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.util.Objects;
35import java.nio.file.FileTreeWalker.Event;
36
37/**
38 * An {@code Iterator to iterate over the nodes of a file tree.
39 *
40 * <pre>{@code
41 *     try (FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options)) {
42 *         while (iterator.hasNext()) {
43 *             Event ev = iterator.next();
44 *             Path path = ev.file();
45 *             BasicFileAttributes attrs = ev.attributes();
46 *         }
47 *     }
48 * }</pre>
49 */
50
51class FileTreeIterator implements Iterator<Event>, Closeable {
52    private final FileTreeWalker walker;
53    private Event next;
54
55    /**
56     * Creates a new iterator to walk the file tree starting at the given file.
57     *
58     * @throws  IllegalArgumentException
59     *          if {@code maxDepth} is negative
60     * @throws  IOException
61     *          if an I/O errors occurs opening the starting file
62     * @throws  SecurityException
63     *          if the security manager denies access to the starting file
64     * @throws  NullPointerException
65     *          if {@code start} or {@code options} is {@ocde null} or
66     *          the options array contains a {@code null} element
67     */
68    FileTreeIterator(Path start, int maxDepth, FileVisitOption... options)
69        throws IOException
70    {
71        this.walker = new FileTreeWalker(Arrays.asList(options), maxDepth);
72        this.next = walker.walk(start);
73        assert next.type() == FileTreeWalker.EventType.ENTRY ||
74               next.type() == FileTreeWalker.EventType.START_DIRECTORY;
75
76        // IOException if there a problem accessing the starting file
77        IOException ioe = next.ioeException();
78        if (ioe != null)
79            throw ioe;
80    }
81
82    private void fetchNextIfNeeded() {
83        if (next == null) {
84            FileTreeWalker.Event ev = walker.next();
85            while (ev != null) {
86                IOException ioe = ev.ioeException();
87                if (ioe != null)
88                    throw new UncheckedIOException(ioe);
89
90                // END_DIRECTORY events are ignored
91                if (ev.type() != FileTreeWalker.EventType.END_DIRECTORY) {
92                    next = ev;
93                    return;
94                }
95                ev = walker.next();
96            }
97        }
98    }
99
100    @Override
101    public boolean hasNext() {
102        if (!walker.isOpen())
103            throw new IllegalStateException();
104        fetchNextIfNeeded();
105        return next != null;
106    }
107
108    @Override
109    public Event next() {
110        if (!walker.isOpen())
111            throw new IllegalStateException();
112        fetchNextIfNeeded();
113        if (next == null)
114            throw new NoSuchElementException();
115        Event result = next;
116        next = null;
117        return result;
118    }
119
120    @Override
121    public void close() {
122        walker.close();
123    }
124}
125