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 {
37 WTF_MAKE_FAST_ALLOCATED;
38public:
39 Box() = default;
40 Box(Box&&) = default;
41 Box(const Box&) = default;
42
43 Box(std::nullptr_t)
44 {
45 }
46
47 Box& operator=(Box&&) = default;
48 Box& operator=(const Box&) = default;
49
50 template<typename... Arguments>
51 static Box create(Arguments&&... arguments)
52 {
53 Box result;
54 result.m_data = adoptRef(new Data(std::forward<Arguments>(arguments)...));
55 return result;
56 }
57
58 T* get() const { return &m_data->value; }
59
60 T& operator*() const { return m_data->value; }
61 T* operator->() const { return &m_data->value; }
62
63 explicit operator bool() const { return static_cast<bool>(m_data); }
64
65private:
66 struct Data : ThreadSafeRefCounted<Data> {
67 template<typename... Arguments>
68 Data(Arguments&&... arguments)
69 : value(std::forward<Arguments>(arguments)...)
70 {
71 }
72
73 T value;
74 };
75
76 RefPtr<Data> m_data;
77};
78
79} // namespace WTF
80
81using WTF::Box;
82