bundles/org.simantics.mapping/src/org/simantics/mapping/constraint/instructions/BinaryPredicateSubjectQuery.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.mapping.constraint.instructions;\r
  13 \r
  14 import gnu.trove.set.hash.TIntHashSet;\r
  15 \r
  16 import java.util.Collection;\r
  17 import java.util.Iterator;\r
  18 \r
  19 import org.simantics.db.ReadGraph;\r
  20 import org.simantics.db.Resource;\r
  21 import org.simantics.db.exception.DatabaseException;\r
  22 import org.simantics.layer0.utils.binaryPredicates.IBinaryPredicate;\r
  23 \r
  24 public class BinaryPredicateSubjectQuery extends BinaryPredicateInstruction {\r
  25         \r
  26         public BinaryPredicateSubjectQuery(int variable0, int variable1,\r
  27                         IBinaryPredicate predicate) {\r
  28                 super(variable0, variable1, predicate);\r
  29         }\r
  30 \r
  31         @Override\r
  32         public Object query(ReadGraph g, Object[] bindings) throws DatabaseException {\r
  33                 Resource r1 = (Resource)bindings[variable1];\r
  34                 Collection<Resource> result = predicate.getSubjects(g, r1);\r
  35                 if(result.isEmpty())\r
  36                         return IInstruction.FAILURE;\r
  37                 Iterator<Resource> it = result.iterator();\r
  38                 bindings[variable0] = it.next();\r
  39                 if(it.hasNext())\r
  40                         return it;\r
  41                 else\r
  42                         return null;\r
  43         }\r
  44         \r
  45         @SuppressWarnings("unchecked")\r
  46         @Override\r
  47         public Object next(ReadGraph g, Object[] bindings, Object continuation) {\r
  48                 Iterator<Resource> it = (Iterator<Resource>)continuation;\r
  49                 if(it.hasNext()) {\r
  50                         bindings[variable0] = it.next();\r
  51                         if(it.hasNext())\r
  52                                 return it;\r
  53                         else\r
  54                                 return null;\r
  55                 }\r
  56                 else\r
  57                         return IInstruction.FAILURE;\r
  58         }       \r
  59         \r
  60         @Override\r
  61         public void collectVariables(TIntHashSet reads, TIntHashSet writes) {\r
  62                 super.collectVariables(reads, writes);\r
  63                 writes.add(variable0);\r
  64         }\r
  65 \r
  66 }\r