banan-os/BAN/include/BAN/HashSet.h

299 lines
7.0 KiB
C++

#pragma once
#include <BAN/Errors.h>
#include <BAN/Hash.h>
#include <BAN/Math.h>
#include <BAN/Move.h>
#include <BAN/Vector.h>
namespace BAN
{
template<typename T, typename HASH>
class HashSetIterator;
template<typename T, typename HASH = hash<T>>
class HashSet
{
public:
using value_type = T;
using size_type = hash_t;
using const_iterator = HashSetIterator<T, HASH>;
public:
HashSet() = default;
HashSet(const HashSet<T, HASH>&);
HashSet(HashSet<T, HASH>&&);
HashSet<T, HASH>& operator=(const HashSet<T, HASH>&);
HashSet<T, HASH>& operator=(HashSet<T, HASH>&&);
[[nodiscard]] ErrorOr<void> insert(const T&);
[[nodiscard]] ErrorOr<void> insert(T&&);
void remove(const T&);
void clear();
const_iterator begin() const { return const_iterator(this, m_buckets.begin()); }
const_iterator end() const { return const_iterator(this, m_buckets.end()); }
bool contains(const T&) const;
size_type size() const;
bool empty() const;
private:
[[nodiscard]] ErrorOr<void> rebucket(size_type);
Vector<T>& get_bucket(const T&);
const Vector<T>& get_bucket(const T&) const;
private:
Vector<Vector<T>> m_buckets;
size_type m_size = 0;
friend class HashSetIterator<T, HASH>;
};
template<typename T, typename HASH>
class HashSetIterator
{
public:
HashSetIterator() = default;
HashSetIterator(const HashSetIterator<T, HASH>&);
HashSetIterator<T, HASH>& operator++();
HashSetIterator<T, HASH> operator++(int);
const T& operator*() const;
const T* operator->() const;
bool operator==(const HashSetIterator<T, HASH>&) const;
bool operator!=(const HashSetIterator<T, HASH>&) const;
operator bool() const { return m_owner && m_current_bucket; }
private:
HashSetIterator(const HashSet<T, HASH>* owner, Vector<Vector<T>>::const_iterator bucket);
void find_next();
private:
const HashSet<T, HASH>* m_owner = nullptr;
Vector<Vector<T>>::const_iterator m_current_bucket;
Vector<T>::const_iterator m_current_key;
friend class HashSet<T, HASH>;
};
template<typename T, typename HASH>
HashSet<T, HASH>::HashSet(const HashSet<T, HASH>& other)
: m_buckets(other.m_buckets)
, m_size(other.m_size)
{
}
template<typename T, typename HASH>
HashSet<T, HASH>::HashSet(HashSet<T, HASH>&& other)
: m_buckets(move(other.m_buckets))
, m_size(other.m_size)
{
other.clear();
}
template<typename T, typename HASH>
HashSet<T, HASH>& HashSet<T, HASH>::operator=(const HashSet<T, HASH>& other)
{
clear();
m_buckets = other.m_buckets;
m_size = other.m_size;
return *this;
}
template<typename T, typename HASH>
HashSet<T, HASH>& HashSet<T, HASH>::operator=(HashSet<T, HASH>&& other)
{
clear();
m_buckets = move(other.m_buckets);
m_size = other.m_size;
other.clear();
return *this;
}
template<typename T, typename HASH>
ErrorOr<void> HashSet<T, HASH>::insert(const T& key)
{
return insert(move(T(key)));
}
template<typename T, typename HASH>
ErrorOr<void> HashSet<T, HASH>::insert(T&& key)
{
if (!empty() && get_bucket(key).contains(key))
return {};
TRY(rebucket(m_size + 1));
TRY(get_bucket(key).push_back(move(key)));
m_size++;
return {};
}
template<typename T, typename HASH>
void HashSet<T, HASH>::remove(const T& key)
{
if (empty()) return;
Vector<T>& bucket = get_bucket(key);
for (size_type i = 0; i < bucket.size(); i++)
{
if (bucket[i] == key)
{
bucket.remove(i);
m_size--;
break;
}
}
}
template<typename T, typename HASH>
void HashSet<T, HASH>::clear()
{
m_buckets.clear();
m_size = 0;
}
template<typename T, typename HASH>
bool HashSet<T, HASH>::contains(const T& key) const
{
if (empty()) return false;
return get_bucket(key).contains(key);
}
template<typename T, typename HASH>
typename HashSet<T, HASH>::size_type HashSet<T, HASH>::size() const
{
return m_size;
}
template<typename T, typename HASH>
bool HashSet<T, HASH>::empty() const
{
return m_size == 0;
}
template<typename T, typename HASH>
ErrorOr<void> HashSet<T, HASH>::rebucket(size_type bucket_count)
{
if (m_buckets.size() >= bucket_count)
return {};
size_type new_bucket_count = BAN::Math::max<size_type>(bucket_count, m_buckets.size() * 3 / 2);
Vector<Vector<T>> new_buckets;
if (new_buckets.resize(new_bucket_count).is_error())
return Error::from_string("HashSet: Could not allocate memory");
// NOTE: We have to copy the old keys to the new keys and not move
// since we might run out of memory half way through.
for (Vector<T>& bucket : m_buckets)
{
for (T& key : bucket)
{
size_type bucket_index = HASH()(key) % new_buckets.size();
if (new_buckets[bucket_index].push_back(key).is_error())
return Error::from_string("HashSet: Could not allocate memory");
}
}
m_buckets = move(new_buckets);
return {};
}
template<typename T, typename HASH>
Vector<T>& HashSet<T, HASH>::get_bucket(const T& key)
{
ASSERT(!m_buckets.empty());
size_type index = HASH()(key) % m_buckets.size();
return m_buckets[index];
}
template<typename T, typename HASH>
const Vector<T>& HashSet<T, HASH>::get_bucket(const T& key) const
{
ASSERT(!m_buckets.empty());
size_type index = HASH()(key) % m_buckets.size();
return m_buckets[index];
}
template<typename T, typename HASH>
HashSetIterator<T, HASH>& HashSetIterator<T, HASH>::operator++()
{
ASSERT(*this);
if (m_current_key == m_current_bucket->end())
m_current_bucket++;
else
m_current_key++;
find_next();
return *this;
}
template<typename T, typename HASH>
HashSetIterator<T, HASH> HashSetIterator<T, HASH>::operator++(int)
{
auto temp = *this;
++(*this);
return temp;
}
template<typename T, typename HASH>
const T& HashSetIterator<T, HASH>::operator*() const
{
ASSERT(m_owner && m_current_bucket && m_current_key);
return *m_current_key;
}
template<typename T, typename HASH>
const T* HashSetIterator<T, HASH>::operator->() const
{
return &**this;
}
template<typename T, typename HASH>
bool HashSetIterator<T, HASH>::operator==(const HashSetIterator<T, HASH>& other) const
{
if (!m_owner || m_owner != other.m_owner)
return false;
return m_current_bucket == other.m_current_bucket
&& m_current_key == other.m_current_key;
}
template<typename T, typename HASH>
bool HashSetIterator<T, HASH>::operator!=(const HashSetIterator<T, HASH>& other) const
{
return !(*this == other);
}
template<typename T, typename HASH>
HashSetIterator<T, HASH>::HashSetIterator(const HashSet<T, HASH>* owner, Vector<Vector<T>>::const_iterator bucket)
: m_owner(owner)
, m_current_bucket(bucket)
{
if (m_current_bucket != m_owner->m_buckets.end())
m_current_key = m_current_bucket->begin();
find_next();
}
template<typename T, typename HASH>
void HashSetIterator<T, HASH>::find_next()
{
ASSERT(m_owner && m_current_bucket);
while (m_current_bucket != m_owner->m_buckets.end())
{
if (m_current_key && m_current_key != m_current_bucket->end())
return;
m_current_bucket++;
m_current_key = m_current_bucket->begin();
}
m_current_key = typename Vector<T>::const_iterator();
}
}