hashmap.hpp¶

#include "noya/hashmap.hpp"

SourceExpanded

#ifndef NOYA_HASHMAP_HPP
#define NOYA_HASHMAP_HPP 1

#include <chrono>
#include <unordered_map>

namespace noya {
/// @brief Randomized splitmix64 hash to prevent hash collision attacks.
struct splitmix64_hash {
  static uint64_t splitmix64(uint64_t x) {
    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        std::chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

/// @brief Unordered map with anti-hash randomized hash function.
template <typename K, typename V, typename Hash = splitmix64_hash>
using HashMap = std::unordered_map<K, V, Hash>;

} // namespace noya

#endif // NOYA_HASHMAP_HPP

#include <chrono>
#include <unordered_map>

namespace noya {
/// @brief Randomized splitmix64 hash to prevent hash collision attacks.
struct splitmix64_hash {
  static uint64_t splitmix64(uint64_t x) {
    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        std::chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

/// @brief Unordered map with anti-hash randomized hash function.
template <typename K, typename V, typename Hash = splitmix64_hash>
using HashMap = std::unordered_map<K, V, Hash>;

} // namespace noya