--- /dev/null
+/*\r
+\r
+ Derby - Class org.apache.derby.impl.sql.execute.SystemAggregator\r
+\r
+ Licensed to the Apache Software Foundation (ASF) under one or more\r
+ contributor license agreements. See the NOTICE file distributed with\r
+ this work for additional information regarding copyright ownership.\r
+ The ASF licenses this file to you under the Apache License, Version 2.0\r
+ (the "License"); you may not use this file except in compliance with\r
+ the License. You may obtain a copy of the License at\r
+\r
+ http://www.apache.org/licenses/LICENSE-2.0\r
+\r
+ Unless required by applicable law or agreed to in writing, software\r
+ distributed under the License is distributed on an "AS IS" BASIS,\r
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
+ See the License for the specific language governing permissions and\r
+ limitations under the License.\r
+\r
+ */\r
+\r
+package org.apache.derby.impl.sql.execute;\r
+\r
+import org.apache.derby.iapi.services.sanity.SanityManager;\r
+import org.apache.derby.iapi.error.StandardException;\r
+import org.apache.derby.iapi.sql.execute.ExecAggregator;\r
+import org.apache.derby.iapi.types.DataValueDescriptor;\r
+import java.io.ObjectOutput;\r
+import java.io.ObjectInput;\r
+import java.io.IOException;\r
+\r
+/**\r
+ * Abstract aggregator that is extended by all internal\r
+ * (system) aggregators.\r
+ *\r
+ */\r
+abstract class SystemAggregator implements ExecAggregator\r
+{\r
+\r
+ private boolean eliminatedNulls;\r
+\r
+\r
+ public boolean didEliminateNulls() {\r
+ return eliminatedNulls;\r
+ }\r
+\r
+ public void accumulate(DataValueDescriptor addend, Object ga) \r
+ throws StandardException\r
+ {\r
+ if ((addend == null) || addend.isNull()) {\r
+ eliminatedNulls = true;\r
+ return;\r
+ }\r
+\r
+ this.accumulate(addend);\r
+ }\r
+\r
+ protected abstract void accumulate(DataValueDescriptor addend)\r
+ throws StandardException;\r
+ /////////////////////////////////////////////////////////////\r
+ // \r
+ // EXTERNALIZABLE INTERFACE\r
+ // \r
+ /////////////////////////////////////////////////////////////\r
+\r
+ public void writeExternal(ObjectOutput out) throws IOException\r
+ {\r
+ out.writeBoolean(eliminatedNulls);\r
+ }\r
+\r
+ public void readExternal(ObjectInput in) \r
+ throws IOException, ClassNotFoundException\r
+ {\r
+ eliminatedNulls = in.readBoolean();\r
+ }\r
+}\r