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spicetools/external/robin_hood.h

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Initial re-upload of spice2x-24-08-24
2024-08-28 15:10:34 +00:00
// ______ _____ ______ _________
// ______________ ___ /_ ___(_)_______ ___ /_ ______ ______ ______ /
// __ ___/_ __ \__ __ \__ / __ __ \ __ __ \_ __ \_ __ \_ __ /
// _ / / /_/ /_ /_/ /_ / _ / / / _ / / // /_/ // /_/ // /_/ /
// /_/ \____/ /_.___/ /_/ /_/ /_/ ________/_/ /_/ \____/ \____/ \__,_/
// _/_____/
//
// 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 2 // 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)
typename std::enable_if<is_set, VT&>::type getFirst() noexcept {
return mData;
}
template <typename VT = value_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, typename VT::first_type const&>::type
getFirst() const noexcept {
return mData.first;
}
template <typename VT = value_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_set, VT const&>::type getFirst() const noexcept {
return mData;
}
template <typename MT = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, MT&>::type getSecond() noexcept {
return mData.second;
}
template <typename MT = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_set, MT const&>::type getSecond() const noexcept {
return mData.second;
}
void swap(DataNode<M, true>& o) noexcept(
noexcept(std::declval<value_type>().swap(std::declval<value_type>()))) {
mData.swap(o.mData);
}
private:
value_type mData;
};
// big object: allocate on heap.
template <typename M>
class DataNode<M, false> {
public:
template <typename... Args>
explicit DataNode(M& map, Args&&... args)
: mData(map.allocate()) {
::new (static_cast<void*>(mData)) value_type(std::forward<Args>(args)...);
}
DataNode(M& ROBIN_HOOD_UNUSED(map) /*unused*/, DataNode<M, false>&& n) noexcept
: mData(std::move(n.mData)) {}
void destroy(M& map) noexcept {
// don't deallocate, just put it into list of datapool.
mData->~value_type();
map.deallocate(mData);
}
void destroyDoNotDeallocate() noexcept {
mData->~value_type();
}
value_type const* operator->() const noexcept {
return mData;
}
value_type* operator->() noexcept {
return mData;
}
const value_type& operator*() const {
return *mData;
}
value_type& operator*() {
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)
typename std::enable_if<is_set, VT&>::type getFirst() noexcept {
return *mData;
}
template <typename VT = value_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, typename VT::first_type const&>::type
getFirst() const noexcept {
return mData->first;
}
template <typename VT = value_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_set, VT const&>::type getFirst() const noexcept {
return *mData;
}
template <typename MT = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, MT&>::type getSecond() noexcept {
return mData->second;
}
template <typename MT = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<is_map, MT const&>::type getSecond() const noexcept {
return mData->second;
}
void swap(DataNode<M, false>& o) noexcept {
using std::swap;
swap(mData, o.mData);
}
private:
value_type* mData;
};
using Node = DataNode<Self, IsFlat>;
// helpers for insertKeyPrepareEmptySpot: extract first entry (only const required)
ROBIN_HOOD(NODISCARD) key_type const& getFirstConst(Node const& n) const noexcept {
return n.getFirst();
}
// in case we have void mapped_type, we are not using a pair, thus we just route k through.
// No need to disable this because it's just not used if not applicable.
ROBIN_HOOD(NODISCARD) key_type const& getFirstConst(key_type const& k) const noexcept {
return k;
}
// in case we have non-void mapped_type, we have a standard robin_hood::pair
template <typename Q = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<!std::is_void<Q>::value, key_type const&>::type
getFirstConst(value_type const& vt) const noexcept {
return vt.first;
}
// Cloner //////////////////////////////////////////////////////////
template <typename M, bool UseMemcpy>
struct Cloner;
// fast path: Just copy data, without allocating anything.
template <typename M>
struct Cloner<M, true> {
void operator()(M const& source, M& target) const {
auto const* const src = reinterpret_cast<char const*>(source.mKeyVals);
auto* tgt = reinterpret_cast<char*>(target.mKeyVals);
auto const numElementsWithBuffer = target.calcNumElementsWithBuffer(target.mMask + 1);
std::copy(src, src + target.calcNumBytesTotal(numElementsWithBuffer), tgt);
}
};
template <typename M>
struct Cloner<M, false> {
void operator()(M const& s, M& t) const {
auto const numElementsWithBuffer = t.calcNumElementsWithBuffer(t.mMask + 1);
std::copy(s.mInfo, s.mInfo + t.calcNumBytesInfo(numElementsWithBuffer), t.mInfo);
for (size_t i = 0; i < numElementsWithBuffer; ++i) {
if (t.mInfo[i]) {
::new (static_cast<void*>(t.mKeyVals + i)) Node(t, *s.mKeyVals[i]);
}
}
}
};
// Destroyer ///////////////////////////////////////////////////////
template <typename M, bool IsFlatAndTrivial>
struct Destroyer {};
template <typename M>
struct Destroyer<M, true> {
void nodes(M& m) const noexcept {
m.mNumElements = 0;
}
void nodesDoNotDeallocate(M& m) const noexcept {
m.mNumElements = 0;
}
};
template <typename M>
struct Destroyer<M, false> {
void nodes(M& m) const noexcept {
m.mNumElements = 0;
// clear also resets mInfo to 0, that's sometimes not necessary.
auto const numElementsWithBuffer = m.calcNumElementsWithBuffer(m.mMask + 1);
for (size_t idx = 0; idx < numElementsWithBuffer; ++idx) {
if (0 != m.mInfo[idx]) {
Node& n = m.mKeyVals[idx];
n.destroy(m);
n.~Node();
}
}
}
void nodesDoNotDeallocate(M& m) const noexcept {
m.mNumElements = 0;
// clear also resets mInfo to 0, that's sometimes not necessary.
auto const numElementsWithBuffer = m.calcNumElementsWithBuffer(m.mMask + 1);
for (size_t idx = 0; idx < numElementsWithBuffer; ++idx) {
if (0 != m.mInfo[idx]) {
Node& n = m.mKeyVals[idx];
n.destroyDoNotDeallocate();
n.~Node();
}
}
}
};
// Iter ////////////////////////////////////////////////////////////
struct fast_forward_tag {};
// generic iterator for both const_iterator and iterator.
template <bool IsConst>
// NOLINTNEXTLINE(hicpp-special-member-functions,cppcoreguidelines-special-member-functions)
class Iter {
private:
using NodePtr = typename std::conditional<IsConst, Node const*, Node*>::type;
public:
using difference_type = std::ptrdiff_t;
using value_type = typename Self::value_type;
using reference = typename std::conditional<IsConst, value_type const&, value_type&>::type;
using pointer = typename std::conditional<IsConst, value_type const*, value_type*>::type;
using iterator_category = std::forward_iterator_tag;
// default constructed iterator can be compared to itself, but WON'T return true when
// compared to end().
Iter() = default;
// Rule of zero: nothing specified. The conversion constructor is only enabled for
// iterator to const_iterator, so it doesn't accidentally work as a copy ctor.
// Conversion constructor from iterator to const_iterator.
template <bool OtherIsConst,
typename = typename std::enable_if<IsConst && !OtherIsConst>::type>
// NOLINTNEXTLINE(hicpp-explicit-conversions)
Iter(Iter<OtherIsConst> const& other) noexcept
: mKeyVals(other.mKeyVals)
, mInfo(other.mInfo) {}
Iter(NodePtr valPtr, uint8_t const* infoPtr) noexcept
: mKeyVals(valPtr)
, mInfo(infoPtr) {}
Iter(NodePtr valPtr, uint8_t const* infoPtr,
fast_forward_tag ROBIN_HOOD_UNUSED(tag) /*unused*/) noexcept
: mKeyVals(valPtr)
, mInfo(infoPtr) {
fastForward();
}
template <bool OtherIsConst,
typename = typename std::enable_if<IsConst && !OtherIsConst>::type>
Iter& operator=(Iter<OtherIsConst> const& other) noexcept {
mKeyVals = other.mKeyVals;
mInfo = other.mInfo;
return *this;
}
// prefix increment. Undefined behavior if we are at end()!
Iter& operator++() noexcept {
mInfo++;
mKeyVals++;
fastForward();
return *this;
}
Iter operator++(int) noexcept {
Iter tmp = *this;
++(*this);
return tmp;
}
reference operator*() const {
return **mKeyVals;
}
pointer operator->() const {
return &**mKeyVals;
}
template <bool O>
bool operator==(Iter<O> const& o) const noexcept {
return mKeyVals == o.mKeyVals;
}
template <bool O>
bool operator!=(Iter<O> const& o) const noexcept {
return mKeyVals != o.mKeyVals;
}
private:
// fast forward to the next non-free info byte
// I've tried a few variants that don't depend on intrinsics, but unfortunately they are
// quite a bit slower than this one. So I've reverted that change again. See map_benchmark.
void fastForward() noexcept {
size_t n = 0;
while (0U == (n = detail::unaligned_load<size_t>(mInfo))) {
mInfo += sizeof(size_t);
mKeyVals += sizeof(size_t);
}
#if defined(ROBIN_HOOD_DISABLE_INTRINSICS)
// we know for certain that within the next 8 bytes we'll find a non-zero one.
if (ROBIN_HOOD_UNLIKELY(0U == detail::unaligned_load<uint32_t>(mInfo))) {
mInfo += 4;
mKeyVals += 4;
}
if (ROBIN_HOOD_UNLIKELY(0U == detail::unaligned_load<uint16_t>(mInfo))) {
mInfo += 2;
mKeyVals += 2;
}
if (ROBIN_HOOD_UNLIKELY(0U == *mInfo)) {
mInfo += 1;
mKeyVals += 1;
}
#else
# if ROBIN_HOOD(LITTLE_ENDIAN)
auto inc = ROBIN_HOOD_COUNT_TRAILING_ZEROES(n) / 8;
# else
auto inc = ROBIN_HOOD_COUNT_LEADING_ZEROES(n) / 8;
# endif
mInfo += inc;
mKeyVals += inc;
#endif
}
friend class Table<IsFlat, MaxLoadFactor100, key_type, mapped_type, hasher, key_equal>;
NodePtr mKeyVals{nullptr};
uint8_t const* mInfo{nullptr};
};
////////////////////////////////////////////////////////////////////
// highly performance relevant code.
// Lower bits are used for indexing into the array (2^n size)
// The upper 1-5 bits need to be a reasonable good hash, to save comparisons.
template <typename HashKey>
void keyToIdx(HashKey&& key, size_t* idx, InfoType* info) const {
// In addition to whatever hash is used, add another mul & shift so we get better hashing.
// This serves as a bad hash prevention, if the given data is
// badly mixed.
auto h = static_cast<uint64_t>(WHash::operator()(key));
h *= mHashMultiplier;
h ^= h >> 33U;
// the lower InitialInfoNumBits are reserved for info.
*info = mInfoInc + static_cast<InfoType>((h & InfoMask) >> mInfoHashShift);
*idx = (static_cast<size_t>(h) >> InitialInfoNumBits) & mMask;
}
// forwards the index by one, wrapping around at the end
void next(InfoType* info, size_t* idx) const noexcept {
*idx = *idx + 1;
*info += mInfoInc;
}
void nextWhileLess(InfoType* info, size_t* idx) const noexcept {
// unrolling this by hand did not bring any speedups.
while (*info < mInfo[*idx]) {
next(info, idx);
}
}
// Shift everything up by one element. Tries to move stuff around.
void
shiftUp(size_t startIdx,
size_t const insertion_idx) noexcept(std::is_nothrow_move_assignable<Node>::value) {
auto idx = startIdx;
::new (static_cast<void*>(mKeyVals + idx)) Node(std::move(mKeyVals[idx - 1]));
while (--idx != insertion_idx) {
mKeyVals[idx] = std::move(mKeyVals[idx - 1]);
}
idx = startIdx;
while (idx != insertion_idx) {
ROBIN_HOOD_COUNT(shiftUp)
mInfo[idx] = static_cast<uint8_t>(mInfo[idx - 1] + mInfoInc);
if (ROBIN_HOOD_UNLIKELY(mInfo[idx] + mInfoInc > 0xFF)) {
mMaxNumElementsAllowed = 0;
}
--idx;
}
}
void shiftDown(size_t idx) noexcept(std::is_nothrow_move_assignable<Node>::value) {
// until we find one that is either empty or has zero offset.
// TODO(martinus) we don't need to move everything, just the last one for the same
// bucket.
mKeyVals[idx].destroy(*this);
// until we find one that is either empty or has zero offset.
while (mInfo[idx + 1] >= 2 * mInfoInc) {
ROBIN_HOOD_COUNT(shiftDown)
mInfo[idx] = static_cast<uint8_t>(mInfo[idx + 1] - mInfoInc);
mKeyVals[idx] = std::move(mKeyVals[idx + 1]);
++idx;
}
mInfo[idx] = 0;
// don't destroy, we've moved it
// mKeyVals[idx].destroy(*this);
mKeyVals[idx].~Node();
}
// copy of find(), except that it returns iterator instead of const_iterator.
template <typename Other>
ROBIN_HOOD(NODISCARD)
size_t findIdx(Other const& key) const {
size_t idx{};
InfoType info{};
keyToIdx(key, &idx, &info);
do {
// unrolling this twice gives a bit of a speedup. More unrolling did not help.
if (info == mInfo[idx] &&
ROBIN_HOOD_LIKELY(WKeyEqual::operator()(key, mKeyVals[idx].getFirst()))) {
return idx;
}
next(&info, &idx);
if (info == mInfo[idx] &&
ROBIN_HOOD_LIKELY(WKeyEqual::operator()(key, mKeyVals[idx].getFirst()))) {
return idx;
}
next(&info, &idx);
} while (info <= mInfo[idx]);
// nothing found!
return mMask == 0 ? 0
: static_cast<size_t>(std::distance(
mKeyVals, reinterpret_cast_no_cast_align_warning<Node*>(mInfo)));
}
void cloneData(const Table& o) {
Cloner<Table, IsFlat && ROBIN_HOOD_IS_TRIVIALLY_COPYABLE(Node)>()(o, *this);
}
// inserts a keyval that is guaranteed to be new, e.g. when the hashmap is resized.
// @return True on success, false if something went wrong
void insert_move(Node&& keyval) {
// we don't retry, fail if overflowing
// don't need to check max num elements
if (0 == mMaxNumElementsAllowed && !try_increase_info()) {
throwOverflowError();
}
size_t idx{};
InfoType info{};
keyToIdx(keyval.getFirst(), &idx, &info);
// skip forward. Use <= because we are certain that the element is not there.
while (info <= mInfo[idx]) {
idx = idx + 1;
info += mInfoInc;
}
// key not found, so we are now exactly where we want to insert it.
auto const insertion_idx = idx;
auto const insertion_info = static_cast<uint8_t>(info);
if (ROBIN_HOOD_UNLIKELY(insertion_info + mInfoInc > 0xFF)) {
mMaxNumElementsAllowed = 0;
}
// find an empty spot
while (0 != mInfo[idx]) {
next(&info, &idx);
}
auto& l = mKeyVals[insertion_idx];
if (idx == insertion_idx) {
::new (static_cast<void*>(&l)) Node(std::move(keyval));
} else {
shiftUp(idx, insertion_idx);
l = std::move(keyval);
}
// put at empty spot
mInfo[insertion_idx] = insertion_info;
++mNumElements;
}
public:
using iterator = Iter<false>;
using const_iterator = Iter<true>;
Table() noexcept(noexcept(Hash()) && noexcept(KeyEqual()))
: WHash()
, WKeyEqual() {
ROBIN_HOOD_TRACE(this)
}
// Creates an empty hash map. Nothing is allocated yet, this happens at the first insert.
// This tremendously speeds up ctor & dtor of a map that never receives an element. The
// penalty is payed at the first insert, and not before. Lookup of this empty map works
// because everybody points to DummyInfoByte::b. parameter bucket_count is dictated by the
// standard, but we can ignore it.
explicit Table(
size_t ROBIN_HOOD_UNUSED(bucket_count) /*unused*/, const Hash& h = Hash{},
const KeyEqual& equal = KeyEqual{}) noexcept(noexcept(Hash(h)) && noexcept(KeyEqual(equal)))
: WHash(h)
, WKeyEqual(equal) {
ROBIN_HOOD_TRACE(this)
}
template <typename Iter>
Table(Iter first, Iter last, size_t ROBIN_HOOD_UNUSED(bucket_count) /*unused*/ = 0,
const Hash& h = Hash{}, const KeyEqual& equal = KeyEqual{})
: WHash(h)
, WKeyEqual(equal) {
ROBIN_HOOD_TRACE(this)
insert(first, last);
}
Table(std::initializer_list<value_type> initlist,
size_t ROBIN_HOOD_UNUSED(bucket_count) /*unused*/ = 0, const Hash& h = Hash{},
const KeyEqual& equal = KeyEqual{})
: WHash(h)
, WKeyEqual(equal) {
ROBIN_HOOD_TRACE(this)
insert(initlist.begin(), initlist.end());
}
Table(Table&& o) noexcept
: WHash(std::move(static_cast<WHash&>(o)))
, WKeyEqual(std::move(static_cast<WKeyEqual&>(o)))
, DataPool(std::move(static_cast<DataPool&>(o))) {
ROBIN_HOOD_TRACE(this)
if (o.mMask) {
mHashMultiplier = std::move(o.mHashMultiplier);
mKeyVals = std::move(o.mKeyVals);
mInfo = std::move(o.mInfo);
mNumElements = std::move(o.mNumElements);
mMask = std::move(o.mMask);
mMaxNumElementsAllowed = std::move(o.mMaxNumElementsAllowed);
mInfoInc = std::move(o.mInfoInc);
mInfoHashShift = std::move(o.mInfoHashShift);
// set other's mask to 0 so its destructor won't do anything
o.init();
}
}
Table& operator=(Table&& o) noexcept {
ROBIN_HOOD_TRACE(this)
if (&o != this) {
if (o.mMask) {
// only move stuff if the other map actually has some data
destroy();
mHashMultiplier = std::move(o.mHashMultiplier);
mKeyVals = std::move(o.mKeyVals);
mInfo = std::move(o.mInfo);
mNumElements = std::move(o.mNumElements);
mMask = std::move(o.mMask);
mMaxNumElementsAllowed = std::move(o.mMaxNumElementsAllowed);
mInfoInc = std::move(o.mInfoInc);
mInfoHashShift = std::move(o.mInfoHashShift);
WHash::operator=(std::move(static_cast<WHash&>(o)));
WKeyEqual::operator=(std::move(static_cast<WKeyEqual&>(o)));
DataPool::operator=(std::move(static_cast<DataPool&>(o)));
o.init();
} else {
// nothing in the other map => just clear us.
clear();
}
}
return *this;
}
Table(const Table& o)
: WHash(static_cast<const WHash&>(o))
, WKeyEqual(static_cast<const WKeyEqual&>(o))
, DataPool(static_cast<const DataPool&>(o)) {
ROBIN_HOOD_TRACE(this)
if (!o.empty()) {
// not empty: create an exact copy. it is also possible to just iterate through all
// elements and insert them, but copying is probably faster.
auto const numElementsWithBuffer = calcNumElementsWithBuffer(o.mMask + 1);
auto const numBytesTotal = calcNumBytesTotal(numElementsWithBuffer);
ROBIN_HOOD_LOG("std::malloc " << numBytesTotal << " = calcNumBytesTotal("
<< numElementsWithBuffer << ")")
mHashMultiplier = o.mHashMultiplier;
mKeyVals = static_cast<Node*>(
detail::assertNotNull<std::bad_alloc>(std::malloc(numBytesTotal)));
// no need for calloc because clonData does memcpy
mInfo = reinterpret_cast<uint8_t*>(mKeyVals + numElementsWithBuffer);
mNumElements = o.mNumElements;
mMask = o.mMask;
mMaxNumElementsAllowed = o.mMaxNumElementsAllowed;
mInfoInc = o.mInfoInc;
mInfoHashShift = o.mInfoHashShift;
cloneData(o);
}
}
// Creates a copy of the given map. Copy constructor of each entry is used.
// Not sure why clang-tidy thinks this doesn't handle self assignment, it does
// NOLINTNEXTLINE(bugprone-unhandled-self-assignment,cert-oop54-cpp)
Table& operator=(Table const& o) {
ROBIN_HOOD_TRACE(this)
if (&o == this) {
// prevent assigning of itself
return *this;
}
// we keep using the old allocator and not assign the new one, because we want to keep
// the memory available. when it is the same size.
if (o.empty()) {
if (0 == mMask) {
// nothing to do, we are empty too
return *this;
}
// not empty: destroy what we have there
// clear also resets mInfo to 0, that's sometimes not necessary.
destroy();
init();
WHash::operator=(static_cast<const WHash&>(o));
WKeyEqual::operator=(static_cast<const WKeyEqual&>(o));
DataPool::operator=(static_cast<DataPool const&>(o));
return *this;
}
// clean up old stuff
Destroyer<Self, IsFlat && std::is_trivially_destructible<Node>::value>{}.nodes(*this);
if (mMask != o.mMask) {
// no luck: we don't have the same array size allocated, so we need to realloc.
if (0 != mMask) {
// only deallocate if we actually have data!
ROBIN_HOOD_LOG("std::free")
std::free(mKeyVals);
}
auto const numElementsWithBuffer = calcNumElementsWithBuffer(o.mMask + 1);
auto const numBytesTotal = calcNumBytesTotal(numElementsWithBuffer);
ROBIN_HOOD_LOG("std::malloc " << numBytesTotal << " = calcNumBytesTotal("
<< numElementsWithBuffer << ")")
mKeyVals = static_cast<Node*>(
detail::assertNotNull<std::bad_alloc>(std::malloc(numBytesTotal)));
// no need for calloc here because cloneData performs a memcpy.
mInfo = reinterpret_cast<uint8_t*>(mKeyVals + numElementsWithBuffer);
// sentinel is set in cloneData
}
WHash::operator=(static_cast<const WHash&>(o));
WKeyEqual::operator=(static_cast<const WKeyEqual&>(o));
DataPool::operator=(static_cast<DataPool const&>(o));
mHashMultiplier = o.mHashMultiplier;
mNumElements = o.mNumElements;
mMask = o.mMask;
mMaxNumElementsAllowed = o.mMaxNumElementsAllowed;
mInfoInc = o.mInfoInc;
mInfoHashShift = o.mInfoHashShift;
cloneData(o);
return *this;
}
// Swaps everything between the two maps.
void swap(Table& o) {
ROBIN_HOOD_TRACE(this)
using std::swap;
swap(o, *this);
}
// Clears all data, without resizing.
void clear() {
ROBIN_HOOD_TRACE(this)
if (empty()) {
// don't do anything! also important because we don't want to write to
// DummyInfoByte::b, even though we would just write 0 to it.
return;
}
Destroyer<Self, IsFlat && std::is_trivially_destructible<Node>::value>{}.nodes(*this);
auto const numElementsWithBuffer = calcNumElementsWithBuffer(mMask + 1);
// clear everything, then set the sentinel again
uint8_t const z = 0;
std::fill(mInfo, mInfo + calcNumBytesInfo(numElementsWithBuffer), z);
mInfo[numElementsWithBuffer] = 1;
mInfoInc = InitialInfoInc;
mInfoHashShift = InitialInfoHashShift;
}
// Destroys the map and all it's contents.
~Table() {
ROBIN_HOOD_TRACE(this)
destroy();
}
// Checks if both tables contain the same entries. Order is irrelevant.
bool operator==(const Table& other) const {
ROBIN_HOOD_TRACE(this)
if (other.size() != size()) {
return false;
}
for (auto const& otherEntry : other) {
if (!has(otherEntry)) {
return false;
}
}
return true;
}
bool operator!=(const Table& other) const {
ROBIN_HOOD_TRACE(this)
return !operator==(other);
}
template <typename Q = mapped_type>
typename std::enable_if<!std::is_void<Q>::value, Q&>::type operator[](const key_type& key) {
ROBIN_HOOD_TRACE(this)
auto idxAndState = insertKeyPrepareEmptySpot(key);
switch (idxAndState.second) {
case InsertionState::key_found:
break;
case InsertionState::new_node:
::new (static_cast<void*>(&mKeyVals[idxAndState.first]))
Node(*this, std::piecewise_construct, std::forward_as_tuple(key),
std::forward_as_tuple());
break;
case InsertionState::overwrite_node:
mKeyVals[idxAndState.first] = Node(*this, std::piecewise_construct,
std::forward_as_tuple(key), std::forward_as_tuple());
break;
case InsertionState::overflow_error:
throwOverflowError();
}
return mKeyVals[idxAndState.first].getSecond();
}
template <typename Q = mapped_type>
typename std::enable_if<!std::is_void<Q>::value, Q&>::type operator[](key_type&& key) {
ROBIN_HOOD_TRACE(this)
auto idxAndState = insertKeyPrepareEmptySpot(key);
switch (idxAndState.second) {
case InsertionState::key_found:
break;
case InsertionState::new_node:
::new (static_cast<void*>(&mKeyVals[idxAndState.first]))
Node(*this, std::piecewise_construct, std::forward_as_tuple(std::move(key)),
std::forward_as_tuple());
break;
case InsertionState::overwrite_node:
mKeyVals[idxAndState.first] =
Node(*this, std::piecewise_construct, std::forward_as_tuple(std::move(key)),
std::forward_as_tuple());
break;
case InsertionState::overflow_error:
throwOverflowError();
}
return mKeyVals[idxAndState.first].getSecond();
}
template <typename Iter>
void insert(Iter first, Iter last) {
for (; first != last; ++first) {
// value_type ctor needed because this might be called with std::pair's
insert(value_type(*first));
}
}
void insert(std::initializer_list<value_type> ilist) {
for (auto&& vt : ilist) {
insert(std::move(vt));
}
}
template <typename... Args>
std::pair<iterator, bool> emplace(Args&&... args) {
ROBIN_HOOD_TRACE(this)
Node n{*this, std::forward<Args>(args)...};
auto idxAndState = insertKeyPrepareEmptySpot(getFirstConst(n));
switch (idxAndState.second) {
case InsertionState::key_found:
n.destroy(*this);
break;
case InsertionState::new_node:
::new (static_cast<void*>(&mKeyVals[idxAndState.first])) Node(*this, std::move(n));
break;
case InsertionState::overwrite_node:
mKeyVals[idxAndState.first] = std::move(n);
break;
case InsertionState::overflow_error:
n.destroy(*this);
throwOverflowError();
break;
}
return std::make_pair(iterator(mKeyVals + idxAndState.first, mInfo + idxAndState.first),
InsertionState::key_found != idxAndState.second);
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(const key_type& key, Args&&... args) {
return try_emplace_impl(key, std::forward<Args>(args)...);
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(key_type&& key, Args&&... args) {
return try_emplace_impl(std::move(key), std::forward<Args>(args)...);
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(const_iterator hint, const key_type& key,
Args&&... args) {
(void)hint;
return try_emplace_impl(key, std::forward<Args>(args)...);
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(const_iterator hint, key_type&& key, Args&&... args) {
(void)hint;
return try_emplace_impl(std::move(key), std::forward<Args>(args)...);
}
template <typename Mapped>
std::pair<iterator, bool> insert_or_assign(const key_type& key, Mapped&& obj) {
return insertOrAssignImpl(key, std::forward<Mapped>(obj));
}
template <typename Mapped>
std::pair<iterator, bool> insert_or_assign(key_type&& key, Mapped&& obj) {
return insertOrAssignImpl(std::move(key), std::forward<Mapped>(obj));
}
template <typename Mapped>
std::pair<iterator, bool> insert_or_assign(const_iterator hint, const key_type& key,
Mapped&& obj) {
(void)hint;
return insertOrAssignImpl(key, std::forward<Mapped>(obj));
}
template <typename Mapped>
std::pair<iterator, bool> insert_or_assign(const_iterator hint, key_type&& key, Mapped&& obj) {
(void)hint;
return insertOrAssignImpl(std::move(key), std::forward<Mapped>(obj));
}
std::pair<iterator, bool> insert(const value_type& keyval) {
ROBIN_HOOD_TRACE(this)
return emplace(keyval);
}
std::pair<iterator, bool> insert(value_type&& keyval) {
return emplace(std::move(keyval));
}
// Returns 1 if key is found, 0 otherwise.
size_t count(const key_type& key) const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
auto kv = mKeyVals + findIdx(key);
if (kv != reinterpret_cast_no_cast_align_warning<Node*>(mInfo)) {
return 1;
}
return 0;
}
template <typename OtherKey, typename Self_ = Self>
// NOLINTNEXTLINE(modernize-use-nodiscard)
typename std::enable_if<Self_::is_transparent, size_t>::type count(const OtherKey& key) const {
ROBIN_HOOD_TRACE(this)
auto kv = mKeyVals + findIdx(key);
if (kv != reinterpret_cast_no_cast_align_warning<Node*>(mInfo)) {
return 1;
}
return 0;
}
bool contains(const key_type& key) const { // NOLINT(modernize-use-nodiscard)
return 1U == count(key);
}
template <typename OtherKey, typename Self_ = Self>
// NOLINTNEXTLINE(modernize-use-nodiscard)
typename std::enable_if<Self_::is_transparent, bool>::type contains(const OtherKey& key) const {
return 1U == count(key);
}
// Returns a reference to the value found for key.
// Throws std::out_of_range if element cannot be found
template <typename Q = mapped_type>
// NOLINTNEXTLINE(modernize-use-nodiscard)
typename std::enable_if<!std::is_void<Q>::value, Q&>::type at(key_type const& key) {
ROBIN_HOOD_TRACE(this)
auto kv = mKeyVals + findIdx(key);
if (kv == reinterpret_cast_no_cast_align_warning<Node*>(mInfo)) {
doThrow<std::out_of_range>("key not found");
}
return kv->getSecond();
}
// Returns a reference to the value found for key.
// Throws std::out_of_range if element cannot be found
template <typename Q = mapped_type>
// NOLINTNEXTLINE(modernize-use-nodiscard)
typename std::enable_if<!std::is_void<Q>::value, Q const&>::type at(key_type const& key) const {
ROBIN_HOOD_TRACE(this)
auto kv = mKeyVals + findIdx(key);
if (kv == reinterpret_cast_no_cast_align_warning<Node*>(mInfo)) {
doThrow<std::out_of_range>("key not found");
}
return kv->getSecond();
}
const_iterator find(const key_type& key) const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return const_iterator{mKeyVals + idx, mInfo + idx};
}
template <typename OtherKey>
const_iterator find(const OtherKey& key, is_transparent_tag /*unused*/) const {
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return const_iterator{mKeyVals + idx, mInfo + idx};
}
template <typename OtherKey, typename Self_ = Self>
typename std::enable_if<Self_::is_transparent, // NOLINT(modernize-use-nodiscard)
const_iterator>::type // NOLINT(modernize-use-nodiscard)
find(const OtherKey& key) const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return const_iterator{mKeyVals + idx, mInfo + idx};
}
iterator find(const key_type& key) {
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return iterator{mKeyVals + idx, mInfo + idx};
}
template <typename OtherKey>
iterator find(const OtherKey& key, is_transparent_tag /*unused*/) {
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return iterator{mKeyVals + idx, mInfo + idx};
}
template <typename OtherKey, typename Self_ = Self>
typename std::enable_if<Self_::is_transparent, iterator>::type find(const OtherKey& key) {
ROBIN_HOOD_TRACE(this)
const size_t idx = findIdx(key);
return iterator{mKeyVals + idx, mInfo + idx};
}
iterator begin() {
ROBIN_HOOD_TRACE(this)
if (empty()) {
return end();
}
return iterator(mKeyVals, mInfo, fast_forward_tag{});
}
const_iterator begin() const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return cbegin();
}
const_iterator cbegin() const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
if (empty()) {
return cend();
}
return const_iterator(mKeyVals, mInfo, fast_forward_tag{});
}
iterator end() {
ROBIN_HOOD_TRACE(this)
// no need to supply valid info pointer: end() must not be dereferenced, and only node
// pointer is compared.
return iterator{reinterpret_cast_no_cast_align_warning<Node*>(mInfo), nullptr};
}
const_iterator end() const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return cend();
}
const_iterator cend() const { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return const_iterator{reinterpret_cast_no_cast_align_warning<Node*>(mInfo), nullptr};
}
iterator erase(const_iterator pos) {
ROBIN_HOOD_TRACE(this)
// its safe to perform const cast here
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
return erase(iterator{const_cast<Node*>(pos.mKeyVals), const_cast<uint8_t*>(pos.mInfo)});
}
// Erases element at pos, returns iterator to the next element.
iterator erase(iterator pos) {
ROBIN_HOOD_TRACE(this)
// we assume that pos always points to a valid entry, and not end().
auto const idx = static_cast<size_t>(pos.mKeyVals - mKeyVals);
shiftDown(idx);
--mNumElements;
if (*pos.mInfo) {
// we've backward shifted, return this again
return pos;
}
// no backward shift, return next element
return ++pos;
}
size_t erase(const key_type& key) {
ROBIN_HOOD_TRACE(this)
size_t idx{};
InfoType info{};
keyToIdx(key, &idx, &info);
// check while info matches with the source idx
do {
if (info == mInfo[idx] && WKeyEqual::operator()(key, mKeyVals[idx].getFirst())) {
shiftDown(idx);
--mNumElements;
return 1;
}
next(&info, &idx);
} while (info <= mInfo[idx]);
// nothing found to delete
return 0;
}
// reserves space for the specified number of elements. Makes sure the old data fits.
// exactly the same as reserve(c).
void rehash(size_t c) {
// forces a reserve
reserve(c, true);
}
// reserves space for the specified number of elements. Makes sure the old data fits.
// Exactly the same as rehash(c). Use rehash(0) to shrink to fit.
void reserve(size_t c) {
// reserve, but don't force rehash
reserve(c, false);
}
// If possible reallocates the map to a smaller one. This frees the underlying table.
// Does not do anything if load_factor is too large for decreasing the table's size.
void compact() {
ROBIN_HOOD_TRACE(this)
auto newSize = InitialNumElements;
while (calcMaxNumElementsAllowed(newSize) < mNumElements && newSize != 0) {
newSize *= 2;
}
if (ROBIN_HOOD_UNLIKELY(newSize == 0)) {
throwOverflowError();
}
ROBIN_HOOD_LOG("newSize > mMask + 1: " << newSize << " > " << mMask << " + 1")
// only actually do anything when the new size is bigger than the old one. This prevents to
// continuously allocate for each reserve() call.
if (newSize < mMask + 1) {
rehashPowerOfTwo(newSize, true);
}
}
size_type size() const noexcept { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return mNumElements;
}
size_type max_size() const noexcept { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return static_cast<size_type>(-1);
}
ROBIN_HOOD(NODISCARD) bool empty() const noexcept {
ROBIN_HOOD_TRACE(this)
return 0 == mNumElements;
}
float max_load_factor() const noexcept { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return MaxLoadFactor100 / 100.0F;
}
// Average number of elements per bucket. Since we allow only 1 per bucket
float load_factor() const noexcept { // NOLINT(modernize-use-nodiscard)
ROBIN_HOOD_TRACE(this)
return static_cast<float>(size()) / static_cast<float>(mMask + 1);
}
ROBIN_HOOD(NODISCARD) size_t mask() const noexcept {
ROBIN_HOOD_TRACE(this)
return mMask;
}
ROBIN_HOOD(NODISCARD) size_t calcMaxNumElementsAllowed(size_t maxElements) const noexcept {
if (ROBIN_HOOD_LIKELY(maxElements <= (std::numeric_limits<size_t>::max)() / 100)) {
return maxElements * MaxLoadFactor100 / 100;
}
// we might be a bit inprecise, but since maxElements is quite large that doesn't matter
return (maxElements / 100) * MaxLoadFactor100;
}
ROBIN_HOOD(NODISCARD) size_t calcNumBytesInfo(size_t numElements) const noexcept {
// we add a uint64_t, which houses the sentinel (first byte) and padding so we can load
// 64bit types.
return numElements + sizeof(uint64_t);
}
ROBIN_HOOD(NODISCARD)
size_t calcNumElementsWithBuffer(size_t numElements) const noexcept {
auto maxNumElementsAllowed = calcMaxNumElementsAllowed(numElements);
return numElements + (std::min)(maxNumElementsAllowed, (static_cast<size_t>(0xFF)));
}
// calculation only allowed for 2^n values
ROBIN_HOOD(NODISCARD) size_t calcNumBytesTotal(size_t numElements) const {
#if ROBIN_HOOD(BITNESS) == 64
return numElements * sizeof(Node) + calcNumBytesInfo(numElements);
#else
// make sure we're doing 64bit operations, so we are at least safe against 32bit overflows.
auto const ne = static_cast<uint64_t>(numElements);
auto const s = static_cast<uint64_t>(sizeof(Node));
auto const infos = static_cast<uint64_t>(calcNumBytesInfo(numElements));
auto const total64 = ne * s + infos;
auto const total = static_cast<size_t>(total64);
if (ROBIN_HOOD_UNLIKELY(static_cast<uint64_t>(total) != total64)) {
throwOverflowError();
}
return total;
#endif
}
private:
template <typename Q = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<!std::is_void<Q>::value, bool>::type has(const value_type& e) const {
ROBIN_HOOD_TRACE(this)
auto it = find(e.first);
return it != end() && it->second == e.second;
}
template <typename Q = mapped_type>
ROBIN_HOOD(NODISCARD)
typename std::enable_if<std::is_void<Q>::value, bool>::type has(const value_type& e) const {
ROBIN_HOOD_TRACE(this)
return find(e) != end();
}
void reserve(size_t c, bool forceRehash) {
ROBIN_HOOD_TRACE(this)
auto const minElementsAllowed = (std::max)(c, mNumElements);
auto newSize = InitialNumElements;
while (calcMaxNumElementsAllowed(newSize) < minElementsAllowed && newSize != 0) {
newSize *= 2;
}
if (ROBIN_HOOD_UNLIKELY(newSize == 0)) {
throwOverflowError();
}
ROBIN_HOOD_LOG("newSize > mMask + 1: " << newSize << " > " << mMask << " + 1")
// only actually do anything when the new size is bigger than the old one. This prevents to
// continuously allocate for each reserve() call.
if (forceRehash || newSize > mMask + 1) {
rehashPowerOfTwo(newSize, false);
}
}
// reserves space for at least the specified number of elements.
// only works if numBuckets if power of two
// True on success, false otherwise
void rehashPowerOfTwo(size_t numBuckets, bool forceFree) {
ROBIN_HOOD_TRACE(this)
Node* const oldKeyVals = mKeyVals;
uint8_t const* const oldInfo = mInfo;
const size_t oldMaxElementsWithBuffer = calcNumElementsWithBuffer(mMask + 1);
// resize operation: move stuff
initData(numBuckets);
if (oldMaxElementsWithBuffer > 1) {
for (size_t i = 0; i < oldMaxElementsWithBuffer; ++i) {
if (oldInfo[i] != 0) {
// might throw an exception, which is really bad since we are in the middle of
// moving stuff.
insert_move(std::move(oldKeyVals[i]));
// destroy the node but DON'T destroy the data.
oldKeyVals[i].~Node();
}
}
// this check is not necessary as it's guarded by the previous if, but it helps
// silence g++'s overeager "attempt to free a non-heap object 'map'
// [-Werror=free-nonheap-object]" warning.
if (oldKeyVals != reinterpret_cast_no_cast_align_warning<Node*>(&mMask)) {
// don't destroy old data: put it into the pool instead
if (forceFree) {
std::free(oldKeyVals);
} else {
DataPool::addOrFree(oldKeyVals, calcNumBytesTotal(oldMaxElementsWithBuffer));
}
}
}
}
ROBIN_HOOD(NOINLINE) void throwOverflowError() const {
#if ROBIN_HOOD(HAS_EXCEPTIONS)
throw std::overflow_error("robin_hood::map overflow");
#else
abort();
#endif
}
template <typename OtherKey, typename... Args>
std::pair<iterator, bool> try_emplace_impl(OtherKey&& key, Args&&... args) {
ROBIN_HOOD_TRACE(this)
auto idxAndState = insertKeyPrepareEmptySpot(key);
switch (idxAndState.second) {
case InsertionState::key_found:
break;
case InsertionState::new_node:
::new (static_cast<void*>(&mKeyVals[idxAndState.first])) Node(
*this, std::piecewise_construct, std::forward_as_tuple(std::forward<OtherKey>(key)),
std::forward_as_tuple(std::forward<Args>(args)...));
break;
case InsertionState::overwrite_node:
mKeyVals[idxAndState.first] = Node(*this, std::piecewise_construct,
std::forward_as_tuple(std::forward<OtherKey>(key)),
std::forward_as_tuple(std::forward<Args>(args)...));
break;
case InsertionState::overflow_error:
throwOverflowError();
break;
}
return std::make_pair(iterator(mKeyVals + idxAndState.first, mInfo + idxAndState.first),
InsertionState::key_found != idxAndState.second);
}
template <typename OtherKey, typename Mapped>
std::pair<iterator, bool> insertOrAssignImpl(OtherKey&& key, Mapped&& obj) {
ROBIN_HOOD_TRACE(this)
auto idxAndState = insertKeyPrepareEmptySpot(key);
switch (idxAndState.second) {
case InsertionState::key_found:
mKeyVals[idxAndState.first].getSecond() = std::forward<Mapped>(obj);
break;
case InsertionState::new_node:
::new (static_cast<void*>(&mKeyVals[idxAndState.first])) Node(
*this, std::piecewise_construct, std::forward_as_tuple(std::forward<OtherKey>(key)),
std::forward_as_tuple(std::forward<Mapped>(obj)));
break;
case InsertionState::overwrite_node:
mKeyVals[idxAndState.first] = Node(*this, std::piecewise_construct,
std::forward_as_tuple(std::forward<OtherKey>(key)),
std::forward_as_tuple(std::forward<Mapped>(obj)));
break;
case InsertionState::overflow_error:
throwOverflowError();
break;
}
return std::make_pair(iterator(mKeyVals + idxAndState.first, mInfo + idxAndState.first),
InsertionState::key_found != idxAndState.second);
}
void initData(size_t max_elements) {
mNumElements = 0;
mMask = max_elements - 1;
mMaxNumElementsAllowed = calcMaxNumElementsAllowed(max_elements);
auto const numElementsWithBuffer = calcNumElementsWithBuffer(max_elements);
// calloc also zeroes everything
auto const numBytesTotal = calcNumBytesTotal(numElementsWithBuffer);
ROBIN_HOOD_LOG("std::calloc " << numBytesTotal << " = calcNumBytesTotal("
<< numElementsWithBuffer << ")")
mKeyVals = reinterpret_cast<Node*>(
detail::assertNotNull<std::bad_alloc>(std::calloc(1, numBytesTotal)));
mInfo = reinterpret_cast<uint8_t*>(mKeyVals + numElementsWithBuffer);
// set sentinel
mInfo[numElementsWithBuffer] = 1;
mInfoInc = InitialInfoInc;
mInfoHashShift = InitialInfoHashShift;
}
enum class InsertionState { overflow_error, key_found, new_node, overwrite_node };
// Finds key, and if not already present prepares a spot where to pot the key & value.
// This potentially shifts nodes out of the way, updates mInfo and number of inserted
// elements, so the only operation left to do is create/assign a new node at that spot.
template <typename OtherKey>
std::pair<size_t, InsertionState> insertKeyPrepareEmptySpot(OtherKey&& key) {
for (int i = 0; i < 256; ++i) {
size_t idx{};
InfoType info{};
keyToIdx(key, &idx, &info);
nextWhileLess(&info, &idx);
// while we potentially have a match
while (info == mInfo[idx]) {
if (WKeyEqual::operator()(key, mKeyVals[idx].getFirst())) {
// key already exists, do NOT insert.
// see http://en.cppreference.com/w/cpp/container/unordered_map/insert
return std::make_pair(idx, InsertionState::key_found);
}
next(&info, &idx);
}
// unlikely that this evaluates to true
if (ROBIN_HOOD_UNLIKELY(mNumElements >= mMaxNumElementsAllowed)) {
if (!increase_size()) {
return std::make_pair(size_t(0), InsertionState::overflow_error);
}
continue;
}
// key not found, so we are now exactly where we want to insert it.
auto const insertion_idx = idx;
auto const insertion_info = info;
if (ROBIN_HOOD_UNLIKELY(insertion_info + mInfoInc > 0xFF)) {
mMaxNumElementsAllowed = 0;
}
// find an empty spot
while (0 != mInfo[idx]) {
next(&info, &idx);
}
if (idx != insertion_idx) {
shiftUp(idx, insertion_idx);
}
// put at empty spot
mInfo[insertion_idx] = static_cast<uint8_t>(insertion_info);
++mNumElements;
return std::make_pair(insertion_idx, idx == insertion_idx
? InsertionState::new_node
: InsertionState::overwrite_node);
}
// enough attempts failed, so finally give up.
return std::make_pair(size_t(0), InsertionState::overflow_error);
}
bool try_increase_info() {
ROBIN_HOOD_LOG("mInfoInc=" << mInfoInc << ", numElements=" << mNumElements
<< ", maxNumElementsAllowed="
<< calcMaxNumElementsAllowed(mMask + 1))
if (mInfoInc <= 2) {
// need to be > 2 so that shift works (otherwise undefined behavior!)
return false;
}
// we got space left, try to make info smaller
mInfoInc = static_cast<uint8_t>(mInfoInc >> 1U);
// remove one bit of the hash, leaving more space for the distance info.
// This is extremely fast because we can operate on 8 bytes at once.
++mInfoHashShift;
auto const numElementsWithBuffer = calcNumElementsWithBuffer(mMask + 1);
for (size_t i = 0; i < numElementsWithBuffer; i += 8) {
auto val = unaligned_load<uint64_t>(mInfo + i);
val = (val >> 1U) & UINT64_C(0x7f7f7f7f7f7f7f7f);
std::memcpy(mInfo + i, &val, sizeof(val));
}
// update sentinel, which might have been cleared out!
mInfo[numElementsWithBuffer] = 1;
mMaxNumElementsAllowed = calcMaxNumElementsAllowed(mMask + 1);
return true;
}
// True if resize was possible, false otherwise
bool increase_size() {
// nothing allocated yet? just allocate InitialNumElements
if (0 == mMask) {
initData(InitialNumElements);
return true;
}
auto const maxNumElementsAllowed = calcMaxNumElementsAllowed(mMask + 1);
if (mNumElements < maxNumElementsAllowed && try_increase_info()) {
return true;
}
ROBIN_HOOD_LOG("mNumElements=" << mNumElements << ", maxNumElementsAllowed="
<< maxNumElementsAllowed << ", load="
<< (static_cast<double>(mNumElements) * 100.0 /
(static_cast<double>(mMask) + 1)))
nextHashMultiplier();
if (mNumElements * 2 < calcMaxNumElementsAllowed(mMask + 1)) {
// we have to resize, even though there would still be plenty of space left!
// Try to rehash instead. Delete freed memory so we don't steadyily increase mem in case
// we have to rehash a few times
rehashPowerOfTwo(mMask + 1, true);
} else {
// Each resize use a different hash so we don't so easily overflow.
// Make sure we only have odd numbers, so that the multiplication is reversible!
rehashPowerOfTwo((mMask + 1) * 2, false);
}
return true;
}
void nextHashMultiplier() {
// adding an *even* number, so that the multiplier will always stay odd. This is necessary
// so that the hash stays a mixing function (and thus doesn't have any information loss).
mHashMultiplier += UINT64_C(0xc4ceb9fe1a85ec54);
}
void destroy() {
if (0 == mMask) {
// don't deallocate!
return;
}
Destroyer<Self, IsFlat && std::is_trivially_destructible<Node>::value>{}
.nodesDoNotDeallocate(*this);
// This protection against not deleting mMask shouldn't be needed as it's sufficiently
// protected with the 0==mMask check, but I have this anyways because g++ 7 otherwise
// reports a compile error: attempt to free a non-heap object 'fm'
// [-Werror=free-nonheap-object]
if (mKeyVals != reinterpret_cast_no_cast_align_warning<Node*>(&mMask)) {
ROBIN_HOOD_LOG("std::free")
std::free(mKeyVals);
}
}
void init() noexcept {
mKeyVals = reinterpret_cast_no_cast_align_warning<Node*>(&mMask);
mInfo = reinterpret_cast<uint8_t*>(&mMask);
mNumElements = 0;
mMask = 0;
mMaxNumElementsAllowed = 0;
mInfoInc = InitialInfoInc;
mInfoHashShift = InitialInfoHashShift;
}
// members are sorted so no padding occurs
uint64_t mHashMultiplier = UINT64_C(0xc4ceb9fe1a85ec53); // 8 byte 8
Node* mKeyVals = reinterpret_cast_no_cast_align_warning<Node*>(&mMask); // 8 byte 16
uint8_t* mInfo = reinterpret_cast<uint8_t*>(&mMask); // 8 byte 24
size_t mNumElements = 0; // 8 byte 32
size_t mMask = 0; // 8 byte 40
size_t mMaxNumElementsAllowed = 0; // 8 byte 48
InfoType mInfoInc = InitialInfoInc; // 4 byte 52
InfoType mInfoHashShift = InitialInfoHashShift; // 4 byte 56
// 16 byte 56 if NodeAllocator
};
} // namespace detail
// map
template <typename Key, typename T, typename Hash = hash<Key>,
typename KeyEqual = std::equal_to<Key>, size_t MaxLoadFactor100 = 80>
using unordered_flat_map = detail::Table<true, MaxLoadFactor100, Key, T, Hash, KeyEqual>;
template <typename Key, typename T, typename Hash = hash<Key>,
typename KeyEqual = std::equal_to<Key>, size_t MaxLoadFactor100 = 80>
using unordered_node_map = detail::Table<false, MaxLoadFactor100, Key, T, Hash, KeyEqual>;
template <typename Key, typename T, typename Hash = hash<Key>,
typename KeyEqual = std::equal_to<Key>, size_t MaxLoadFactor100 = 80>
using unordered_map =
detail::Table<sizeof(robin_hood::pair<Key, T>) <= sizeof(size_t) * 6 &&
std::is_nothrow_move_constructible<robin_hood::pair<Key, T>>::value &&
std::is_nothrow_move_assignable<robin_hood::pair<Key, T>>::value,
MaxLoadFactor100, Key, T, Hash, KeyEqual>;
// set
template <typename Key, typename Hash = hash<Key>, typename KeyEqual = std::equal_to<Key>,
size_t MaxLoadFactor100 = 80>
using unordered_flat_set = detail::Table<true, MaxLoadFactor100, Key, void, Hash, KeyEqual>;
template <typename Key, typename Hash = hash<Key>, typename KeyEqual = std::equal_to<Key>,
size_t MaxLoadFactor100 = 80>
using unordered_node_set = detail::Table<false, MaxLoadFactor100, Key, void, Hash, KeyEqual>;
template <typename Key, typename Hash = hash<Key>, typename KeyEqual = std::equal_to<Key>,
size_t MaxLoadFactor100 = 80>
using unordered_set = detail::Table<sizeof(Key) <= sizeof(size_t) * 6 &&
std::is_nothrow_move_constructible<Key>::value &&
std::is_nothrow_move_assignable<Key>::value,
MaxLoadFactor100, Key, void, Hash, KeyEqual>;
} // namespace robin_hood
#endif
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