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 }
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