ArgumentIterator.java revision 2593:035b01d356ee 
1/*
2 * Copyright (c) 2014, 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.tools.sjavac.options;
27
28import java.util.Iterator;
29
30/**
31 *  <p><b>This is NOT part of any supported API.
32 *  If you write code that depends on this, you do so at your own risk.
33 *  This code and its internal interfaces are subject to change or
34 *  deletion without notice.</b>
35 */
36public class ArgumentIterator implements Iterator<String> {
37
38    /** The underlying argument iterator */
39    private Iterator<String> iter;
40
41    /** Extra state used to implement peek and current */
42    private String current;
43    private String buffered;
44
45    public ArgumentIterator(Iterable<String> iter) {
46        this.iter = iter.iterator();
47    }
48
49    @Override
50    public boolean hasNext() {
51        return buffered != null || iter.hasNext();
52    }
53
54    @Override
55    public String next() {
56        fillBuffer();
57        current = buffered;
58        buffered = null;
59        return current;
60    }
61
62    /**
63     * @return the last element returned by next() (or {@code null} if next has
64     * never been invoked on this iterator).
65     */
66    public String current() {
67        return current;
68    }
69
70    /** Can't remove current element, since we may have buffered it. */
71    @Override
72    public void remove() {
73        throw new UnsupportedOperationException();
74    }
75
76    /**
77     * @return Returns the next element without advancing the iterator
78     */
79    public String peek() {
80        fillBuffer();
81        return buffered;
82    }
83
84    private void fillBuffer() {
85        if (buffered == null && iter.hasNext())
86            buffered = iter.next();
87    }
88
89}
90