001/*
002 * (C) Copyright 2006-2016 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     bstefanescu
018 */
019package org.nuxeo.common.utils;
020
021import java.io.File;
022import java.io.FileFilter;
023import java.util.Iterator;
024import java.util.LinkedList;
025import java.util.NoSuchElementException;
026import java.util.Queue;
027
028/**
029 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a>
030 */
031public class FileTreeIterator implements Iterator<File> {
032
033    private final Queue<Iterator<File>> queue = new LinkedList<>();
034
035    private File file; // last iterated file
036
037    private FileFilter filter;
038
039    public FileTreeIterator(File root) {
040        queue.add(new OneFileIterator(root));
041    }
042
043    public FileTreeIterator(File root, boolean excludeRoot) {
044        if (excludeRoot) {
045            queue.add(new LazyChildrenIterator(root));
046        } else {
047            queue.add(new OneFileIterator(root));
048        }
049    }
050
051    public void setFilter(FileFilter filter) {
052        this.filter = filter;
053    }
054
055    public FileFilter getFilter() {
056        return filter;
057    }
058
059    @Override
060    public boolean hasNext() {
061        if (queue.isEmpty()) {
062            return false;
063        }
064        Iterator<File> it = queue.peek();
065        if (it.hasNext()) {
066            return true;
067        } else {
068            queue.poll();
069            return hasNext();
070        }
071    }
072
073    @Override
074    public File next() {
075        if (!hasNext()) {
076            throw new NoSuchElementException("No more files to iterate over");
077        }
078        file = queue.peek().next();
079        if (file.isDirectory()) {
080            queue.add(new LazyChildrenIterator(file));
081        }
082        return file;
083    }
084
085    @Override
086    public void remove() {
087        if (file == null) {
088            throw new IllegalStateException("there is no current file to delete");
089        }
090        org.apache.commons.io.FileUtils.deleteQuietly(file);
091    }
092
093    // we don't fulfill iterator contract - we don't need a real iterator,
094    // this is used only internally
095    private static class OneFileIterator implements Iterator<File> {
096
097        private File file;
098
099        private OneFileIterator(File file) {
100            this.file = file;
101        }
102
103        @Override
104        public boolean hasNext() {
105            return file != null;
106        }
107
108        @Override
109        public File next() {
110            if (!hasNext()) {
111                throw new NoSuchElementException();
112            }
113            File next = file;
114            file = null;
115            return next;
116        }
117
118        @Override
119        public void remove() {
120            throw new UnsupportedOperationException("remove not supported");
121        }
122    }
123
124    // we don't fulfill iterator contract - we don't need a real iterator,
125    // this is used only internally
126    private class LazyChildrenIterator implements Iterator<File> {
127
128        private final File dir;
129
130        private File[] children;
131
132        private int pos = -1; // last pos
133
134        private LazyChildrenIterator(File dir) {
135            this.dir = dir;
136        }
137
138        @Override
139        public boolean hasNext() {
140            if (children == null) {
141                children = filter == null ? dir.listFiles() : dir.listFiles(filter);
142                if (children == null) {
143                    return false; // not a dir
144                }
145                return children.length > 0;
146            } else {
147                return pos < children.length - 1;
148            }
149        }
150
151        @Override
152        public File next() {
153            if (!hasNext()) {
154                throw new NoSuchElementException();
155            }
156            return children[++pos];
157        }
158
159        @Override
160        public void remove() {
161            throw new UnsupportedOperationException("remove not supported");
162        }
163    }
164
165    public static void main(String[] args) {
166        FileTreeIterator it = new FileTreeIterator(new File("/root/kits"), false);
167        while (it.hasNext()) {
168            System.out.println(">> " + it.next());
169        }
170    }
171
172}