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 {@link Iterable}s or
041 * {@link Iterator}s.
042 *
043 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
044 *
045 * @param <T>
046 *            type of objects provided by underlying iterators
047 */
048public class ConcatenatedIterable<T> implements Iterable<T> {
049        class ConcatenatedIterator implements Iterator<T> {
050                Iterator<Iterator<T>> it;
051                Iterator<T> current;
052
053                public ConcatenatedIterator() {
054                        if (iterators == null) {
055                                return;
056                        }
057
058                        it = iterators.iterator();
059
060                        if (!it.hasNext()) {
061                                it = null;
062                                return;
063                        }
064
065                        current = it.next();
066                }
067
068                @Override
069                public boolean hasNext() {
070                        if (it == null)
071                                return false;
072
073                        if (current.hasNext())
074                                return true;
075
076                        if (!it.hasNext())
077                                return false;
078
079                        current = it.next();
080                        return hasNext();
081                }
082
083                @Override
084                public T next() {
085                        if (!current.hasNext()) {
086                                if (!it.hasNext())
087                                        throw new NoSuchElementException();
088
089                                current = it.next();
090                        }
091
092                        return current.next();
093                }
094
095                @Override
096                public void remove() {
097                        throw new UnsupportedOperationException("Not supported");
098                }
099        };
100
101        private List<Iterator<T>> iterators;
102
103        /**
104         * Construct with {@link Iterable}s.
105         * 
106         * @param iterables
107         */
108        @SafeVarargs
109        public ConcatenatedIterable(Iterable<T>... iterables) {
110                iterators = new ArrayList<Iterator<T>>();
111
112                for (final Iterable<T> i : iterables) {
113                        iterators.add(i.iterator());
114                }
115        }
116
117        /**
118         * Construct with {@link Iterable}s.
119         * 
120         * @param iterables
121         */
122        public ConcatenatedIterable(Collection<? extends Iterable<T>> iterables) {
123                iterators = new ArrayList<Iterator<T>>();
124
125                for (final Iterable<T> i : iterables) {
126                        iterators.add(i.iterator());
127                }
128        }
129
130        /**
131         * Construct with {@link Iterator}s.
132         * 
133         * @param iterables
134         */
135        @SafeVarargs
136        public ConcatenatedIterable(Iterator<T>... iterables) {
137                iterators = Arrays.asList(iterables);
138        }
139
140        @Override
141        public Iterator<T> iterator() {
142                return new ConcatenatedIterator();
143        }
144}