1 /** 2 * Copyright 2019-2021 Huawei Technologies Co., Ltd 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef MINDSPORE_CORE_UTILS_HASHING_H_ 18 #define MINDSPORE_CORE_UTILS_HASHING_H_ 19 20 #include <initializer_list> 21 #include <memory> 22 23 namespace mindspore { hash_combine(std::size_t hash_sum,std::size_t hash_val)24inline std::size_t hash_combine(std::size_t hash_sum, std::size_t hash_val) { 25 // Reference from http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0814r0.pdf 26 return ((hash_sum << 6) + (hash_sum >> 2) + 0x9e3779b9 + hash_val) ^ hash_sum; 27 } 28 hash_combine(const std::initializer_list<std::size_t> & hash_vals)29inline std::size_t hash_combine(const std::initializer_list<std::size_t> &hash_vals) { 30 std::size_t hash_sum = 0; 31 for (auto hash_val : hash_vals) { 32 hash_sum = hash_combine(hash_sum, hash_val); 33 } 34 return hash_sum; 35 } 36 37 template <typename T> 38 struct PointerHash { operatorPointerHash39 constexpr std::size_t operator()(const T *ptr) const noexcept { 40 constexpr int shift_bits = (sizeof(std::size_t) == 8 ? 3 : 1); 41 return (reinterpret_cast<std::size_t>(ptr) >> shift_bits); 42 } 43 }; 44 45 template <typename T> 46 struct PointerHash<std::shared_ptr<T>> { 47 constexpr std::size_t operator()(const std::shared_ptr<T> &ptr) const noexcept { 48 constexpr int shift_bits = (sizeof(std::size_t) == 8 ? 3 : 1); 49 return (reinterpret_cast<std::size_t>(ptr.get()) >> shift_bits); 50 } 51 }; 52 53 } // namespace mindspore 54 #endif // MINDSPORE_CORE_UTILS_HASHING_H_ 55