1/*
2 * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <type_traits>
29
30namespace WTF {
31
32template<class Container>
33class IndexedContainerIterator {
34public:
35 IndexedContainerIterator()
36 : m_container(nullptr)
37 , m_index(0)
38 {
39 }
40
41 IndexedContainerIterator(const Container& container, unsigned index)
42 : m_container(&container)
43 , m_index(findNext(index))
44 {
45 }
46
47 auto operator*() -> typename std::result_of<decltype(&Container::at)(const Container, unsigned)>::type
48 {
49 return m_container->at(m_index);
50 }
51
52 IndexedContainerIterator& operator++()
53 {
54 m_index = findNext(m_index + 1);
55 return *this;
56 }
57
58 bool operator==(const IndexedContainerIterator& other) const
59 {
60 ASSERT(m_container == other.m_container);
61 return m_index == other.m_index;
62 }
63
64 bool operator!=(const IndexedContainerIterator& other) const
65 {
66 return !(*this == other);
67 }
68
69private:
70 unsigned findNext(unsigned index)
71 {
72 while (index < m_container->size() && !m_container->at(index))
73 index++;
74 return index;
75 }
76
77 const Container* m_container;
78 unsigned m_index;
79};
80
81} // namespace WTF
82