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