BLI_hash.hh

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/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
 
#pragma once
 
#include <functional>
#include <memory>
#include <string>
#include <utility>
 
#include "BLI_math_base.h"
#include "BLI_string_ref.hh"
#include "BLI_utildefines.h"
 
namespace blender {
 
template<typename T> struct DefaultHash {
  uint64_t operator()(const T &value) const
  {
    if constexpr (std::is_enum_v<T>) {
      return (uint64_t)value;
    }
    else {
      return value.hash();
    }
  }
};
 
template<typename T> struct DefaultHash<const T> {
  uint64_t operator()(const T &value) const
  {
    return DefaultHash<T>{}(value);
  }
};
 
#define TRIVIAL_DEFAULT_INT_HASH(TYPE) \
  template<> struct DefaultHash<TYPE> { \
    uint64_t operator()(TYPE value) const \
    { \
      return static_cast<uint64_t>(value); \
    } \
  }
 
TRIVIAL_DEFAULT_INT_HASH(int8_t);
TRIVIAL_DEFAULT_INT_HASH(uint8_t);
TRIVIAL_DEFAULT_INT_HASH(int16_t);
TRIVIAL_DEFAULT_INT_HASH(uint16_t);
TRIVIAL_DEFAULT_INT_HASH(int32_t);
TRIVIAL_DEFAULT_INT_HASH(uint32_t);
TRIVIAL_DEFAULT_INT_HASH(int64_t);
TRIVIAL_DEFAULT_INT_HASH(uint64_t);
 
template<> struct DefaultHash<float> {
  uint64_t operator()(float value) const
  {
    return *reinterpret_cast<uint32_t *>(&value);
  }
};
 
template<> struct DefaultHash<bool> {
  uint64_t operator()(bool value) const
  {
    return static_cast<uint64_t>((value != false) * 1298191);
  }
};
 
inline uint64_t hash_string(StringRef str)
{
  uint64_t hash = 5381;
  for (char c : str) {
    hash = hash * 33 + c;
  }
  return hash;
}
 
template<> struct DefaultHash<std::string> {
  uint64_t operator()(StringRef value) const
  {
    return hash_string(value);
  }
};
 
template<> struct DefaultHash<StringRef> {
  uint64_t operator()(StringRef value) const
  {
    return hash_string(value);
  }
};
 
template<> struct DefaultHash<StringRefNull> {
  uint64_t operator()(StringRef value) const
  {
    return hash_string(value);
  }
};
 
template<> struct DefaultHash<std::string_view> {
  uint64_t operator()(StringRef value) const
  {
    return hash_string(value);
  }
};
 
template<typename T> struct DefaultHash<T *> {
  uint64_t operator()(const T *value) const
  {
    uintptr_t ptr = reinterpret_cast<uintptr_t>(value);
    uint64_t hash = static_cast<uint64_t>(ptr >> 4);
    return hash;
  }
};
 
template<typename T> uint64_t get_default_hash(const T &v)
{
  return DefaultHash<T>{}(v);
}
 
template<typename T1, typename T2> uint64_t get_default_hash_2(const T1 &v1, const T2 &v2)
{
  const uint64_t h1 = get_default_hash(v1);
  const uint64_t h2 = get_default_hash(v2);
  return h1 ^ (h2 * 19349669);
}
 
template<typename T1, typename T2, typename T3>
uint64_t get_default_hash_3(const T1 &v1, const T2 &v2, const T3 &v3)
{
  const uint64_t h1 = get_default_hash(v1);
  const uint64_t h2 = get_default_hash(v2);
  const uint64_t h3 = get_default_hash(v3);
  return h1 ^ (h2 * 19349669) ^ (h3 * 83492791);
}
 
template<typename T> struct DefaultHash<std::unique_ptr<T>> {
  uint64_t operator()(const std::unique_ptr<T> &value) const
  {
    return get_default_hash(value.get());
  }
};
 
template<typename T1, typename T2> struct DefaultHash<std::pair<T1, T2>> {
  uint64_t operator()(const std::pair<T1, T2> &value) const
  {
    return get_default_hash_2(value.first, value.second);
  }
};
 
}  // namespace blender