MoveCommand


1   /**
2    * <copyright> 
3    *
4    * Copyright (c) 2002-2004 IBM Corporation and others.
5    * All rights reserved.   This program and the accompanying materials
6    * are made available under the terms of the Eclipse Public License v1.0
7    * which accompanies this distribution, and is available at
8    * http://www.eclipse.org/legal/epl-v10.html
9    * 
10   * Contributors: 
11   *   IBM - Initial API and implementation
12   *
13   * </copyright>
14   *
15   * $Id: MoveCommand.java,v 1.3 2005/06/08 06:17:05 nickb Exp $
16   */
17  package org.eclipse.emf.edit.command;
18  
19  
20  import java.util.Collection  ;
21  import java.util.Collections  ;
22  
23  import org.eclipse.emf.common.command.Command;
24  import org.eclipse.emf.common.util.EList;
25  import org.eclipse.emf.ecore.EObject;
26  import org.eclipse.emf.ecore.EStructuralFeature;
27  import org.eclipse.emf.edit.EMFEditPlugin;
28  import org.eclipse.emf.edit.domain.EditingDomain;
29  
30  
31  /**
32   * The move command logically acts upon an owner object that has a collection-based feature 
33   * containing an object that is to be moved to a new position within the collection.
34   * The static create method delegates command creation to {@link EditingDomain#createCommand EditingDomain.createCommand},
35   * which may or may not result in the actual creation of an instance of this class.
36   * Like all the low level comands in this package, the move command is undoable.
37   *
38   * <p>
39   * The implementation of this class is low-level and EMF specific;
40   * it allows an object to be moved to a new position within a many-valued feature of an owner,
41   * i.e., it is equivalent of the call
42   * <pre>
43   *   ((EList)((EObject)owner).eGet((EStructuralFeature)feature)).move(index, object);
44   * </pre>
45   *
46   * <p>
47   * It can also be used as an equivalent to the call
48   * <pre>
49   *   ((EList)extent).move(index, object);
50   * </pre>
51   * which is how root objects are moved within the contents of a resource.
52   * Like all the low-level comands in this package, the move command is undoable.
53   *
54   * <p>
55   * A move command is an {@link OverrideableCommand}.
56   */
57  public class MoveCommand extends AbstractOverrideableCommand
58  {
59    /**
60     * This creates a command to move particular value to a particular index in the specified feature of the owner.
61     * The feature will often be null because the domain will deduce it.
62     */
63    public static Command create(EditingDomain domain, Object   owner, Object   feature, Object   value, int index)
64    {
65      return domain.createCommand(MoveCommand.class, new CommandParameter(owner, feature, value, index));
66    }
67  
68  
69    /**
70     * This caches the label.
71     */
72    protected static final String   LABEL = EMFEditPlugin.INSTANCE.getString("_UI_MoveCommand_label");
73  
74    /**
75     * This caches the description.
76     */
77    protected static final String   DESCRIPTION = EMFEditPlugin.INSTANCE.getString("_UI_MoveCommand_description");
78  
79    /**
80     * This caches the description for a list-based command.
81     */
82    protected static final String   DESCRIPTION_FOR_LIST = EMFEditPlugin.INSTANCE.getString("_UI_MoveCommand_description_for_list");
83  
84    /**
85     * This is the owner object upon which the command will act.
86     * It could be null in the case that we are dealing with an {@link org.eclipse.emf.common.util.EList}.
87     */
88    protected EObject owner;
89  
90    /**
91     * This is the feature of the owner object upon the command will act.
92     * It could be null, in the case that we are dealing with an {@link org.eclipse.emf.common.util.EList}.
93     */
94    protected EStructuralFeature feature;
95  
96    /**
97     * This is the list in which the command will move an object.
98     */
99    protected EList ownerList;
100 
101   /**
102    * This is the value being moved within the owner list.
103    */
104   protected Object   value;
105 
106   /**
107    * This is the position to which the object will be moved.
108    */
109   protected int index;
110 
111   /**
112    * This is the orginal position to which the object will be moved upon undo.
113    */
114   protected int oldIndex;
115 
116   /**
117    * This constructs a primitive command to move a particular value to a particular index 
118    * of the specified many-valued feature of the owner.
119    */
120   public MoveCommand(EditingDomain domain, EObject owner, EStructuralFeature feature, Object   value, int index)
121   {
122     super (domain, LABEL, DESCRIPTION);
123 
124     this.owner = owner;
125     this.feature = feature;
126     this.value = value;
127     this.index = index;
128 
129     ownerList = getOwnerList(this.owner, feature);
130   }
131 
132   /**
133    * This constructs a primitive command to move a particular value to a particular index of the specified extent.
134    */
135   public MoveCommand(EditingDomain domain, EList list, Object   value, int index)
136   {
137     super(domain, LABEL, DESCRIPTION_FOR_LIST);
138 
139     this.value = value;
140     this.index = index;
141 
142     ownerList = list;
143   }
144 
145   /**
146    * This returns the owner object upon which the command will act.
147    * It could be null in the case that we are dealing with an {@link org.eclipse.emf.common.util.EList}.
148    */
149   public EObject getOwner()
150   {
151     return owner;
152   }
153 
154   /**
155    * This returns the feature of the owner object upon the command will act.
156    * It could be null, in the case that we are dealing with an {@link org.eclipse.emf.common.util.EList}.
157    */
158   public EStructuralFeature getFeature()
159   {
160     return feature;
161   }
162 
163   /**
164    * This returns the list in which the command will move an object.
165    */
166   public EList getOwnerList()
167   {
168     return ownerList;
169   }
170 
171   /**
172    * This returns the value being moved.
173    */
174   public Object   getValue()
175   {
176     return value;
177   }
178 
179   /**
180    * This returns the position to which the value will be moved.
181    */
182   public int getIndex()
183   {
184     return index;
185   }
186 
187   /**
188    * This returns the orginal position to which the object will be moved upon undo.
189    */
190   public int getOldIndex()
191   {
192     return oldIndex;
193   }
194 
195   protected boolean prepare()
196   {
197     // Return whether there is a list, the value is in the list, and index is in range...
198     //
199     boolean result =
200       ownerList != null  && 
201          ownerList.contains(value) &&
202          index >= 0 && 
203          index < ownerList.size() &&
204          (owner == null || !domain.isReadOnly(owner.eResource()));
205 
206     return result;
207   }
208 
209   public void doExecute() 
210   {
211     oldIndex = ownerList.indexOf(value);
212     ownerList.move(index, value);
213   }
214 
215   public void doUndo() 
216   {
217     ownerList.move(oldIndex, value);
218   }
219 
220   public void doRedo()
221   {
222     ownerList.move(index, value);
223   }
224 
225   public Collection   doGetResult()
226   {
227     return Collections.singleton(value);
228   }
229 
230   public Collection   doGetAffectedObjects()
231   {
232     return Collections.singleton(value);
233   }
234 
235   /**
236    * This gives an abbreviated name using this object's own class' name, without package qualification,
237    * followed by a space separated list of <tt>field:value</tt> pairs.
238    */
239   public String   toString()
240   {
241     StringBuffer   result = new StringBuffer  (super.toString());
242     result.append(" (owner: " + owner + ")");
243     result.append(" (feature: " + feature + ")");
244     result.append(" (ownerList: " + ownerList + ")");
245     result.append(" (value: " + value + ")");
246     result.append(" (index: " + index + ")");
247     result.append(" (oldIndex: " + oldIndex + ")");
248 
249     return result.toString();
250   }
251 }
252
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