bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/SingleSetAsyncListener.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.procedure.single;
  13
  14 import java.util.Collection;
  15 import java.util.HashSet;
  16
  17 import org.simantics.db.AsyncReadGraph;
  18 import org.simantics.db.procedure.AsyncListener;
  19
  20 abstract public class SingleSetAsyncListener<T> implements AsyncListener<Collection<T>>{
  21
  22         final private boolean changesOnly;
  23         private Collection<T> previous = null;
  24
  25     public void add(AsyncReadGraph graph, T item) {}
  26     public void remove(AsyncReadGraph graph, T item) {}
  27
  28     public SingleSetAsyncListener() {
  29         this(false);
  30     }
  31
  32     public SingleSetAsyncListener(boolean changesOnly) {
  33         this.changesOnly = changesOnly;
  34     }
  35
  36     @Override
  37     public void execute(AsyncReadGraph graph, final Collection<T> result) {
  38
  39         if(previous == null) {
  40
  41                 if(!changesOnly) {
  42 //                      for(T t : result)
  43 //                              add(graph, t);
  44 //              } else {
  45                         first(graph, result);
  46                 }
  47
  48         } else {
  49
  50             HashSet<T> added = new HashSet<T>(result);
  51             added.removeAll(previous);
  52             HashSet<T> removed = new HashSet<T>(previous);
  53             removed.removeAll(result);
  54
  55             for(T t : added) add(graph, t);
  56             for(T t : removed) remove(graph, t);
  57
  58         }
  59
  60         previous = result;
  61
  62     }
  63
  64     public void first(AsyncReadGraph graph, final Collection<T> result) {
  65         for(T t : result) add(graph, t);
  66     }
  67
  68 }