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
|
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef dap_variant_h
#define dap_variant_h
#include "any.h"
namespace dap {
// internal functionality
namespace detail {
template <typename T, typename...>
struct TypeIsIn {
static constexpr bool value = false;
};
template <typename T, typename List0, typename... ListN>
struct TypeIsIn<T, List0, ListN...> {
static constexpr bool value =
std::is_same<T, List0>::value || TypeIsIn<T, ListN...>::value;
};
} // namespace detail
// variant represents a type-safe union of DAP types.
// variant can hold a value of any of the template argument types.
// variant defaults to a default-constructed T0.
template <typename T0, typename... Types>
class variant {
public:
// constructors
inline variant();
template <typename T>
inline variant(const T& val);
// assignment
template <typename T>
inline variant& operator=(const T& val);
// get() returns the contained value of the type T.
// If the any does not contain a value of type T, then get() will assert.
template <typename T>
inline T& get() const;
// is() returns true iff the contained value is of type T.
template <typename T>
inline bool is() const;
// accepts() returns true iff the variant accepts values of type T.
template <typename T>
static constexpr bool accepts();
private:
friend class Serializer;
friend class Deserializer;
any value;
};
template <typename T0, typename... Types>
variant<T0, Types...>::variant() : value(T0()) {}
template <typename T0, typename... Types>
template <typename T>
variant<T0, Types...>::variant(const T& v) : value(v) {
static_assert(accepts<T>(), "variant does not accept template type T");
}
template <typename T0, typename... Types>
template <typename T>
variant<T0, Types...>& variant<T0, Types...>::operator=(const T& v) {
static_assert(accepts<T>(), "variant does not accept template type T");
value = v;
return *this;
}
template <typename T0, typename... Types>
template <typename T>
T& variant<T0, Types...>::get() const {
static_assert(accepts<T>(), "variant does not accept template type T");
return value.get<T>();
}
template <typename T0, typename... Types>
template <typename T>
bool variant<T0, Types...>::is() const {
return value.is<T>();
}
template <typename T0, typename... Types>
template <typename T>
constexpr bool variant<T0, Types...>::accepts() {
return detail::TypeIsIn<T, T0, Types...>::value;
}
} // namespace dap
#endif // dap_variant_h
|
