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
145
146
147
148
149
150
151
152
153
|
/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <boost/optional.hpp>
#include <optional>
#include <ostream>
#include <string>
#include <type_traits>
#include "mongo/stdx/type_traits.h"
namespace mongo {
template <typename T>
inline constexpr bool isBoostOptional = false;
template <typename... Ts>
inline constexpr bool isBoostOptional<boost::optional<Ts...>> = true;
template <typename T>
inline constexpr bool isStdOptional = false;
template <typename... Ts>
inline constexpr bool isStdOptional<std::optional<Ts...>> = true; // NOLINT
/**
* Some utilities for formatting optional<T> values, (either std or boost).
* Meant as a substitute for boost/optional_io.hpp.
*/
namespace optional_io {
template <typename T>
using CanStreamOp = decltype(std::declval<std::ostream&>() << std::declval<const T&>());
template <typename T>
inline constexpr bool canStream = stdx::is_detected_v<CanStreamOp, T>;
/**
* True if `Extension<T>` is supported. Cumbersome, but this set of
* specializations is necessary because `boost::optional<T>` defines a
* SFINAE-hostile `operator<<`.
*/
template <typename T>
inline constexpr bool canStreamWithExtension = canStream<T>;
template <>
inline constexpr bool canStreamWithExtension<std::nullopt_t> = true; // NOLINT
template <typename T>
inline constexpr bool canStreamWithExtension<std::optional<T>> = // NOLINT
canStreamWithExtension<T>;
template <>
inline constexpr bool canStreamWithExtension<boost::none_t> = true;
template <typename T>
inline constexpr bool canStreamWithExtension<boost::optional<T>> = canStreamWithExtension<T>;
namespace detail {
/**
* The `stream` overloads provide the same formatting as boost/optional_io.hpp,
* but support both the `boost` and `std` optional types.
*/
template <typename T, std::enable_if_t<canStream<T>, int> = 0>
std::ostream& stream(std::ostream& os, const T& v) {
return os << v;
}
inline std::ostream& stream(std::ostream& os, std::nullopt_t) { // NOLINT
return os << "--";
}
template <typename T, std::enable_if_t<canStreamWithExtension<T>, int> = 0>
std::ostream& stream(std::ostream& os, const std::optional<T>& v) { // NOLINT
if (!v)
return stream(os, std::nullopt);
return stream(os << " ", *v);
}
inline std::ostream& stream(std::ostream& os, boost::none_t) {
return os << "--";
}
template <typename T, std::enable_if_t<canStreamWithExtension<T>, int> = 0>
std::ostream& stream(std::ostream& os, const boost::optional<T>& v) {
if (!v)
return stream(os, std::nullopt);
return stream(os << " ", *v);
}
} // namespace detail
/**
* Streamable wrapper for an object reference.
* This object formats just like the object it refers to.
*
* But if the object happens to be an optional, then the wrapper will be
* streamble in the `boost/optional_io.hpp` formatting style. That is, non-empty
* optionals are formatted with a space followed by the value's representation.
* Empty optionals are "--".
*
* Example:
* std::cout << Extension{someOptional};
* std::cout << Extension{123};
*/
template <typename T, std::enable_if_t<canStreamWithExtension<T>, int> = 0>
class Extension {
public:
explicit Extension(const T& v) : v{v} {}
private:
friend std::ostream& operator<<(std::ostream& os, const Extension& o) {
return detail::stream(os, o.v);
}
const T& v;
};
template <typename T, std::enable_if_t<canStreamWithExtension<T>, int> = 0>
Extension(const T& t)->Extension<T>;
} // namespace optional_io
namespace optional_util {
template <typename T, typename U>
void setOrAdd(boost::optional<T>& counter, U value) {
if (!counter) {
counter = value;
return;
}
counter = *counter + value;
}
} // namespace optional_util
} // namespace mongo
|
