| // Protocol Buffers - Google's data interchange format |
| // Copyright 2008 Google Inc. All rights reserved. |
| // https://developers.google.com/protocol-buffers/ |
| // |
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| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
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| // in the documentation and/or other materials provided with the |
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| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| |
| // Author: kenton@google.com (Kenton Varda) |
| |
| #ifndef GOOGLE_PROTOBUF_STUBS_HASH_H__ |
| #define GOOGLE_PROTOBUF_STUBS_HASH_H__ |
| |
| #include <cstring> |
| #include <string> |
| #include <unordered_map> |
| #include <unordered_set> |
| |
| # define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START \ |
| namespace google { \ |
| namespace protobuf { |
| # define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END }} |
| |
| namespace google { |
| namespace protobuf { |
| |
| template <typename Key> |
| struct hash : public std::hash<Key> {}; |
| |
| template <typename Key> |
| struct hash<const Key*> { |
| inline size_t operator()(const Key* key) const { |
| return reinterpret_cast<size_t>(key); |
| } |
| }; |
| |
| // Unlike the old SGI version, the TR1 "hash" does not special-case char*. So, |
| // we go ahead and provide our own implementation. |
| template <> |
| struct hash<const char*> { |
| inline size_t operator()(const char* str) const { |
| size_t result = 0; |
| for (; *str != '\0'; str++) { |
| result = 5 * result + static_cast<size_t>(*str); |
| } |
| return result; |
| } |
| }; |
| |
| template<> |
| struct hash<bool> { |
| size_t operator()(bool x) const { |
| return static_cast<size_t>(x); |
| } |
| }; |
| |
| template <> |
| struct hash<std::string> { |
| inline size_t operator()(const std::string& key) const { |
| return hash<const char*>()(key.c_str()); |
| } |
| |
| static const size_t bucket_size = 4; |
| static const size_t min_buckets = 8; |
| inline bool operator()(const std::string& a, const std::string& b) const { |
| return a < b; |
| } |
| }; |
| |
| template <typename First, typename Second> |
| struct hash<std::pair<First, Second> > { |
| inline size_t operator()(const std::pair<First, Second>& key) const { |
| size_t first_hash = hash<First>()(key.first); |
| size_t second_hash = hash<Second>()(key.second); |
| |
| // FIXME(kenton): What is the best way to compute this hash? I have |
| // no idea! This seems a bit better than an XOR. |
| return first_hash * ((1 << 16) - 1) + second_hash; |
| } |
| |
| static const size_t bucket_size = 4; |
| static const size_t min_buckets = 8; |
| inline bool operator()(const std::pair<First, Second>& a, |
| const std::pair<First, Second>& b) const { |
| return a < b; |
| } |
| }; |
| |
| } // namespace protobuf |
| } // namespace google |
| |
| #endif // GOOGLE_PROTOBUF_STUBS_HASH_H__ |