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| #ifndef MY_HASH_TABLE
#define MY_HASH_TABLE
#include "my_allocator.h"
#include "my_iterator.h"
#include "my_utility.h"
#include "my_vector.h"
#include <vector>
#include <functional>
#include <cstddef>
#include <initializer_list>
namespace mystl{
template <typename Key, typename Value>
struct hash_node{
mystl::pair<Key, Value> data;
hash_node* next{nullptr};
hash_node(const Key& k, const Value& v, hash_node* n = nullptr)
: data(k, v), next(n) {}
};
template <
typename Key,
typename Value,
typename Hash = std::hash<Key>,
typename KeyEqual = mystl::equal_to<Key>,
typename Alloc = mystl::MyAllocator<hash_node<Key, Value>>>
class MyHashTable{
public:
using key_type = Key;
using mapped_type = Value;
using value_type = mystl::pair<Key,Value>;
using size_type = std::size_t;
using node_type = hash_node<Key, Value>;
using allocator_type = Alloc;
private:
mystl::MyVector<node_type*> buckets_;
size_type size_{0};
float max_load_factor_{0.75f};
Hash hasher_;
KeyEqual key_equal_;
allocator_type alloc_;
public:
MyHashTable(size_type bucket_count = 8)
: buckets_(bucket_count, nullptr), size_(0) {}
~MyHashTable(){
clear();
}
bool empty() const noexcept {return size_ ==0;}
size_type size() const noexcept { return size_;}
size_type bucket_count() const noexcept {return buckets_.size();}
void clear(){
for(auto& head : buckets_){
while(head){
}
}
}
void rehash(size_type new_count){
mystl::MyVector<node_type*> new_buckets(new_count, nullptr);
for(auto& head : buckets_){
while(head){
node_type* next = head->next;
size_t index = hasher_(head->data.first) % new_count;
head->next = new_buckets[index];
new_buckets[index] = head;
head = next;
}
}
buckets_.swap(new_buckets);
}
float load_factor() const noexcept{
return static_cast<float>(size_) / static_cast<float>(buckets_.size());
}
void insert(const Key& key, const Value& value){
if(load_factor() > max_load_factor_){
rehash(buckets_.size() * 2);
}
size_t idx = hasher_(key) % buckets_.size();
node_type* head = buckets_[idx];
for(node_type* node = head; node; node = node->next){
if(key_equal_(node->data.first, key)){
node->data.second = value;
return;
}
}
node_type* new_node = alloc_.allocate(1);
alloc_.construct(new_node, key, value, head);
buckets_[idx] = new_node;
++size_;
}
Value* find(const Key& key){
size_t idx = hasher_(key) % buckets_.size();
for(node_type* node = buckets_[idx]; node; node = node->next){
if(key_equal_(node->data.first, key))
return &node->data.second;;
}
return nullptr;
}
bool erase(const Key& key){
size_t idx = hasher_(key) % buckets_.size();
node_type* prev = nullptr;
node_type* curr = buckets_[idx];
while(curr){
if(key_equal_(curr->data.first, key)){
if(prev) prev->next = curr->next;
else buckets_[idx] = curr->next;
alloc_.destroy(curr);
alloc_.deallocate(curr, 1);
--size_;
return true;
}
prev = curr;
curr = curr->next;
}
return false;
}
Value& operator[](const Key& key){
Value* val = find(key);
if(val) return *val;
insert(key, Value());
return *find(key);
}
void print_debug() const {
for (size_t i = 0; i < buckets_.size(); ++i) {
node_type* node = buckets_[i];
if (!node) continue;
std::cout << "[" << i << "]: ";
while (node) {
std::cout << "(" << node->data.first << "," << node->data.second << ") -> ";
node = node->next;
}
std::cout << "nullptr\n";
}
}
};
}
#endif
|
