001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.util.iterator;
031
032import java.util.ArrayList;
033import java.util.Arrays;
034import java.util.Collection;
035import java.util.Iterator;
036import java.util.List;
037import java.util.NoSuchElementException;
038
039/**
040 * An {@link Iterable} that chains together other 
041 * {@link Iterable}s or {@link Iterator}s.  
042 * 
043 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
044 *
045 * @param <T> type of objects provided by underlying iterators
046 */
047public class ConcatenatedIterable<T> implements Iterable<T> {
048        class ConcatenatedIterator implements Iterator<T> {
049                Iterator<Iterator<T>> it;
050                Iterator<T> current;
051                
052                public ConcatenatedIterator() {
053                        if (iterators == null) {
054                                return;
055                        }
056
057                        it = iterators.iterator();
058
059                        if (!it.hasNext()) {
060                                it = null;
061                                return;
062                        }
063                        
064                        current = it.next();
065                }
066                
067                @Override
068                public boolean hasNext() {
069                        if (it == null)
070                                return false;
071                        
072                        if (current.hasNext())
073                                return true;
074
075                        if (!it.hasNext())
076                                return false;
077
078                        current = it.next();
079                        return hasNext();
080                }
081
082                @Override
083                public T next() {
084                        if (!current.hasNext()) {
085                                if (!it.hasNext()) 
086                                        throw new NoSuchElementException();
087                                
088                                current = it.next();
089                        }
090                        
091                        return current.next();
092                }
093
094                @Override
095                public void remove() {
096                        throw new UnsupportedOperationException( "Not supported" );
097                }
098        };
099        
100        private List<Iterator<T>> iterators;
101        
102        /**
103         * Construct with {@link Iterable}s.
104         * @param iterables
105         */
106        public ConcatenatedIterable(Iterable<T>... iterables) {
107                iterators = new ArrayList<Iterator<T>>();
108                
109                for (Iterable<T> i : iterables) {
110                        iterators.add(i.iterator());
111                }
112        }
113        
114        /**
115         * Construct with {@link Iterable}s.
116         * @param iterables
117         */
118        public ConcatenatedIterable(Collection<? extends Iterable<T>> iterables) {
119                iterators = new ArrayList<Iterator<T>>();
120                
121                for (Iterable<T> i : iterables) {
122                        iterators.add(i.iterator());
123                }
124        }
125        
126        /**
127         * Construct with {@link Iterator}s.
128         * @param iterables
129         */
130        public ConcatenatedIterable(Iterator<T>... iterables) {
131                iterators = Arrays.asList(iterables);
132        }
133
134        @Override
135        public Iterator<T> iterator() {
136                return new ConcatenatedIterator();
137        }
138}