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