Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/5555#discussion_r182481625 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/DistinctAccumulator.scala --- @@ -0,0 +1,102 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.table.functions.aggfunctions + +import java.lang.{Iterable => JIterable} +import java.util.{Map => JMap} +import org.apache.flink.table.api.dataview.MapView + +/** + * The base class for accumulator wrapper when applying distinct aggregation. + * @param realAcc the actual accumulator which gets invoke after distinct filter. + * @param mapView the [[MapView]] element used to store the distinct filter hash map. + * @tparam E the element type for the distinct filter hash map. + * @tparam ACC the accumulator type for the realAcc. + */ +class DistinctAccumulator[E, ACC](var realAcc: ACC, var mapView: MapView[E, Integer]) { + def this() { + this(null.asInstanceOf[ACC], new MapView[E, Integer]()) + } + + def this(realAcc: ACC) { + this(realAcc, new MapView[E, Integer]()) + } + + def getRealAcc: ACC = realAcc + + def canEqual(a: Any): Boolean = a.isInstanceOf[DistinctAccumulator[E, ACC]] + + override def equals(that: Any): Boolean = + that match { + case that: DistinctAccumulator[E, ACC] => that.canEqual(this) && + this.mapView == that.mapView + case _ => false + } + + def add(element: E): Boolean = { + if (element != null) { + if (mapView.contains(element)) { --- End diff -- +1
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