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      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 
     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      */
     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