mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-18 02:41:39 +03:00
462 lines
12 KiB
C++
462 lines
12 KiB
C++
/*
|
|
* Copyright 2016 Facebook, Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <cstdint>
|
|
#include <cstring>
|
|
#include <string>
|
|
#include <tuple>
|
|
#include <type_traits>
|
|
#include <utility>
|
|
|
|
#include <folly/ApplyTuple.h>
|
|
#include <folly/Bits.h>
|
|
#include <folly/SpookyHashV1.h>
|
|
#include <folly/SpookyHashV2.h>
|
|
|
|
/*
|
|
* Various hashing functions.
|
|
*/
|
|
|
|
namespace folly { namespace hash {
|
|
|
|
// This is a general-purpose way to create a single hash from multiple
|
|
// hashable objects. hash_combine_generic takes a class Hasher implementing
|
|
// hash<T>; hash_combine uses a default hasher StdHasher that uses std::hash.
|
|
// hash_combine_generic hashes each argument and combines those hashes in
|
|
// an order-dependent way to yield a new hash.
|
|
|
|
|
|
// 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 uint64_t hash_128_to_64(const uint64_t upper, const uint64_t lower) {
|
|
// Murmur-inspired hashing.
|
|
const uint64_t kMul = 0x9ddfea08eb382d69ULL;
|
|
uint64_t a = (lower ^ upper) * kMul;
|
|
a ^= (a >> 47);
|
|
uint64_t b = (upper ^ a) * kMul;
|
|
b ^= (b >> 47);
|
|
b *= kMul;
|
|
return b;
|
|
}
|
|
|
|
// Never used, but gcc demands it.
|
|
template <class Hasher>
|
|
inline size_t hash_combine_generic() {
|
|
return 0;
|
|
}
|
|
|
|
template <
|
|
class Iter,
|
|
class Hash = std::hash<typename std::iterator_traits<Iter>::value_type>>
|
|
uint64_t hash_range(Iter begin,
|
|
Iter end,
|
|
uint64_t hash = 0,
|
|
Hash hasher = Hash()) {
|
|
for (; begin != end; ++begin) {
|
|
hash = hash_128_to_64(hash, hasher(*begin));
|
|
}
|
|
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);
|
|
if (sizeof...(ts) == 0) {
|
|
return seed;
|
|
}
|
|
size_t remainder = hash_combine_generic<Hasher>(ts...);
|
|
/* 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
|
|
// to be a very good hash function; provided std::hash doesn't collide on
|
|
// the individual inputs, you are fine, but that won't be true for, say,
|
|
// strings or pairs
|
|
class StdHasher {
|
|
public:
|
|
template <typename T>
|
|
static size_t hash(const T& t) {
|
|
return std::hash<T>()(t);
|
|
}
|
|
};
|
|
|
|
template <typename T, typename... Ts>
|
|
size_t hash_combine(const T& t, const Ts&... ts) {
|
|
return hash_combine_generic<StdHasher>(t, ts...);
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
/*
|
|
* Thomas Wang 64 bit mix hash function
|
|
*/
|
|
|
|
inline uint64_t twang_mix64(uint64_t key) {
|
|
key = (~key) + (key << 21); // key *= (1 << 21) - 1; key -= 1;
|
|
key = key ^ (key >> 24);
|
|
key = key + (key << 3) + (key << 8); // key *= 1 + (1 << 3) + (1 << 8)
|
|
key = key ^ (key >> 14);
|
|
key = key + (key << 2) + (key << 4); // key *= 1 + (1 << 2) + (1 << 4)
|
|
key = key ^ (key >> 28);
|
|
key = key + (key << 31); // key *= 1 + (1 << 31)
|
|
return key;
|
|
}
|
|
|
|
/*
|
|
* Inverse of twang_mix64
|
|
*
|
|
* Note that twang_unmix64 is significantly slower than twang_mix64.
|
|
*/
|
|
|
|
inline uint64_t twang_unmix64(uint64_t key) {
|
|
// See the comments in jenkins_rev_unmix32 for an explanation as to how this
|
|
// was generated
|
|
key *= 4611686016279904257U;
|
|
key ^= (key >> 28) ^ (key >> 56);
|
|
key *= 14933078535860113213U;
|
|
key ^= (key >> 14) ^ (key >> 28) ^ (key >> 42) ^ (key >> 56);
|
|
key *= 15244667743933553977U;
|
|
key ^= (key >> 24) ^ (key >> 48);
|
|
key = (key + 1) * 9223367638806167551U;
|
|
return key;
|
|
}
|
|
|
|
/*
|
|
* Thomas Wang downscaling hash function
|
|
*/
|
|
|
|
inline uint32_t twang_32from64(uint64_t key) {
|
|
key = (~key) + (key << 18);
|
|
key = key ^ (key >> 31);
|
|
key = key * 21;
|
|
key = key ^ (key >> 11);
|
|
key = key + (key << 6);
|
|
key = key ^ (key >> 22);
|
|
return (uint32_t) key;
|
|
}
|
|
|
|
/*
|
|
* Robert Jenkins' reversible 32 bit mix hash function
|
|
*/
|
|
|
|
inline uint32_t jenkins_rev_mix32(uint32_t key) {
|
|
key += (key << 12); // key *= (1 + (1 << 12))
|
|
key ^= (key >> 22);
|
|
key += (key << 4); // key *= (1 + (1 << 4))
|
|
key ^= (key >> 9);
|
|
key += (key << 10); // key *= (1 + (1 << 10))
|
|
key ^= (key >> 2);
|
|
// key *= (1 + (1 << 7)) * (1 + (1 << 12))
|
|
key += (key << 7);
|
|
key += (key << 12);
|
|
return key;
|
|
}
|
|
|
|
/*
|
|
* Inverse of jenkins_rev_mix32
|
|
*
|
|
* Note that jenkinks_rev_unmix32 is significantly slower than
|
|
* jenkins_rev_mix32.
|
|
*/
|
|
|
|
inline uint32_t jenkins_rev_unmix32(uint32_t key) {
|
|
// These are the modular multiplicative inverses (in Z_2^32) of the
|
|
// multiplication factors in jenkins_rev_mix32, in reverse order. They were
|
|
// computed using the Extended Euclidean algorithm, see
|
|
// http://en.wikipedia.org/wiki/Modular_multiplicative_inverse
|
|
key *= 2364026753U;
|
|
|
|
// The inverse of a ^= (a >> n) is
|
|
// b = a
|
|
// for (int i = n; i < 32; i += n) {
|
|
// b ^= (a >> i);
|
|
// }
|
|
key ^=
|
|
(key >> 2) ^ (key >> 4) ^ (key >> 6) ^ (key >> 8) ^
|
|
(key >> 10) ^ (key >> 12) ^ (key >> 14) ^ (key >> 16) ^
|
|
(key >> 18) ^ (key >> 20) ^ (key >> 22) ^ (key >> 24) ^
|
|
(key >> 26) ^ (key >> 28) ^ (key >> 30);
|
|
key *= 3222273025U;
|
|
key ^= (key >> 9) ^ (key >> 18) ^ (key >> 27);
|
|
key *= 4042322161U;
|
|
key ^= (key >> 22);
|
|
key *= 16773121U;
|
|
return key;
|
|
}
|
|
|
|
/*
|
|
* Fowler / Noll / Vo (FNV) Hash
|
|
* http://www.isthe.com/chongo/tech/comp/fnv/
|
|
*/
|
|
|
|
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) {
|
|
for (; *s; ++s) {
|
|
hash += (hash << 1) + (hash << 4) + (hash << 7) +
|
|
(hash << 8) + (hash << 24);
|
|
hash ^= *s;
|
|
}
|
|
return hash;
|
|
}
|
|
|
|
inline uint32_t fnv32_buf(const void* buf,
|
|
size_t n,
|
|
uint32_t hash = FNV_32_HASH_START) {
|
|
// 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) +
|
|
(hash << 8) + (hash << 24);
|
|
hash ^= char_buf[i];
|
|
}
|
|
|
|
return hash;
|
|
}
|
|
|
|
inline uint32_t fnv32(const std::string& str,
|
|
uint32_t hash = FNV_32_HASH_START) {
|
|
return fnv32_buf(str.data(), str.size(), hash);
|
|
}
|
|
|
|
inline uint64_t fnv64(const char* s,
|
|
uint64_t hash = FNV_64_HASH_START) {
|
|
for (; *s; ++s) {
|
|
hash += (hash << 1) + (hash << 4) + (hash << 5) + (hash << 7) +
|
|
(hash << 8) + (hash << 40);
|
|
hash ^= *s;
|
|
}
|
|
return hash;
|
|
}
|
|
|
|
inline uint64_t fnv64_buf(const void* buf,
|
|
size_t n,
|
|
uint64_t hash = FNV_64_HASH_START) {
|
|
// 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) +
|
|
(hash << 8) + (hash << 40);
|
|
hash ^= char_buf[i];
|
|
}
|
|
return hash;
|
|
}
|
|
|
|
inline uint64_t fnv64(const std::string& str,
|
|
uint64_t hash = FNV_64_HASH_START) {
|
|
return fnv64_buf(str.data(), str.size(), hash);
|
|
}
|
|
|
|
/*
|
|
* Paul Hsieh: http://www.azillionmonkeys.com/qed/hash.html
|
|
*/
|
|
|
|
#define get16bits(d) folly::loadUnaligned<uint16_t>(d)
|
|
|
|
inline uint32_t hsieh_hash32_buf(const void* buf, size_t len) {
|
|
// 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;
|
|
|
|
if (len <= 0 || buf == 0) {
|
|
return 0;
|
|
}
|
|
|
|
rem = len & 3;
|
|
len >>= 2;
|
|
|
|
/* Main loop */
|
|
for (;len > 0; len--) {
|
|
hash += get16bits (s);
|
|
tmp = (get16bits (s+2) << 11) ^ hash;
|
|
hash = (hash << 16) ^ tmp;
|
|
s += 2*sizeof (uint16_t);
|
|
hash += hash >> 11;
|
|
}
|
|
|
|
/* Handle end cases */
|
|
switch (rem) {
|
|
case 3:
|
|
hash += get16bits(s);
|
|
hash ^= hash << 16;
|
|
hash ^= s[sizeof (uint16_t)] << 18;
|
|
hash += hash >> 11;
|
|
break;
|
|
case 2:
|
|
hash += get16bits(s);
|
|
hash ^= hash << 11;
|
|
hash += hash >> 17;
|
|
break;
|
|
case 1:
|
|
hash += *s;
|
|
hash ^= hash << 10;
|
|
hash += hash >> 1;
|
|
}
|
|
|
|
/* Force "avalanching" of final 127 bits */
|
|
hash ^= hash << 3;
|
|
hash += hash >> 5;
|
|
hash ^= hash << 4;
|
|
hash += hash >> 17;
|
|
hash ^= hash << 25;
|
|
hash += hash >> 6;
|
|
|
|
return hash;
|
|
};
|
|
|
|
#undef get16bits
|
|
|
|
inline uint32_t hsieh_hash32(const char* s) {
|
|
return hsieh_hash32_buf(s, std::strlen(s));
|
|
}
|
|
|
|
inline uint32_t hsieh_hash32_str(const std::string& str) {
|
|
return hsieh_hash32_buf(str.data(), str.size());
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
} // namespace hash
|
|
|
|
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<int32_t> {
|
|
size_t operator()(int32_t key) const {
|
|
return hash::jenkins_rev_mix32(uint32_t(key));
|
|
}
|
|
};
|
|
|
|
template<> struct hasher<uint32_t> {
|
|
size_t operator()(uint32_t key) const {
|
|
return hash::jenkins_rev_mix32(key);
|
|
}
|
|
};
|
|
|
|
template<> struct hasher<int64_t> {
|
|
size_t operator()(int64_t key) const {
|
|
return static_cast<size_t>(hash::twang_mix64(uint64_t(key)));
|
|
}
|
|
};
|
|
|
|
template<> struct hasher<uint64_t> {
|
|
size_t operator()(uint64_t key) const {
|
|
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);
|
|
}
|
|
};
|
|
|
|
// recursion
|
|
template <size_t index, typename... Ts>
|
|
struct TupleHasher {
|
|
size_t operator()(std::tuple<Ts...> const& key) const {
|
|
return hash::hash_combine(
|
|
TupleHasher<index - 1, Ts...>()(key),
|
|
std::get<index>(key));
|
|
}
|
|
};
|
|
|
|
// base
|
|
template <typename... Ts>
|
|
struct TupleHasher<0, Ts...> {
|
|
size_t operator()(std::tuple<Ts...> const& key) const {
|
|
// we could do std::hash here directly, but hash_combine hides all the
|
|
// ugly templating implicitly
|
|
return hash::hash_combine(std::get<0>(key));
|
|
}
|
|
};
|
|
|
|
} // namespace folly
|
|
|
|
// Custom hash functions.
|
|
namespace std {
|
|
// Hash function for pairs. Requires default hash functions for both
|
|
// items in the pair.
|
|
template <typename T1, typename T2>
|
|
struct hash<std::pair<T1, T2> > {
|
|
public:
|
|
size_t operator()(const std::pair<T1, T2>& x) const {
|
|
return folly::hash::hash_combine(x.first, x.second);
|
|
}
|
|
};
|
|
|
|
// Hash function for tuples. Requires default hash functions for all types.
|
|
template <typename... Ts>
|
|
struct hash<std::tuple<Ts...>> {
|
|
size_t operator()(std::tuple<Ts...> const& key) const {
|
|
folly::TupleHasher<
|
|
std::tuple_size<std::tuple<Ts...>>::value - 1, // start index
|
|
Ts...> hasher;
|
|
|
|
return hasher(key);
|
|
}
|
|
};
|
|
} // namespace std
|