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
|
// Copyright 2017 Peter Dimov.
//
// Distributed under the Boost Software License, Version 1.0.
//
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
#include <boost/variant2/variant.hpp>
using namespace boost::variant2;
struct X
{
constexpr operator int() const { return 2; }
};
#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
int main()
{
{
constexpr variant<int> v( 1 );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 1 );
}
{
constexpr variant<int> v( 'a' );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 'a' );
}
{
constexpr variant<int> v( X{} );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 2 );
}
{
constexpr variant<int const> v( 1 );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 1 );
}
{
constexpr variant<int const> v( 'a' );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 'a' );
}
{
constexpr variant<int const> v( X{} );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( get<0>(v) == 2 );
}
{
constexpr variant<int, float, X> v( 1 );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( holds_alternative<int>(v) );
STATIC_ASSERT( get<0>(v) == 1 );
}
{
constexpr variant<int, float, X> v( 'a' );
STATIC_ASSERT( v.index() == 0 );
STATIC_ASSERT( holds_alternative<int>(v) );
STATIC_ASSERT( get<0>(v) == 'a' );
}
{
constexpr variant<int, float, X> v( 3.14f );
STATIC_ASSERT( v.index() == 1 );
STATIC_ASSERT( holds_alternative<float>(v) );
STATIC_ASSERT( get<1>(v) == (float)3.14f ); // see FLT_EVAL_METHOD
}
{
constexpr variant<int, float, X> v( X{} );
STATIC_ASSERT( v.index() == 2 );
STATIC_ASSERT( holds_alternative<X>(v) );
}
{
constexpr variant<int, int, float, X> v( 3.14f );
STATIC_ASSERT( v.index() == 2 );
STATIC_ASSERT( holds_alternative<float>(v) );
STATIC_ASSERT( get<2>(v) == (float)3.14f );
}
{
constexpr variant<int, int, float, X> v( X{} );
STATIC_ASSERT( v.index() == 3 );
STATIC_ASSERT( holds_alternative<X>(v) );
}
}
|
