bundles/org.simantics.db.common/src/org/simantics/db/common/request/TransientResourceRead.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.common.request;
  13
  14 import org.simantics.db.ReadGraph;
  15 import org.simantics.db.Resource;
  16 import org.simantics.db.exception.DatabaseException;
  17 import org.simantics.db.request.ReadExt;
  18 import org.simantics.db.service.QueryControl;
  19
  20 abstract public class TransientResourceRead<R> extends BinaryRead<Object,Resource,R> implements ReadExt {
  21
  22         protected static final Object WITH_PARENT = new Object();
  23
  24         public TransientResourceRead(ReadGraph graph, Resource parameter) throws DatabaseException {
  25                 this(graph, graph.getService(QueryControl.class), parameter);
  26         }
  27
  28         public TransientResourceRead(ReadGraph graph, QueryControl qc, Resource parameter) throws DatabaseException {
  29                 super(resolveFirstParameter(graph, qc), parameter);
  30         }
  31
  32         final private static Object resolveFirstParameter(ReadGraph graph, QueryControl qc) throws DatabaseException {
  33                 if(qc.hasParentRequest(graph)) return WITH_PARENT;
  34                 else return graph.getModificationCounter();
  35         }
  36
  37         @Override
  38         final public R perform(ReadGraph _graph) throws DatabaseException {
  39                 if(parameter == WITH_PARENT) {
  40                         return perform(_graph, parameter2);
  41                 } else {
  42                         QueryControl qc = _graph.getService(QueryControl.class);
  43                         ReadGraph graph = qc.getIndependentGraph(_graph);
  44                         return perform(graph, parameter2);
  45                 }
  46         }
  47
  48         abstract public R perform(ReadGraph graph, Resource parameter) throws DatabaseException;
  49
  50         @Override
  51         public boolean isImmutable(ReadGraph graph) throws DatabaseException {
  52                 return graph.isImmutable(parameter2);
  53         }
  54
  55 }