Coverage Report

Created: 2023-06-07 07:09

/src/LPM/external.protobuf/include/google/protobuf/explicitly_constructed.h
Line
Count
Source (jump to first uncovered line)
1
// Protocol Buffers - Google's data interchange format
2
// Copyright 2008 Google Inc.  All rights reserved.
3
// https://developers.google.com/protocol-buffers/
4
//
5
// Redistribution and use in source and binary forms, with or without
6
// modification, are permitted provided that the following conditions are
7
// met:
8
//
9
//     * Redistributions of source code must retain the above copyright
10
// notice, this list of conditions and the following disclaimer.
11
//     * Redistributions in binary form must reproduce the above
12
// copyright notice, this list of conditions and the following disclaimer
13
// in the documentation and/or other materials provided with the
14
// distribution.
15
//     * Neither the name of Google Inc. nor the names of its
16
// contributors may be used to endorse or promote products derived from
17
// this software without specific prior written permission.
18
//
19
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31
#ifndef GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__
32
#define GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__
33
34
#include <stdint.h>
35
36
#include <string>
37
#include <utility>
38
39
// clang-format off
40
#include "google/protobuf/port_def.inc"
41
// clang-format on
42
43
namespace google {
44
namespace protobuf {
45
namespace internal {
46
47
// Wraps a variable whose constructor and destructor are explicitly
48
// called. It is particularly useful for a global variable, without its
49
// constructor and destructor run on start and end of the program lifetime.
50
// This circumvents the initial construction order fiasco, while keeping
51
// the address of the empty string a compile time constant.
52
//
53
// Pay special attention to the initialization state of the object.
54
// 1. The object is "uninitialized" to begin with.
55
// 2. Call Construct() or DefaultConstruct() only if the object is
56
//    uninitialized. After the call, the object becomes "initialized".
57
// 3. Call get() and get_mutable() only if the object is initialized.
58
// 4. Call Destruct() only if the object is initialized.
59
//    After the call, the object becomes uninitialized.
60
template <typename T, size_t min_align = 1>
61
class ExplicitlyConstructed {
62
 public:
63
  void DefaultConstruct() { new (&union_) T(); }
64
65
  template <typename... Args>
66
  void Construct(Args&&... args) {
67
    new (&union_) T(std::forward<Args>(args)...);
68
  }
69
70
  void Destruct() { get_mutable()->~T(); }
71
72
0
  constexpr const T& get() const { return reinterpret_cast<const T&>(union_); }
73
  T* get_mutable() { return reinterpret_cast<T*>(&union_); }
74
75
 private:
76
  union AlignedUnion {
77
    alignas(min_align > alignof(T) ? min_align
78
                                   : alignof(T)) char space[sizeof(T)];
79
    int64_t align_to_int64;
80
    void* align_to_ptr;
81
  } union_;
82
};
83
84
// ArenaStringPtr compatible explicitly constructed string type.
85
// This empty string type is aligned with a minimum alignment of 8 bytes
86
// which is the minimum requirement of ArenaStringPtr
87
using ExplicitlyConstructedArenaString = ExplicitlyConstructed<std::string, 8>;
88
89
}  // namespace internal
90
}  // namespace protobuf
91
}  // namespace google
92
93
#include "google/protobuf/port_undef.inc"
94
95
#endif  // GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__