1/*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.nio.file;
27
28import java.io.Closeable;
29import java.io.IOException;
30import java.io.UncheckedIOException;
31import java.util.Arrays;
32import java.util.Iterator;
33import java.util.NoSuchElementException;
34import java.nio.file.FileTreeWalker.Event;
35
36/**
37 * An {@code Iterator} to iterate over the nodes of a file tree.
38 *
39 * <pre>{@code
40 *     try (FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options)) {
41 *         while (iterator.hasNext()) {
42 *             Event ev = iterator.next();
43 *             Path path = ev.file();
44 *             BasicFileAttributes attrs = ev.attributes();
45 *         }
46 *     }
47 * }</pre>
48 */
49
50class FileTreeIterator implements Iterator<Event>, Closeable {
51    private final FileTreeWalker walker;
52    private Event next;
53
54    /**
55     * Creates a new iterator to walk the file tree starting at the given file.
56     *
57     * @throws  IllegalArgumentException
58     *          if {@code maxDepth} is negative
59     * @throws  IOException
60     *          if an I/O errors occurs opening the starting file
61     * @throws  SecurityException
62     *          if the security manager denies access to the starting file
63     * @throws  NullPointerException
64     *          if {@code start} or {@code options} is {@code null} or
65     *          the options array contains a {@code null} element
66     */
67    FileTreeIterator(Path start, int maxDepth, FileVisitOption... options)
68        throws IOException
69    {
70        this.walker = new FileTreeWalker(Arrays.asList(options), maxDepth);
71        this.next = walker.walk(start);
72        assert next.type() == FileTreeWalker.EventType.ENTRY ||
73               next.type() == FileTreeWalker.EventType.START_DIRECTORY;
74
75        // IOException if there a problem accessing the starting file
76        IOException ioe = next.ioeException();
77        if (ioe != null)
78            throw ioe;
79    }
80
81    private void fetchNextIfNeeded() {
82        if (next == null) {
83            FileTreeWalker.Event ev = walker.next();
84            while (ev != null) {
85                IOException ioe = ev.ioeException();
86                if (ioe != null)
87                    throw new UncheckedIOException(ioe);
88
89                // END_DIRECTORY events are ignored
90                if (ev.type() != FileTreeWalker.EventType.END_DIRECTORY) {
91                    next = ev;
92                    return;
93                }
94                ev = walker.next();
95            }
96        }
97    }
98
99    @Override
100    public boolean hasNext() {
101        if (!walker.isOpen())
102            throw new IllegalStateException();
103        fetchNextIfNeeded();
104        return next != null;
105    }
106
107    @Override
108    public Event next() {
109        if (!walker.isOpen())
110            throw new IllegalStateException();
111        fetchNextIfNeeded();
112        if (next == null)
113            throw new NoSuchElementException();
114        Event result = next;
115        next = null;
116        return result;
117    }
118
119    @Override
120    public void close() {
121        walker.close();
122    }
123}
124