ClickHouse/dbms/include/DB/Common/HashTable/HashMap.h

167 lines
5.2 KiB
C++

#pragma once
#include <DB/Common/HashTable/Hash.h>
#include <DB/Common/HashTable/HashTable.h>
#include <DB/Common/HashTable/HashTableAllocator.h>
struct NoInitTag {};
/// Пара, которая не инициализирует элементы, если не нужно.
template <typename First, typename Second>
struct PairNoInit
{
First first;
Second second;
PairNoInit() {}
template <typename First_>
PairNoInit(First_ && first_, NoInitTag)
: first(std::forward<First_>(first_)) {}
template <typename First_, typename Second_>
PairNoInit(First_ && first_, Second_ && second_)
: first(std::forward<First_>(first_)), second(std::forward<Second_>(second_)) {}
};
template <typename Key, typename TMapped, typename Hash, typename TState = HashTableNoState>
struct HashMapCell
{
typedef TMapped Mapped;
typedef TState State;
typedef PairNoInit<Key, Mapped> value_type;
value_type value;
HashMapCell() {}
HashMapCell(const Key & key_, const State & state) : value(key_, NoInitTag()) {}
HashMapCell(const value_type & value_, const State & state) : value(value_) {}
value_type & getValue() { return value; }
const value_type & getValue() const { return value; }
static Key & getKey(value_type & value) { return value.first; }
static const Key & getKey(const value_type & value) { return value.first; }
bool keyEquals(const Key & key_) const { return value.first == key_; }
bool keyEquals(const Key & key_, size_t hash_) const { return value.first == key_; }
void setHash(size_t hash_value) {}
size_t getHash(const Hash & hash) const { return hash(value.first); }
bool isZero(const State & state) const { return isZero(value.first, state); }
static bool isZero(const Key & key, const State & state) { return ZeroTraits::check(key); }
/// Установить значение ключа в ноль.
void setZero() { ZeroTraits::set(value.first); }
/// Нужно ли хранить нулевой ключ отдельно (то есть, могут ли в хэш-таблицу вставить нулевой ключ).
static constexpr bool need_zero_value_storage = true;
/// Является ли ячейка удалённой.
bool isDeleted() const { return false; }
void setMapped(const value_type & value_) { value.second = value_.second; }
/// Сериализация, в бинарном и текстовом виде.
void write(DB::WriteBuffer & wb) const
{
DB::writeBinary(value.first, wb);
DB::writeBinary(value.second, wb);
}
void writeText(DB::WriteBuffer & wb) const
{
DB::writeDoubleQuoted(value.first, wb);
DB::writeChar(',', wb);
DB::writeDoubleQuoted(value.second, wb);
}
/// Десериализация, в бинарном и текстовом виде.
void read(DB::ReadBuffer & rb)
{
DB::readBinary(value.first, rb);
DB::readBinary(value.second, rb);
}
void readText(DB::ReadBuffer & rb)
{
DB::readDoubleQuoted(value.first, rb);
DB::assertString(",", rb);
DB::readDoubleQuoted(value.second, rb);
}
};
template <typename Key, typename TMapped, typename Hash, typename TState = HashTableNoState>
struct HashMapCellWithSavedHash : public HashMapCell<Key, TMapped, Hash, TState>
{
typedef HashMapCell<Key, TMapped, Hash, TState> Base;
size_t saved_hash;
HashMapCellWithSavedHash() : Base() {}
HashMapCellWithSavedHash(const Key & key_, const typename Base::State & state) : Base(key_, state) {}
HashMapCellWithSavedHash(const typename Base::value_type & value_, const typename Base::State & state) : Base(value_, state) {}
bool keyEquals(const Key & key_) const { return this->value.first == key_; }
bool keyEquals(const Key & key_, size_t hash_) const { return saved_hash == hash_ && this->value.first == key_; }
void setHash(size_t hash_value) { saved_hash = hash_value; }
size_t getHash(const Hash & hash) const { return saved_hash; }
};
template
<
typename Key,
typename Cell,
typename Hash = DefaultHash<Key>,
typename Grower = HashTableGrower<>,
typename Allocator = HashTableAllocator
>
class HashMapTable : public HashTable<Key, Cell, Hash, Grower, Allocator>
{
public:
typedef Key key_type;
typedef typename Cell::Mapped mapped_type;
typedef typename Cell::value_type value_type;
mapped_type & operator[](Key x)
{
typename HashMapTable::iterator it;
bool inserted;
this->emplace(x, it, inserted);
/// Если тривиальный конструктор, то инициализация нулями (через вызов конструктора для POD-ов) не нужна, так как таблица и так заполнена нулями.
if (!__has_trivial_constructor(mapped_type) && inserted)
new(&it->second) mapped_type();
return it->second;
}
};
template
<
typename Key,
typename Mapped,
typename Hash = DefaultHash<Key>,
typename Grower = HashTableGrower<>,
typename Allocator = HashTableAllocator
>
using HashMap = HashMapTable<Key, HashMapCell<Key, Mapped, Hash>, Hash, Grower, Allocator>;
template
<
typename Key,
typename Mapped,
typename Hash = DefaultHash<Key>,
typename Grower = HashTableGrower<>,
typename Allocator = HashTableAllocator
>
using HashMapWithSavedHash = HashMapTable<Key, HashMapCellWithSavedHash<Key, Mapped, Hash>, Hash, Grower, Allocator>;