blob: 5fe2d4d6c7c61800739a82c3aa4194365722cc7d (
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
|
// Copyright (C) 2024 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QMAYBE_P_H
#define QMAYBE_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <QtCore/private/qglobal_p.h>
#include <qstring.h>
#include <optional>
#include <utility>
#include <memory>
QT_BEGIN_NAMESPACE
struct QUnexpect
{
};
static constexpr QUnexpect unexpect{};
template <typename Value, typename Error = QString>
class QMaybe
{
public:
QMaybe(const Value &v)
{
if constexpr (std::is_pointer_v<Value>) {
if (!v)
return; // nullptr is treated as nullopt (for raw pointer types only)
}
m_value = v;
}
QMaybe(Value &&v)
{
if constexpr (std::is_pointer_v<Value>) {
if (!v)
return; // nullptr is treated as nullopt (for raw pointer types only)
}
m_value = std::move(v);
}
QMaybe(const QMaybe &other) = default;
QMaybe &operator=(const QMaybe &other) = default;
QMaybe(const Error &error) : m_error(error) { }
template <class... Args>
QMaybe(QUnexpect, Args &&...args) : m_error{ std::forward<Args>(args)... }
{
static_assert(std::is_constructible_v<Error, Args &&...>,
"Invalid arguments for creating an error type");
}
constexpr explicit operator bool() const noexcept { return m_value.has_value(); }
constexpr Value &value()
{
Q_ASSERT(m_value.has_value());
return *m_value;
}
constexpr const Value &value() const
{
Q_ASSERT(m_value.has_value());
return *m_value;
}
constexpr Value *operator->() noexcept { return std::addressof(value()); }
constexpr const Value *operator->() const noexcept { return std::addressof(value()); }
constexpr Value &operator*() &noexcept { return value(); }
constexpr const Value &operator*() const &noexcept { return value(); }
constexpr const Error &error() const { return m_error; }
private:
std::optional<Value> m_value;
Error m_error;
};
QT_END_NAMESPACE
#endif // QMAYBE_P_H
|
