X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;ds=sidebyside;f=bundles%2Forg.simantics.db.common%2Fsrc%2Forg%2Fsimantics%2Fdb%2Fcommon%2Fprocedure%2Fsingle%2FStagedSingleSetListener.java;fp=bundles%2Forg.simantics.db.common%2Fsrc%2Forg%2Fsimantics%2Fdb%2Fcommon%2Fprocedure%2Fsingle%2FStagedSingleSetListener.java;h=4c5b0eb009487dde017c46cc5d3651122ecdfc40;hb=969bd23cab98a79ca9101af33334000879fb60c5;hp=0000000000000000000000000000000000000000;hpb=866dba5cd5a3929bbeae85991796acb212338a08;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/StagedSingleSetListener.java b/bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/StagedSingleSetListener.java
new file mode 100644
index 000000000..4c5b0eb00
--- /dev/null
+++ b/bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/StagedSingleSetListener.java
@@ -0,0 +1,50 @@
+/*******************************************************************************
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management
+ * in Industry THTH ry.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+package org.simantics.db.common.procedure.single;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.simantics.db.procedure.Listener;
+
+abstract public class StagedSingleSetListener<T> implements Listener<Set<T>>{
+    
+    private Set<T> previous = null;
+    
+    public void start(Set<T> items) {}
+    public void add(T item) {}
+    public void remove(T item) {}
+    
+    @Override
+    public synchronized void execute(final Set<T> result) {
+    	
+        if(previous == null) {
+
+            start(result);
+
+        } else {
+
+            HashSet<T> added = new HashSet<T>(result);
+            added.removeAll(previous);
+            HashSet<T> removed = new HashSet<T>(previous);
+            removed.removeAll(result);
+
+            for(T t : added) add(t);
+            for(T t : removed) remove(t);
+
+        }
+
+        previous = result;
+        
+    }
+    
+}