// ______ _____ ______ _________

// ______________ ___ /_ ___(_)_______ ___ /_ ______ ______ ______ /

// __ ___/_ __ \__ __ \__ / __ __ \ __ __ \_ __ \_ __ \_ __ /

// _ / / /_/ /_ /_/ /_ / _ / / / _ / / // /_/ // /_/ // /_/ /

// /_/ \____/ /_.___/ /_/ /_/ /_/ ________/_/ /_/ \____/ \____/ \__,_/

// _/_____/

//

// 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>

ROBIN_HOOD(NODISCARD)