1/*
2 * Copyright (C) 2015 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 <wtf/RefPtr.h>
29#include <wtf/ThreadSafeRefCounted.h>
30
31namespace WTF {
32
33// Box<T> is a reference-counted pointer to T that allocates T using FastMalloc and prepends a reference
34// count to it.
35template<typename T>
36class Box {
37public:
38 Box() = default;
39 Box(Box&&) = default;
40 Box(const Box&) = default;
41
42 Box(std::nullptr_t)
43 {
44 }
45
46 Box& operator=(Box&&) = default;
47 Box& operator=(const Box&) = default;
48
49 template<typename... Arguments>
50 static Box create(Arguments&&... arguments)
51 {
52 Box result;
53 result.m_data = adoptRef(new Data(std::forward<Arguments>(arguments)...));
54 return result;
55 }
56
57 T* get() const { return &m_data->value; }
58
59 T& operator*() const { return m_data->value; }
60 T* operator->() const { return &m_data->value; }
61
62 explicit operator bool() const { return static_cast<bool>(m_data); }
63
64private:
65 struct Data : ThreadSafeRefCounted<Data> {
66 template<typename... Arguments>
67 Data(Arguments&&... arguments)
68 : value(std::forward<Arguments>(arguments)...)
69 {
70 }
71
72 T value;
73 };
74
75 RefPtr<Data> m_data;
76};
77
78} // namespace WTF
79
80using WTF::Box;
81