mirror of
https://github.com/SerenityOS/serenity
synced 2024-07-21 18:15:58 +00:00
367 lines
9.7 KiB
C++
367 lines
9.7 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/HashFunctions.h>
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#include <AK/StdLibExtras.h>
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#include <AK/Types.h>
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#include <AK/kmalloc.h>
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namespace AK {
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enum class HashSetResult {
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InsertedNewEntry,
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ReplacedExistingEntry
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};
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template<typename HashTableType, typename T, typename BucketType>
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class HashTableIterator {
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friend HashTableType;
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public:
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bool operator==(const HashTableIterator& other) const { return m_bucket == other.m_bucket; }
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bool operator!=(const HashTableIterator& other) const { return m_bucket != other.m_bucket; }
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T& operator*() { return *m_bucket->slot(); }
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T* operator->() { return m_bucket->slot(); }
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void operator++() { skip_to_next(); }
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private:
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void skip_to_next()
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{
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if (!m_bucket)
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return;
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do {
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++m_bucket;
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if (m_bucket->used)
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return;
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} while (!m_bucket->end);
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if (m_bucket->end)
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m_bucket = nullptr;
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}
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explicit HashTableIterator(BucketType* bucket)
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: m_bucket(bucket)
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{
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}
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BucketType* m_bucket { nullptr };
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};
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template<typename T, typename TraitsForT>
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class HashTable {
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static constexpr size_t load_factor_in_percent = 60;
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struct Bucket {
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bool used;
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bool deleted;
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bool end;
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alignas(T) u8 storage[sizeof(T)];
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T* slot() { return reinterpret_cast<T*>(storage); }
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const T* slot() const { return reinterpret_cast<const T*>(storage); }
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};
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public:
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HashTable() = default;
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explicit HashTable(size_t capacity) { rehash(capacity); }
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~HashTable()
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{
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if (!m_buckets)
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return;
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for (size_t i = 0; i < m_capacity; ++i) {
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if (m_buckets[i].used)
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m_buckets[i].slot()->~T();
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}
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kfree(m_buckets);
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}
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HashTable(const HashTable& other)
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{
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rehash(other.capacity());
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for (auto& it : other)
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set(it);
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}
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HashTable& operator=(const HashTable& other)
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{
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HashTable temporary(other);
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swap(*this, temporary);
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return *this;
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}
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HashTable(HashTable&& other) noexcept
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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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, m_deleted_count(other.m_deleted_count)
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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_deleted_count = 0;
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other.m_buckets = nullptr;
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}
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HashTable& operator=(HashTable&& other) noexcept
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{
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swap(*this, other);
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return *this;
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}
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friend void swap(HashTable& a, HashTable& b) noexcept
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{
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swap(a.m_buckets, b.m_buckets);
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swap(a.m_size, b.m_size);
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swap(a.m_capacity, b.m_capacity);
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swap(a.m_deleted_count, b.m_deleted_count);
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}
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[[nodiscard]] bool is_empty() const { return !m_size; }
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[[nodiscard]] size_t size() const { return m_size; }
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[[nodiscard]] size_t capacity() const { return m_capacity; }
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template<typename U, size_t N>
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void set_from(U (&from_array)[N])
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{
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for (size_t i = 0; i < N; ++i) {
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set(from_array[i]);
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}
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}
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void ensure_capacity(size_t capacity)
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{
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VERIFY(capacity >= size());
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rehash(capacity * 2);
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}
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bool contains(const T& value) const
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{
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return find(value) != end();
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}
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using Iterator = HashTableIterator<HashTable, T, Bucket>;
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Iterator begin()
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{
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for (size_t i = 0; i < m_capacity; ++i) {
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if (m_buckets[i].used)
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return Iterator(&m_buckets[i]);
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}
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return end();
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}
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Iterator end()
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{
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return Iterator(nullptr);
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}
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using ConstIterator = HashTableIterator<const HashTable, const T, const Bucket>;
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ConstIterator begin() const
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{
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for (size_t i = 0; i < m_capacity; ++i) {
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if (m_buckets[i].used)
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return ConstIterator(&m_buckets[i]);
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}
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return end();
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}
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ConstIterator end() const
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{
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return ConstIterator(nullptr);
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}
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void clear()
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{
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*this = HashTable();
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}
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template<typename U = T>
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HashSetResult set(U&& value)
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{
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auto& bucket = lookup_for_writing(value);
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if (bucket.used) {
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(*bucket.slot()) = forward<U>(value);
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return HashSetResult::ReplacedExistingEntry;
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}
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new (bucket.slot()) T(forward<U>(value));
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bucket.used = true;
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if (bucket.deleted) {
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bucket.deleted = false;
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--m_deleted_count;
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}
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++m_size;
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return HashSetResult::InsertedNewEntry;
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}
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template<typename Finder>
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Iterator find(unsigned hash, Finder finder)
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{
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return Iterator(lookup_with_hash(hash, move(finder)));
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}
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Iterator find(const T& value)
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{
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return find(TraitsForT::hash(value), [&](auto& other) { return TraitsForT::equals(value, other); });
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}
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template<typename Finder>
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ConstIterator find(unsigned hash, Finder finder) const
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{
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return ConstIterator(lookup_with_hash(hash, move(finder)));
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}
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ConstIterator find(const T& value) const
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{
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return find(TraitsForT::hash(value), [&](auto& other) { return TraitsForT::equals(value, other); });
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}
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bool 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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return true;
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}
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return false;
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}
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void remove(Iterator iterator)
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{
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VERIFY(iterator.m_bucket);
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auto& bucket = *iterator.m_bucket;
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VERIFY(bucket.used);
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VERIFY(!bucket.end);
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VERIFY(!bucket.deleted);
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bucket.slot()->~T();
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bucket.used = false;
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bucket.deleted = true;
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--m_size;
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++m_deleted_count;
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}
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private:
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void insert_during_rehash(T&& value)
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{
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auto& bucket = lookup_for_writing(value);
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new (bucket.slot()) T(move(value));
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bucket.used = true;
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}
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void rehash(size_t new_capacity)
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{
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new_capacity = max(new_capacity, static_cast<size_t>(4));
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auto* old_buckets = m_buckets;
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auto old_capacity = m_capacity;
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m_buckets = (Bucket*)kmalloc(sizeof(Bucket) * (new_capacity + 1));
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__builtin_memset(m_buckets, 0, sizeof(Bucket) * (new_capacity + 1));
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m_capacity = new_capacity;
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m_deleted_count = 0;
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m_buckets[m_capacity].end = true;
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if (!old_buckets)
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return;
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for (size_t i = 0; i < old_capacity; ++i) {
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auto& old_bucket = old_buckets[i];
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if (old_bucket.used) {
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insert_during_rehash(move(*old_bucket.slot()));
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old_bucket.slot()->~T();
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}
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}
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kfree(old_buckets);
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}
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template<typename Finder>
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Bucket* lookup_with_hash(unsigned hash, Finder finder) const
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{
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if (is_empty())
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return nullptr;
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for (;;) {
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auto& bucket = m_buckets[hash % m_capacity];
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if (bucket.used && finder(*bucket.slot()))
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return &bucket;
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if (!bucket.used && !bucket.deleted)
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return nullptr;
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hash = double_hash(hash);
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}
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}
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const Bucket* lookup_for_reading(const T& value) const
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{
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return lookup_with_hash(TraitsForT::hash(value), [&value](auto& entry) { return TraitsForT::equals(entry, value); });
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}
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Bucket& lookup_for_writing(const T& value)
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{
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if (should_grow())
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rehash(capacity() * 2);
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auto hash = TraitsForT::hash(value);
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Bucket* first_empty_bucket = nullptr;
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for (;;) {
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auto& bucket = m_buckets[hash % m_capacity];
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if (bucket.used && TraitsForT::equals(*bucket.slot(), value))
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return bucket;
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if (!bucket.used) {
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if (!first_empty_bucket)
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first_empty_bucket = &bucket;
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if (!bucket.deleted)
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return *const_cast<Bucket*>(first_empty_bucket);
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}
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hash = double_hash(hash);
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}
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}
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[[nodiscard]] size_t used_bucket_count() const { return m_size + m_deleted_count; }
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[[nodiscard]] bool should_grow() const { return ((used_bucket_count() + 1) * 100) >= (m_capacity * load_factor_in_percent); }
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Bucket* m_buckets { nullptr };
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size_t m_size { 0 };
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size_t m_capacity { 0 };
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size_t m_deleted_count { 0 };
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};
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}
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using AK::HashTable;
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