json/include/nlohmann/detail/hash.hpp
2020-07-14 14:31:19 +02:00

93 lines
2.9 KiB
C++

#pragma once
#include <functional> // hash
namespace nlohmann
{
namespace detail
{
std::size_t combine(std::size_t seed, std::size_t h)
{
seed ^= h + 0x9e3779b9 + (seed << 6U) + (seed >> 2U);
return seed;
}
template<typename BasicJsonType>
std::size_t hash(const BasicJsonType& j)
{
switch (j.type())
{
case BasicJsonType::value_t::null:
case BasicJsonType::discarded:
return combine(static_cast<std::size_t>(j.type()), 0);
case BasicJsonType::value_t::object:
{
auto seed = combine(static_cast<std::size_t>(j.type()), j.size());
for (const auto& element : j.items())
{
const auto h = std::hash<typename BasicJsonType::string_t> {}(element.key());
seed = combine(seed, h);
seed = combine(seed, hash(element.value()));
}
return seed;
}
case BasicJsonType::value_t::array:
{
auto seed = combine(static_cast<std::size_t>(j.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<typename BasicJsonType::string_t> {}(j.template get_ref<const typename BasicJsonType::string_t&>());
return combine(static_cast<std::size_t>(j.type()), h);
}
case BasicJsonType::value_t::boolean:
{
const auto h = std::hash<bool> {}(j.template get<bool>());
return combine(static_cast<std::size_t>(j.type()), h);
}
case BasicJsonType::value_t::number_integer:
{
const auto h = std::hash<typename BasicJsonType::number_integer_t> {}(j.template get<typename BasicJsonType::number_integer_t>());
return combine(static_cast<std::size_t>(j.type()), h);
}
case nlohmann::detail::value_t::number_unsigned:
{
const auto h = std::hash<typename BasicJsonType::number_unsigned_t> {}(j.template get<typename BasicJsonType::number_unsigned_t>());
return combine(static_cast<std::size_t>(j.type()), h);
}
case nlohmann::detail::value_t::number_float:
{
const auto h = std::hash<typename BasicJsonType::number_float_t> {}(j.template get<typename BasicJsonType::number_float_t>());
return combine(static_cast<std::size_t>(j.type()), h);
}
case nlohmann::detail::value_t::binary:
{
auto seed = combine(static_cast<std::size_t>(j.type()), j.get_binary().size());
seed = combine(seed, j.get_binary().subtype());
for (const auto byte : j.get_binary())
{
seed = combine(seed, std::hash<std::uint8_t> {}(byte));
}
return seed;
}
}
return 0;
}
} // namespace detail
} // namespace nlohmann