001/* 002 * Copyright (c) 2007-2016 Concurrent, Inc. All Rights Reserved. 003 * 004 * Project and contact information: http://www.cascading.org/ 005 * 006 * This file is part of the Cascading project. 007 * 008 * Licensed under the Apache License, Version 2.0 (the "License"); 009 * you may not use this file except in compliance with the License. 010 * You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, software 015 * distributed under the License is distributed on an "AS IS" BASIS, 016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 017 * See the License for the specific language governing permissions and 018 * limitations under the License. 019 */ 020 021package cascading.flow.stream.duct; 022 023import java.util.Iterator; 024 025/** 026 * 027 */ 028public class OpenReducingDuct<Incoming, Outgoing> extends Duct<Grouping<Incoming, Iterator<Incoming>>, Outgoing> implements OpenWindow 029 { 030 final Reducing reducing; 031 032 public OpenReducingDuct( Duct<Outgoing, ?> next ) 033 { 034 super( next ); 035 036 reducing = (Reducing) getNext(); 037 } 038 039 @Override 040 public void receive( Duct previous, Grouping<Incoming, Iterator<Incoming>> grouping ) 041 { 042 // don't start a grouping if there are no values in the group 043 if( !grouping.joinIterator.hasNext() ) 044 return; 045 046 reducing.startGroup( previous, grouping.key ); 047 048 while( grouping.joinIterator.hasNext() ) 049 next.receive( this, (Outgoing) grouping.joinIterator.next() ); 050 051 reducing.completeGroup( previous, grouping.key ); 052 } 053 }