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:[email protected]">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    public boolean hasNext() {
060        if (queue.isEmpty()) {
061            return false;
062        }
063        Iterator<File> it = queue.peek();
064        if (it.hasNext()) {
065            return true;
066        } else {
067            queue.poll();
068            return hasNext();
069        }
070    }
071
072    public File next() {
073        if (!hasNext()) {
074            throw new NoSuchElementException("No more files to iterate over");
075        }
076        file = queue.peek().next();
077        if (file.isDirectory()) {
078            queue.add(new LazyChildrenIterator(file));
079        }
080        return file;
081    }
082
083    public void remove() {
084        if (file == null) {
085            throw new IllegalStateException("there is no current file to delete");
086        }
087        org.apache.commons.io.FileUtils.deleteQuietly(file);
088    }
089
090    // we don't fulfill iterator contract - we don't need a real iterator,
091    // this is used only internally
092    private static class OneFileIterator implements Iterator<File> {
093
094        private File file;
095
096        private OneFileIterator(File file) {
097            this.file = file;
098        }
099
100        public boolean hasNext() {
101            return file != null;
102        }
103
104        public File next() {
105            File next = file;
106            file = null;
107            return next;
108        }
109
110        public void remove() {
111            throw new UnsupportedOperationException("remove not supported");
112        }
113    }
114
115    // we don't fulfill iterator contract - we don't need a real iterator,
116    // this is used only internally
117    private class LazyChildrenIterator implements Iterator<File> {
118
119        private final File dir;
120
121        private File[] children;
122
123        private int pos = -1; // last pos
124
125        private LazyChildrenIterator(File dir) {
126            this.dir = dir;
127        }
128
129        public boolean hasNext() {
130            if (children == null) {
131                children = filter == null ? dir.listFiles() : dir.listFiles(filter);
132                if (children == null) {
133                    return false; // not a dir
134                }
135                return children.length > 0;
136            } else {
137                return pos < children.length - 1;
138            }
139        }
140
141        public File next() {
142            return children[++pos];
143        }
144
145        public void remove() {
146            throw new UnsupportedOperationException("remove not supported");
147        }
148    }
149
150    public static void main(String[] args) {
151        FileTreeIterator it = new FileTreeIterator(new File("/root/kits"), false);
152        while (it.hasNext()) {
153            System.out.println(">> " + it.next());
154        }
155    }
156
157}