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426 lines
12 KiB
C++
426 lines
12 KiB
C++
#pragma once
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#include "Assertions.h"
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#include "DoublyLinkedList.h"
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#include "Traits.h"
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#include "StdLibExtras.h"
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#include "kstdio.h"
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//#define HASHTABLE_DEBUG
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namespace AK {
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template<typename T, typename = Traits<T>> class HashTable;
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template<typename T, typename TraitsForT>
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class HashTable {
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private:
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struct Bucket {
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DoublyLinkedList<T> chain;
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};
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public:
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HashTable() { }
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explicit HashTable(HashTable&& other)
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: m_buckets(other.m_buckets)
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, m_size(other.m_size)
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, m_capacity(other.m_capacity)
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{
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other.m_size = 0;
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other.m_capacity = 0;
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other.m_buckets = nullptr;
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}
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HashTable& operator=(HashTable&& other)
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{
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if (this != &other) {
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clear();
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m_buckets = other.m_buckets;
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m_size = other.m_size;
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m_capacity = other.m_capacity;
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other.m_size = 0;
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other.m_capacity = 0;
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other.m_buckets = nullptr;
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}
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return *this;
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}
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~HashTable() { clear(); }
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bool is_empty() const { return !m_size; }
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unsigned size() const { return m_size; }
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unsigned capacity() const { return m_capacity; }
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void set(const T&);
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void set(T&&);
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bool contains(const T&) const;
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void clear();
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void dump() const;
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class Iterator {
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public:
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bool operator!=(const Iterator& other) const
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{
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if (m_is_end && other.m_is_end)
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return false;
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return &m_table != &other.m_table
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|| m_is_end != other.m_is_end
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|| m_bucket_index != other.m_bucket_index
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|| m_bucket_iterator != other.m_bucket_iterator;
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}
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bool operator==(const Iterator& other) const { return !(*this != other); }
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T& operator*()
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{
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#ifdef HASHTABLE_DEBUG
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kprintf("retrieve { bucket_index: %u, is_end: %u }\n", m_bucket_index, m_is_end);
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#endif
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return *m_bucket_iterator;
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}
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T* operator->() { return m_bucket_iterator.operator->(); }
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Iterator& operator++()
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{
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skip_to_next();
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return *this;
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}
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void skip_to_next()
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{
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#ifdef HASHTABLE_DEBUG
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unsigned pass = 0;
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#endif
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while (!m_is_end) {
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#ifdef HASHTABLE_DEBUG
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++pass;
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kprintf("skip_to_next pass %u, m_bucket_index=%u\n", pass, m_bucket_index);
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#endif
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if (m_bucket_iterator.is_end()) {
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++m_bucket_index;
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if (m_bucket_index >= m_table.capacity()) {
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m_is_end = true;
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return;
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}
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m_bucket_iterator = m_table.m_buckets[m_bucket_index].chain.begin();
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} else {
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++m_bucket_iterator;
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}
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if (!m_bucket_iterator.is_end())
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return;
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}
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}
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private:
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friend class HashTable;
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explicit Iterator(HashTable& table, bool is_end, typename DoublyLinkedList<T>::Iterator bucket_iterator = DoublyLinkedList<T>::Iterator::universal_end(), unsigned bucket_index = 0)
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: m_table(table)
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, m_bucket_index(bucket_index)
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, m_is_end(is_end)
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, m_bucket_iterator(bucket_iterator)
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{
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if (!is_end && !m_table.is_empty() && !(m_bucket_iterator != DoublyLinkedList<T>::Iterator::universal_end())) {
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#ifdef HASHTABLE_DEBUG
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kprintf("bucket iterator init!\n");
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#endif
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m_bucket_iterator = m_table.m_buckets[0].chain.begin();
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if (m_bucket_iterator.is_end())
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skip_to_next();
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}
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}
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HashTable& m_table;
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unsigned m_bucket_index { 0 };
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bool m_is_end { false };
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typename DoublyLinkedList<T>::Iterator m_bucket_iterator;
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};
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Iterator begin() { return Iterator(*this, is_empty()); }
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Iterator end() { return Iterator(*this, true); }
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class ConstIterator {
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public:
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bool operator!=(const ConstIterator& other) const
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{
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if (m_is_end && other.m_is_end)
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return false;
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return &m_table != &other.m_table
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|| m_is_end != other.m_is_end
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|| m_bucket_index != other.m_bucket_index
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|| m_bucket_iterator != other.m_bucket_iterator;
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}
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bool operator==(const ConstIterator& other) const { return !(*this != other); }
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const T& operator*() const
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{
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#ifdef HASHTABLE_DEBUG
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kprintf("retrieve { bucket_index: %u, is_end: %u }\n", m_bucket_index, m_is_end);
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#endif
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return *m_bucket_iterator;
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}
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const T* operator->() const { return m_bucket_iterator.operator->(); }
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ConstIterator& operator++()
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{
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skip_to_next();
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return *this;
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}
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void skip_to_next()
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{
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#ifdef HASHTABLE_DEBUG
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unsigned pass = 0;
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#endif
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while (!m_is_end) {
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#ifdef HASHTABLE_DEBUG
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++pass;
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kprintf("skip_to_next pass %u, m_bucket_index=%u\n", pass, m_bucket_index);
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#endif
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if (m_bucket_iterator.is_end()) {
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++m_bucket_index;
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if (m_bucket_index >= m_table.capacity()) {
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m_is_end = true;
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return;
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}
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const DoublyLinkedList<T>& chain = m_table.m_buckets[m_bucket_index].chain;
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m_bucket_iterator = chain.begin();
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} else {
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++m_bucket_iterator;
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}
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if (!m_bucket_iterator.is_end())
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return;
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}
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}
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private:
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friend class HashTable;
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ConstIterator(const HashTable& table, bool is_end, typename DoublyLinkedList<T>::ConstIterator bucket_iterator = DoublyLinkedList<T>::ConstIterator::universal_end(), unsigned bucket_index = 0)
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: m_table(table)
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, m_bucket_index(bucket_index)
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, m_is_end(is_end)
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, m_bucket_iterator(bucket_iterator)
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{
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if (!is_end && !m_table.is_empty() && !(m_bucket_iterator != DoublyLinkedList<T>::ConstIterator::universal_end())) {
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#ifdef HASHTABLE_DEBUG
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kprintf("const bucket iterator init!\n");
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#endif
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const DoublyLinkedList<T>& chain = m_table.m_buckets[0].chain;
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m_bucket_iterator = chain.begin();
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if (m_bucket_iterator.is_end())
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skip_to_next();
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}
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}
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const HashTable& m_table;
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unsigned m_bucket_index { 0 };
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bool m_is_end { false };
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typename DoublyLinkedList<T>::ConstIterator m_bucket_iterator;
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};
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ConstIterator begin() const { return ConstIterator(*this, is_empty()); }
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ConstIterator end() const { return ConstIterator(*this, true); }
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Iterator find(const T&);
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ConstIterator find(const T&) const;
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void remove(const T& value)
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{
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auto it = find(value);
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if (it != end())
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remove(it);
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}
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void remove(Iterator);
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private:
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Bucket& lookup(const T&, unsigned* bucket_index = nullptr);
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const Bucket& lookup(const T&, unsigned* bucket_index = nullptr) const;
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void rehash(unsigned capacity);
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void insert(const T&);
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void insert(T&&);
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Bucket* m_buckets { nullptr };
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unsigned m_size { 0 };
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unsigned m_capacity { 0 };
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};
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::set(T&& value)
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{
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if (!m_capacity)
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rehash(1);
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auto& bucket = lookup(value);
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for (auto& e : bucket.chain) {
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if (e == value) {
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e = move(value);
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return;
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}
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}
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if (size() >= capacity()) {
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rehash(size() + 1);
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insert(move(value));
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} else {
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bucket.chain.append(move(value));
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}
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m_size++;
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::set(const T& value)
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{
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if (!m_capacity)
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rehash(1);
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auto& bucket = lookup(value);
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for (auto& e : bucket.chain) {
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if (e == value) {
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e = move(value);
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return;
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}
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}
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if (size() >= capacity()) {
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rehash(size() + 1);
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insert(value);
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} else {
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bucket.chain.append(value);
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}
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m_size++;
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::rehash(unsigned new_capacity)
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{
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new_capacity *= 2;
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#ifdef HASHTABLE_DEBUG
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kprintf("rehash to %u buckets\n", new_capacity);
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#endif
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auto* new_buckets = new Bucket[new_capacity];
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auto* old_buckets = m_buckets;
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unsigned old_capacity = m_capacity;
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m_buckets = new_buckets;
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m_capacity = new_capacity;
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#ifdef HASHTABLE_DEBUG
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kprintf("reinsert %u buckets\n", old_capacity);
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#endif
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for (unsigned i = 0; i < old_capacity; ++i) {
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for (auto& value : old_buckets[i].chain) {
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insert(move(value));
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}
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}
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delete [] old_buckets;
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::clear()
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{
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if (m_buckets) {
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delete [] m_buckets;
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m_buckets = nullptr;
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}
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m_capacity = 0;
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m_size = 0;
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::insert(T&& value)
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{
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auto& bucket = lookup(value);
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bucket.chain.append(move(value));
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::insert(const T& value)
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{
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auto& bucket = lookup(value);
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bucket.chain.append(value);
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}
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template<typename T, typename TraitsForT>
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bool HashTable<T, TraitsForT>::contains(const T& value) const
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{
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if (is_empty())
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return false;
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auto& bucket = lookup(value);
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for (auto& e : bucket.chain) {
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if (e == value)
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return true;
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}
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return false;
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}
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template<typename T, typename TraitsForT>
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auto HashTable<T, TraitsForT>::find(const T& value) -> Iterator
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{
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if (is_empty())
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return end();
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unsigned bucket_index;
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auto& bucket = lookup(value, &bucket_index);
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auto bucket_iterator = bucket.chain.find(value);
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if (bucket_iterator != bucket.chain.end())
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return Iterator(*this, false, bucket_iterator, bucket_index);
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return end();
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}
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template<typename T, typename TraitsForT>
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auto HashTable<T, TraitsForT>::find(const T& value) const -> ConstIterator
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{
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if (is_empty())
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return end();
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unsigned bucket_index;
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auto& bucket = lookup(value, &bucket_index);
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auto bucket_iterator = bucket.chain.find(value);
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if (bucket_iterator != bucket.chain.end())
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return ConstIterator(*this, false, bucket_iterator, bucket_index);
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return end();
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::remove(Iterator it)
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{
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ASSERT(!is_empty());
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m_buckets[it.m_bucket_index].chain.remove(it.m_bucket_iterator);
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--m_size;
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}
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template<typename T, typename TraitsForT>
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typename HashTable<T, TraitsForT>::Bucket& HashTable<T, TraitsForT>::lookup(const T& value, unsigned* bucket_index)
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{
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unsigned hash = TraitsForT::hash(value);
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#ifdef HASHTABLE_DEBUG
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kprintf("hash for ");
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TraitsForT::dump(value);
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kprintf(" is %u\n", hash);
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#endif
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if (bucket_index)
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*bucket_index = hash % m_capacity;
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return m_buckets[hash % m_capacity];
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}
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template<typename T, typename TraitsForT>
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const typename HashTable<T, TraitsForT>::Bucket& HashTable<T, TraitsForT>::lookup(const T& value, unsigned* bucket_index) const
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{
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unsigned hash = TraitsForT::hash(value);
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#ifdef HASHTABLE_DEBUG
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kprintf("hash for ");
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TraitsForT::dump(value);
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kprintf(" is %u\n", hash);
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#endif
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if (bucket_index)
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*bucket_index = hash % m_capacity;
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return m_buckets[hash % m_capacity];
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}
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template<typename T, typename TraitsForT>
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void HashTable<T, TraitsForT>::dump() const
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{
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kprintf("HashTable{%p} m_size=%u, m_capacity=%u, m_buckets=%p\n", this, m_size, m_capacity, m_buckets);
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for (unsigned i = 0; i < m_capacity; ++i) {
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auto& bucket = m_buckets[i];
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kprintf("Bucket %u\n", i);
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for (auto& e : bucket.chain) {
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kprintf(" > ");
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TraitsForT::dump(e);
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kprintf("\n");
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}
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}
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}
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}
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using AK::HashTable;
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