001/*
002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. 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.tap;
022
023import java.util.Collection;
024import java.util.Iterator;
025import java.util.Set;
026
027import cascading.util.Util;
028
029/**
030 * Helper utilities for {@link CompositeTap} instances.
031 */
032public class CompositeTaps
033  {
034  private CompositeTaps()
035    {
036    }
037
038  public static Collection<? extends Tap> unwindNarrow( Class<? extends Tap> type, Tap tap )
039    {
040    return Util.narrowIdentitySet( type, unwind( tap ) );
041    }
042
043  public static Collection<Tap> unwind( Tap tap )
044    {
045    Set<Tap> taps = Util.createIdentitySet();
046
047    addLeaves( tap, taps );
048
049    return taps;
050    }
051
052  private static void addLeaves( Tap tap, Set<Tap> taps )
053    {
054    if( tap instanceof CompositeTap )
055      {
056      Iterator<? extends Tap> childTaps = ( (CompositeTap<? extends Tap>) tap ).getChildTaps();
057
058      while( childTaps.hasNext() )
059        addLeaves( childTaps.next(), taps );
060      }
061    else
062      {
063      taps.add( tap );
064      }
065    }
066  }