json-validator/include/jvalidate/compat/hash.h

#pragma once

#include <cstddef>
#include <cstdint>
#include <utility> // IWYU pragma: keep std::hash

// NOLINTBEGIN(cppcoreguidelines-avoid-magic-numbers,readability-identifier-length)
namespace jvalidate::compat {
// Taken from boostorg/container_hash
// https://github.com/boostorg/container_hash/blob/2698b43803c012601e6bb1a6116e83767b97986c/include/boost/container_hash/detail/hash_mix.hpp#L67-L81
inline std::size_t hash_mix(std::size_t x) {
  static_assert(sizeof(std::size_t) == 8);
  constexpr static std::uint64_t m = 0xe9846af9b1a615d;

  x ^= x >> 32;
  x *= m;
  x ^= x >> 32;
  x *= m;
  x ^= x >> 28;

  return x;
}

// Taken from boostorg/container_hash
// https://github.com/boostorg/container_hash/blob/2698b43803c012601e6bb1a6116e83767b97986c/include/boost/container_hash/hash.hpp#L474-L477
template <class T> inline void hash_combine(std::size_t & seed, T const & v) {
  seed = hash_mix(seed + 0x9e3779b9 + std::hash<T>()(v));
}
}
// NOLINTEND(cppcoreguidelines-avoid-magic-numbers,readability-identifier-length)