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/*
* libfud
* Copyright 2025 Dominick Allen
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FUD_HASH_MAP_IMPL_HPP
#define FUD_HASH_MAP_IMPL_HPP
#include "fud_hash.hpp"
namespace fud {
template <typename Key, typename Value, typename Hash = detail::DefaultHash<Key>>
class HashMap;
} // namespace fud
namespace fud::detail {
enum class BucketState : uint8_t
{
Disengaged,
Engaged,
Tombstoned
};
template <typename Key, typename Value>
struct MapEntry {
static_assert(!std::is_same_v<Key, option_detail::NullOptionType>);
static_assert(!std::is_same_v<Value, option_detail::NullOptionType>);
static_assert(!std::is_reference_v<Key>);
static_assert(!std::is_reference_v<Value>);
constexpr MapEntry() noexcept : m_state{BucketState::Disengaged}
{
}
constexpr MapEntry(const Key& key, const Value& value) : m_state{BucketState::Engaged}
{
new (m_keyData.data()) Key(key);
new (m_valueData.data()) Value(value);
}
constexpr MapEntry(Key&& key, const Value& value) : m_state{BucketState::Engaged}
{
new (m_keyData.data()) Key(std::move(key));
new (m_valueData.data()) Value(value);
}
constexpr MapEntry(const Key& key, Value&& value) : m_state{BucketState::Engaged}
{
new (m_keyData.data()) Key(key);
new (m_valueData.data()) Value(std::move(value));
}
constexpr MapEntry(Key&& key, Value&& value) : m_state{BucketState::Engaged}
{
new (m_keyData.data()) Key(std::move(key));
new (m_valueData.data()) Value(std::move(value));
}
constexpr MapEntry(const MapEntry& rhs) noexcept :
m_keyData(rhs.m_keyData), m_valueData(rhs.m_valueData), m_state(rhs.m_state)
{
}
constexpr MapEntry(MapEntry&& rhs) noexcept :
m_keyData(std::move(rhs.m_keyData)), m_valueData(std::move(rhs.m_valueData)), m_state(rhs.m_state)
{
rhs.destroy(false);
}
constexpr MapEntry& operator=(const MapEntry& rhs) noexcept
{
if (&rhs == this) {
return *this;
}
destroy(false);
m_keyData = rhs.m_keyData;
m_valueData = rhs.m_valueData;
m_state = rhs.m_state;
return *this;
}
constexpr MapEntry& operator=(MapEntry&& rhs) noexcept
{
if (&rhs == this) {
return *this;
}
destroy(false);
m_keyData = rhs.m_keyData;
m_valueData = rhs.m_valueData;
m_state = rhs.m_state;
rhs.destroy(false);
return *this;
}
constexpr ~MapEntry() noexcept
{
destroy(false);
}
[[nodiscard]] constexpr bool hasValue() const
{
return m_state == BucketState::Engaged;
}
[[nodiscard]] constexpr bool isNone() const
{
return m_state == BucketState::Disengaged;
}
[[nodiscard]] constexpr bool isTombstone() const
{
return m_state == BucketState::Tombstoned;
}
[[nodiscard]] constexpr const Key& key() const&
{
fudAssert(hasValue());
return *std::bit_cast<const Key*>(m_keyData.data());
}
[[nodiscard]] constexpr const Value& value() const&
{
fudAssert(hasValue());
return *std::bit_cast<const Value*>(m_valueData.data());
}
[[nodiscard]] constexpr Key& key() &
{
fudAssert(hasValue());
return *std::bit_cast<Key*>(m_keyData.data());
}
[[nodiscard]] constexpr Value& value() &
{
fudAssert(hasValue());
return *std::bit_cast<Value*>(m_valueData.data());
}
constexpr void tombstone() noexcept
{
destroy(true);
}
constexpr void destroy(bool entomb) noexcept
{
if (m_state == BucketState::Engaged) {
std::bit_cast<Key*>(m_keyData.data())->~Key();
m_keyData.clear();
std::bit_cast<Value*>(m_valueData.data())->~Value();
m_valueData.clear();
m_state = entomb ? BucketState::Tombstoned : BucketState::Disengaged;
} else if (m_state == BucketState::Tombstoned and not entomb) {
m_state = BucketState::Disengaged;
}
}
static constexpr auto Align = max(alignof(Key), alignof(Value));
alignas(alignof(Key)) option_detail::DataArray<sizeof(Key)> m_keyData{};
alignas(alignof(Value)) option_detail::DataArray<sizeof(Value)> m_valueData{};
BucketState m_state{BucketState::Disengaged};
};
} // namespace fud::detail
#endif
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