bundles/org.simantics.databoard/src/org/simantics/databoard/binding/reflection/UnionClassBinding.java

   1 /*******************************************************************************
   2  *  Copyright (c) 2010 Association for Decentralized Information Management in
   3  *  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.databoard.binding.reflection;
  13
  14 import org.simantics.databoard.Bindings;
  15 import org.simantics.databoard.adapter.AdaptException;
  16 import org.simantics.databoard.binding.Binding;
  17 import org.simantics.databoard.binding.UnionBinding;
  18 import org.simantics.databoard.binding.error.BindingConstructionException;
  19 import org.simantics.databoard.binding.error.BindingException;
  20 import org.simantics.databoard.serialization.Serializer;
  21 import org.simantics.databoard.serialization.SpecializedSerializerProvider;
  22 import org.simantics.databoard.type.UnionType;
  23
  24 /**
  25  * Bindings an abstract class with @Union annotation to a DataBoard's UnionType.
  26  *
  27  * Example of usage:
  28  *  @Union({Rectangle.class, Circle.class, Triangle.class}) class Shape {}
  29  *
  30  *  class Rectangle extends Shape { public int width, height; }
  31  *  class Circle extends Shape { public int radius; }
  32  *  class Triangle extends Shape { public int sideLength; }
  33  *
  34  * @author Toni Kalajainen
  35  */
  36 class UnionClassBinding extends UnionBinding implements SpecializedSerializerProvider {
  37
  38         Class<?>[] componentClasses;
  39         Serializer specializedSerializer;
  40
  41         public UnionClassBinding(UnionType type)
  42         throws BindingConstructionException {
  43                 this.type = type;
  44         }
  45
  46         @Override
  47         public Object create(int tag, Object value) {
  48                 return value;
  49         }
  50
  51     @Override
  52     public void setValue(Object union, int tag, Object value)
  53         throws BindingException {
  54         if (tag != getTag(union)) throw new BindingException("Cannot change the class of an instance");
  55         Binding cb = getComponentBinding(tag);
  56         cb.readFrom(cb, value, union);
  57     }
  58
  59         @Override
  60         public int getTag(Object obj) throws BindingException {
  61                 for (int i=0; i<componentClasses.length; i++)
  62                         if (componentClasses[i].isInstance(obj)) return i;
  63                 throw new BindingException(obj.getClass().getSimpleName()+" is not a known component class");
  64         }
  65         @Override
  66         public Object getValue(Object obj) {
  67                 return obj;
  68         }
  69         @Override
  70         public boolean isInstance(Object obj) {
  71                 for (Class<?> c : componentClasses)
  72                         if (c.isInstance(obj)) return true;
  73                 return false;
  74         }
  75
  76     @Override
  77     public Serializer getSpecializedSerializer() {
  78         return specializedSerializer;
  79     }
  80
  81
  82         transient Boolean isImmutable;
  83
  84         @Override
  85         public synchronized boolean isImmutable() {
  86                 if ( isImmutable == null ) {
  87                         boolean b = true;
  88                         for ( Binding cb : getComponentBindings() ) {
  89                                 b &= cb.isImmutable();
  90                                 if (!b) break;
  91                         }
  92                         isImmutable = b;
  93                 }
  94                 return isImmutable;
  95         }
  96
  97         @Override
  98     public Object readFromTry(Binding srcBinding, Object src, Object dst) throws BindingException
  99     {
 100                 UnionBinding sb = (UnionBinding) srcBinding;
 101                 int st = sb.getTag(src);
 102                 int dt = getTag(dst);
 103                 Binding scb = sb.getComponentBinding(st);
 104                 Object sv = sb.getValue(src);
 105
 106
 107                 if (st==dt) {
 108                         // Same Tag
 109                         Object dv = getValue(dst);
 110                         Binding dcb = getComponentBinding(dt);
 111                         dcb.readFrom(scb, sv, dv);
 112                         return dv;
 113                 } else {
 114                         // Different Tag -> return cloned or (same, if immutable) value
 115                         try {
 116                                 Binding dcb = getComponentBinding(st);
 117                                 return Bindings.adapt(src, scb, dcb);
 118                         } catch(AdaptException e) {
 119                                 throw new BindingException(e);
 120                         }
 121                 }
 122
 123         }
 124
 125         /**
 126          * Returns true if the tag of this union type can be modified
 127          *
 128          * @return
 129          */
 130         public boolean isTagMutable() {
 131                 return true;
 132         }
 133
 134         @Override
 135         protected boolean baseEquals(Object obj) {
 136                 if (!super.baseEquals(obj)) return false;
 137
 138                 UnionClassBinding o = (UnionClassBinding)obj;
 139                 if (isImmutable != o.isImmutable) return false;
 140                 if (specializedSerializer != o.specializedSerializer) return false;
 141                 if (componentClasses.length != o.componentClasses.length) return false;
 142
 143                 for (int i = 0; i < componentClasses.length; i++) {
 144                         if (!componentClasses[i].equals(o.componentClasses[i]))
 145                                 return false;
 146                 }
 147
 148                 return true;
 149         }
 150
 151         @Override
 152         public int baseHashCode() {
 153                 int code = super.baseHashCode();
 154                 for (int i = 0; i < componentClasses.length; i++)
 155                         code = 23 * code + componentClasses.hashCode();
 156
 157                 return code;
 158         }
 159 }