mirror of
https://github.com/nlohmann/json.git
synced 2024-12-30 09:07:51 +08:00
122 lines
3.6 KiB
C++
122 lines
3.6 KiB
C++
#pragma once
|
|
|
|
#include <cstdint> // uint8_t
|
|
#include <cstddef> // size_t
|
|
#include <functional> // hash
|
|
|
|
#include <nlohmann/detail/macro_scope.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
|