1 /*
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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
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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.
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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
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19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24  */
25 
26 package java.nio.file;
27 
28 import java.io.Closeable;
29 import java.io.IOException;
30 import java.io.UncheckedIOException;
31 import java.util.Arrays;
32 import java.util.Iterator;
33 import java.util.NoSuchElementException;
34 import java.util.Objects;
35 import 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 
51 class 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      */
FileTreeIterator(Path start, int maxDepth, FileVisitOption... options)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 
fetchNextIfNeeded()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
hasNext()101     public boolean hasNext() {
102         if (!walker.isOpen())
103             throw new IllegalStateException();
104         fetchNextIfNeeded();
105         return next != null;
106     }
107 
108     @Override
next()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
close()121     public void close() {
122         walker.close();
123     }
124 }
125