bundles/org.simantics.browsing.ui.graph.impl/src/org/simantics/browsing/ui/graph/impl/LazyViewpointFactory.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.browsing.ui.graph.impl;
  13
  14 import java.util.Collection;
  15
  16 import org.simantics.browsing.ui.NodeContext;
  17 import org.simantics.browsing.ui.PrimitiveQueryUpdater;
  18 import org.simantics.browsing.ui.BuiltinKeys.ViewpointKey;
  19 import org.simantics.browsing.ui.content.Viewpoint;
  20 import org.simantics.browsing.ui.content.ViewpointFactory;
  21 import org.simantics.db.ReadGraph;
  22 import org.simantics.db.exception.DatabaseException;
  23
  24 /**
  25  * Extend and implement {@link #getChildren(ReadGraph, NodeContext)} to create a
  26  * viewpoint factory that reads from the graph database.
  27  *
  28  * @author Antti Villberg
  29  */
  30 public abstract class LazyViewpointFactory implements ViewpointFactory {
  31
  32     @Override
  33     public Viewpoint create(PrimitiveQueryUpdater updater,
  34             NodeContext context, ViewpointKey key) {
  35         return new LazyViewpoint(updater, context, key) {
  36             @Override
  37             public NodeContext[] children(ReadGraph graph) throws DatabaseException {
  38                 return toContextsWithInput(LazyViewpointFactory.this.
  39                         getChildren(graph, context));
  40             }
  41
  42             @Override
  43             public Boolean hasChildren(ReadGraph graph) throws DatabaseException {
  44                 return children(graph).length > 0;
  45             }
  46
  47             @Override
  48             public String toString() {
  49                 return LazyViewpointFactory.this.toString();
  50             }
  51
  52             @Override
  53             public Object getIdentity() {
  54                 return LazyViewpointFactory.this.getClass();
  55             }
  56         };
  57     }
  58
  59     abstract protected Collection<?> getChildren(ReadGraph g, NodeContext context) throws DatabaseException;
  60
  61     protected boolean hasChildren(ReadGraph g, NodeContext context) throws DatabaseException {
  62         return !getChildren(g, context).isEmpty();
  63     }
  64
  65 }