/*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-#ifndef FOLLY_BASE_HASH_H_
-#define FOLLY_BASE_HASH_H_
+#pragma once
+#include <cstdint>
#include <cstring>
-#include <stdint.h>
+#include <limits>
#include <string>
-#include <utility>
#include <tuple>
+#include <type_traits>
+#include <utility>
+#include <folly/ApplyTuple.h>
+#include <folly/Bits.h>
#include <folly/SpookyHashV1.h>
#include <folly/SpookyHashV2.h>
// This is the Hash128to64 function from Google's cityhash (available
// under the MIT License). We use it to reduce multiple 64 bit hashes
// into a single hash.
-inline size_t hash_128_to_64(const size_t upper, const size_t lower) {
+inline uint64_t hash_128_to_64(const uint64_t upper, const uint64_t lower) {
// Murmur-inspired hashing.
- const size_t kMul = 0x9ddfea08eb382d69ULL;
- size_t a = (lower ^ upper) * kMul;
+ const uint64_t kMul = 0x9ddfea08eb382d69ULL;
+ uint64_t a = (lower ^ upper) * kMul;
a ^= (a >> 47);
- size_t b = (upper ^ a) * kMul;
+ uint64_t b = (upper ^ a) * kMul;
b ^= (b >> 47);
b *= kMul;
return b;
return hash;
}
+inline uint32_t twang_32from64(uint64_t key);
+
template <class Hasher, typename T, typename... Ts>
size_t hash_combine_generic(const T& t, const Ts&... ts) {
size_t seed = Hasher::hash(t);
return seed;
}
size_t remainder = hash_combine_generic<Hasher>(ts...);
- return hash_128_to_64(seed, remainder);
+ /* static */ if (sizeof(size_t) == sizeof(uint32_t)) {
+ return twang_32from64((uint64_t(seed) << 32) | remainder);
+ } else {
+ return static_cast<size_t>(hash_128_to_64(seed, remainder));
+ }
}
// Simply uses std::hash to hash. Note that std::hash is not guaranteed
const uint32_t FNV_32_HASH_START = 2166136261UL;
const uint64_t FNV_64_HASH_START = 14695981039346656037ULL;
-inline uint32_t fnv32(const char* s,
- uint32_t hash = FNV_32_HASH_START) {
+inline uint32_t fnv32(const char* buf, uint32_t hash = FNV_32_HASH_START) {
+ // forcing signed char, since other platforms can use unsigned
+ const signed char* s = reinterpret_cast<const signed char*>(buf);
+
for (; *s; ++s) {
hash += (hash << 1) + (hash << 4) + (hash << 7) +
(hash << 8) + (hash << 24);
inline uint32_t fnv32_buf(const void* buf,
size_t n,
uint32_t hash = FNV_32_HASH_START) {
- const char* char_buf = reinterpret_cast<const char*>(buf);
+ // forcing signed char, since other platforms can use unsigned
+ const signed char* char_buf = reinterpret_cast<const signed char*>(buf);
for (size_t i = 0; i < n; ++i) {
hash += (hash << 1) + (hash << 4) + (hash << 7) +
return fnv32_buf(str.data(), str.size(), hash);
}
-inline uint64_t fnv64(const char* s,
- uint64_t hash = FNV_64_HASH_START) {
+inline uint64_t fnv64(const char* buf, uint64_t hash = FNV_64_HASH_START) {
+ // forcing signed char, since other platforms can use unsigned
+ const signed char* s = reinterpret_cast<const signed char*>(buf);
+
for (; *s; ++s) {
hash += (hash << 1) + (hash << 4) + (hash << 5) + (hash << 7) +
(hash << 8) + (hash << 40);
inline uint64_t fnv64_buf(const void* buf,
size_t n,
uint64_t hash = FNV_64_HASH_START) {
- const char* char_buf = reinterpret_cast<const char*>(buf);
+ // forcing signed char, since other platforms can use unsigned
+ const signed char* char_buf = reinterpret_cast<const signed char*>(buf);
for (size_t i = 0; i < n; ++i) {
hash += (hash << 1) + (hash << 4) + (hash << 5) + (hash << 7) +
* Paul Hsieh: http://www.azillionmonkeys.com/qed/hash.html
*/
-#define get16bits(d) (*((const uint16_t*) (d)))
+#define get16bits(d) folly::loadUnaligned<uint16_t>(d)
inline uint32_t hsieh_hash32_buf(const void* buf, size_t len) {
- const char* s = reinterpret_cast<const char*>(buf);
+ // forcing signed char, since other platforms can use unsigned
+ const unsigned char* s = reinterpret_cast<const unsigned char*>(buf);
uint32_t hash = static_cast<uint32_t>(len);
uint32_t tmp;
size_t rem;
} // namespace hash
-template<class Key>
+template<class Key, class Enable = void>
struct hasher;
+struct Hash {
+ template <class T>
+ size_t operator()(const T& v) const {
+ return hasher<T>()(v);
+ }
+
+ template <class T, class... Ts>
+ size_t operator()(const T& t, const Ts&... ts) const {
+ return hash::hash_128_to_64((*this)(t), (*this)(ts...));
+ }
+};
+
+template <>
+struct hasher<bool> {
+ size_t operator()(bool key) const {
+ // Make sure that all the output bits depend on the input.
+ return key ? std::numeric_limits<size_t>::max() : 0;
+ }
+};
+
template<> struct hasher<int32_t> {
size_t operator()(int32_t key) const {
return hash::jenkins_rev_mix32(uint32_t(key));
}
};
+template<> struct hasher<int16_t> {
+ size_t operator()(int16_t key) const {
+ return hasher<int32_t>()(key); // as impl accident, sign-extends
+ }
+};
+
+template<> struct hasher<uint16_t> {
+ size_t operator()(uint16_t key) const {
+ return hasher<uint32_t>()(key);
+ }
+};
+
+template<> struct hasher<int8_t> {
+ size_t operator()(int8_t key) const {
+ return hasher<int32_t>()(key); // as impl accident, sign-extends
+ }
+};
+
+template<> struct hasher<uint8_t> {
+ size_t operator()(uint8_t key) const {
+ return hasher<uint32_t>()(key);
+ }
+};
+
+template<> struct hasher<char> {
+ using explicit_type =
+ std::conditional<std::is_signed<char>::value, int8_t, uint8_t>::type;
+ size_t operator()(char key) const {
+ return hasher<explicit_type>()(key); // as impl accident, sign-extends
+ }
+};
+
template<> struct hasher<int64_t> {
size_t operator()(int64_t key) const {
- return hash::twang_mix64(uint64_t(key));
+ return static_cast<size_t>(hash::twang_mix64(uint64_t(key)));
}
};
template<> struct hasher<uint64_t> {
size_t operator()(uint64_t key) const {
- return hash::twang_mix64(key);
+ return static_cast<size_t>(hash::twang_mix64(key));
+ }
+};
+
+template<> struct hasher<std::string> {
+ size_t operator()(const std::string& key) const {
+ return static_cast<size_t>(
+ hash::SpookyHashV2::Hash64(key.data(), key.size(), 0));
+ }
+};
+
+template <class T>
+struct hasher<T, typename std::enable_if<std::is_enum<T>::value, void>::type> {
+ size_t operator()(T key) const {
+ return Hash()(static_cast<typename std::underlying_type<T>::type>(key));
+ }
+};
+
+template <class T1, class T2>
+struct hasher<std::pair<T1, T2>> {
+ size_t operator()(const std::pair<T1, T2>& key) const {
+ return Hash()(key.first, key.second);
+ }
+};
+
+template <typename... Ts>
+struct hasher<std::tuple<Ts...>> {
+ size_t operator() (const std::tuple<Ts...>& key) const {
+ return applyTuple(Hash(), key);
}
};
}
};
} // namespace std
-
-#endif
projects / folly.git / blobdiff