From 5c305acc9c1052e62786e6f6523fc50cc47d4aff Mon Sep 17 00:00:00 2001
From: Aydar Asadullin <aiasadullin_2@edu.hse.ru>
Date: Wed, 1 Mar 2023 00:53:50 +0300
Subject: [PATCH] deleting data from hash_map

---
 HashMap.h | 358 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 358 insertions(+)

diff --git a/HashMap.h b/HashMap.h
index e69de29..ff59371 100644
--- a/HashMap.h
+++ b/HashMap.h
@@ -0,0 +1,358 @@
+#pragma once
+
+#include <typeindex>
+#include <iterator>
+#include <vector>
+#include <memory>
+
+template<class KeyType, class ValueType, class Hash = std::hash<KeyType> >
+class HashMap {
+    using ElementType = std::pair<const KeyType, ValueType>;
+
+    struct ElementHash {
+        std::unique_ptr<ElementType> element = nullptr;
+        size_t hash = 0;
+
+        ElementHash() {}
+
+        ElementHash(ElementType element, size_t hash) : element(std::make_unique<ElementType>(element)), hash(hash) {}
+    };
+
+public:
+    class iterator {
+    public:
+        iterator() : hm_(nullptr), index_(0) {}
+
+        iterator(HashMap<KeyType, ValueType, Hash> *hm, size_t index) : hm_(hm), index_(index) {}
+
+        ElementType &operator*() const {
+            return *hm_->vec_[index_].element;
+        }
+
+        ElementType *operator->() const {
+            return (hm_->vec_[index_].element).get();
+        }
+
+        iterator &operator=(iterator other) {
+            if (this != &other) {
+                hm_ = other.hm_;
+                index_ = other.index_;
+            }
+            return *this;
+        }
+
+        iterator &operator++() {
+            ++index_;
+            index_ = hm_->next_bucket(index_);
+            return *this;
+        }
+
+        iterator operator++(int) {
+            iterator tmp(hm_, index_);
+            ++index_;
+            index_ = hm_->next_bucket(index_);
+            return tmp;
+        }
+
+        bool operator==(const iterator &other) const {
+            return hm_ == other.hm_ && index_ == other.index_;
+        }
+
+        bool operator!=(const iterator &other) const {
+            return !(*this == other);
+        }
+
+    private:
+        HashMap<KeyType, ValueType, Hash> *hm_;
+        size_t index_;
+    };
+
+    class const_iterator {
+    public:
+        const_iterator() : hm_(nullptr), index_(0) {}
+
+        const_iterator(HashMap<KeyType, ValueType, Hash> const *hm, size_t index) : hm_(hm), index_(index) {}
+
+        const ElementType &operator*() const {
+            return *hm_->vec_[index_].element;
+        }
+
+        const ElementType *operator->() const {
+            return (hm_->vec_[index_].element).get();
+        }
+
+        const_iterator &operator=(const_iterator other) {
+            if (this != &other) {
+                hm_ = other.hm_;
+                index_ = other.index_;
+            }
+            return *this;
+        }
+
+        const_iterator &operator++() {
+            ++index_;
+            index_ = hm_->next_bucket(index_);
+            return *this;
+        }
+
+        const_iterator operator++(int) {
+            const_iterator tmp(hm_, index_);
+            ++index_;
+            index_ = hm_->next_bucket(index_);
+            return tmp;
+        }
+
+        bool operator==(const const_iterator &other) const {
+            return hm_ == other.hm_ && index_ == other.index_;
+        }
+
+        bool operator!=(const const_iterator &other) const {
+            return !(*this == other);
+        }
+
+    private:
+        HashMap<KeyType, ValueType, Hash> const *hm_;
+        size_t index_;
+    };
+
+    HashMap(Hash hasher = Hash()) : hasher_(hasher) {
+        vec_.resize(capacity_);
+    }
+
+    template<class Forwarditerator>
+    HashMap(Forwarditerator begin, Forwarditerator end, Hash hasher = Hash()): hasher_(hasher) {
+        vec_.resize(capacity_);
+        while (begin != end) {
+            insert(std::make_pair((*begin).first, (*begin).second));
+            begin++;
+        }
+    }
+
+    HashMap(std::initializer_list<ElementType> initializerList, Hash hasher = Hash()) {
+        vec_.resize(capacity_);
+        for (const auto &[key, value]: initializerList) {
+            insert({key, value});
+        }
+    }
+
+    HashMap(const HashMap &other) {
+        hasher_ = other.hasher_;
+        H = other.H;
+        vec_.clear();
+        capacity_ = other.capacity_;
+        vec_.clear();
+        vec_.resize(capacity_);
+        auto begin_iterator = other.begin();
+        auto end_iterator = other.end();
+        while (begin_iterator != end_iterator) {
+            insert(std::make_pair((*begin_iterator).first, (*begin_iterator).second));
+            begin_iterator++;
+        }
+    }
+
+    ~HashMap() {
+        clear();
+    }
+
+    HashMap &operator=(const HashMap &other) {
+        if (this == &other) {
+            return *this;
+        }
+        clear();
+        hasher_ = other.hasher_;
+        H = other.H;
+        capacity_ = other.capacity_;
+        vec_.clear();
+        vec_.resize(capacity_);
+        auto begin_iterator = other.begin();
+        auto end_iterator = other.end();
+        while (begin_iterator != end_iterator) {
+            insert(std::make_pair((*begin_iterator).first, (*begin_iterator).second));
+            begin_iterator++;
+        }
+        return *this;
+    }
+
+
+    iterator begin() { // NOLINT
+        return iterator(this, next_bucket(0));
+    }
+
+    iterator end() { // NOLINT
+        return iterator(this, capacity_);
+    }
+
+    const_iterator begin() const { // NOLINT
+        return const_iterator(this, next_bucket(0));
+    }
+
+    const_iterator end() const { // NOLINT
+        return const_iterator(this, capacity_);
+    }
+
+    [[nodiscard]] size_t size() const {
+        return size_;
+    }
+
+    [[nodiscard]] bool empty() const {
+        return size() == 0;
+    }
+
+    Hash hash_function() const {
+        return hasher_;
+    }
+
+
+    void insert(ElementType element) {
+        if (find(element.first) != end()) {
+            return;
+        }
+        ElementHash element_hash = ElementHash(element, hasher_(element.first) % capacity_);
+        size_t begin = element_hash.hash;
+        size_t pos = begin;
+        while (vec_[pos].element != nullptr) {
+            pos = sum(pos, 1);
+        }
+        while (distance(begin, pos) >= H) {
+            bool found_swap = false;
+            while (true) {
+                size_t now = subtract(pos, 1);
+                for (size_t i = 0; i < H - 1; ++i) {
+                    if (distance(vec_[now].hash, pos) < H) {
+                        found_swap = true;
+                        std::swap(vec_[now], vec_[pos]);
+                        pos = now;
+                        break;
+                    }
+                    now = subtract(now, 1);
+                }
+                if (found_swap) {
+                    break;
+                }
+                H *= 2;
+            }
+        }
+        vec_[pos] = std::move(element_hash);
+        size_ += 1;
+        if (load_factor() >= max_load_factor) {
+            rebuild();
+        }
+    }
+
+    void erase(KeyType key) {
+        size_t begin = hasher_(key) % capacity_;
+        size_t pos = begin;
+        for (size_t i = 0; i < H; ++i) {
+            if (vec_[pos].element != nullptr && key == vec_[pos].element->first) {
+                vec_[pos].element = nullptr;
+                size_--;
+                return;
+            }
+            pos = sum(pos, 1);
+        }
+    }
+
+    iterator find(KeyType key) {
+        size_t begin = hasher_(key) % capacity_;
+        size_t pos = begin;
+        for (size_t i = 0; i < H; ++i) {
+            if (vec_[pos].element != nullptr && key == vec_[pos].element->first) {
+                return iterator(this, pos);
+            }
+            pos = sum(pos, 1);
+        }
+        return end();
+    }
+
+    const_iterator find(KeyType key) const {
+        size_t begin = hasher_(key) % capacity_;
+        size_t pos = begin;
+        for (size_t i = 0; i < H; ++i) {
+            if (vec_[pos].element != nullptr && key == vec_[pos].element->first) {
+                return const_iterator(this, pos);
+            }
+            pos = sum(pos, 1);
+        }
+        return end();
+    }
+
+    ValueType &operator[](KeyType key) {
+        auto it = find(key);
+        if (it == end()) {
+            insert(std::make_pair(key, ValueType()));
+            it = find(key);
+        }
+        return it->second;
+    }
+
+    const ValueType &at(KeyType key) const {
+        auto it = find(key);
+        if (it == end()) {
+            throw std::out_of_range("No ElementType at this key");
+        }
+        return it->second;
+    }
+
+    void clear() {
+        size_ = 0;
+        for (size_t i = 0; i < capacity_; ++i) {
+            vec_[i].element = nullptr;
+        }
+    }
+
+
+private:
+    size_t next_bucket(size_t index) const {
+        while (index != capacity_ && vec_[index].element == nullptr) {
+            index++;
+        }
+        return index;
+    }
+
+    size_t sum(size_t a, size_t b) const {
+        size_t c = a + b;
+        if (c >= capacity_) {
+            return c - capacity_;
+        }
+        return c;
+    }
+
+    size_t subtract(size_t a, size_t b) const {
+        if (a >= b) {
+            return a - b;
+        } else {
+            return a + capacity_ - b;
+        }
+    }
+
+    size_t distance(size_t beg, size_t end) const {
+        return subtract(end, beg);
+    }
+
+    double load_factor() const {
+        return (double) size_ / capacity_;
+    }
+
+    void rebuild() {
+        std::vector<ElementType> elements;
+        for (auto element: *this) {
+            elements.push_back(element);
+        }
+        clear();
+        H = H_begin_value;
+        capacity_ *= capacity_multiplier;
+        vec_.resize(capacity_);
+        for (auto element: elements) {
+            insert(element);
+        }
+    }
+
+    std::vector<ElementHash> vec_;
+    Hash hasher_;
+    size_t capacity_ = 64;
+    size_t size_ = 0;
+    const size_t H_begin_value = 2;
+    size_t H = H_begin_value;
+    const double capacity_multiplier = 2.0;
+    const double max_load_factor = 0.90;
+};