mirror of
https://github.com/SerenityOS/serenity
synced 2024-07-09 10:00:46 +00:00
378 lines
10 KiB
C++
378 lines
10 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 <cstdlib>
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#include <utility>
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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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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 isEmpty() 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(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)
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{
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if (m_isEnd && other.m_isEnd)
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return false;
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return &m_table != &other.m_table
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|| m_isEnd != other.m_isEnd
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|| m_bucketIndex != other.m_bucketIndex
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|| m_bucketIterator != other.m_bucketIterator;
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}
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T& operator*()
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{
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#ifdef HASHTABLE_DEBUG
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printf("retrieve { bucketIndex: %u, isEnd: %u }\n", m_bucketIndex, m_isEnd);
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#endif
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return *m_bucketIterator;
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}
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Iterator& operator++()
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{
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skipToNext();
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return *this;
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}
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void skipToNext()
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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_isEnd) {
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#ifdef HASHTABLE_DEBUG
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++pass;
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printf("skipToNext pass %u, m_bucketIndex=%u\n", pass, m_bucketIndex);
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#endif
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if (m_bucketIterator.isEnd()) {
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++m_bucketIndex;
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if (m_bucketIndex >= m_table.capacity()) {
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m_isEnd = true;
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return;
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}
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m_bucketIterator = m_table.m_buckets[m_bucketIndex].chain.begin();
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} else {
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++m_bucketIterator;
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}
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if (!m_bucketIterator.isEnd())
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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 isEnd, typename DoublyLinkedList<T>::Iterator bucketIterator = DoublyLinkedList<T>::Iterator::universalEnd())
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: m_table(table)
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, m_isEnd(isEnd)
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, m_bucketIterator(bucketIterator)
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{
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if (!isEnd && !m_table.isEmpty() && !(m_bucketIterator != DoublyLinkedList<T>::Iterator::universalEnd())) {
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#ifdef HASHTABLE_DEBUG
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printf("bucket iterator init!\n");
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#endif
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m_bucketIterator = m_table.m_buckets[0].chain.begin();
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if (m_bucketIterator.isEnd())
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skipToNext();
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}
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}
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HashTable& m_table;
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unsigned m_bucketIndex { 0 };
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bool m_isEnd { false };
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typename DoublyLinkedList<T>::Iterator m_bucketIterator;
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};
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Iterator begin() { return Iterator(*this, false); }
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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)
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{
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if (m_isEnd && other.m_isEnd)
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return false;
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return &m_table != &other.m_table
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|| m_isEnd != other.m_isEnd
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|| m_bucketIndex != other.m_bucketIndex
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|| m_bucketIterator != other.m_bucketIterator;
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}
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const T& operator*() const
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{
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#ifdef HASHTABLE_DEBUG
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printf("retrieve { bucketIndex: %u, isEnd: %u }\n", m_bucketIndex, m_isEnd);
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#endif
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return *m_bucketIterator;
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}
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ConstIterator& operator++()
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{
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skipToNext();
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return *this;
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}
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void skipToNext()
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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_isEnd) {
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#ifdef HASHTABLE_DEBUG
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++pass;
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printf("skipToNext pass %u, m_bucketIndex=%u\n", pass, m_bucketIndex);
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#endif
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if (m_bucketIterator.isEnd()) {
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++m_bucketIndex;
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if (m_bucketIndex >= m_table.capacity()) {
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m_isEnd = true;
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return;
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}
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const DoublyLinkedList<T>& chain = m_table.m_buckets[m_bucketIndex].chain;
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m_bucketIterator = chain.begin();
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} else {
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++m_bucketIterator;
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}
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if (!m_bucketIterator.isEnd())
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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 isEnd, typename DoublyLinkedList<T>::ConstIterator bucketIterator = DoublyLinkedList<T>::ConstIterator::universalEnd())
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: m_table(table)
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, m_isEnd(isEnd)
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, m_bucketIterator(bucketIterator)
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{
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if (!isEnd && !m_table.isEmpty() && !(m_bucketIterator != DoublyLinkedList<T>::ConstIterator::universalEnd())) {
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#ifdef HASHTABLE_DEBUG
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printf("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_bucketIterator = chain.begin();
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if (m_bucketIterator.isEnd())
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skipToNext();
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}
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}
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const HashTable& m_table;
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unsigned m_bucketIndex { 0 };
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bool m_isEnd { false };
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typename DoublyLinkedList<T>::ConstIterator m_bucketIterator;
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};
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ConstIterator begin() const { return ConstIterator(*this, false); }
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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&);
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const Bucket& lookup(const T&) const;
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void rehash(unsigned capacity);
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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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return;
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}
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if (size() >= capacity()) {
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rehash(size() + 1);
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insert(std::move(value));
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} else {
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bucket.chain.append(std::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>::rehash(unsigned newCapacity)
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{
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newCapacity *= 2;
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#ifdef HASHTABLE_DEBUG
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printf("rehash to %u buckets\n", newCapacity);
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#endif
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auto* newBuckets = new Bucket[newCapacity];
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auto* oldBuckets = m_buckets;
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unsigned oldCapacity = m_capacity;
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m_buckets = newBuckets;
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m_capacity = newCapacity;
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#ifdef HASHTABLE_DEBUG
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printf("reinsert %u buckets\n", oldCapacity);
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#endif
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for (unsigned i = 0; i < oldCapacity; ++i) {
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for (auto& value : oldBuckets[i].chain) {
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insert(std::move(value));
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}
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}
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delete [] oldBuckets;
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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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delete [] m_buckets;
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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(std::move(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 (isEmpty())
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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 (isEmpty())
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return end();
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auto& bucket = lookup(value);
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auto bucketIterator = bucket.chain.find(value);
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if (bucketIterator != bucket.chain.end())
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return Iterator(*this, false, bucketIterator);
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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 (isEmpty())
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return end();
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auto& bucket = lookup(value);
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auto bucketIterator = bucket.chain.find(value);
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if (bucketIterator != bucket.chain.end())
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return ConstIterator(*this, false, bucketIterator);
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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(!isEmpty());
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m_buckets[it.m_bucketIndex].chain.remove(it.m_bucketIterator);
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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)
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{
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unsigned hash = TraitsForT::hash(value);
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#ifdef HASHTABLE_DEBUG
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printf("hash for ");
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TraitsForT::dump(value);
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printf(" is %u\n", hash);
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#endif
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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) 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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printf("hash for ");
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TraitsForT::dump(value);
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printf(" is %u\n", hash);
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#endif
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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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printf("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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printf("Bucket %u\n", i);
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for (auto& e : bucket.chain) {
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printf(" > ");
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TraitsForT::dump(e);
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printf("\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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