From d3ae1ae47c1deca3da483febe9c20dd3253e28c7 Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Mon, 2 May 2022 14:34:44 +0100
Subject: [PATCH] mcl: ihmap: Implement inline variant of hmap

---
 include/mcl/container/ihmap.hpp | 548 ++++++++++++++++++++++++++++++++
 tests/CMakeLists.txt            |   1 +
 tests/container/ihmap.cpp       |  66 ++++
 3 files changed, 615 insertions(+)
 create mode 100644 include/mcl/container/ihmap.hpp
 create mode 100644 tests/container/ihmap.cpp

diff --git a/include/mcl/container/ihmap.hpp b/include/mcl/container/ihmap.hpp
new file mode 100644
index 0000000..c9d666c
--- /dev/null
+++ b/include/mcl/container/ihmap.hpp
@@ -0,0 +1,548 @@
+// This file is part of the mcl project.
+// Copyright (c) 2022 merryhime
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include <array>
+#include <cstddef>
+#include <functional>
+#include <limits>
+#include <type_traits>
+#include <utility>
+
+#include "mcl/assert.hpp"
+#include "mcl/container/detail/meta_byte.hpp"
+#include "mcl/container/detail/slot_union.hpp"
+#include "mcl/hash/xmrx.hpp"
+#include "mcl/hint/assume.hpp"
+
+namespace mcl {
+
+template<typename KeyType, typename MappedType, typename Hash, typename Pred>
+class ihmap;
+
+namespace detail {
+
+constexpr std::array<meta_byte, 16> ihmap_default_meta{
+    meta_byte::empty, meta_byte::empty, meta_byte::empty, meta_byte::empty,
+    meta_byte::empty, meta_byte::empty, meta_byte::empty, meta_byte::empty,
+    meta_byte::empty, meta_byte::empty, meta_byte::empty, meta_byte::empty,
+    meta_byte::empty, meta_byte::empty, meta_byte::empty, meta_byte::tombstone};
+
+template<typename KeyType, typename MappedType>
+struct ihmap_group {
+    using base_value_type = std::pair<const KeyType, MappedType>;
+    using slot_type = detail::slot_union<base_value_type>;
+
+    static constexpr std::size_t group_size{meta_byte_group::max_group_size - 1};
+
+    meta_byte_group meta{ihmap_default_meta};
+    std::array<slot_type, group_size> slots{};
+};
+
+}  // namespace detail
+
+template<bool IsConst, typename KeyType, typename MappedType, typename Hash, typename Pred>
+class ihmap_iterator {
+    using group_type = detail::ihmap_group<KeyType, MappedType>;
+    using base_value_type = typename group_type::base_value_type;
+
+public:
+    using key_type = KeyType;
+    using mapped_type = MappedType;
+    using iterator_category = std::forward_iterator_tag;
+    using difference_type = std::ptrdiff_t;
+    using value_type = std::conditional_t<IsConst, std::add_const_t<base_value_type>, base_value_type>;
+    using pointer = value_type*;
+    using const_pointer = const value_type*;
+    using reference = value_type&;
+    using const_reference = const value_type&;
+
+    ihmap_iterator() = default;
+    ihmap_iterator(const ihmap_iterator& other) = default;
+    ihmap_iterator& operator=(const ihmap_iterator& other) = default;
+
+    ihmap_iterator& operator++()
+    {
+        if (group_ptr == nullptr)
+            return *this;
+
+        ++slot_index;
+
+        skip_empty_or_tombstone();
+
+        return *this;
+    }
+    ihmap_iterator operator++(int)
+    {
+        ihmap_iterator it(*this);
+        ++*this;
+        return it;
+    }
+
+    bool operator==(const ihmap_iterator& other) const
+    {
+        return std::tie(group_ptr, slot_index) == std::tie(other.group_ptr, other.slot_index);
+    }
+    bool operator!=(const ihmap_iterator& other) const
+    {
+        return !operator==(other);
+    }
+
+    reference operator*() const
+    {
+        return static_cast<reference>(group_ptr->slots[slot_index].value);
+    }
+    pointer operator->() const
+    {
+        return std::addressof(operator*());
+    }
+
+private:
+    friend class ihmap<KeyType, MappedType, Hash, Pred>;
+
+    ihmap_iterator(group_type* group_ptr, size_t slot_index)
+        : group_ptr{group_ptr}, slot_index{slot_index}
+    {
+        ASSUME(group_ptr != nullptr);
+    }
+
+    void skip_empty_or_tombstone()
+    {
+        if (!group_ptr)
+            return;
+
+        while (true) {
+            const detail::meta_byte mb = group_ptr->meta.get(slot_index);
+            if (slot_index == group_type::group_size) {
+                slot_index = 0;
+                ++group_ptr;
+
+                if (mb == detail::meta_byte::end_sentinel) {
+                    group_ptr = nullptr;
+                    return;
+                }
+
+                continue;
+            }
+            if (is_full(mb)) {
+                break;
+            }
+            ++slot_index;
+        }
+    }
+
+    group_type* group_ptr{nullptr};
+    std::size_t slot_index{0};
+};
+
+template<typename KeyType, typename MappedType, typename Hash = hash::avalanche_xmrx<KeyType>, typename Pred = std::equal_to<KeyType>>
+class ihmap {
+    using group_type = detail::ihmap_group<KeyType, MappedType>;
+
+public:
+    using key_type = KeyType;
+    using mapped_type = MappedType;
+    using hasher = Hash;
+    using key_equal = Pred;
+    using value_type = typename group_type::base_value_type;
+    using reference = value_type&;
+    using const_reference = const value_type&;
+    using pointer = value_type*;
+    using const_pointer = const value_type*;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
+
+    using iterator = ihmap_iterator<false, key_type, mapped_type, hasher, key_equal>;
+    using const_iterator = ihmap_iterator<true, key_type, mapped_type, hasher, key_equal>;
+
+private:
+    static_assert(!std::is_reference_v<key_type>);
+    static_assert(!std::is_reference_v<mapped_type>);
+
+    static constexpr std::size_t group_size{group_type::group_size};
+    static constexpr std::size_t average_max_group_load{group_size - 2};
+
+    struct position {
+        std::size_t group_index;
+        std::size_t slot_index;
+    };
+
+public:
+    ihmap()
+    {
+        initialize_members(1);
+    }
+    ihmap(const ihmap& other)
+    {
+        deep_copy(other);
+    }
+    ihmap(ihmap&& other)
+        : group_index_mask{std::exchange(other.group_index_mask, 0)}
+        , empty_slots{std::exchange(other.empty_slots, 0)}
+        , full_slots{std::exchange(other.full_slots, 0)}
+        , groups{std::move(other.groups)}
+    {
+    }
+    ihmap& operator=(const ihmap& other)
+    {
+        deep_copy(other);
+        return *this;
+    }
+    ihmap& operator=(ihmap&& other)
+    {
+        group_index_mask = std::exchange(other.group_index_mask, 0);
+        empty_slots = std::exchange(other.empty_slots, 0);
+        full_slots = std::exchange(other.full_slots, 0);
+        groups = std::move(other.groups);
+        return *this;
+    }
+
+    ~ihmap()
+    {
+        if (!groups)
+            return;
+
+        clear();
+    }
+
+    [[nodiscard]] bool empty() const noexcept { return full_slots == 0; }
+    size_type size() const noexcept { return full_slots; }
+    size_type max_size() const noexcept { return static_cast<size_type>(std::numeric_limits<difference_type>::max()); }
+
+    iterator begin()
+    {
+        iterator result{iterator_at({0, 0})};
+        result.skip_empty_or_tombstone();
+        return result;
+    }
+    iterator end()
+    {
+        return {};
+    }
+    const_iterator cbegin() const
+    {
+        const_iterator result{const_iterator_at({0, 0})};
+        result.skip_empty_or_tombstone();
+        return result;
+    }
+    const_iterator cend() const
+    {
+        return {};
+    }
+    const_iterator begin() const
+    {
+        return cbegin();
+    }
+    const_iterator end() const
+    {
+        return cend();
+    }
+
+    template<typename K = key_type, typename... Args>
+    std::pair<iterator, bool> try_emplace(K&& k, Args&&... args)
+    {
+        auto [pos, item_found] = find_key_or_empty_slot(k);
+        if (!item_found) {
+            new (&groups[pos.group_index].slots[pos.slot_index].value) value_type(
+                std::piecewise_construct,
+                std::forward_as_tuple(std::forward<K>(k)),
+                std::forward_as_tuple(std::forward<Args>(args)...));
+        }
+        return {iterator_at(pos), !item_found};
+    }
+
+    template<typename K = key_type, typename V = mapped_type>
+    std::pair<iterator, bool> insert_or_assign(K&& k, V&& v)
+    {
+        auto [pos, item_found] = find_key_or_empty_slot(k);
+        if (item_found) {
+            groups[pos.group_index].slots[pos.slot_index].value.second = std::forward<V>(v);
+        } else {
+            new (&groups[pos.group_index].slots[pos.slot_index].value) value_type(
+                std::forward<K>(k),
+                std::forward<V>(v));
+        }
+        return {iterator_at(pos), !item_found};
+    }
+
+    void erase(const_iterator iter)
+    {
+        if (iter == cend()) {
+            return;
+        }
+
+        const std::size_t group_index{static_cast<std::size_t>(std::distance(groups.get(), iter.group_ptr))};
+
+        erase_impl({group_index, iter.slot_index});
+    }
+    void erase(iterator iter)
+    {
+        if (iter == end()) {
+            return;
+        }
+
+        const std::size_t group_index{static_cast<std::size_t>(std::distance(groups.get(), iter.group_ptr))};
+
+        erase_impl({group_index, iter.slot_index});
+    }
+    template<typename K = key_type>
+    std::size_t erase(const K& key)
+    {
+        const std::size_t hash{hasher{}(key)};
+        const detail::meta_byte mb{detail::meta_byte_from_hash(hash)};
+
+        std::size_t group_index{detail::group_index_from_hash(hash, group_index_mask)};
+
+        while (true) {
+            const group_type& g{groups[group_index]};
+
+            MCL_HMAP_MATCH_META_BYTE_GROUP_EXCEPT_LAST(g.meta.match(mb), {
+                if (key_equal{}(g.slots[match_index].value.first, key)) [[likely]] {
+                    erase_impl({group_index, match_index});
+                    return 1;
+                }
+            });
+
+            if (g.meta.is_any_empty()) [[likely]] {
+                return 0;
+            }
+
+            group_index = (group_index + 1) & group_index_mask;
+        }
+    }
+
+    template<typename K = key_type>
+    iterator find(const K& key)
+    {
+        const std::size_t hash{hasher{}(key)};
+        const detail::meta_byte mb{detail::meta_byte_from_hash(hash)};
+
+        std::size_t group_index{detail::group_index_from_hash(hash, group_index_mask)};
+
+        while (true) {
+            const group_type& g{groups[group_index]};
+
+            MCL_HMAP_MATCH_META_BYTE_GROUP_EXCEPT_LAST(g.meta.match(mb), {
+                if (key_equal{}(g.slots[match_index].value.first, key)) [[likely]] {
+                    return iterator_at({group_index, match_index});
+                }
+            });
+
+            if (g.meta.is_any_empty()) [[likely]] {
+                return {};
+            }
+
+            group_index = (group_index + 1) & group_index_mask;
+        }
+    }
+    template<typename K = key_type>
+    const_iterator find(const K& key) const
+    {
+        const std::size_t hash{hasher{}(key)};
+        const detail::meta_byte mb{detail::meta_byte_from_hash(hash)};
+
+        std::size_t group_index{detail::group_index_from_hash(hash, group_index_mask)};
+
+        while (true) {
+            const group_type& g{groups[group_index]};
+
+            MCL_HMAP_MATCH_META_BYTE_GROUP_EXCEPT_LAST(g.meta.match(mb), {
+                if (key_equal{}(g.slots[match_index].value.first, key)) [[likely]] {
+                    return const_iterator_at({group_index, match_index});
+                }
+            });
+
+            if (g.meta.is_any_empty()) [[likely]] {
+                return {};
+            }
+
+            group_index = (group_index + 1) & group_index_mask;
+        }
+    }
+    template<typename K = key_type>
+    bool contains(const K& key) const
+    {
+        return find(key) != end();
+    }
+    template<typename K = key_type>
+    std::size_t count(const K& key) const
+    {
+        return contains(key) ? 1 : 0;
+    }
+
+    template<typename K = key_type>
+    mapped_type& operator[](K&& k)
+    {
+        return try_emplace(std::forward<K>(k)).first->second;
+    }
+    template<typename K = key_type>
+    mapped_type& at(K&& k)
+    {
+        const auto iter{find(k)};
+        if (iter == end()) {
+            throw std::out_of_range("ihmap::at: key not found");
+        }
+        return iter->second;
+    }
+    template<typename K = key_type>
+    const mapped_type& at(K&& k) const
+    {
+        const auto iter{find(k)};
+        if (iter == end()) {
+            throw std::out_of_range("ihmap::at: key not found");
+        }
+        return iter->second;
+    }
+
+    void clear()
+    {
+        for (auto iter{begin()}; iter != end(); ++iter) {
+            iter->~value_type();
+        }
+
+        clear_metadata();
+    }
+
+private:
+    iterator iterator_at(position pos)
+    {
+        return {groups.get() + pos.group_index, pos.slot_index};
+    }
+    const_iterator const_iterator_at(position pos) const
+    {
+        return {groups.get() + pos.group_index, pos.slot_index};
+    }
+
+    std::pair<position, bool> find_key_or_empty_slot(const key_type& key)
+    {
+        const std::size_t hash{hasher{}(key)};
+        const detail::meta_byte mb{detail::meta_byte_from_hash(hash)};
+
+        std::size_t group_index{detail::group_index_from_hash(hash, group_index_mask)};
+
+        while (true) {
+            const group_type& g{groups[group_index]};
+
+            MCL_HMAP_MATCH_META_BYTE_GROUP_EXCEPT_LAST(g.meta.match(mb), {
+                if (key_equal{}(g.slots[match_index].value.first, key)) [[likely]] {
+                    return {{group_index, match_index}, true};
+                }
+            });
+
+            if (g.meta.is_any_empty()) [[likely]] {
+                return {find_empty_slot_to_insert(hash), false};
+            }
+
+            group_index = (group_index + 1) & group_index_mask;
+        }
+    }
+
+    position find_empty_slot_to_insert(const std::size_t hash)
+    {
+        if (empty_slots == 0) [[unlikely]] {
+            grow_and_rehash();
+        }
+
+        std::size_t group_index{detail::group_index_from_hash(hash, group_index_mask)};
+
+        while (true) {
+            group_type& g{groups[group_index]};
+
+            MCL_HMAP_MATCH_META_BYTE_GROUP_EXCEPT_LAST(g.meta.match_empty_or_tombstone(), {
+                if (g.meta.get(match_index) == detail::meta_byte::empty) [[likely]] {
+                    --empty_slots;
+                }
+                ++full_slots;
+
+                g.meta.set(match_index, detail::meta_byte_from_hash(hash));
+
+                return {group_index, match_index};
+            });
+
+            group_index = (group_index + 1) & group_index_mask;
+        }
+    }
+
+    void erase_impl(position pos)
+    {
+        group_type& g{groups[pos.group_index]};
+
+        g.slots[pos.slot_index].value->~value_type();
+
+        --full_slots;
+        if (g.meta.is_any_empty()) {
+            g.meta.set(pos.slot_index, detail::meta_byte::empty);
+            ++empty_slots;
+        } else {
+            g.meta.set(pos.slot_index, detail::meta_byte::tombstone);
+        }
+    }
+
+    void grow_and_rehash()
+    {
+        const std::size_t new_group_count{2 * (group_index_mask + 1)};
+
+        pow2_resize(new_group_count);
+    }
+
+    void pow2_resize(std::size_t new_group_count)
+    {
+        auto iter{begin()};
+
+        const auto old_groups{std::move(groups)};
+
+        initialize_members(new_group_count);
+
+        for (; iter != end(); ++iter) {
+            const std::size_t hash{hasher{}(iter->first)};
+            const position pos{find_empty_slot_to_insert(hash)};
+
+            new (&groups[pos.group_index].slots[pos.slot_index].value) value_type(std::move(iter.group_ptr->slots[iter.slot_index].value));
+            iter.group_ptr->slots[iter.slot_index].value.~value_type();
+        }
+    }
+
+    void deep_copy(const ihmap& other)
+    {
+        initialize_members(other.group_index_mask + 1);
+
+        for (auto iter = other.begin(); iter != other.end(); ++iter) {
+            const std::size_t hash{hasher{}(iter->first)};
+            const position pos{find_empty_slot_to_insert(hash)};
+
+            new (&groups[pos.group_index].slots[pos.slot_index].value) value_type(iter.group_ptr->slots[iter.slot_index].value);
+        }
+    }
+
+    void initialize_members(std::size_t group_count)
+    {
+        // DEBUG_ASSERT(group_count != 0 && std::ispow2(group_count));
+
+        group_index_mask = group_count - 1;
+        groups = std::unique_ptr<group_type[]>{new group_type[group_count]};
+
+        clear_metadata();
+    }
+
+    void clear_metadata()
+    {
+        const std::size_t group_count{group_index_mask + 1};
+
+        empty_slots = group_count * average_max_group_load;
+        full_slots = 0;
+
+        for (size_t i{0}; i < group_count; ++i) {
+            groups[i].meta = detail::meta_byte_group{detail::ihmap_default_meta};
+        }
+        groups[group_count - 1].meta.set(group_size, detail::meta_byte::end_sentinel);
+    }
+
+    std::size_t group_index_mask;
+    std::size_t empty_slots;
+    std::size_t full_slots;
+    std::unique_ptr<group_type[]> groups;
+};
+
+}  // namespace mcl
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index b88900f..e0ce032 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,6 +1,7 @@
 add_executable(mcl-tests
     bit/bit_field_tests.cpp
     container/hmap.cpp
+    container/ihmap.cpp
     main.cpp
     mp/metavalue_tests.cpp
     mp/typelist_tests.cpp
diff --git a/tests/container/ihmap.cpp b/tests/container/ihmap.cpp
new file mode 100644
index 0000000..693b541
--- /dev/null
+++ b/tests/container/ihmap.cpp
@@ -0,0 +1,66 @@
+// This file is part of the mcl project.
+// Copyright (c) 2022 merryhime
+// SPDX-License-Identifier: MIT
+
+#include <unordered_map>
+
+#include <catch2/catch.hpp>
+#include <fmt/core.h>
+#include <mcl/container/ihmap.hpp>
+#include <mcl/stdint.hpp>
+
+TEST_CASE("mcl::ihmap", "[ihmap]")
+{
+    mcl::ihmap<u64, u64> double_map;
+
+    constexpr int count = 100000;
+
+    REQUIRE(double_map.empty());
+
+    for (int i = 0; i < count; ++i) {
+        double_map[i] = i * 2;
+        REQUIRE(double_map.size() == i + 1);
+    }
+
+    for (int i = 0; i < count; ++i) {
+        REQUIRE(double_map[i] == i * 2);
+        REQUIRE(double_map.contains(i));
+    }
+
+    for (int i = 0; i < count; ++i) {
+        auto iter = double_map.find(i);
+        REQUIRE(iter->first == i);
+        REQUIRE(iter->second == i * 2);
+    }
+
+    for (int i = count; i < count * 2; ++i) {
+        REQUIRE(!double_map.contains(i));
+    }
+
+    for (int i = 0; i < count; ++i) {
+        auto result = double_map.try_emplace(i, 0);
+        REQUIRE(!result.second);
+    }
+
+    for (auto [k, v] : double_map) {
+        REQUIRE(k * 2 == v);
+    }
+
+    std::unordered_map<u64, size_t> indexes_count;
+    for (auto [k, v] : double_map) {
+        (void)v;
+        indexes_count[k]++;
+    }
+    for (auto [k, v] : indexes_count) {
+        (void)k;
+        REQUIRE(v == 1);
+    }
+
+    REQUIRE(!double_map.empty());
+    double_map.clear();
+    REQUIRE(double_map.empty());
+
+    for (auto [k, v] : double_map) {
+        REQUIRE(false);
+    }
+}