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
|
#pragma once
#include <cstdint> // uint8_t
#include <cstddef> // size_t
#include <functional> // hash
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/value_t.hpp>
namespace nlohmann
{
namespace detail
{
// boost::hash_combine
inline std::size_t combine(std::size_t seed, std::size_t h) noexcept
{
seed ^= h + 0x9e3779b9 + (seed << 6U) + (seed >> 2U);
return seed;
}
/*!
@brief hash a JSON value
The hash function tries to rely on std::hash where possible. Furthermore, the
type of the JSON value is taken into account to have different hash values for
null, 0, 0U, and false, etc.
@tparam BasicJsonType basic_json specialization
@param j JSON value to hash
@return hash value of j
*/
template<typename BasicJsonType>
std::size_t hash(const BasicJsonType& j)
{
using string_t = typename BasicJsonType::string_t;
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
const auto type = static_cast<std::size_t>(j.type());
switch (j.type())
{
case BasicJsonType::value_t::null:
case BasicJsonType::value_t::discarded:
{
return combine(type, 0);
}
case BasicJsonType::value_t::object:
{
auto seed = combine(type, j.size());
for (const auto& element : j.items())
{
const auto h = std::hash<string_t> {}(element.key());
seed = combine(seed, h);
seed = combine(seed, hash(element.value()));
}
return seed;
}
case BasicJsonType::value_t::array:
{
auto seed = combine(type, j.size());
for (const auto& element : j)
{
seed = combine(seed, hash(element));
}
return seed;
}
case BasicJsonType::value_t::string:
{
const auto h = std::hash<string_t> {}(j.template get_ref<const string_t&>());
return combine(type, h);
}
case BasicJsonType::value_t::boolean:
{
const auto h = std::hash<bool> {}(j.template get<bool>());
return combine(type, h);
}
case BasicJsonType::value_t::number_integer:
{
const auto h = std::hash<number_integer_t> {}(j.template get<number_integer_t>());
return combine(type, h);
}
case BasicJsonType::value_t::number_unsigned:
{
const auto h = std::hash<number_unsigned_t> {}(j.template get<number_unsigned_t>());
return combine(type, h);
}
case BasicJsonType::value_t::number_float:
{
const auto h = std::hash<number_float_t> {}(j.template get<number_float_t>());
return combine(type, h);
}
case BasicJsonType::value_t::binary:
{
auto seed = combine(type, j.get_binary().size());
const auto h = std::hash<bool> {}(j.get_binary().has_subtype());
seed = combine(seed, h);
seed = combine(seed, static_cast<std::size_t>(j.get_binary().subtype()));
for (const auto byte : j.get_binary())
{
seed = combine(seed, std::hash<std::uint8_t> {}(byte));
}
return seed;
}
default: // LCOV_EXCL_LINE
JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
return 0; // LCOV_EXCL_LINE
}
}
} // namespace detail
} // namespace nlohmann
|
