001/*
002 * Copyright (c) 2007-2015 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.hadoop.util;
022
023import java.util.Collection;
024import java.util.Iterator;
025
026import cascading.tuple.Tuple;
027
028/**
029 *
030 */
031public class LazyCollection implements Collection<Tuple>, ResettableCollection<Iterator<Tuple>>
032  {
033  Iterator<Tuple> iterator;
034  Collection<Tuple> parent;
035
036  public static Collection<Tuple> getParent( LazyCollection collection )
037    {
038    return collection.parent;
039    }
040
041  public LazyCollection( Collection<Tuple> parent )
042    {
043    this.parent = parent;
044    }
045
046  @Override
047  public int size()
048    {
049    return parent.size();
050    }
051
052  @Override
053  public boolean isEmpty()
054    {
055    return !iterator.hasNext() && parent.isEmpty();
056    }
057
058  @Override
059  public boolean contains( Object o )
060    {
061    return parent.contains( o );
062    }
063
064  @Override
065  public Iterator<Tuple> iterator()
066    {
067    if( !iterator.hasNext() )
068      return parent.iterator();
069
070    return new Iterator<Tuple>()
071    {
072    @Override
073    public boolean hasNext()
074      {
075      return iterator.hasNext();
076      }
077
078    @Override
079    public Tuple next()
080      {
081      Tuple next = iterator.next();
082
083      parent.add( next );
084
085      return next;
086      }
087
088    @Override
089    public void remove()
090      {
091      iterator.remove();
092      }
093    };
094    }
095
096  @Override
097  public Object[] toArray()
098    {
099    return parent.toArray();
100    }
101
102  @Override
103  public <T> T[] toArray( T[] a )
104    {
105    return parent.toArray( a );
106    }
107
108  @Override
109  public boolean add( Tuple objects )
110    {
111    return parent.add( objects );
112    }
113
114  @Override
115  public boolean remove( Object o )
116    {
117    return parent.remove( o );
118    }
119
120  @Override
121  public boolean containsAll( Collection<?> c )
122    {
123    return parent.containsAll( c );
124    }
125
126  @Override
127  public boolean addAll( Collection<? extends Tuple> c )
128    {
129    return parent.addAll( c );
130    }
131
132  @Override
133  public boolean removeAll( Collection<?> c )
134    {
135    return parent.removeAll( c );
136    }
137
138  @Override
139  public boolean retainAll( Collection<?> c )
140    {
141    return parent.retainAll( c );
142    }
143
144  @Override
145  public void clear()
146    {
147    parent.clear();
148    }
149
150  @Override
151  public boolean equals( Object o )
152    {
153    return parent.equals( o );
154    }
155
156  @Override
157  public int hashCode()
158    {
159    return parent.hashCode();
160    }
161
162  @Override
163  public void reset( Iterator<Tuple> iterator )
164    {
165    this.iterator = iterator;
166    }
167  }