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 { return reinterpret_cast<std::size_t>(ptr); } 40 }; 41 42 template <typename T> 43 struct PointerHash<std::shared_ptr<T>> { 44 constexpr std::size_t operator()(const std::shared_ptr<T> &ptr) const noexcept { 45 return reinterpret_cast<std::size_t>(ptr.get()); 46 } 47 }; 48 49 // Generate hash code for a string literal at compile time. 50 // We using Java string hash algorithm here. 51 constexpr uint32_t ConstStringHash(const char *str) { 52 uint32_t hash = 0; 53 while (*str) { 54 hash = hash * 31 + static_cast<uint32_t>(*str++); 55 } 56 return hash; 57 } 58 59 } // namespace mindspore 60 #endif // MINDSPORE_CORE_UTILS_HASHING_H_ 61