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robin_hood.h
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robin_hood.h
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// ______ _____ ______ _________
// ______________ ___ /_ ___(_)_______ ___ /_ ______ ______ ______ /
// __ ___/_ __ \__ __ \__ / __ __ \ __ __ \_ __ \_ __ \_ __ /
// _ / / /_/ /_ /_/ /_ / _ / / / _ / / // /_/ // /_/ // /_/ /
// /_/ \____/ /_.___/ /_/ /_/ /_/ ________/_/ /_/ \____/ \____/ \__,_/
// _/_____/
//
// Fast & memory efficient hashtable based on robin hood hashing for C++11/14/17/20
// https://github.com/martinus/robin-hood-hashing
//
// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
// SPDX-License-Identifier: MIT
// Copyright (c) 2018-2021 Martin Ankerl <http://martin.ankerl.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#ifndef ROBIN_HOOD_H_INCLUDED
#define ROBIN_HOOD_H_INCLUDED
// see https://semver.org/
#define ROBIN_HOOD_VERSION_MAJOR 3 // for incompatible API changes
#define ROBIN_HOOD_VERSION_MINOR 11 // for adding functionality in a backwards-compatible manner
#define ROBIN_HOOD_VERSION_PATCH 5 // for backwards-compatible bug fixes
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <limits>
#include <memory> // only to support hash of smart pointers
#include <stdexcept>
#include <string>
#include <type_traits>
#include <utility>
#if __cplusplus >= 201703L
# include <string_view>
#endif
// #define ROBIN_HOOD_LOG_ENABLED
#ifdef ROBIN_HOOD_LOG_ENABLED
# include <iostream>
# define ROBIN_HOOD_LOG(...) \
std::cout << __FUNCTION__ << "@" << __LINE__ << ": " << __VA_ARGS__ << std::endl;
#else
# define ROBIN_HOOD_LOG(x)
#endif
// #define ROBIN_HOOD_TRACE_ENABLED
#ifdef ROBIN_HOOD_TRACE_ENABLED
# include <iostream>
# define ROBIN_HOOD_TRACE(...) \
std::cout << __FUNCTION__ << "@" << __LINE__ << ": " << __VA_ARGS__ << std::endl;
#else
# define ROBIN_HOOD_TRACE(x)
#endif
// #define ROBIN_HOOD_COUNT_ENABLED
#ifdef ROBIN_HOOD_COUNT_ENABLED
# include <iostream>
# define ROBIN_HOOD_COUNT(x) ++counts().x;
namespace robin_hood {
struct Counts {
uint64_t shiftUp{};
uint64_t shiftDown{};
};
inline std::ostream& operator<<(std::ostream& os, Counts const& c) {
return os << c.shiftUp << " shiftUp" << std::endl << c.shiftDown << " shiftDown" << std::endl;
}
static Counts& counts() {
static Counts counts{};
return counts;
}
} // namespace robin_hood
#else
# define ROBIN_HOOD_COUNT(x)
#endif
// all non-argument macros should use this facility. See
// https://www.fluentcpp.com/2019/05/28/better-macros-better-flags/
#define ROBIN_HOOD(x) ROBIN_HOOD_PRIVATE_DEFINITION_##x()
// mark unused members with this macro
#define ROBIN_HOOD_UNUSED(identifier)
// bitness
#if SIZE_MAX == UINT32_MAX
# define ROBIN_HOOD_PRIVATE_DEFINITION_BITNESS() 32
#elif SIZE_MAX == UINT64_MAX
# define ROBIN_HOOD_PRIVATE_DEFINITION_BITNESS() 64
#else
# error Unsupported bitness
#endif
// endianess
#ifdef _MSC_VER
# define ROBIN_HOOD_PRIVATE_DEFINITION_LITTLE_ENDIAN() 1
# define ROBIN_HOOD_PRIVATE_DEFINITION_BIG_ENDIAN() 0
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_LITTLE_ENDIAN() \
(__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
# define ROBIN_HOOD_PRIVATE_DEFINITION_BIG_ENDIAN() (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
#endif
// inline
#ifdef _MSC_VER
# define ROBIN_HOOD_PRIVATE_DEFINITION_NOINLINE() __declspec(noinline)
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_NOINLINE() __attribute__((noinline))
#endif
// exceptions
#if !defined(__cpp_exceptions) && !defined(__EXCEPTIONS) && !defined(_CPPUNWIND)
# define ROBIN_HOOD_PRIVATE_DEFINITION_HAS_EXCEPTIONS() 0
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_HAS_EXCEPTIONS() 1
#endif
// count leading/trailing bits
#if !defined(ROBIN_HOOD_DISABLE_INTRINSICS)
# ifdef _MSC_VER
# if ROBIN_HOOD(BITNESS) == 32
# define ROBIN_HOOD_PRIVATE_DEFINITION_BITSCANFORWARD() _BitScanForward
# else
# define ROBIN_HOOD_PRIVATE_DEFINITION_BITSCANFORWARD() _BitScanForward64
# endif
# include <intrin.h>
# pragma intrinsic(ROBIN_HOOD(BITSCANFORWARD))
# define ROBIN_HOOD_COUNT_TRAILING_ZEROES(x) \
[](size_t mask) noexcept -> int { \
unsigned long index; \
return ROBIN_HOOD(BITSCANFORWARD)(&index, mask) ? static_cast<int>(index) \
: ROBIN_HOOD(BITNESS); \
}(x)
# else
# if ROBIN_HOOD(BITNESS) == 32
# define ROBIN_HOOD_PRIVATE_DEFINITION_CTZ() __builtin_ctzl
# define ROBIN_HOOD_PRIVATE_DEFINITION_CLZ() __builtin_clzl
# else
# define ROBIN_HOOD_PRIVATE_DEFINITION_CTZ() __builtin_ctzll
# define ROBIN_HOOD_PRIVATE_DEFINITION_CLZ() __builtin_clzll
# endif
# define ROBIN_HOOD_COUNT_LEADING_ZEROES(x) ((x) ? ROBIN_HOOD(CLZ)(x) : ROBIN_HOOD(BITNESS))
# define ROBIN_HOOD_COUNT_TRAILING_ZEROES(x) ((x) ? ROBIN_HOOD(CTZ)(x) : ROBIN_HOOD(BITNESS))
# endif
#endif
// fallthrough
#ifndef __has_cpp_attribute // For backwards compatibility
# define __has_cpp_attribute(x) 0
#endif
#if __has_cpp_attribute(clang::fallthrough)
# define ROBIN_HOOD_PRIVATE_DEFINITION_FALLTHROUGH() [[clang::fallthrough]]
#elif __has_cpp_attribute(gnu::fallthrough)
# define ROBIN_HOOD_PRIVATE_DEFINITION_FALLTHROUGH() [[gnu::fallthrough]]
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_FALLTHROUGH()
#endif
// likely/unlikely
#ifdef _MSC_VER
# define ROBIN_HOOD_LIKELY(condition) condition
# define ROBIN_HOOD_UNLIKELY(condition) condition
#else
# define ROBIN_HOOD_LIKELY(condition) __builtin_expect(condition, 1)
# define ROBIN_HOOD_UNLIKELY(condition) __builtin_expect(condition, 0)
#endif
// detect if native wchar_t type is availiable in MSVC
#ifdef _MSC_VER
# ifdef _NATIVE_WCHAR_T_DEFINED
# define ROBIN_HOOD_PRIVATE_DEFINITION_HAS_NATIVE_WCHART() 1
# else
# define ROBIN_HOOD_PRIVATE_DEFINITION_HAS_NATIVE_WCHART() 0
# endif
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_HAS_NATIVE_WCHART() 1
#endif
// detect if MSVC supports the pair(std::piecewise_construct_t,...) consructor being constexpr
#ifdef _MSC_VER
# if _MSC_VER <= 1900
# define ROBIN_HOOD_PRIVATE_DEFINITION_BROKEN_CONSTEXPR() 1
# else
# define ROBIN_HOOD_PRIVATE_DEFINITION_BROKEN_CONSTEXPR() 0
# endif
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_BROKEN_CONSTEXPR() 0
#endif
// workaround missing "is_trivially_copyable" in g++ < 5.0
// See https://stackoverflow.com/a/31798726/48181
#if defined(__GNUC__) && __GNUC__ < 5
# define ROBIN_HOOD_IS_TRIVIALLY_COPYABLE(...) __has_trivial_copy(__VA_ARGS__)
#else
# define ROBIN_HOOD_IS_TRIVIALLY_COPYABLE(...) std::is_trivially_copyable<__VA_ARGS__>::value
#endif
// helpers for C++ versions, see https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html
#define ROBIN_HOOD_PRIVATE_DEFINITION_CXX() __cplusplus
#define ROBIN_HOOD_PRIVATE_DEFINITION_CXX98() 199711L
#define ROBIN_HOOD_PRIVATE_DEFINITION_CXX11() 201103L
#define ROBIN_HOOD_PRIVATE_DEFINITION_CXX14() 201402L
#define ROBIN_HOOD_PRIVATE_DEFINITION_CXX17() 201703L
#if ROBIN_HOOD(CXX) >= ROBIN_HOOD(CXX17)
# define ROBIN_HOOD_PRIVATE_DEFINITION_NODISCARD() [[nodiscard]]
#else
# define ROBIN_HOOD_PRIVATE_DEFINITION_NODISCARD()
#endif
namespace robin_hood {
#if ROBIN_HOOD(CXX) >= ROBIN_HOOD(CXX14)
# define ROBIN_HOOD_STD std
#else
// c++11 compatibility layer
namespace ROBIN_HOOD_STD {
template <class T>
struct alignment_of
: std::integral_constant<std::size_t, alignof(typename std::remove_all_extents<T>::type)> {};
template <class T, T... Ints>
class integer_sequence {
public:
using value_type = T;
static_assert(std::is_integral<value_type>::value, "not integral type");
static constexpr std::size_t size() noexcept {
return sizeof...(Ints);
}
};
template <std::size_t... Inds>
using index_sequence = integer_sequence<std::size_t, Inds...>;
namespace detail_ {
template <class T, T Begin, T End, bool>
struct IntSeqImpl {
using TValue = T;
static_assert(std::is_integral<TValue>::value, "not integral type");
static_assert(Begin >= 0 && Begin < End, "unexpected argument (Begin<0 || Begin<=End)");
template <class, class>
struct IntSeqCombiner;
template <TValue... Inds0, TValue... Inds1>
struct IntSeqCombiner<integer_sequence<TValue, Inds0...>, integer_sequence<TValue, Inds1...>> {
using TResult = integer_sequence<TValue, Inds0..., Inds1...>;
};
using TResult =
typename IntSeqCombiner<typename IntSeqImpl<TValue, Begin, Begin + (End - Begin) / 2,
(End - Begin) / 2 == 1>::TResult,
typename IntSeqImpl<TValue, Begin + (End - Begin) / 2, End,
(End - Begin + 1) / 2 == 1>::TResult>::TResult;
};
template <class T, T Begin>
struct IntSeqImpl<T, Begin, Begin, false> {
using TValue = T;
static_assert(std::is_integral<TValue>::value, "not integral type");
static_assert(Begin >= 0, "unexpected argument (Begin<0)");
using TResult = integer_sequence<TValue>;
};
template <class T, T Begin, T End>
struct IntSeqImpl<T, Begin, End, true> {
using TValue = T;
static_assert(std::is_integral<TValue>::value, "not integral type");
static_assert(Begin >= 0, "unexpected argument (Begin<0)");
using TResult = integer_sequence<TValue, Begin>;
};
} // namespace detail_
template <class T, T N>
using make_integer_sequence = typename detail_::IntSeqImpl<T, 0, N, (N - 0) == 1>::TResult;
template <std::size_t N>
using make_index_sequence = make_integer_sequence<std::size_t, N>;
template <class... T>
using index_sequence_for = make_index_sequence<sizeof...(T)>;
} // namespace ROBIN_HOOD_STD
#endif
namespace detail {
// make sure we static_cast to the correct type for hash_int
#if ROBIN_HOOD(BITNESS) == 64
using SizeT = uint64_t;
#else
using SizeT = uint32_t;
#endif
template <typename T>
T rotr(T x, unsigned k) {
return (x >> k) | (x << (8U * sizeof(T) - k));
}
// This cast gets rid of warnings like "cast from 'uint8_t*' {aka 'unsigned char*'} to
// 'uint64_t*' {aka 'long unsigned int*'} increases required alignment of target type". Use with
// care!
template <typename T>
inline T reinterpret_cast_no_cast_align_warning(void* ptr) noexcept {
return reinterpret_cast<T>(ptr);
}
template <typename T>
inline T reinterpret_cast_no_cast_align_warning(void const* ptr) noexcept {
return reinterpret_cast<T>(ptr);
}
// make sure this is not inlined as it is slow and dramatically enlarges code, thus making other
// inlinings more difficult. Throws are also generally the slow path.
template <typename E, typename... Args>
[[noreturn]] ROBIN_HOOD(NOINLINE)
#if ROBIN_HOOD(HAS_EXCEPTIONS)
void doThrow(Args&&... args) {
// NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-array-to-pointer-decay)
throw E(std::forward<Args>(args)...);
}
#else
void doThrow(Args&&... ROBIN_HOOD_UNUSED(args) /*unused*/) {
abort();
}
#endif
template <typename E, typename T, typename... Args>
T* assertNotNull(T* t, Args&&... args) {
if (ROBIN_HOOD_UNLIKELY(nullptr == t)) {
doThrow<E>(std::forward<Args>(args)...);
}
return t;
}
template <typename T>
inline T unaligned_load(void const* ptr) noexcept {
// using memcpy so we don't get into unaligned load problems.
// compiler should optimize this very well anyways.
T t;
std::memcpy(&t, ptr, sizeof(T));
return t;
}
// Allocates bulks of memory for objects of type T. This deallocates the memory in the destructor,
// and keeps a linked list of the allocated memory around. Overhead per allocation is the size of a
// pointer.
template <typename T, size_t MinNumAllocs = 4, size_t MaxNumAllocs = 256>
class BulkPoolAllocator {
public:
BulkPoolAllocator() noexcept = default;
// does not copy anything, just creates a new allocator.
BulkPoolAllocator(const BulkPoolAllocator& ROBIN_HOOD_UNUSED(o) /*unused*/) noexcept
: mHead(nullptr)
, mListForFree(nullptr) {}
BulkPoolAllocator(BulkPoolAllocator&& o) noexcept
: mHead(o.mHead)
, mListForFree(o.mListForFree) {
o.mListForFree = nullptr;
o.mHead = nullptr;
}
BulkPoolAllocator& operator=(BulkPoolAllocator&& o) noexcept {
reset();
mHead = o.mHead;
mListForFree = o.mListForFree;
o.mListForFree = nullptr;
o.mHead = nullptr;
return *this;
}
BulkPoolAllocator&
// NOLINTNEXTLINE(bugprone-unhandled-self-assignment,cert-oop54-cpp)
operator=(const BulkPoolAllocator& ROBIN_HOOD_UNUSED(o) /*unused*/) noexcept {
// does not do anything
return *this;
}
~BulkPoolAllocator() noexcept {
reset();
}
// Deallocates all allocated memory.
void reset() noexcept {
while (mListForFree) {
T* tmp = *mListForFree;
ROBIN_HOOD_LOG("std::free")
std::free(mListForFree);
mListForFree = reinterpret_cast_no_cast_align_warning<T**>(tmp);
}
mHead = nullptr;
}
// allocates, but does NOT initialize. Use in-place new constructor, e.g.
// T* obj = pool.allocate();
// ::new (static_cast<void*>(obj)) T();
T* allocate() {
T* tmp = mHead;
if (!tmp) {
tmp = performAllocation();
}
mHead = *reinterpret_cast_no_cast_align_warning<T**>(tmp);
return tmp;
}
// does not actually deallocate but puts it in store.
// make sure you have already called the destructor! e.g. with
// obj->~T();
// pool.deallocate(obj);
void deallocate(T* obj) noexcept {
*reinterpret_cast_no_cast_align_warning<T**>(obj) = mHead;
mHead = obj;
}
// Adds an already allocated block of memory to the allocator. This allocator is from now on
// responsible for freeing the data (with free()). If the provided data is not large enough to
// make use of, it is immediately freed. Otherwise it is reused and freed in the destructor.
void addOrFree(void* ptr, const size_t numBytes) noexcept {
// calculate number of available elements in ptr
if (numBytes < ALIGNMENT + ALIGNED_SIZE) {
// not enough data for at least one element. Free and return.
ROBIN_HOOD_LOG("std::free")
std::free(ptr);
}
else {
ROBIN_HOOD_LOG("add to buffer")
add(ptr, numBytes);
}
}
void swap(BulkPoolAllocator<T, MinNumAllocs, MaxNumAllocs>& other) noexcept {
using std::swap;
swap(mHead, other.mHead);
swap(mListForFree, other.mListForFree);
}
private:
// iterates the list of allocated memory to calculate how many to alloc next.
// Recalculating this each time saves us a size_t member.
// This ignores the fact that memory blocks might have been added manually with addOrFree. In
// practice, this should not matter much.
ROBIN_HOOD(NODISCARD) size_t calcNumElementsToAlloc() const noexcept {
auto tmp = mListForFree;
size_t numAllocs = MinNumAllocs;
while (numAllocs * 2 <= MaxNumAllocs && tmp) {
auto x = reinterpret_cast<T***>(tmp);
tmp = *x;
numAllocs *= 2;
}
return numAllocs;
}
// WARNING: Underflow if numBytes < ALIGNMENT! This is guarded in addOrFree().
void add(void* ptr, const size_t numBytes) noexcept {
const size_t numElements = (numBytes - ALIGNMENT) / ALIGNED_SIZE;
auto data = reinterpret_cast<T**>(ptr);
// link free list
auto x = reinterpret_cast<T***>(data);
*x = mListForFree;
mListForFree = data;
// create linked list for newly allocated data
auto* const headT =
reinterpret_cast_no_cast_align_warning<T*>(reinterpret_cast<char*>(ptr) + ALIGNMENT);
auto* const head = reinterpret_cast<char*>(headT);
// Visual Studio compiler automatically unrolls this loop, which is pretty cool
for (size_t i = 0; i < numElements; ++i) {
*reinterpret_cast_no_cast_align_warning<char**>(head + i * ALIGNED_SIZE) =
head + (i + 1) * ALIGNED_SIZE;
}
// last one points to 0
*reinterpret_cast_no_cast_align_warning<T**>(head + (numElements - 1) * ALIGNED_SIZE) =
mHead;
mHead = headT;
}
// Called when no memory is available (mHead == 0).
// Don't inline this slow path.
ROBIN_HOOD(NOINLINE) T* performAllocation() {
size_t const numElementsToAlloc = calcNumElementsToAlloc();
// alloc new memory: [prev |T, T, ... T]
size_t const bytes = ALIGNMENT + ALIGNED_SIZE * numElementsToAlloc;
ROBIN_HOOD_LOG("std::malloc " << bytes << " = " << ALIGNMENT << " + " << ALIGNED_SIZE
<< " * " << numElementsToAlloc)
add(assertNotNull<std::bad_alloc>(std::malloc(bytes)), bytes);
return mHead;
}
// enforce byte alignment of the T's
#if ROBIN_HOOD(CXX) >= ROBIN_HOOD(CXX14)
static constexpr size_t ALIGNMENT =
(std::max)(std::alignment_of<T>::value, std::alignment_of<T*>::value);
#else
static const size_t ALIGNMENT =
(ROBIN_HOOD_STD::alignment_of<T>::value > ROBIN_HOOD_STD::alignment_of<T*>::value)
? ROBIN_HOOD_STD::alignment_of<T>::value
: +ROBIN_HOOD_STD::alignment_of<T*>::value; // the + is for walkarround
#endif
static constexpr size_t ALIGNED_SIZE = ((sizeof(T) - 1) / ALIGNMENT + 1) * ALIGNMENT;
static_assert(MinNumAllocs >= 1, "MinNumAllocs");
static_assert(MaxNumAllocs >= MinNumAllocs, "MaxNumAllocs");
static_assert(ALIGNED_SIZE >= sizeof(T*), "ALIGNED_SIZE");
static_assert(0 == (ALIGNED_SIZE % sizeof(T*)), "ALIGNED_SIZE mod");
static_assert(ALIGNMENT >= sizeof(T*), "ALIGNMENT");
T* mHead{ nullptr };
T** mListForFree{ nullptr };
};
template <typename T, size_t MinSize, size_t MaxSize, bool IsFlat>
struct NodeAllocator;
// dummy allocator that does nothing
template <typename T, size_t MinSize, size_t MaxSize>
struct NodeAllocator<T, MinSize, MaxSize, true> {
// we are not using the data, so just free it.
void addOrFree(void* ptr, size_t ROBIN_HOOD_UNUSED(numBytes) /*unused*/) noexcept {
ROBIN_HOOD_LOG("std::free")
std::free(ptr);
}
};
template <typename T, size_t MinSize, size_t MaxSize>
struct NodeAllocator<T, MinSize, MaxSize, false> : public BulkPoolAllocator<T, MinSize, MaxSize> {};
// c++14 doesn't have is_nothrow_swappable, and clang++ 6.0.1 doesn't like it either, so I'm making
// my own here.
namespace swappable {
#if ROBIN_HOOD(CXX) < ROBIN_HOOD(CXX17)
using std::swap;
template <typename T>
struct nothrow {
static const bool value = noexcept(swap(std::declval<T&>(), std::declval<T&>()));
};
#else
template <typename T>
struct nothrow {
static const bool value = std::is_nothrow_swappable<T>::value;
};
#endif
} // namespace swappable
} // namespace detail
struct is_transparent_tag {};
// A custom pair implementation is used in the map because std::pair is not is_trivially_copyable,
// which means it would not be allowed to be used in std::memcpy. This struct is copyable, which is
// also tested.
template <typename T1, typename T2>
struct pair {
using first_type = T1;
using second_type = T2;
template <typename U1 = T1, typename U2 = T2,
typename = typename std::enable_if<std::is_default_constructible<U1>::value&&
std::is_default_constructible<U2>::value>::type>
constexpr pair() noexcept(noexcept(U1()) && noexcept(U2()))
: first()
, second() {}
// pair constructors are explicit so we don't accidentally call this ctor when we don't have to.
explicit constexpr pair(std::pair<T1, T2> const& o) noexcept(
noexcept(T1(std::declval<T1 const&>())) && noexcept(T2(std::declval<T2 const&>())))
: first(o.first)
, second(o.second) {}
// pair constructors are explicit so we don't accidentally call this ctor when we don't have to.
explicit constexpr pair(std::pair<T1, T2>&& o) noexcept(noexcept(
T1(std::move(std::declval<T1&&>()))) && noexcept(T2(std::move(std::declval<T2&&>()))))
: first(std::move(o.first))
, second(std::move(o.second)) {}
constexpr pair(T1&& a, T2&& b) noexcept(noexcept(
T1(std::move(std::declval<T1&&>()))) && noexcept(T2(std::move(std::declval<T2&&>()))))
: first(std::move(a))
, second(std::move(b)) {}
template <typename U1, typename U2>
constexpr pair(U1&& a, U2&& b) noexcept(noexcept(T1(std::forward<U1>(
std::declval<U1&&>()))) && noexcept(T2(std::forward<U2>(std::declval<U2&&>()))))
: first(std::forward<U1>(a))
, second(std::forward<U2>(b)) {}
template <typename... U1, typename... U2>
// MSVC 2015 produces error "C2476: constexpr constructor does not initialize all members"
// if this constructor is constexpr
#if !ROBIN_HOOD(BROKEN_CONSTEXPR)
constexpr
#endif
pair(std::piecewise_construct_t /*unused*/, std::tuple<U1...> a,
std::tuple<U2...>
b) noexcept(noexcept(pair(std::declval<std::tuple<U1...>&>(),
std::declval<std::tuple<U2...>&>(),
ROBIN_HOOD_STD::index_sequence_for<U1...>(),
ROBIN_HOOD_STD::index_sequence_for<U2...>())))
: pair(a, b, ROBIN_HOOD_STD::index_sequence_for<U1...>(),
ROBIN_HOOD_STD::index_sequence_for<U2...>()) {
}
// constructor called from the std::piecewise_construct_t ctor
template <typename... U1, size_t... I1, typename... U2, size_t... I2>
pair(std::tuple<U1...>& a, std::tuple<U2...>& b, ROBIN_HOOD_STD::index_sequence<I1...> /*unused*/, ROBIN_HOOD_STD::index_sequence<I2...> /*unused*/) noexcept(
noexcept(T1(std::forward<U1>(std::get<I1>(
std::declval<std::tuple<
U1...>&>()))...)) && noexcept(T2(std::
forward<U2>(std::get<I2>(
std::declval<std::tuple<U2...>&>()))...)))
: first(std::forward<U1>(std::get<I1>(a))...)
, second(std::forward<U2>(std::get<I2>(b))...) {
// make visual studio compiler happy about warning about unused a & b.
// Visual studio's pair implementation disables warning 4100.
(void)a;
(void)b;
}
void swap(pair<T1, T2>& o) noexcept((detail::swappable::nothrow<T1>::value) &&
(detail::swappable::nothrow<T2>::value)) {
using std::swap;
swap(first, o.first);
swap(second, o.second);
}
T1 first; // NOLINT(misc-non-private-member-variables-in-classes)
T2 second; // NOLINT(misc-non-private-member-variables-in-classes)
};
template <typename A, typename B>
inline void swap(pair<A, B>& a, pair<A, B>& b) noexcept(
noexcept(std::declval<pair<A, B>&>().swap(std::declval<pair<A, B>&>()))) {
a.swap(b);
}
template <typename A, typename B>
inline constexpr bool operator==(pair<A, B> const& x, pair<A, B> const& y) {
return (x.first == y.first) && (x.second == y.second);
}
template <typename A, typename B>
inline constexpr bool operator!=(pair<A, B> const& x, pair<A, B> const& y) {
return !(x == y);
}
template <typename A, typename B>
inline constexpr bool operator<(pair<A, B> const& x, pair<A, B> const& y) noexcept(noexcept(
std::declval<A const&>() < std::declval<A const&>()) && noexcept(std::declval<B const&>() <
std::declval<B const&>())) {
return x.first < y.first || (!(y.first < x.first) && x.second < y.second);
}
template <typename A, typename B>
inline constexpr bool operator>(pair<A, B> const& x, pair<A, B> const& y) {
return y < x;
}
template <typename A, typename B>
inline constexpr bool operator<=(pair<A, B> const& x, pair<A, B> const& y) {
return !(x > y);
}
template <typename A, typename B>
inline constexpr bool operator>=(pair<A, B> const& x, pair<A, B> const& y) {
return !(x < y);
}
inline size_t hash_bytes(void const* ptr, size_t len) noexcept {
static constexpr uint64_t m = UINT64_C(0xc6a4a7935bd1e995);
static constexpr uint64_t seed = UINT64_C(0xe17a1465);
static constexpr unsigned int r = 47;
auto const* const data64 = static_cast<uint64_t const*>(ptr);
uint64_t h = seed ^ (len * m);
size_t const n_blocks = len / 8;
for (size_t i = 0; i < n_blocks; ++i) {
auto k = detail::unaligned_load<uint64_t>(data64 + i);
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
}
auto const* const data8 = reinterpret_cast<uint8_t const*>(data64 + n_blocks);
switch (len & 7U) {
case 7:
h ^= static_cast<uint64_t>(data8[6]) << 48U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 6:
h ^= static_cast<uint64_t>(data8[5]) << 40U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 5:
h ^= static_cast<uint64_t>(data8[4]) << 32U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 4:
h ^= static_cast<uint64_t>(data8[3]) << 24U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 3:
h ^= static_cast<uint64_t>(data8[2]) << 16U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 2:
h ^= static_cast<uint64_t>(data8[1]) << 8U;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
case 1:
h ^= static_cast<uint64_t>(data8[0]);
h *= m;
ROBIN_HOOD(FALLTHROUGH); // FALLTHROUGH
default:
break;
}
h ^= h >> r;
// not doing the final step here, because this will be done by keyToIdx anyways
// h *= m;
// h ^= h >> r;
return static_cast<size_t>(h);
}
inline size_t hash_int(uint64_t x) noexcept {
// tried lots of different hashes, let's stick with murmurhash3. It's simple, fast, well tested,
// and doesn't need any special 128bit operations.
x ^= x >> 33U;
x *= UINT64_C(0xff51afd7ed558ccd);
x ^= x >> 33U;
// not doing the final step here, because this will be done by keyToIdx anyways
// x *= UINT64_C(0xc4ceb9fe1a85ec53);
// x ^= x >> 33U;
return static_cast<size_t>(x);
}
// A thin wrapper around std::hash, performing an additional simple mixing step of the result.
template <typename T, typename Enable = void>
struct hash : public std::hash<T> {
size_t operator()(T const& obj) const
noexcept(noexcept(std::declval<std::hash<T>>().operator()(std::declval<T const&>()))) {
// call base hash
auto result = std::hash<T>::operator()(obj);
// return mixed of that, to be save against identity has
return hash_int(static_cast<detail::SizeT>(result));
}
};
template <typename CharT>
struct hash<std::basic_string<CharT>> {
size_t operator()(std::basic_string<CharT> const& str) const noexcept {
return hash_bytes(str.data(), sizeof(CharT) * str.size());
}
};
#if ROBIN_HOOD(CXX) >= ROBIN_HOOD(CXX17)
template <typename CharT>
struct hash<std::basic_string_view<CharT>> {
size_t operator()(std::basic_string_view<CharT> const& sv) const noexcept {
return hash_bytes(sv.data(), sizeof(CharT) * sv.size());
}
};
#endif
template <class T>
struct hash<T*> {
size_t operator()(T* ptr) const noexcept {
return hash_int(reinterpret_cast<detail::SizeT>(ptr));
}
};
template <class T>
struct hash<std::unique_ptr<T>> {
size_t operator()(std::unique_ptr<T> const& ptr) const noexcept {
return hash_int(reinterpret_cast<detail::SizeT>(ptr.get()));
}
};
template <class T>
struct hash<std::shared_ptr<T>> {
size_t operator()(std::shared_ptr<T> const& ptr) const noexcept {
return hash_int(reinterpret_cast<detail::SizeT>(ptr.get()));
}
};
template <typename Enum>
struct hash<Enum, typename std::enable_if<std::is_enum<Enum>::value>::type> {
size_t operator()(Enum e) const noexcept {
using Underlying = typename std::underlying_type<Enum>::type;
return hash<Underlying>{}(static_cast<Underlying>(e));
}
};
#define ROBIN_HOOD_HASH_INT(T) \
template <> \
struct hash<T> { \
size_t operator()(T const& obj) const noexcept { \
return hash_int(static_cast<uint64_t>(obj)); \
} \
}
#if defined(__GNUC__) && !defined(__clang__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
// see https://en.cppreference.com/w/cpp/utility/hash
ROBIN_HOOD_HASH_INT(bool);
ROBIN_HOOD_HASH_INT(char);
ROBIN_HOOD_HASH_INT(signed char);
ROBIN_HOOD_HASH_INT(unsigned char);
ROBIN_HOOD_HASH_INT(char16_t);
ROBIN_HOOD_HASH_INT(char32_t);
#if ROBIN_HOOD(HAS_NATIVE_WCHART)
ROBIN_HOOD_HASH_INT(wchar_t);
#endif
ROBIN_HOOD_HASH_INT(short);
ROBIN_HOOD_HASH_INT(unsigned short);
ROBIN_HOOD_HASH_INT(int);
ROBIN_HOOD_HASH_INT(unsigned int);
ROBIN_HOOD_HASH_INT(long);
ROBIN_HOOD_HASH_INT(long long);
ROBIN_HOOD_HASH_INT(unsigned long);
ROBIN_HOOD_HASH_INT(unsigned long long);
#if defined(__GNUC__) && !defined(__clang__)
# pragma GCC diagnostic pop
#endif
namespace detail {
template <typename T>
struct void_type {
using type = void;
};
template <typename T, typename = void>
struct has_is_transparent : public std::false_type {};
template <typename T>
struct has_is_transparent<T, typename void_type<typename T::is_transparent>::type>
: public std::true_type {};
// using wrapper classes for hash and key_equal prevents the diamond problem when the same type
// is used. see https://stackoverflow.com/a/28771920/48181
template <typename T>
struct WrapHash : public T {
WrapHash() = default;
explicit WrapHash(T const& o) noexcept(noexcept(T(std::declval<T const&>())))
: T(o) {}
};
template <typename T>
struct WrapKeyEqual : public T {
WrapKeyEqual() = default;
explicit WrapKeyEqual(T const& o) noexcept(noexcept(T(std::declval<T const&>())))
: T(o) {}
};
// A highly optimized hashmap implementation, using the Robin Hood algorithm.
//
// In most cases, this map should be usable as a drop-in replacement for std::unordered_map, but
// be about 2x faster in most cases and require much less allocations.
//
// This implementation uses the following memory layout:
//
// [Node, Node, ... Node | info, info, ... infoSentinel ]
//
// * Node: either a DataNode that directly has the std::pair<key, val> as member,
// or a DataNode with a pointer to std::pair<key,val>. Which DataNode representation to use
// depends on how fast the swap() operation is. Heuristically, this is automatically choosen
// based on sizeof(). there are always 2^n Nodes.
//
// * info: Each Node in the map has a corresponding info byte, so there are 2^n info bytes.
// Each byte is initialized to 0, meaning the corresponding Node is empty. Set to 1 means the
// corresponding node contains data. Set to 2 means the corresponding Node is filled, but it
// actually belongs to the previous position and was pushed out because that place is already
// taken.
//
// * infoSentinel: Sentinel byte set to 1, so that iterator's ++ can stop at end() without the
// need for a idx variable.
//
// According to STL, order of templates has effect on throughput. That's why I've moved the
// boolean to the front.
// https://www.reddit.com/r/cpp/comments/ahp6iu/compile_time_binary_size_reductions_and_cs_future/eeguck4/
template <bool IsFlat, size_t MaxLoadFactor100, typename Key, typename T, typename Hash,
typename KeyEqual>
class Table
: public WrapHash<Hash>,
public WrapKeyEqual<KeyEqual>,
detail::NodeAllocator<
typename std::conditional<
std::is_void<T>::value, Key,
robin_hood::pair<typename std::conditional<IsFlat, Key, Key const>::type, T>>::type,
4, 16384, IsFlat> {
public:
static constexpr bool is_flat = IsFlat;
static constexpr bool is_map = !std::is_void<T>::value;
static constexpr bool is_set = !is_map;
static constexpr bool is_transparent =
has_is_transparent<Hash>::value && has_is_transparent<KeyEqual>::value;
using key_type = Key;
using mapped_type = T;
using value_type = typename std::conditional<
is_set, Key,
robin_hood::pair<typename std::conditional<is_flat, Key, Key const>::type, T>>::type;
using size_type = size_t;
using hasher = Hash;
using key_equal = KeyEqual;
using Self = Table<IsFlat, MaxLoadFactor100, key_type, mapped_type, hasher, key_equal>;
private:
static_assert(MaxLoadFactor100 > 10 && MaxLoadFactor100 < 100,
"MaxLoadFactor100 needs to be >10 && < 100");
using WHash = WrapHash<Hash>;
using WKeyEqual = WrapKeyEqual<KeyEqual>;
// configuration defaults
// make sure we have 8 elements, needed to quickly rehash mInfo
static constexpr size_t InitialNumElements = sizeof(uint64_t);
static constexpr uint32_t InitialInfoNumBits = 5;
static constexpr uint8_t InitialInfoInc = 1U << InitialInfoNumBits;
static constexpr size_t InfoMask = InitialInfoInc - 1U;
static constexpr uint8_t InitialInfoHashShift = 0;
using DataPool = detail::NodeAllocator<value_type, 4, 16384, IsFlat>;
// type needs to be wider than uint8_t.
using InfoType = uint32_t;
// DataNode ////////////////////////////////////////////////////////
// Primary template for the data node. We have special implementations for small and big
// objects. For large objects it is assumed that swap() is fairly slow, so we allocate these
// on the heap so swap merely swaps a pointer.
template <typename M, bool>
class DataNode {};
// Small: just allocate on the stack.
template <typename M>
class DataNode<M, true> final {
public:
template <typename... Args>
explicit DataNode(M& ROBIN_HOOD_UNUSED(map) /*unused*/, Args&&... args) noexcept(
noexcept(value_type(std::forward<Args>(args)...)))
: mData(std::forward<Args>(args)...) {}
DataNode(M& ROBIN_HOOD_UNUSED(map) /*unused*/, DataNode<M, true>&& n) noexcept(
std::is_nothrow_move_constructible<value_type>::value)
: mData(std::move(n.mData)) {}
// doesn't do anything
void destroy(M& ROBIN_HOOD_UNUSED(map) /*unused*/) noexcept {}
void destroyDoNotDeallocate() noexcept {}
value_type const* operator->() const noexcept {
return &mData;
}
value_type* operator->() noexcept {
return &mData;
}
const value_type& operator*() const noexcept {
return mData;
}
value_type& operator*() noexcept {
return mData;
}
template <typename VT = value_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, typename VT::first_type&>::type getFirst() noexcept {
return mData.first;
}
template <typename VT = value_type>