JAL-1503 update version in GPL header

[jalview.git] / src / jalview / structure / StructureSelectionManager.java

diff --git a/src/jalview/structure/StructureSelectionManager.java b/src/jalview/structure/StructureSelectionManager.java
index a76a27e..bf14000 100644 (file)
--- a/src/jalview/structure/StructureSelectionManager.java
+++ b/src/jalview/structure/StructureSelectionManager.java
@@ -1,19 +1,20 @@
 /*
- * Jalview - A Sequence Alignment Editor and Viewer (Version 2.7)
- * Copyright (C) 2011 J Procter, AM Waterhouse, J Engelhardt, LM Lui, G Barton, M Clamp, S Searle
+ * Jalview - A Sequence Alignment Editor and Viewer (Version 2.8.1)
+ * Copyright (C) 2014 The Jalview Authors
  * 
  * This file is part of Jalview.
  * 
  * Jalview is free software: you can redistribute it and/or
  * modify it under the terms of the GNU General Public License 
  * as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
- * 
+ *  
  * Jalview is distributed in the hope that it will be useful, but 
  * WITHOUT ANY WARRANTY; without even the implied warranty 
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
  * PURPOSE.  See the GNU General Public License for more details.
  * 
  * You should have received a copy of the GNU General Public License along with Jalview.  If not, see <http://www.gnu.org/licenses/>.
+ * The Jalview Authors are detailed in the 'AUTHORS' file.
  */
 package jalview.structure;
 
@@ -53,10 +54,26 @@ public class StructureSelectionManager
   }
 
   Hashtable mappingData = new Hashtable();
-
+  private static StructureSelectionManager nullProvider = null;
   public static StructureSelectionManager getStructureSelectionManager(
           StructureSelectionManagerProvider context)
   {
+    if (context==null) { 
+      if (nullProvider == null)
+      {
+        if (instances != null)
+        {
+          throw new Error(
+                  "Implementation error. Structure selection manager's context is 'null'",
+                  new NullPointerException("SSM context is null"));
+        }
+        else
+        {
+          nullProvider = new StructureSelectionManager();
+        }
+        return nullProvider;
+      }
+    }
     if (instances == null)
     {
       instances = new java.util.IdentityHashMap<StructureSelectionManagerProvider, StructureSelectionManager>();
@@ -64,7 +81,13 @@ public class StructureSelectionManager
     StructureSelectionManager instance = instances.get(context);
     if (instance == null)
     {
-      instances.put(context, instance = new StructureSelectionManager());
+      if (nullProvider!=null)
+      {
+        instance = nullProvider;
+      } else {
+        instance = new StructureSelectionManager();
+      }
+      instances.put(context, instance);
     }
     return instance;
   }