summaryrefslogtreecommitdiffstats
path: root/xpcom/base/DarwinObjectPtr.h
blob: 3d5842553b64974add815b6dc3a99f5d3a3751e8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
/*
 * Copyright (C) 2014-2021 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

// Adapted from
// https://github.com/WebKit/WebKit/blob/ad340677c00a4b4b6a299c93a6e18cd073b3f4e9/Source/WTF/wtf/OSObjectPtr.h

#ifndef mozilla_DarwinObjectPtr_h
#define mozilla_DarwinObjectPtr_h

#include <os/object.h>
#include <utility>
#include "mozilla/Attributes.h"

// Because ARC enablement is a compile-time choice, and we compile this header
// both ways, we need a separate copy of our code when ARC is enabled.
#if __has_feature(objc_arc)
#  define AdoptDarwinObject AdoptDarwinObjectArc
#  define RetainDarwinObject RetainDarwinObjectArc
#  define ReleaseDarwinObject ReleaseDarwinObjectArc
#endif

namespace mozilla {

template <typename>
class DarwinObjectPtr;
template <typename T>
[[nodiscard]] DarwinObjectPtr<T> AdoptDarwinObject(T);

template <typename T>
static inline void RetainDarwinObject(T aPtr) {
#if !__has_feature(objc_arc)
  os_retain(aPtr);
#endif
}

template <typename T>
static inline void ReleaseDarwinObject(T aPtr) {
#if !__has_feature(objc_arc)
  os_release(aPtr);
#endif
}

template <typename T>
class DarwinObjectPtr {
 public:
  DarwinObjectPtr() : mPtr(nullptr) {}

  ~DarwinObjectPtr() {
    if (mPtr) {
      ReleaseDarwinObject(mPtr);
    }
  }

  T get() const { return mPtr; }

  explicit operator bool() const { return mPtr; }
  bool operator!() const { return !mPtr; }

  DarwinObjectPtr(const DarwinObjectPtr& aOther) : mPtr(aOther.mPtr) {
    if (mPtr) {
      RetainDarwinObject(mPtr);
    }
  }

  DarwinObjectPtr(DarwinObjectPtr&& aOther) : mPtr(std::move(aOther.mPtr)) {
    aOther.mPtr = nullptr;
  }

  MOZ_IMPLICIT DarwinObjectPtr(T aPtr) : mPtr(std::move(aPtr)) {
    if (mPtr) {
      RetainDarwinObject(mPtr);
    }
  }

  DarwinObjectPtr& operator=(const DarwinObjectPtr& aOther) {
    DarwinObjectPtr ptr = aOther;
    swap(ptr);
    return *this;
  }

  DarwinObjectPtr& operator=(DarwinObjectPtr&& aOther) {
    DarwinObjectPtr ptr = std::move(aOther);
    swap(ptr);
    return *this;
  }

  DarwinObjectPtr& operator=(std::nullptr_t) {
    if (mPtr) {
      ReleaseDarwinObject(mPtr);
    }
    mPtr = nullptr;
    return *this;
  }

  DarwinObjectPtr& operator=(T aOther) {
    DarwinObjectPtr ptr = std::move(aOther);
    swap(ptr);
    return *this;
  }

  void swap(DarwinObjectPtr& aOther) { std::swap(mPtr, aOther.mPtr); }

  [[nodiscard]] T forget() { return std::exchange(mPtr, nullptr); }

  friend DarwinObjectPtr AdoptDarwinObject<T>(T);

 private:
  struct AdoptDarwinObjectTag {};
  DarwinObjectPtr(AdoptDarwinObjectTag, T aPtr) : mPtr(std::move(aPtr)) {}

  T mPtr;
};

template <typename T>
inline DarwinObjectPtr<T> AdoptDarwinObject(T aPtr) {
  return DarwinObjectPtr<T>{typename DarwinObjectPtr<T>::AdoptDarwinObjectTag{},
                            std::move(aPtr)};
}

}  // namespace mozilla

#endif