1/*
2 * Copyright (c) 1997, 2012, 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 com.sun.xml.internal.bind.v2.util;
27
28import java.util.Iterator;
29import java.util.Map;
30import java.util.NoSuchElementException;
31
32/**
33 * {@link Iterator} that walks over a map of maps.
34 *
35 * @author Kohsuke Kawaguchi
36 * @since 2.0
37 */
38public final class FlattenIterator<T> implements Iterator<T> {
39
40    private final Iterator<? extends Map<?,? extends T>> parent;
41    private Iterator<? extends T> child = null;
42    private T next;
43
44    public FlattenIterator( Iterable<? extends Map<?,? extends T>> core ) {
45        this.parent = core.iterator();
46    }
47
48
49    public void remove() {
50        throw new UnsupportedOperationException();
51    }
52
53    public boolean hasNext() {
54        getNext();
55        return next!=null;
56    }
57
58    public T next() {
59        T r = next;
60        next = null;
61        if(r==null)
62            throw new NoSuchElementException();
63        return r;
64    }
65
66    private void getNext() {
67        if(next!=null)  return;
68
69        if(child!=null && child.hasNext()) {
70            next = child.next();
71            return;
72        }
73        // child is empty
74        if(parent.hasNext()) {
75            child = parent.next().values().iterator();
76            getNext();
77        }
78        // else
79        //      no more object
80    }
81}
82