<Resource> it = result.iterator();
  37                 bindings[variable2] = it.next();
  38                 if(it.hasNext())
  39                         return it;
  40                 else
  41                         return null;
  42         }
  43
  44         @SuppressWarnings("unchecked")
  45         @Override
  46         public Object next(ReadGraph g, Object[] bindings, Object continuation) {
  47                 Iterator<Resource> it = (Iterator<Resource>)continuation;
  48                 if(it.hasNext()) {
  49                         bindings[variable2] = it.next();
  50                         if(it.hasNext())
  51                                 return it;
  52                         else
  53                                 return null;
  54                 }
  55                 else
  56                         return IInstruction.FAILURE;
  57         }
  58
  59         @Override
  60         public void collectVariables(TIntHashSet reads, TIntHashSet writes) {
  61                 super.collectVariables(reads, writes);
  62                 writes.add(variable2);
  63         }
  64
  65 }