[Rework] Use another version of hash table from the same author

3 files changed, 2213 insertions, 0 deletions

diff --git a/contrib/ankerl/LICENSE b/contrib/ankerl/LICENSE
new file mode 100644
index 000000000..c4d1a0e48
--- /dev/null
+++ b/contrib/ankerl/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 Martin Leitner-Ankerl
+
+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.
diff --git a/contrib/ankerl/svector.h b/contrib/ankerl/svector.h
new file mode 100644
index 000000000..b6ef1ad68
--- /dev/null
+++ b/contrib/ankerl/svector.h
@@ -0,0 +1,993 @@
+// ┌─┐┬  ┬┌─┐┌─┐┌┬┐┌─┐┬─┐   Compact SVO optimized vector C++17 or higher
+// └─┐└┐┌┘├┤ │   │ │ │├┬┘   Version 1.0.0
+// └─┘ └┘ └─┘└─┘ ┴ └─┘┴└─   https://github.com/martinus/svector
+//
+// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2022 Martin Leitner-Ankerl <martin.ankerl@gmail.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 ANKERL_SVECTOR_H
+#define ANKERL_SVECTOR_H
+
+// see https://semver.org/spec/v2.0.0.html
+#define ANKERL_SVECTOR_VERSION_MAJOR 1 // incompatible API changes
+#define ANKERL_SVECTOR_VERSION_MINOR 0 // add functionality in a backwards compatible manner
+#define ANKERL_SVECTOR_VERSION_PATCH 0 // backwards compatible bug fixes
+
+// API versioning with inline namespace, see https://www.foonathan.net/2018/11/inline-namespaces/
+#define ANKERL_SVECTOR_VERSION_CONCAT1(major, minor, patch) v##major##_##minor##_##patch
+#define ANKERL_SVECTOR_VERSION_CONCAT(major, minor, patch) ANKERL_SVECTOR_VERSION_CONCAT1(major, minor, patch)
+#define ANKERL_SVECTOR_NAMESPACE \
+    ANKERL_SVECTOR_VERSION_CONCAT(ANKERL_SVECTOR_VERSION_MAJOR, ANKERL_SVECTOR_VERSION_MINOR, ANKERL_SVECTOR_VERSION_PATCH)
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <initializer_list>
+#include <iterator>
+#include <limits>
+#include <memory>
+#include <new>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+
+namespace ankerl {
+inline namespace ANKERL_SVECTOR_NAMESPACE {
+namespace detail {
+
+template <typename Condition, typename T = void>
+using enable_if_t = typename std::enable_if<Condition::value, T>::type;
+
+template <typename It>
+using is_input_iterator = std::is_base_of<std::input_iterator_tag, typename std::iterator_traits<It>::iterator_category>;
+
+constexpr auto round_up(size_t n, size_t multiple) -> size_t {
+    return ((n + (multiple - 1)) / multiple) * multiple;
+}
+
+template <typename T>
+constexpr auto cx_min(T a, T b) -> T {
+    return a < b ? a : b;
+}
+
+template <typename T>
+constexpr auto cx_max(T a, T b) -> T {
+    return a > b ? a : b;
+}
+
+template <typename T>
+constexpr auto alignment_of_svector() -> size_t {
+    return cx_max(sizeof(void*), std::alignment_of_v<T>);
+}
+
+/**
+ * @brief Calculates sizeof(svector<T, N>) for a given type and inline capacity
+ */
+template <typename T>
+constexpr auto size_of_svector(size_t min_inline_capacity) -> size_t {
+    // + 1 for one byte size in direct mode
+    return round_up(sizeof(T) * min_inline_capacity + 1, alignment_of_svector<T>());
+}
+
+/**
+ * @brief Calculates how many T we can actually store inside of an svector without increasing its sizeof().
+ *
+ * E.g. svector<char, 1> could store 7 bytes even though 1 is specified. This makes sure we don't waste any
+ * of the padding.
+ */
+template <typename T>
+constexpr auto automatic_capacity(size_t min_inline_capacity) -> size_t {
+    return cx_min((size_of_svector<T>(min_inline_capacity) - 1U) / sizeof(T), size_t(127));
+}
+
+/**
+ * Holds size & capacity, a glorified struct.
+ */
+class header {
+    size_t m_size{};
+    size_t const m_capacity;
+
+public:
+    inline explicit header(size_t capacity)
+        : m_capacity{capacity} {}
+
+    [[nodiscard]] inline auto size() const -> size_t {
+        return m_size;
+    }
+
+    [[nodiscard]] inline auto capacity() const -> size_t {
+        return m_capacity;
+    }
+
+    inline void size(size_t s) {
+        m_size = s;
+    }
+};
+
+/**
+ * @brief Holds header (size+capacity) plus an arbitrary number of T.
+ *
+ * To make storage compact, we don't actually store a pointer to T. We don't have to
+ * because we know exactly at which location it begins.
+ */
+template <typename T>
+struct storage : public header {
+    static constexpr auto alignment_of_t = std::alignment_of_v<T>;
+    static constexpr auto max_alignment = std::max(std::alignment_of_v<header>, std::alignment_of_v<T>);
+    static constexpr auto offset_to_data = detail::round_up(sizeof(header), alignment_of_t);
+    static_assert(max_alignment <= __STDCPP_DEFAULT_NEW_ALIGNMENT__);
+
+    explicit storage(size_t capacity)
+        : header(capacity) {}
+
+    auto data() -> T* {
+        auto ptr_to_data = reinterpret_cast<std::byte*>(this) + offset_to_data;
+        return std::launder(reinterpret_cast<T*>(ptr_to_data));
+    }
+
+    /**
+     * @brief Allocates space for storage plus capacity*T objects.
+     *
+     * Checks to make sure that allocation won't overflow.
+     *
+     * @param capacity Number of T to allocate.
+     * @return storage<T>*
+     */
+    static auto alloc(size_t capacity) -> storage<T>* {
+        // make sure we don't overflow!
+        auto mem = sizeof(T) * capacity;
+        if (mem < capacity) {
+            throw std::bad_alloc();
+        }
+        if (offset_to_data + mem < mem) {
+            throw std::bad_alloc();
+        }
+        mem += offset_to_data;
+        if (static_cast<uint64_t>(mem) > static_cast<uint64_t>(std::numeric_limits<std::ptrdiff_t>::max())) {
+            throw std::bad_alloc();
+        }
+
+        void* ptr = ::operator new(offset_to_data + sizeof(T) * capacity);
+        if (nullptr == ptr) {
+            throw std::bad_alloc();
+        }
+        // use void* to ensure we don't use an overload for T*
+        return new (ptr) storage<T>(capacity);
+    }
+};
+
+} // namespace detail
+
+template <typename T, size_t MinInlineCapacity>
+class svector {
+    static_assert(MinInlineCapacity <= 127, "sorry, can't have more than 127 direct elements");
+    static constexpr auto N = detail::automatic_capacity<T>(MinInlineCapacity);
+
+    enum class direction { direct, indirect };
+
+    /**
+     * A buffer to hold the data of the svector Depending on direct/indirect mode, the content it holds is like so:
+     *
+     * direct:
+     *    m_data[0] & 1: lowest bit is 1 for direct mode.
+     *    m_data[0] >> 1: size for direct mode
+     *    Then 0-X bytes unused (padding), and then the actual inline T data.
+     * indirect:
+     *    m_data[0] & 1: lowest bit is 0 for indirect mode
+     *    m_data[0..7]: stores an uintptr_t, which points to the indirect data.
+     */
+    alignas(detail::alignment_of_svector<T>()) std::array<uint8_t, detail::size_of_svector<T>(MinInlineCapacity)> m_data;
+
+    // direct mode ///////////////////////////////////////////////////////////
+
+    [[nodiscard]] auto is_direct() const -> bool {
+        return (m_data[0] & 1U) != 0U;
+    }
+
+    [[nodiscard]] auto direct_size() const -> size_t {
+        return m_data[0] >> 1U;
+    }
+
+    // sets size of direct mode and mode to direct too.
+    constexpr void set_direct_and_size(size_t s) {
+        m_data[0] = (s << 1U) | 1U;
+    }
+
+    [[nodiscard]] auto direct_data() -> T* {
+        return std::launder(reinterpret_cast<T*>(m_data.data() + std::alignment_of_v<T>));
+    }
+
+    // indirect mode /////////////////////////////////////////////////////////
+
+    [[nodiscard]] auto indirect() -> detail::storage<T>* {
+        detail::storage<T>* ptr; // NOLINT(cppcoreguidelines-init-variables)
+        std::memcpy(&ptr, m_data.data(), sizeof(ptr));
+        return ptr;
+    }
+
+    [[nodiscard]] auto indirect() const -> detail::storage<T> const* {
+        return const_cast<svector*>(this)->indirect(); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    void set_indirect(detail::storage<T>* ptr) {
+        std::memcpy(m_data.data(), &ptr, sizeof(ptr));
+
+        // safety check to guarantee the lowest bit is 0
+        if (is_direct()) {
+            throw std::bad_alloc(); // LCOV_EXCL_LINE
+        }
+    }
+
+    // helpers ///////////////////////////////////////////////////////////////
+
+    /**
+     * @brief Moves size objects from source_ptr to target_ptr, and destroys what remains in source_ptr.
+     *
+     * Assumes data is not overlapping
+     */
+    static void uninitialized_move_and_destroy(T* source_ptr, T* target_ptr, size_t size) {
+        if constexpr (std::is_trivially_copyable_v<T>) {
+            std::memcpy(target_ptr, source_ptr, size * sizeof(T));
+        } else {
+            std::uninitialized_move_n(source_ptr, size, target_ptr);
+            std::destroy_n(source_ptr, size);
+        }
+    }
+
+    /**
+     * @brief Reallocates all data when capacity changes.
+     *
+     * if new_capacity <= N chooses direct memory, otherwise indirect.
+     */
+    void realloc(size_t new_capacity) {
+        if (new_capacity <= N) {
+            // put everything into direct storage
+            if (is_direct()) {
+                // direct -> direct: nothing to do!
+                return;
+            }
+
+            // indirect -> direct
+            auto* storage = indirect();
+            uninitialized_move_and_destroy(storage->data(), direct_data(), storage->size());
+            set_direct_and_size(storage->size());
+            delete storage;
+        } else {
+            // put everything into indirect storage
+            auto* storage = detail::storage<T>::alloc(new_capacity);
+            if (is_direct()) {
+                // direct -> indirect
+                uninitialized_move_and_destroy(data<direction::direct>(), storage->data(), size<direction::direct>());
+                storage->size(size<direction::direct>());
+            } else {
+                // indirect -> indirect
+                uninitialized_move_and_destroy(data<direction::indirect>(), storage->data(), size<direction::indirect>());
+                storage->size(size<direction::indirect>());
+                delete indirect();
+            }
+            set_indirect(storage);
+        }
+    }
+
+    /**
+     * @brief Doubles starting_capacity until it is >= size_to_fit.
+     */
+    [[nodiscard]] static auto calculate_new_capacity(size_t size_to_fit, size_t starting_capacity) -> size_t {
+        if (size_to_fit > max_size()) {
+            // not enough space
+            throw std::bad_alloc();
+        }
+
+        if (size_to_fit == 0) {
+            // special handling for 0 so N==0 works
+            return starting_capacity;
+        }
+        // start with at least 1, so N==0 works
+        auto new_capacity = std::max<size_t>(1, starting_capacity);
+
+        // double capacity until its large enough, but make sure we don't overflow
+        while (new_capacity < size_to_fit && new_capacity * 2 > new_capacity) {
+            new_capacity *= 2;
+        }
+        if (new_capacity < size_to_fit) {
+            // got an overflow, set capacity to max
+            new_capacity = max_size();
+        }
+        return std::min(new_capacity, max_size());
+    }
+
+    template <direction D>
+    [[nodiscard]] auto capacity() const -> size_t {
+        if constexpr (D == direction::direct) {
+            return N;
+        } else {
+            return indirect()->capacity();
+        }
+    }
+
+    template <direction D>
+    [[nodiscard]] auto size() const -> size_t {
+        if constexpr (D == direction::direct) {
+            return direct_size();
+        } else {
+            return indirect()->size();
+        }
+    }
+
+    template <direction D>
+    void set_size(size_t s) {
+        if constexpr (D == direction::direct) {
+            set_direct_and_size(s);
+        } else {
+            indirect()->size(s);
+        }
+    }
+
+    void set_size(size_t s) {
+        if (is_direct()) {
+            set_size<direction::direct>(s);
+        } else {
+            set_size<direction::indirect>(s);
+        }
+    }
+
+    template <direction D>
+    [[nodiscard]] auto data() -> T* {
+        if constexpr (D == direction::direct) {
+            return direct_data();
+        } else {
+            return indirect()->data();
+        }
+    }
+
+    template <direction D>
+    [[nodiscard]] auto data() const -> T const* {
+        return const_cast<svector*>(this)->data<D>(); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    template <direction D>
+    void pop_back() {
+        if constexpr (std::is_trivially_destructible_v<T>) {
+            set_size<D>(size<D>() - 1);
+        } else {
+            auto s = size<D>() - 1;
+            (data<D>() + s)->~T();
+            set_size<D>(s);
+        }
+    }
+
+    /**
+     * @brief We need variadic arguments so we can either use copy ctor or default ctor
+     */
+    template <direction D, class... Args>
+    void resize_after_reserve(size_t count, Args&&... args) {
+        auto current_size = size<D>();
+        if (current_size > count) {
+            if constexpr (!std::is_trivially_destructible_v<T>) {
+                auto* d = data<D>();
+                std::destroy(d + count, d + current_size);
+            }
+        } else {
+            auto* d = data<D>();
+            for (auto ptr = d + current_size, end = d + count; ptr != end; ++ptr) {
+                new (static_cast<void*>(ptr)) T(std::forward<Args>(args)...);
+            }
+        }
+        set_size<D>(count);
+    }
+
+    // Makes sure that to is not past the end iterator
+    template <direction D>
+    auto erase_checked_end(T const* cfrom, T const* to) -> T* {
+        auto* const erase_begin = const_cast<T*>(cfrom); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+        auto* const container_end = data<D>() + size<D>();
+        auto* const erase_end = std::min(const_cast<T*>(to), container_end); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+
+        std::move(erase_end, container_end, erase_begin);
+        auto const num_erased = std::distance(erase_begin, erase_end);
+        std::destroy(container_end - num_erased, container_end);
+        set_size<D>(size<D>() - num_erased);
+        return erase_begin;
+    }
+
+    template <typename It>
+    void assign(It first, It last, std::input_iterator_tag /*unused*/) {
+        clear();
+
+        // TODO this can be made faster, e.g. by setting size only when finished.
+        while (first != last) {
+            push_back(*first);
+            ++first;
+        }
+    }
+
+    template <typename It>
+    void assign(It first, It last, std::forward_iterator_tag /*unused*/) {
+        clear();
+
+        auto s = std::distance(first, last);
+        reserve(s);
+        std::uninitialized_copy(first, last, data());
+        set_size(s);
+    }
+
+    // precondition: all uninitialized
+    void do_move_assign(svector&& other) {
+        if (!other.is_direct()) {
+            // take other's memory, even when empty
+            set_indirect(other.indirect());
+        } else {
+            auto* other_ptr = other.data<direction::direct>();
+            auto s = other.size<direction::direct>();
+            auto* other_end = other_ptr + s;
+
+            std::uninitialized_move(other_ptr, other_end, data<direction::direct>());
+            std::destroy(other_ptr, other_end);
+            set_size(s);
+        }
+        other.set_direct_and_size(0);
+    }
+
+    /**
+     * @brief Shifts data [source_begin, source_end( to the right, starting on target_begin.
+     *
+     * Preconditions:
+     * * contiguous memory
+     * * source_begin <= target_begin
+     * * source_end onwards is uninitialized memory
+     *
+     * Destroys then empty elements in [source_begin, source_end(
+     */
+    static auto shift_right(T* source_begin, T* source_end, T* target_begin) {
+        // 1. uninitialized moves
+        auto const num_moves = std::distance(source_begin, source_end);
+        auto const target_end = target_begin + num_moves;
+        auto const num_uninitialized_move = std::min(num_moves, std::distance(source_end, target_end));
+        std::uninitialized_move(source_end - num_uninitialized_move, source_end, target_end - num_uninitialized_move);
+        std::move_backward(source_begin, source_end - num_uninitialized_move, target_end - num_uninitialized_move);
+        std::destroy(source_begin, std::min(source_end, target_begin));
+    }
+
+    template <direction D>
+    [[nodiscard]] auto make_uninitialized_space_new(size_t s, T* p, size_t count) -> T* {
+        auto target = svector();
+        // we know target is indirect because we're increasing capacity
+        target.reserve(s + count);
+
+        // move everything [begin, pos[
+        auto* target_pos = std::uninitialized_move(data<D>(), p, target.template data<direction::indirect>());
+
+        // move everything [pos, end]
+        std::uninitialized_move(p, data<D>() + s, target_pos + count);
+
+        target.template set_size<direction::indirect>(s + count);
+        *this = std::move(target);
+        return target_pos;
+    }
+
+    template <direction D>
+    [[nodiscard]] auto make_uninitialized_space(T const* pos, size_t count) -> T* {
+        auto* const p = const_cast<T*>(pos); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+        auto s = size<D>();
+        if (s + count > capacity<D>()) {
+            return make_uninitialized_space_new<D>(s, p, count);
+        }
+
+        shift_right(p, data<D>() + s, p + count);
+        set_size<D>(s + count);
+        return p;
+    }
+
+    // makes space for uninitialized data of cout elements. Also updates size.
+    [[nodiscard]] auto make_uninitialized_space(T const* pos, size_t count) -> T* {
+        if (is_direct()) {
+            return make_uninitialized_space<direction::direct>(pos, count);
+        }
+        return make_uninitialized_space<direction::indirect>(pos, count);
+    }
+
+    void destroy() {
+        auto const is_dir = is_direct();
+        if constexpr (!std::is_trivially_destructible_v<T>) {
+            T* ptr = nullptr;
+            size_t s = 0;
+            if (is_dir) {
+                ptr = data<direction::direct>();
+                s = size<direction::direct>();
+            } else {
+                ptr = data<direction::indirect>();
+                s = size<direction::indirect>();
+            }
+            std::destroy_n(ptr, s);
+        }
+        if (!is_dir) {
+            delete indirect();
+        }
+    }
+
+    // performs a const_cast so we don't need this implementation twice
+    template <direction D>
+    auto at(size_t idx) -> T& {
+        if (idx >= size<D>()) {
+            throw std::out_of_range{"svector: idx out of range"};
+        }
+        auto* ptr = const_cast<T*>(data<D>() + idx); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+        return *ptr;
+    } // LCOV_EXCL_LINE why is this single } marked as not covered? gcov bug?
+
+public:
+    using value_type = T;
+    using size_type = size_t;
+    using difference_type = std::ptrdiff_t;
+    using reference = value_type&;
+    using const_reference = value_type const&;
+    using pointer = T*;
+    using const_pointer = T const*;
+    using iterator = T*;
+    using const_iterator = T const*;
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+    svector() {
+        set_direct_and_size(0);
+    }
+
+    svector(size_t count, T const& value)
+        : svector() {
+        resize(count, value);
+    }
+
+    explicit svector(size_t count)
+        : svector() {
+        reserve(count);
+        if (is_direct()) {
+            resize_after_reserve<direction::direct>(count);
+        } else {
+            resize_after_reserve<direction::indirect>(count);
+        }
+    }
+
+    template <typename InputIt, typename = detail::enable_if_t<detail::is_input_iterator<InputIt>>>
+    svector(InputIt first, InputIt last)
+        : svector() {
+        assign(first, last);
+    }
+
+    svector(svector const& other)
+        : svector() {
+        auto s = other.size();
+        reserve(s);
+        std::uninitialized_copy(other.begin(), other.end(), begin());
+        set_size(s);
+    }
+
+    svector(svector&& other) noexcept
+        : svector() {
+        do_move_assign(std::move(other));
+    }
+
+    svector(std::initializer_list<T> init)
+        : svector(init.begin(), init.end()) {}
+
+    ~svector() {
+        destroy();
+    }
+
+    void assign(size_t count, T const& value) {
+        clear();
+        resize(count, value);
+    }
+
+    template <typename InputIt, typename = detail::enable_if_t<detail::is_input_iterator<InputIt>>>
+    void assign(InputIt first, InputIt last) {
+        assign(first, last, typename std::iterator_traits<InputIt>::iterator_category());
+    }
+
+    void assign(std::initializer_list<T> l) {
+        assign(l.begin(), l.end());
+    }
+
+    auto operator=(svector const& other) -> svector& {
+        if (&other == this) {
+            return *this;
+        }
+
+        assign(other.begin(), other.end());
+        return *this;
+    }
+
+    auto operator=(svector&& other) noexcept -> svector& {
+        if (&other == this) {
+            // It doesn't seem to be required to do self-check, but let's do it anyways to be safe
+            return *this;
+        }
+        destroy();
+        do_move_assign(std::move(other));
+        return *this;
+    }
+
+    auto operator=(std::initializer_list<T> l) -> svector& {
+        assign(l.begin(), l.end());
+        return *this;
+    }
+
+    void resize(size_t count) {
+        if (count > capacity()) {
+            reserve(count);
+        }
+        if (is_direct()) {
+            resize_after_reserve<direction::direct>(count);
+        } else {
+            resize_after_reserve<direction::indirect>(count);
+        }
+    }
+
+    void resize(size_t count, T const& value) {
+        if (count > capacity()) {
+            reserve(count);
+        }
+        if (is_direct()) {
+            resize_after_reserve<direction::direct>(count, value);
+        } else {
+            resize_after_reserve<direction::indirect>(count, value);
+        }
+    }
+
+    auto reserve(size_t s) {
+        auto old_capacity = capacity();
+        auto new_capacity = calculate_new_capacity(s, old_capacity);
+        if (new_capacity > old_capacity) {
+            realloc(new_capacity);
+        }
+    }
+
+    [[nodiscard]] auto capacity() const -> size_t {
+        if (is_direct()) {
+            return capacity<direction::direct>();
+        }
+        return capacity<direction::indirect>();
+    }
+
+    [[nodiscard]] auto size() const -> size_t {
+        if (is_direct()) {
+            return size<direction::direct>();
+        }
+        return size<direction::indirect>();
+    }
+
+    [[nodiscard]] auto data() -> T* {
+        if (is_direct()) {
+            return direct_data();
+        }
+        return indirect()->data();
+    }
+
+    [[nodiscard]] auto data() const -> T const* {
+        return const_cast<svector*>(this)->data(); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    template <class... Args>
+    auto emplace_back(Args&&... args) -> T& {
+        size_t c; // NOLINT(cppcoreguidelines-init-variables)
+        size_t s; // NOLINT(cppcoreguidelines-init-variables)
+        bool is_dir = is_direct();
+        if (is_dir) {
+            c = capacity<direction::direct>();
+            s = size<direction::direct>();
+        } else {
+            c = capacity<direction::indirect>();
+            s = size<direction::indirect>();
+        }
+
+        if (s == c) {
+            auto new_capacity = calculate_new_capacity(s + 1, c);
+            realloc(new_capacity);
+            // reallocation happened, so we definitely are now in indirect mode
+            is_dir = false;
+        }
+
+        T* ptr; // NOLINT(cppcoreguidelines-init-variables)
+        if (is_dir) {
+            ptr = data<direction::direct>() + s;
+            set_size<direction::direct>(s + 1);
+        } else {
+            ptr = data<direction::indirect>() + s;
+            set_size<direction::indirect>(s + 1);
+        }
+        return *new (static_cast<void*>(ptr)) T(std::forward<Args>(args)...);
+    }
+
+    void push_back(T const& value) {
+        emplace_back(value);
+    }
+
+    void push_back(T&& value) {
+        emplace_back(std::move(value));
+    }
+
+    [[nodiscard]] auto operator[](size_t idx) const -> T const& {
+        return *(data() + idx);
+    }
+
+    [[nodiscard]] auto operator[](size_t idx) -> T& {
+        return *(data() + idx);
+    }
+
+    auto at(size_t idx) -> T& {
+        if (is_direct()) {
+            return at<direction::direct>(idx);
+        }
+        return at<direction::indirect>(idx);
+    }
+
+    auto at(size_t idx) const -> T const& {
+        return const_cast<svector*>(this)->at(idx); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    [[nodiscard]] auto begin() const -> T const* {
+        return data();
+    }
+
+    [[nodiscard]] auto cbegin() const -> T const* {
+        return begin();
+    }
+
+    [[nodiscard]] auto begin() -> T* {
+        return data();
+    }
+
+    [[nodiscard]] auto end() -> T* {
+        if (is_direct()) {
+            return data<direction::direct>() + size<direction::direct>();
+        }
+        return data<direction::indirect>() + size<direction::indirect>();
+    }
+
+    [[nodiscard]] auto end() const -> T const* {
+        return const_cast<svector*>(this)->end(); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    [[nodiscard]] auto cend() const -> T const* {
+        return end();
+    }
+
+    [[nodiscard]] auto rbegin() -> reverse_iterator {
+        return reverse_iterator{end()};
+    }
+
+    [[nodiscard]] auto rbegin() const -> const_reverse_iterator {
+        return crbegin();
+    }
+
+    [[nodiscard]] auto crbegin() const -> const_reverse_iterator {
+        return const_reverse_iterator{end()};
+    }
+
+    [[nodiscard]] auto rend() -> reverse_iterator {
+        return reverse_iterator{begin()};
+    }
+
+    [[nodiscard]] auto rend() const -> const_reverse_iterator {
+        return crend();
+    }
+
+    [[nodiscard]] auto crend() const -> const_reverse_iterator {
+        return const_reverse_iterator{begin()};
+    }
+
+    [[nodiscard]] auto front() const -> T const& {
+        return *data();
+    }
+
+    [[nodiscard]] auto front() -> T& {
+        return *data();
+    }
+
+    [[nodiscard]] auto back() -> T& {
+        if (is_direct()) {
+            return *(data<direction::direct>() + size<direction::direct>() - 1);
+        }
+        return *(data<direction::indirect>() + size<direction::indirect>() - 1);
+    }
+
+    [[nodiscard]] auto back() const -> T const& {
+        return const_cast<svector*>(this)->back(); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    void clear() {
+        if constexpr (!std::is_trivially_destructible_v<T>) {
+            std::destroy(begin(), end());
+        }
+
+        if (is_direct()) {
+            set_size<direction::direct>(0);
+        } else {
+            set_size<direction::indirect>(0);
+        }
+    }
+
+    [[nodiscard]] auto empty() const -> bool {
+        return 0U == size();
+    }
+
+    void pop_back() {
+        if (is_direct()) {
+            pop_back<direction::direct>();
+        } else {
+            pop_back<direction::indirect>();
+        }
+    }
+
+    [[nodiscard]] static auto max_size() -> size_t {
+        return std::numeric_limits<std::ptrdiff_t>::max();
+    }
+
+    void swap(svector& other) {
+        // TODO we could try to do the minimum number of moves
+        std::swap(*this, other);
+    }
+
+    void shrink_to_fit() {
+        // per the standard we wouldn't need to do anything here. But since we are so nice,
+        // let's do the shrink.
+        auto const c = capacity();
+        auto const s = size();
+        if (s >= c) {
+            return;
+        }
+
+        auto new_capacity = calculate_new_capacity(s, N);
+        if (new_capacity == c) {
+            // nothing change!
+            return;
+        }
+
+        realloc(new_capacity);
+    }
+
+    template <class... Args>
+    auto emplace(const_iterator pos, Args&&... args) -> iterator {
+        auto* p = make_uninitialized_space(pos, 1);
+        return new (static_cast<void*>(p)) T(std::forward<Args>(args)...);
+    }
+
+    auto insert(const_iterator pos, T const& value) -> iterator {
+        return emplace(pos, value);
+    }
+
+    auto insert(const_iterator pos, T&& value) -> iterator {
+        return emplace(pos, std::move(value));
+    }
+
+    auto insert(const_iterator pos, size_t count, T const& value) -> iterator {
+        auto* p = make_uninitialized_space(pos, count);
+        std::uninitialized_fill_n(p, count, value);
+        return p;
+    }
+
+    template <typename It>
+    auto insert(const_iterator pos, It first, It last, std::input_iterator_tag /*unused*/) {
+        if (!(first != last)) {
+            return const_cast<T*>(pos); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+        }
+
+        // just input_iterator_tag makes this very slow. Let's do the same as the STL.
+        if (pos == end()) {
+            auto s = size();
+            while (first != last) {
+                emplace_back(*first);
+                ++first;
+            }
+            return begin() + s;
+        }
+
+        auto tmp = svector(first, last);
+        return insert(pos, std::make_move_iterator(tmp.begin()), std::make_move_iterator(tmp.end()));
+    }
+
+    template <typename It>
+    auto insert(const_iterator pos, It first, It last, std::forward_iterator_tag /*unused*/) {
+        auto* p = make_uninitialized_space(pos, std::distance(first, last));
+        std::uninitialized_copy(first, last, p);
+        return p;
+    }
+
+    template <typename InputIt, typename = detail::enable_if_t<detail::is_input_iterator<InputIt>>>
+    auto insert(const_iterator pos, InputIt first, InputIt last) -> iterator {
+        return insert(pos, first, last, typename std::iterator_traits<InputIt>::iterator_category());
+    }
+
+    auto insert(const_iterator pos, std::initializer_list<T> l) -> iterator {
+        return insert(pos, l.begin(), l.end());
+    }
+
+    auto erase(const_iterator pos) -> iterator {
+        return erase(pos, pos + 1);
+    }
+
+    auto erase(const_iterator first, const_iterator last) -> iterator {
+        if (is_direct()) {
+            return erase_checked_end<direction::direct>(first, last);
+        }
+        return erase_checked_end<direction::indirect>(first, last);
+    }
+};
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator==(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return std::equal(a.begin(), a.end(), b.begin(), b.end());
+}
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator!=(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return !(a == b);
+}
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator<(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end());
+}
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator>=(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return !(a < b);
+}
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator>(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return std::lexicographical_compare(b.begin(), b.end(), a.begin(), a.end());
+}
+
+template <typename T, size_t NA, size_t NB>
+[[nodiscard]] auto operator<=(svector<T, NA> const& a, svector<T, NB> const& b) -> bool {
+    return !(a > b);
+}
+
+} // namespace ANKERL_SVECTOR_NAMESPACE
+} // namespace ankerl
+
+// NOLINTNEXTLINE(cert-dcl58-cpp)
+namespace std {
+inline namespace ANKERL_SVECTOR_NAMESPACE {
+
+template <class T, size_t N, class U>
+constexpr auto erase(ankerl::svector<T, N>& sv, U const& value) -> typename ankerl::svector<T, N>::size_type {
+    auto* removed_begin = std::remove(sv.begin(), sv.end(), value);
+    auto num_removed = std::distance(removed_begin, sv.end());
+    sv.erase(removed_begin, sv.end());
+    return num_removed;
+}
+
+template <class T, size_t N, class Pred>
+constexpr auto erase_if(ankerl::svector<T, N>& sv, Pred pred) -> typename ankerl::svector<T, N>::size_type {
+    auto* removed_begin = std::remove_if(sv.begin(), sv.end(), pred);
+    auto num_removed = std::distance(removed_begin, sv.end());
+    sv.erase(removed_begin, sv.end());
+    return num_removed;
+}
+
+} // namespace ANKERL_SVECTOR_NAMESPACE
+} // namespace std
+
+#endif
diff --git a/contrib/ankerl/unordered_dense.h b/contrib/ankerl/unordered_dense.h
new file mode 100644
index 000000000..9ae108173
--- /dev/null
+++ b/contrib/ankerl/unordered_dense.h
@@ -0,0 +1,1199 @@
+///////////////////////// ankerl::unordered_dense::{map, set} /////////////////////////
+
+// A fast & densely stored hashmap and hashset based on robin-hood backward shift deletion.
+// Version 1.0.2
+// https://github.com/martinus/unordered_dense
+//
+// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2022 Martin Leitner-Ankerl <martin.ankerl@gmail.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 ANKERL_UNORDERED_DENSE_H
+#define ANKERL_UNORDERED_DENSE_H
+
+// see https://semver.org/spec/v2.0.0.html
+#define ANKERL_UNORDERED_DENSE_VERSION_MAJOR 1 // incompatible API changes
+#define ANKERL_UNORDERED_DENSE_VERSION_MINOR 0 // add functionality in a backwards compatible manner
+#define ANKERL_UNORDERED_DENSE_VERSION_PATCH 2 // backwards compatible bug fixes
+
+#if __cplusplus < 201703L
+#    error ankerl::unordered_dense requires C++17 or higher
+#else
+
+#    include <array>            // for array
+#    include <cstdint>          // for uint64_t, uint32_t, uint8_t, UINT64_C
+#    include <cstring>          // for size_t, memcpy, memset
+#    include <functional>       // for equal_to, hash
+#    include <initializer_list> // for initializer_list
+#    include <iterator>         // for pair, distance
+#    include <limits>           // for numeric_limits
+#    include <memory>           // for allocator, allocator_traits, shared_ptr
+#    include <stdexcept>        // for out_of_range
+#    include <string>           // for basic_string
+#    include <string_view>      // for basic_string_view, hash
+#    include <tuple>            // for forward_as_tuple
+#    include <type_traits>      // for enable_if_t, declval, conditional_t, ena...
+#    include <utility>          // for forward, exchange, pair, as_const, piece...
+#    include <vector>           // for vector
+
+#    define ANKERL_UNORDERED_DENSE_PMR 0
+#    if defined(__has_include)
+#        if __has_include(<memory_resource>)
+#            undef ANKERL_UNORDERED_DENSE_PMR
+#            define ANKERL_UNORDERED_DENSE_PMR 1
+#            include <memory_resource> // for polymorphic_allocator
+#        endif
+#    endif
+
+#    if defined(_MSC_VER) && defined(_M_X64)
+#        include <intrin.h>
+#        pragma intrinsic(_umul128)
+#    endif
+
+#    if defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__clang__)
+#        define ANKERL_UNORDERED_DENSE_LIKELY(x) __builtin_expect(x, 1)
+#        define ANKERL_UNORDERED_DENSE_UNLIKELY(x) __builtin_expect(x, 0)
+#    else
+#        define ANKERL_UNORDERED_DENSE_LIKELY(x) (x)
+#        define ANKERL_UNORDERED_DENSE_UNLIKELY(x) (x)
+#    endif
+
+namespace ankerl::unordered_dense {
+
+// hash ///////////////////////////////////////////////////////////////////////
+
+// This is a stripped-down implementation of wyhash: https://github.com/wangyi-fudan/wyhash
+// No big-endian support (because different values on different machines don't matter),
+// hardcodes seed and the secret, reformattes the code, and clang-tidy fixes.
+namespace detail::wyhash {
+
+static inline void mum(uint64_t* a, uint64_t* b) {
+#    if defined(__SIZEOF_INT128__)
+    __uint128_t r = *a;
+    r *= *b;
+    *a = static_cast<uint64_t>(r);
+    *b = static_cast<uint64_t>(r >> 64U);
+#    elif defined(_MSC_VER) && defined(_M_X64)
+    *a = _umul128(*a, *b, b);
+#    else
+    uint64_t ha = *a >> 32U;
+    uint64_t hb = *b >> 32U;
+    uint64_t la = static_cast<uint32_t>(*a);
+    uint64_t lb = static_cast<uint32_t>(*b);
+    uint64_t hi{};
+    uint64_t lo{};
+    uint64_t rh = ha * hb;
+    uint64_t rm0 = ha * lb;
+    uint64_t rm1 = hb * la;
+    uint64_t rl = la * lb;
+    uint64_t t = rl + (rm0 << 32U);
+    auto c = static_cast<uint64_t>(t < rl);
+    lo = t + (rm1 << 32U);
+    c += static_cast<uint64_t>(lo < t);
+    hi = rh + (rm0 >> 32U) + (rm1 >> 32U) + c;
+    *a = lo;
+    *b = hi;
+#    endif
+}
+
+// multiply and xor mix function, aka MUM
+[[nodiscard]] static inline auto mix(uint64_t a, uint64_t b) -> uint64_t {
+    mum(&a, &b);
+    return a ^ b;
+}
+
+// read functions. WARNING: we don't care about endianness, so results are different on big endian!
+[[nodiscard]] static inline auto r8(const uint8_t* p) -> uint64_t {
+    uint64_t v{};
+    std::memcpy(&v, p, 8);
+    return v;
+}
+
+[[nodiscard]] static inline auto r4(const uint8_t* p) -> uint64_t {
+    uint32_t v{};
+    std::memcpy(&v, p, 4);
+    return v;
+}
+
+// reads 1, 2, or 3 bytes
+[[nodiscard]] static inline auto r3(const uint8_t* p, size_t k) -> uint64_t {
+    return (static_cast<uint64_t>(p[0]) << 16U) | (static_cast<uint64_t>(p[k >> 1U]) << 8U) | p[k - 1];
+}
+
+[[nodiscard]] static inline auto hash(void const* key, size_t len) -> uint64_t {
+    static constexpr auto secret = std::array{UINT64_C(0xa0761d6478bd642f),
+                                              UINT64_C(0xe7037ed1a0b428db),
+                                              UINT64_C(0x8ebc6af09c88c6e3),
+                                              UINT64_C(0x589965cc75374cc3)};
+
+    auto const* p = static_cast<uint8_t const*>(key);
+    uint64_t seed = secret[0];
+    uint64_t a{};
+    uint64_t b{};
+    if (ANKERL_UNORDERED_DENSE_LIKELY(len <= 16)) {
+        if (ANKERL_UNORDERED_DENSE_LIKELY(len >= 4)) {
+            a = (r4(p) << 32U) | r4(p + ((len >> 3U) << 2U));
+            b = (r4(p + len - 4) << 32U) | r4(p + len - 4 - ((len >> 3U) << 2U));
+        } else if (ANKERL_UNORDERED_DENSE_LIKELY(len > 0)) {
+            a = r3(p, len);
+            b = 0;
+        } else {
+            a = 0;
+            b = 0;
+        }
+    } else {
+        size_t i = len;
+        if (ANKERL_UNORDERED_DENSE_UNLIKELY(i > 48)) {
+            uint64_t see1 = seed;
+            uint64_t see2 = seed;
+            do {
+                seed = mix(r8(p) ^ secret[1], r8(p + 8) ^ seed);
+                see1 = mix(r8(p + 16) ^ secret[2], r8(p + 24) ^ see1);
+                see2 = mix(r8(p + 32) ^ secret[3], r8(p + 40) ^ see2);
+                p += 48;
+                i -= 48;
+            } while (ANKERL_UNORDERED_DENSE_LIKELY(i > 48));
+            seed ^= see1 ^ see2;
+        }
+        while (ANKERL_UNORDERED_DENSE_UNLIKELY(i > 16)) {
+            seed = mix(r8(p) ^ secret[1], r8(p + 8) ^ seed);
+            i -= 16;
+            p += 16;
+        }
+        a = r8(p + i - 16);
+        b = r8(p + i - 8);
+    }
+
+    return mix(secret[1] ^ len, mix(a ^ secret[1], b ^ seed));
+}
+
+[[nodiscard]] static inline auto hash(uint64_t x) -> uint64_t {
+    return detail::wyhash::mix(x, UINT64_C(0x9E3779B97F4A7C15));
+}
+
+} // namespace detail::wyhash
+
+template <typename T, typename Enable = void>
+struct hash : public std::hash<T> {
+    using is_avalanching = void;
+    auto operator()(T const& obj) const noexcept(noexcept(std::declval<std::hash<T>>().operator()(std::declval<T const&>())))
+        -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(std::hash<T>::operator()(obj)));
+    }
+};
+
+template <typename CharT>
+struct hash<std::basic_string<CharT>> {
+    using is_avalanching = void;
+    auto operator()(std::basic_string<CharT> const& str) const noexcept -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(str.data(), sizeof(CharT) * str.size()));
+    }
+};
+
+template <typename CharT>
+struct hash<std::basic_string_view<CharT>> {
+    using is_avalanching = void;
+    auto operator()(std::basic_string_view<CharT> const& sv) const noexcept -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(sv.data(), sizeof(CharT) * sv.size()));
+    }
+};
+
+template <class T>
+struct hash<T*> {
+    using is_avalanching = void;
+    auto operator()(T* ptr) const noexcept -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(reinterpret_cast<uintptr_t>(ptr)));
+    }
+};
+
+template <class T>
+struct hash<std::unique_ptr<T>> {
+    using is_avalanching = void;
+    auto operator()(std::unique_ptr<T> const& ptr) const noexcept -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(reinterpret_cast<uintptr_t>(ptr.get())));
+    }
+};
+
+template <class T>
+struct hash<std::shared_ptr<T>> {
+    using is_avalanching = void;
+    auto operator()(std::shared_ptr<T> const& ptr) const noexcept -> size_t {
+        return static_cast<size_t>(detail::wyhash::hash(reinterpret_cast<uintptr_t>(ptr.get())));
+    }
+};
+
+template <typename Enum>
+struct hash<Enum, typename std::enable_if<std::is_enum<Enum>::value>::type> {
+    using is_avalanching = void;
+    auto operator()(Enum e) const noexcept -> size_t {
+        using Underlying = typename std::underlying_type_t<Enum>;
+        return static_cast<size_t>(detail::wyhash::hash(static_cast<Underlying>(e)));
+    }
+};
+
+#    define ANKERL_UNORDERED_DENSE_HASH_STATICCAST(T)                                         \
+        template <>                                                                           \
+        struct hash<T> {                                                                      \
+            using is_avalanching = void;                                                      \
+            auto operator()(T const& obj) const noexcept -> size_t {                          \
+                return static_cast<size_t>(detail::wyhash::hash(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
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(bool);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(char);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(signed char);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(unsigned char);
+#    if __cplusplus >= 202002L
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(char8_t);
+#    endif
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(char16_t);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(char32_t);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(wchar_t);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(short);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(unsigned short);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(int);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(unsigned int);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(long);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(long long);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(unsigned long);
+ANKERL_UNORDERED_DENSE_HASH_STATICCAST(unsigned long long);
+
+#    if defined(__GNUC__) && !defined(__clang__)
+#        pragma GCC diagnostic pop
+#    endif
+
+namespace detail {
+
+struct nonesuch {};
+
+template <class Default, class AlwaysVoid, template <class...> class Op, class... Args>
+struct detector {
+    using value_t = std::false_type;
+    using type = Default;
+};
+
+template <class Default, template <class...> class Op, class... Args>
+struct detector<Default, std::void_t<Op<Args...>>, Op, Args...> {
+    using value_t = std::true_type;
+    using type = Op<Args...>;
+};
+
+template <template <class...> class Op, class... Args>
+using is_detected = typename detail::detector<detail::nonesuch, void, Op, Args...>::value_t;
+
+template <template <class...> class Op, class... Args>
+constexpr bool is_detected_v = is_detected<Op, Args...>::value;
+
+template <typename T>
+using detect_avalanching = typename T::is_avalanching;
+
+template <typename T>
+using detect_is_transparent = typename T::is_transparent;
+
+template <typename H, typename KE>
+using is_transparent =
+    std::enable_if_t<is_detected_v<detect_is_transparent, H> && is_detected_v<detect_is_transparent, KE>, bool>;
+
+// This is it, the table. Doubles as map and set, and uses `void` for T when its used as a set.
+template <class Key,
+          class T, // when void, treat it as a set.
+          class Hash,
+          class KeyEqual,
+          class Allocator>
+class table {
+    struct Bucket;
+    using ValueContainer =
+        typename std::vector<typename std::conditional_t<std::is_void_v<T>, Key, std::pair<Key, T>>, Allocator>;
+    using BucketAlloc = typename std::allocator_traits<Allocator>::template rebind_alloc<Bucket>;
+    using BucketAllocTraits = std::allocator_traits<BucketAlloc>;
+
+    static constexpr uint32_t BUCKET_DIST_INC = 1U << 8U;                    // skip 1 byte fingerprint
+    static constexpr uint32_t BUCKET_FINGERPRINT_MASK = BUCKET_DIST_INC - 1; // mask for 1 byte of fingerprint
+    static constexpr uint8_t INITIAL_SHIFTS = 64 - 3;                        // 2^(64-m_shift) number of buckets
+    static constexpr float DEFAULT_MAX_LOAD_FACTOR = 0.8F;
+
+public:
+    using key_type = Key;
+    using mapped_type = T;
+    using value_type = typename ValueContainer::value_type;
+    using size_type = typename ValueContainer::size_type;
+    using difference_type = typename ValueContainer::difference_type;
+    using hasher = Hash;
+    using key_equal = KeyEqual;
+    using allocator_type = typename ValueContainer::allocator_type;
+    using reference = typename ValueContainer::reference;
+    using const_reference = typename ValueContainer::const_reference;
+    using pointer = typename ValueContainer::pointer;
+    using const_pointer = typename ValueContainer::const_pointer;
+    using iterator = typename ValueContainer::iterator;
+    using const_iterator = typename ValueContainer::const_iterator;
+
+private:
+    struct Bucket {
+        uint32_t dist_and_fingerprint; // upper 3 byte: distance to original bucket. lower byte: fingerprint from hash
+        uint32_t value_idx;            // index into the m_values vector.
+    };
+    static_assert(std::is_trivially_destructible_v<Bucket>, "assert there's no need to call destructor / std::destroy");
+    static_assert(std::is_trivially_copyable_v<Bucket>, "assert we can just memset / memcpy");
+
+    ValueContainer m_values{}; // Contains all the key-value pairs in one densely stored container. No holes.
+    Bucket* m_buckets_start = nullptr;
+    Bucket* m_buckets_end = nullptr;
+    uint32_t m_max_bucket_capacity = 0;
+    float m_max_load_factor = DEFAULT_MAX_LOAD_FACTOR;
+    Hash m_hash{};
+    KeyEqual m_equal{};
+    uint8_t m_shifts = INITIAL_SHIFTS;
+
+    [[nodiscard]] auto next(Bucket const* bucket) const -> Bucket const* {
+        return ANKERL_UNORDERED_DENSE_UNLIKELY(bucket + 1 == m_buckets_end) ? m_buckets_start : bucket + 1;
+    }
+
+    [[nodiscard]] auto next(Bucket* bucket) -> Bucket* {
+        return ANKERL_UNORDERED_DENSE_UNLIKELY(bucket + 1 == m_buckets_end) ? m_buckets_start : bucket + 1;
+    }
+
+    template <typename K>
+    [[nodiscard]] constexpr auto mixed_hash(K const& key) const -> uint64_t {
+        if constexpr (is_detected_v<detect_avalanching, Hash>) {
+            return m_hash(key);
+        } else {
+            return wyhash::hash(m_hash(key));
+        }
+    }
+
+    [[nodiscard]] constexpr auto dist_and_fingerprint_from_hash(uint64_t hash) const -> uint32_t {
+        return BUCKET_DIST_INC | (hash & BUCKET_FINGERPRINT_MASK);
+    }
+
+    [[nodiscard]] constexpr auto bucket_from_hash(uint64_t hash) const -> Bucket const* {
+        return m_buckets_start + (hash >> m_shifts);
+    }
+
+    [[nodiscard]] constexpr auto bucket_from_hash(uint64_t hash) -> Bucket* {
+        return m_buckets_start + (hash >> m_shifts);
+    }
+
+    [[nodiscard]] static constexpr auto get_key(value_type const& vt) -> key_type const& {
+        if constexpr (std::is_void_v<T>) {
+            return vt;
+        } else {
+            return vt.first;
+        }
+    }
+
+    template <typename K>
+    [[nodiscard]] auto next_while_less(K const& key) -> std::pair<uint32_t, Bucket*> {
+        auto const& pair = std::as_const(*this).next_while_less(key);
+        return {pair.first, const_cast<Bucket*>(pair.second)}; // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    template <typename K>
+    [[nodiscard]] auto next_while_less(K const& key) const -> std::pair<uint32_t, Bucket const*> {
+        auto hash = mixed_hash(key);
+        auto dist_and_fingerprint = dist_and_fingerprint_from_hash(hash);
+        auto const* bucket = bucket_from_hash(hash);
+
+        while (dist_and_fingerprint < bucket->dist_and_fingerprint) {
+            dist_and_fingerprint += BUCKET_DIST_INC;
+            bucket = next(bucket);
+        }
+        return {dist_and_fingerprint, bucket};
+    }
+
+    void place_and_shift_up(Bucket bucket, Bucket* place) {
+        while (0 != place->dist_and_fingerprint) {
+            bucket = std::exchange(*place, bucket);
+            bucket.dist_and_fingerprint += BUCKET_DIST_INC;
+            place = next(place);
+        }
+        *place = bucket;
+    }
+
+    [[nodiscard]] static constexpr auto calc_num_buckets(uint8_t shifts) -> uint64_t {
+        return UINT64_C(1) << (64U - shifts);
+    }
+
+    [[nodiscard]] constexpr auto calc_shifts_for_size(size_t s) const -> uint8_t {
+        auto shifts = INITIAL_SHIFTS;
+        while (shifts > 0 && static_cast<uint64_t>(calc_num_buckets(shifts) * max_load_factor()) < s) {
+            --shifts;
+        }
+        return shifts;
+    }
+
+    // assumes m_values has data, m_buckets_start=m_buckets_end=nullptr, m_shifts is INITIAL_SHIFTS
+    void copy_buckets(table const& other) {
+        if (!empty()) {
+            m_shifts = other.m_shifts;
+            allocate_buckets_from_shift();
+            std::memcpy(m_buckets_start, other.m_buckets_start, sizeof(Bucket) * bucket_count());
+        }
+    }
+
+    /**
+     * True when no element can be added any more without increasing the size
+     */
+    [[nodiscard]] auto is_full() const -> bool {
+        return size() >= m_max_bucket_capacity;
+    }
+
+    void deallocate_buckets() {
+        auto bucket_alloc = BucketAlloc(m_values.get_allocator());
+        BucketAllocTraits::deallocate(bucket_alloc, m_buckets_start, bucket_count());
+        m_buckets_start = nullptr;
+        m_buckets_end = nullptr;
+        m_max_bucket_capacity = 0;
+    }
+
+    void allocate_buckets_from_shift() {
+        auto bucket_alloc = BucketAlloc(m_values.get_allocator());
+        auto num_buckets = calc_num_buckets(m_shifts);
+        m_buckets_start = BucketAllocTraits::allocate(bucket_alloc, num_buckets);
+        m_buckets_end = m_buckets_start + num_buckets;
+        m_max_bucket_capacity = static_cast<uint64_t>(num_buckets * max_load_factor());
+    }
+
+    void clear_buckets() {
+        if (m_buckets_start != nullptr) {
+            std::memset(m_buckets_start, 0, sizeof(Bucket) * bucket_count());
+        }
+    }
+
+    void clear_and_fill_buckets_from_values() {
+        clear_buckets();
+        for (uint32_t value_idx = 0, end_idx = static_cast<uint32_t>(m_values.size()); value_idx < end_idx; ++value_idx) {
+            auto const& key = get_key(m_values[value_idx]);
+            auto [dist_and_fingerprint, bucket] = next_while_less(key);
+
+            // we know for certain that key has not yet been inserted, so no need to check it.
+            place_and_shift_up({dist_and_fingerprint, value_idx}, bucket);
+        }
+    }
+
+    void increase_size() {
+        --m_shifts;
+        deallocate_buckets();
+        allocate_buckets_from_shift();
+        clear_and_fill_buckets_from_values();
+    }
+
+    void do_erase(Bucket* bucket) {
+        auto const value_idx_to_remove = bucket->value_idx;
+
+        // shift down until either empty or an element with correct spot is found
+        auto* next_bucket = next(bucket);
+        while (next_bucket->dist_and_fingerprint >= BUCKET_DIST_INC * 2) {
+            *bucket = {next_bucket->dist_and_fingerprint - BUCKET_DIST_INC, next_bucket->value_idx};
+            bucket = std::exchange(next_bucket, next(next_bucket));
+        }
+        *bucket = {};
+
+        // update m_values
+        if (value_idx_to_remove != m_values.size() - 1) {
+            // no luck, we'll have to replace the value with the last one and update the index accordingly
+            auto& val = m_values[value_idx_to_remove];
+            val = std::move(m_values.back());
+
+            // update the values_idx of the moved entry. No need to play the info game, just look until we find the values_idx
+            auto mh = mixed_hash(get_key(val));
+            bucket = bucket_from_hash(mh);
+
+            auto const values_idx_back = static_cast<uint32_t>(m_values.size() - 1);
+            while (values_idx_back != bucket->value_idx) {
+                bucket = next(bucket);
+            }
+            bucket->value_idx = value_idx_to_remove;
+        }
+        m_values.pop_back();
+    }
+
+    template <typename K>
+    auto do_erase_key(K&& key) -> size_t {
+        if (empty()) {
+            return 0;
+        }
+
+        auto [dist_and_fingerprint, bucket] = next_while_less(key);
+
+        while (dist_and_fingerprint == bucket->dist_and_fingerprint && !m_equal(key, get_key(m_values[bucket->value_idx]))) {
+            dist_and_fingerprint += BUCKET_DIST_INC;
+            bucket = next(bucket);
+        }
+
+        if (dist_and_fingerprint != bucket->dist_and_fingerprint) {
+            return 0;
+        }
+        do_erase(bucket);
+        return 1;
+    }
+
+    template <class K, class M>
+    auto do_insert_or_assign(K&& key, M&& mapped) -> std::pair<iterator, bool> {
+        auto it_isinserted = try_emplace(std::forward<K>(key), std::forward<M>(mapped));
+        if (!it_isinserted.second) {
+            it_isinserted.first->second = std::forward<M>(mapped);
+        }
+        return it_isinserted;
+    }
+
+    template <typename K, typename... Args>
+    auto do_try_emplace(K&& key, Args&&... args) -> std::pair<iterator, bool> {
+        if (is_full()) {
+            increase_size();
+        }
+
+        auto hash = mixed_hash(key);
+        auto dist_and_fingerprint = dist_and_fingerprint_from_hash(hash);
+        auto* bucket = bucket_from_hash(hash);
+
+        while (dist_and_fingerprint <= bucket->dist_and_fingerprint) {
+            if (dist_and_fingerprint == bucket->dist_and_fingerprint && m_equal(key, m_values[bucket->value_idx].first)) {
+                return {begin() + bucket->value_idx, false};
+            }
+            dist_and_fingerprint += BUCKET_DIST_INC;
+            bucket = next(bucket);
+        }
+
+        // emplace the new value. If that throws an exception, no harm done; index is still in a valid state
+        m_values.emplace_back(std::piecewise_construct,
+                              std::forward_as_tuple(std::forward<K>(key)),
+                              std::forward_as_tuple(std::forward<Args>(args)...));
+
+        // place element and shift up until we find an empty spot
+        uint32_t value_idx = static_cast<uint32_t>(m_values.size()) - 1;
+        place_and_shift_up({dist_and_fingerprint, value_idx}, bucket);
+        return {begin() + value_idx, true};
+    }
+
+    template <typename K>
+    auto do_find(K const& key) -> iterator {
+        if (empty()) {
+            return end();
+        }
+
+        auto mh = mixed_hash(key);
+        auto dist_and_fingerprint = dist_and_fingerprint_from_hash(mh);
+        auto const* bucket = bucket_from_hash(mh);
+
+        // unrolled loop. *Always* check a few directly, then enter the loop. This is faster.
+        if (dist_and_fingerprint == bucket->dist_and_fingerprint && m_equal(key, get_key(m_values[bucket->value_idx]))) {
+            return begin() + bucket->value_idx;
+        }
+        dist_and_fingerprint += BUCKET_DIST_INC;
+        bucket = next(bucket);
+
+        if (dist_and_fingerprint == bucket->dist_and_fingerprint && m_equal(key, get_key(m_values[bucket->value_idx]))) {
+            return begin() + bucket->value_idx;
+        }
+        dist_and_fingerprint += BUCKET_DIST_INC;
+        bucket = next(bucket);
+
+        do {
+            if (dist_and_fingerprint == bucket->dist_and_fingerprint && m_equal(key, get_key(m_values[bucket->value_idx]))) {
+                return begin() + bucket->value_idx;
+            }
+            dist_and_fingerprint += BUCKET_DIST_INC;
+            bucket = next(bucket);
+        } while (dist_and_fingerprint <= bucket->dist_and_fingerprint);
+        return end();
+    }
+
+    template <typename K>
+    auto do_find(K const& key) const -> const_iterator {
+        return const_cast<table*>(this)->do_find(key); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+public:
+    table()
+        : table(0) {}
+
+    explicit table(size_t /*bucket_count*/,
+                   Hash const& hash = Hash(),
+                   KeyEqual const& equal = KeyEqual(),
+                   Allocator const& alloc = Allocator())
+        : m_values(alloc)
+        , m_hash(hash)
+        , m_equal(equal) {}
+
+    table(size_t bucket_count, Allocator const& alloc)
+        : table(bucket_count, Hash(), KeyEqual(), alloc) {}
+
+    table(size_t bucket_count, Hash const& hash, Allocator const& alloc)
+        : table(bucket_count, hash, KeyEqual(), alloc) {}
+
+    explicit table(Allocator const& alloc)
+        : table(0, Hash(), KeyEqual(), alloc) {}
+
+    template <class InputIt>
+    table(InputIt first,
+          InputIt last,
+          size_type bucket_count = 0,
+          Hash const& hash = Hash(),
+          KeyEqual const& equal = KeyEqual(),
+          Allocator const& alloc = Allocator())
+        : table(bucket_count, hash, equal, alloc) {
+        insert(first, last);
+    }
+
+    template <class InputIt>
+    table(InputIt first, InputIt last, size_type bucket_count, Allocator const& alloc)
+        : table(first, last, bucket_count, Hash(), KeyEqual(), alloc) {}
+
+    template <class InputIt>
+    table(InputIt first, InputIt last, size_type bucket_count, Hash const& hash, Allocator const& alloc)
+        : table(first, last, bucket_count, hash, KeyEqual(), alloc) {}
+
+    table(table const& other)
+        : table(other, other.m_values.get_allocator()) {}
+
+    table(table const& other, Allocator const& alloc)
+        : m_values(other.m_values, alloc)
+        , m_max_load_factor(other.m_max_load_factor)
+        , m_hash(other.m_hash)
+        , m_equal(other.m_equal) {
+        copy_buckets(other);
+    }
+
+    table(table&& other) noexcept
+        : table(std::move(other), other.m_values.get_allocator()) {}
+
+    table(table&& other, Allocator const& alloc) noexcept
+        : m_values(std::move(other.m_values), alloc)
+        , m_buckets_start(std::exchange(other.m_buckets_start, nullptr))
+        , m_buckets_end(std::exchange(other.m_buckets_end, nullptr))
+        , m_max_bucket_capacity(std::exchange(other.m_max_bucket_capacity, 0))
+        , m_max_load_factor(std::exchange(other.m_max_load_factor, DEFAULT_MAX_LOAD_FACTOR))
+        , m_hash(std::exchange(other.m_hash, {}))
+        , m_equal(std::exchange(other.m_equal, {}))
+        , m_shifts(std::exchange(other.m_shifts, INITIAL_SHIFTS)) {
+        other.m_values.clear();
+    }
+
+    table(std::initializer_list<value_type> ilist,
+          size_t bucket_count = 0,
+          Hash const& hash = Hash(),
+          KeyEqual const& equal = KeyEqual(),
+          Allocator const& alloc = Allocator())
+        : table(bucket_count, hash, equal, alloc) {
+        insert(ilist);
+    }
+
+    table(std::initializer_list<value_type> ilist, size_type bucket_count, const Allocator& alloc)
+        : table(ilist, bucket_count, Hash(), KeyEqual(), alloc) {}
+
+    table(std::initializer_list<value_type> init, size_type bucket_count, Hash const& hash, Allocator const& alloc)
+        : table(init, bucket_count, hash, KeyEqual(), alloc) {}
+
+    ~table() {
+        auto bucket_alloc = BucketAlloc(m_values.get_allocator());
+        BucketAllocTraits::deallocate(bucket_alloc, m_buckets_start, bucket_count());
+    }
+
+    auto operator=(table const& other) -> table& {
+        if (&other != this) {
+            deallocate_buckets(); // deallocate before m_values is set (might have another allocator)
+            m_values = other.m_values;
+            m_max_load_factor = other.m_max_load_factor;
+            m_hash = other.m_hash;
+            m_equal = other.m_equal;
+            m_shifts = INITIAL_SHIFTS;
+            copy_buckets(other);
+        }
+        return *this;
+    }
+
+    auto operator=(table&& other) noexcept(
+        noexcept(std::is_nothrow_move_assignable_v<ValueContainer>&& std::is_nothrow_move_assignable_v<Hash>&&
+                     std::is_nothrow_move_assignable_v<KeyEqual>)) -> table& {
+        if (&other != this) {
+            deallocate_buckets(); // deallocate before m_values is set (might have another allocator)
+            m_values = std::move(other.m_values);
+            m_buckets_start = std::exchange(other.m_buckets_start, nullptr);
+            m_buckets_end = std::exchange(other.m_buckets_end, nullptr);
+            m_max_bucket_capacity = std::exchange(other.m_max_bucket_capacity, 0);
+            m_max_load_factor = std::exchange(other.m_max_load_factor, DEFAULT_MAX_LOAD_FACTOR);
+            m_hash = std::exchange(other.m_hash, {});
+            m_equal = std::exchange(other.m_equal, {});
+            m_shifts = std::exchange(other.m_shifts, INITIAL_SHIFTS);
+            other.m_values.clear();
+        }
+        return *this;
+    }
+
+    auto operator=(std::initializer_list<value_type> ilist) -> table& {
+        clear();
+        insert(ilist);
+        return *this;
+    }
+
+    auto get_allocator() const noexcept -> allocator_type {
+        return m_values.get_allocator();
+    }
+
+    // iterators //////////////////////////////////////////////////////////////
+
+    auto begin() noexcept -> iterator {
+        return m_values.begin();
+    }
+
+    auto begin() const noexcept -> const_iterator {
+        return m_values.begin();
+    }
+
+    auto cbegin() const noexcept -> const_iterator {
+        return m_values.cbegin();
+    }
+
+    auto end() noexcept -> iterator {
+        return m_values.end();
+    }
+
+    auto cend() const noexcept -> const_iterator {
+        return m_values.cend();
+    }
+
+    auto end() const noexcept -> const_iterator {
+        return m_values.end();
+    }
+
+    // capacity ///////////////////////////////////////////////////////////////
+
+    [[nodiscard]] auto empty() const noexcept -> bool {
+        return m_values.empty();
+    }
+
+    [[nodiscard]] auto size() const noexcept -> size_t {
+        return m_values.size();
+    }
+
+    [[nodiscard]] auto max_size() const noexcept -> size_t {
+        return std::numeric_limits<uint32_t>::max();
+    }
+
+    // modifiers //////////////////////////////////////////////////////////////
+
+    void clear() {
+        m_values.clear();
+        clear_buckets();
+    }
+
+    auto insert(value_type const& value) -> std::pair<iterator, bool> {
+        return emplace(value);
+    }
+
+    auto insert(value_type&& value) -> std::pair<iterator, bool> {
+        return emplace(std::move(value));
+    }
+
+    template <class P, std::enable_if_t<std::is_constructible_v<value_type, P&&>, bool> = true>
+    auto insert(P&& value) -> std::pair<iterator, bool> {
+        return emplace(std::forward<P>(value));
+    }
+
+    auto insert(const_iterator /*hint*/, value_type const& value) -> iterator {
+        return insert(value).first;
+    }
+
+    auto insert(const_iterator /*hint*/, value_type&& value) -> iterator {
+        return insert(std::move(value)).first;
+    }
+
+    template <class P, std::enable_if_t<std::is_constructible_v<value_type, P&&>, bool> = true>
+    auto insert(const_iterator /*hint*/, P&& value) -> iterator {
+        return insert(std::forward<P>(value)).first;
+    }
+
+    template <class InputIt>
+    void insert(InputIt first, InputIt last) {
+        while (first != last) {
+            insert(*first);
+            ++first;
+        }
+    }
+
+    void insert(std::initializer_list<value_type> ilist) {
+        insert(ilist.begin(), ilist.end());
+    }
+
+    template <class M, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto insert_or_assign(Key const& key, M&& mapped) -> std::pair<iterator, bool> {
+        return do_insert_or_assign(key, std::forward<M>(mapped));
+    }
+
+    template <class M, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto insert_or_assign(Key&& key, M&& mapped) -> std::pair<iterator, bool> {
+        return do_insert_or_assign(std::move(key), std::forward<M>(mapped));
+    }
+
+    template <class M, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto insert_or_assign(const_iterator /*hint*/, Key const& key, M&& mapped) -> iterator {
+        return do_insert_or_assign(key, std::forward<M>(mapped)).first;
+    }
+
+    template <class M, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto insert_or_assign(const_iterator /*hint*/, Key&& key, M&& mapped) -> iterator {
+        return do_insert_or_assign(std::move(key), std::forward<M>(mapped)).first;
+    }
+
+    template <class... Args>
+    auto emplace(Args&&... args) -> std::pair<iterator, bool> {
+        if (is_full()) {
+            increase_size();
+        }
+
+        // first emplace_back the object so it is constructed. If the key is already there, pop it.
+        auto& val = m_values.emplace_back(std::forward<Args>(args)...);
+        auto hash = mixed_hash(get_key(val));
+        auto dist_and_fingerprint = dist_and_fingerprint_from_hash(hash);
+        auto* bucket = bucket_from_hash(hash);
+
+        while (dist_and_fingerprint <= bucket->dist_and_fingerprint) {
+            if (dist_and_fingerprint == bucket->dist_and_fingerprint &&
+                m_equal(get_key(val), get_key(m_values[bucket->value_idx]))) {
+                m_values.pop_back(); // value was already there, so get rid of it
+                return {begin() + bucket->value_idx, false};
+            }
+            dist_and_fingerprint += BUCKET_DIST_INC;
+            bucket = next(bucket);
+        }
+
+        // value is new, place the bucket and shift up until we find an empty spot
+        uint32_t value_idx = static_cast<uint32_t>(m_values.size()) - 1;
+        place_and_shift_up({dist_and_fingerprint, value_idx}, bucket);
+
+        return {begin() + value_idx, true};
+    }
+
+    template <class... Args>
+    auto emplace_hint(const_iterator /*hint*/, Args&&... args) -> iterator {
+        return emplace(std::forward<Args>(args)...).first;
+    }
+
+    template <class... Args, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto try_emplace(Key const& key, Args&&... args) -> std::pair<iterator, bool> {
+        return do_try_emplace(key, std::forward<Args>(args)...);
+    }
+
+    template <class... Args, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto try_emplace(Key&& key, Args&&... args) -> std::pair<iterator, bool> {
+        return do_try_emplace(std::move(key), std::forward<Args>(args)...);
+    }
+
+    template <class... Args, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto try_emplace(const_iterator /*hint*/, Key const& key, Args&&... args) -> iterator {
+        return do_try_emplace(key, std::forward<Args>(args)...).first;
+    }
+
+    template <class... Args, typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto try_emplace(const_iterator /*hint*/, Key&& key, Args&&... args) -> iterator {
+        return do_try_emplace(std::move(key), std::forward<Args>(args)...).first;
+    }
+
+    auto erase(iterator it) -> iterator {
+        auto hash = mixed_hash(get_key(*it));
+        auto* bucket = bucket_from_hash(hash);
+
+        auto const value_idx_to_remove = static_cast<uint32_t>(it - cbegin());
+        while (bucket->value_idx != value_idx_to_remove) {
+            bucket = next(bucket);
+        }
+
+        do_erase(bucket);
+        return begin() + value_idx_to_remove;
+    }
+
+    auto erase(const_iterator it) -> iterator {
+        return erase(begin() + (it - cbegin()));
+    }
+
+    auto erase(const_iterator first, const_iterator last) -> iterator {
+        auto const idx_first = first - cbegin();
+        auto const idx_last = last - cbegin();
+        auto const first_to_last = std::distance(first, last);
+        auto const last_to_end = std::distance(last, cend());
+
+        // remove elements from left to right which moves elements from the end back
+        auto const mid = idx_first + std::min(first_to_last, last_to_end);
+        auto idx = idx_first;
+        while (idx != mid) {
+            erase(begin() + idx);
+            ++idx;
+        }
+
+        // all elements from the right are moved, now remove the last element until all done
+        idx = idx_last;
+        while (idx != mid) {
+            --idx;
+            erase(begin() + idx);
+        }
+
+        return begin() + idx_first;
+    }
+
+    auto erase(Key const& key) -> size_t {
+        return do_erase_key(key);
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto erase(K&& key) -> size_t {
+        return do_erase_key(std::forward<K>(key));
+    }
+
+    void swap(table& other) noexcept(noexcept(std::is_nothrow_swappable_v<ValueContainer>&& std::is_nothrow_swappable_v<Hash>&&
+                                                  std::is_nothrow_swappable_v<KeyEqual>)) {
+        using std::swap;
+        swap(other, *this);
+    }
+
+    // lookup /////////////////////////////////////////////////////////////////
+
+    template <typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto at(key_type const& key) -> Q& {
+        if (auto it = find(key); end() != it) {
+            return it->second;
+        }
+        throw std::out_of_range("ankerl::unordered_dense::map::at(): key not found");
+    } // LCOV_EXCL_LINE is this a gcov/lcov bug? this method is fully tested.
+
+    template <typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto at(key_type const& key) const -> Q const& {
+        return const_cast<table*>(this)->at(key); // NOLINT(cppcoreguidelines-pro-type-const-cast)
+    }
+
+    template <typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto operator[](Key const& key) -> Q& {
+        return try_emplace(key).first->second;
+    }
+
+    template <typename Q = T, std::enable_if_t<!std::is_void_v<Q>, bool> = true>
+    auto operator[](Key&& key) -> Q& {
+        return try_emplace(std::move(key)).first->second;
+    }
+
+    auto count(Key const& key) const -> size_t {
+        return find(key) == end() ? 0 : 1;
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto count(K const& key) const -> size_t {
+        return find(key) == end() ? 0 : 1;
+    }
+
+    auto find(Key const& key) -> iterator {
+        return do_find(key);
+    }
+
+    auto find(Key const& key) const -> const_iterator {
+        return do_find(key);
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto find(K const& key) -> iterator {
+        return do_find(key);
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto find(K const& key) const -> const_iterator {
+        return do_find(key);
+    }
+
+    auto contains(Key const& key) const -> size_t {
+        return find(key) != end();
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto contains(K const& key) const -> size_t {
+        return find(key) != end();
+    }
+
+    auto equal_range(Key const& key) -> std::pair<iterator, iterator> {
+        auto it = do_find(key);
+        return {it, it == end() ? end() : it + 1};
+    }
+
+    auto equal_range(const Key& key) const -> std::pair<const_iterator, const_iterator> {
+        auto it = do_find(key);
+        return {it, it == end() ? end() : it + 1};
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto equal_range(K const& key) -> std::pair<iterator, iterator> {
+        auto it = do_find(key);
+        return {it, it == end() ? end() : it + 1};
+    }
+
+    template <class K, class H = Hash, class KE = KeyEqual, is_transparent<H, KE> = true>
+    auto equal_range(K const& key) const -> std::pair<const_iterator, const_iterator> {
+        auto it = do_find(key);
+        return {it, it == end() ? end() : it + 1};
+    }
+
+    // bucket interface ///////////////////////////////////////////////////////
+
+    auto bucket_count() const noexcept -> size_t { // NOLINT(modernize-use-nodiscard)
+        return m_buckets_end - m_buckets_start;
+    }
+
+    auto max_bucket_count() const noexcept -> size_t { // NOLINT(modernize-use-nodiscard)
+        return std::numeric_limits<uint32_t>::max();
+    }
+
+    // hash policy ////////////////////////////////////////////////////////////
+
+    [[nodiscard]] auto load_factor() const -> float {
+        return bucket_count() ? static_cast<float>(size()) / bucket_count() : 0.0F;
+    }
+
+    [[nodiscard]] auto max_load_factor() const -> float {
+        return m_max_load_factor;
+    }
+
+    void max_load_factor(float ml) {
+        m_max_load_factor = ml;
+        m_max_bucket_capacity = static_cast<uint32_t>(bucket_count() * max_load_factor());
+    }
+
+    void rehash(size_t count) {
+        auto shifts = calc_shifts_for_size(std::max(count, size()));
+        if (shifts != m_shifts) {
+            m_shifts = shifts;
+            deallocate_buckets();
+            m_values.shrink_to_fit();
+            allocate_buckets_from_shift();
+            clear_and_fill_buckets_from_values();
+        }
+    }
+
+    void reserve(size_t capa) {
+        auto shifts = calc_shifts_for_size(std::max(capa, size()));
+        if (shifts < m_shifts) {
+            m_shifts = shifts;
+            deallocate_buckets();
+            allocate_buckets_from_shift();
+            clear_and_fill_buckets_from_values();
+        }
+    }
+
+    // observers //////////////////////////////////////////////////////////////
+
+    auto hash_function() const -> hasher {
+        return m_hash;
+    }
+
+    auto key_eq() const -> key_equal {
+        return m_equal;
+    }
+
+    // non-member functions ///////////////////////////////////////////////////
+
+    friend auto operator==(table const& a, table const& b) -> bool {
+        if (&a == &b) {
+            return true;
+        }
+        if (a.size() != b.size()) {
+            return false;
+        }
+        for (auto const& b_entry : b) {
+            auto it = a.find(get_key(b_entry));
+            if constexpr (std::is_void_v<T>) {
+                // set: only check that the key is here
+                if (a.end() == it) {
+                    return false;
+                }
+            } else {
+                // map: check that key is here, then also check that value is the same
+                if (a.end() == it || !(b_entry.second == it->second)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    friend auto operator!=(table const& a, table const& b) -> bool {
+        return !(a == b);
+    }
+};
+
+} // namespace detail
+
+template <class Key,
+          class T,
+          class Hash = hash<Key>,
+          class KeyEqual = std::equal_to<Key>,
+          class Allocator = std::allocator<std::pair<Key, T>>>
+using map = detail::table<Key, T, Hash, KeyEqual, Allocator>;
+
+template <class Key, class Hash = hash<Key>, class KeyEqual = std::equal_to<Key>, class Allocator = std::allocator<Key>>
+using set = detail::table<Key, void, Hash, KeyEqual, Allocator>;
+
+#    if ANKERL_UNORDERED_DENSE_PMR
+
+namespace pmr {
+
+template <class Key, class T, class Hash = hash<Key>, class KeyEqual = std::equal_to<Key>>
+using map = detail::table<Key, T, Hash, KeyEqual, std::pmr::polymorphic_allocator<std::pair<Key, T>>>;
+
+template <class Key, class Hash = hash<Key>, class KeyEqual = std::equal_to<Key>>
+using set = detail::table<Key, void, Hash, KeyEqual, std::pmr::polymorphic_allocator<Key>>;
+
+} // namespace pmr
+
+#    endif
+
+// deduction guides ///////////////////////////////////////////////////////////
+
+// deduction guides for alias templates are only possible since C++20
+// see https://en.cppreference.com/w/cpp/language/class_template_argument_deduction
+
+} // namespace ankerl::unordered_dense
+
+// std extensions /////////////////////////////////////////////////////////////
+
+namespace std { // NOLINT(cert-dcl58-cpp)
+
+template <class Key, class T, class Hash, class KeyEqual, class Allocator, class Pred>
+auto erase_if(ankerl::unordered_dense::detail::table<Key, T, Hash, KeyEqual, Allocator>& map, Pred pred) -> size_t {
+    // going back to front because erase() invalidates the end iterator
+    auto const old_size = map.size();
+    auto idx = old_size;
+    while (idx) {
+        --idx;
+        auto it = map.begin() + idx;
+        if (pred(*it)) {
+            map.erase(it);
+        }
+    }
+
+    return map.size() - old_size;
+}
+
+} // namespace std
+
+#endif
+#endif