text: #pragma once
  
  #include <DB/Dictionaries/IDictionary.h>
  #include <DB/Dictionaries/IDictionarySource.h>
  #include <DB/Dictionaries/DictionaryStructure.h>
  #include <DB/Columns/ColumnString.h>
  #include <DB/Common/Arena.h>
  #include <ext/range.hpp>
  #include <ext/size.hpp>
  #include <atomic>
  #include <vector>
  #include <tuple>
  
  
  namespace DB
  {
  
  class FlatDictionary final : public IDictionary
  {
  public:
      FlatDictionary(const std::string & name, const DictionaryStructure & dict_struct,
  		DictionarySourcePtr source_ptr, const DictionaryLifetime dict_lifetime, bool require_nonempty);
  
  	FlatDictionary(const FlatDictionary & other);
  
  	std::exception_ptr getCreationException() const override { return creation_exception; }
  
  	std::string getName() const override { return name; }
  
  	std::string getTypeName() const override { return "Flat"; }
  
  	std::size_t getBytesAllocated() const override { return bytes_allocated; }
  
  	std::size_t getQueryCount() const override { return query_count.load(std::memory_order_relaxed); }
  
  	double getHitRate() const override { return 1.0; }
  
  	std::size_t getElementCount() const override { return element_count; }
  
  	double getLoadFactor() const override { return static_cast<double>(element_count) / bucket_count; }
  
  	bool isCached() const override { return false; }
  
  	DictionaryPtr clone() const override { return std::make_unique<FlatDictionary>(*this); }
  
  	const IDictionarySource * getSource() const override { return source_ptr.get(); }
  
  	const DictionaryLifetime & getLifetime() const override { return dict_lifetime; }
  
  	const DictionaryStructure & getStructure() const override { return dict_struct; }
  
  	std::chrono::time_point<std::chrono::system_clock> getCreationTime() const override
  	{
  		return creation_time;
  	}
  
  	bool isInjective(const std::string & attribute_name) const override
  	{
  		return dict_struct.attributes[&getAttribute(attribute_name) - attributes.data()].injective;
  	}
  
  	bool hasHierarchy() const override { return hierarchical_attribute; }
  
  	void toParent(const PaddedPODArray<Key> & ids, PaddedPODArray<Key> & out) const override;
  
  #define DECLARE(TYPE)\
  	void get##TYPE(const std::string & attribute_name, const PaddedPODArray<Key> & ids, PaddedPODArray<TYPE> & out) const;
  	DECLARE(UInt8)
  	DECLARE(UInt16)
  	DECLARE(UInt32)
  	DECLARE(UInt64)
  	DECLARE(Int8)
  	DECLARE(Int16)
  	DECLARE(Int32)
  	DECLARE(Int64)
  	DECLARE(Float32)
  	DECLARE(Float64)
  #undef DECLARE
  
  	void getString(const std::string & attribute_name, const PaddedPODArray<Key> & ids, ColumnString * out) const;
  
  #define DECLARE(TYPE)\
  	void get##TYPE(\
  		const std::string & attribute_name, const PaddedPODArray<Key> & ids, const PaddedPODArray<TYPE> & def,\
  		PaddedPODArray<TYPE> & out) const;
  	DECLARE(UInt8)
  	DECLARE(UInt16)
  	DECLARE(UInt32)
  	DECLARE(UInt64)
  	DECLARE(Int8)
  	DECLARE(Int16)
  	DECLARE(Int32)
  	DECLARE(Int64)
  	DECLARE(Float32)
  	DECLARE(Float64)
  #undef DECLARE
  
  	void getString(
  		const std::string & attribute_name, const PaddedPODArray<Key> & ids, const ColumnString * const def,
  		ColumnString * const out) const;
  
  #define DECLARE(TYPE)\
  	void get##TYPE(\
  		const std::string & attribute_name, const PaddedPODArray<Key> & ids, const TYPE def,\
  		PaddedPODArray<TYPE> & out) const;
  	DECLARE(UInt8)
  	DECLARE(UInt16)
  	DECLARE(UInt32)
  	DECLARE(UInt64)
  	DECLARE(Int8)
  	DECLARE(Int16)
  	DECLARE(Int32)
  	DECLARE(Int64)
  	DECLARE(Float32)
  	DECLARE(Float64)
  #undef DECLARE
  
  	void getString(
  		const std::string & attribute_name, const PaddedPODArray<Key> & ids, const String & def,
  		ColumnString * const out) const;;
  
  	void has(const PaddedPODArray<Key> & ids, PaddedPODArray<UInt8> & out) const override;
  
  private:
  	template <typename Value> using ContainerType = PaddedPODArray<Value>;
  	template <typename Value> using ContainerPtrType = std::unique_ptr<ContainerType<Value>>;
  
  	struct Attribute final
  	{
  		AttributeUnderlyingType type;
  		std::tuple<
  			UInt8, UInt16, UInt32, UInt64,
  			Int8, Int16, Int32, Int64,
  			Float32, Float64,
  			String> null_values;
  		std::tuple<
  			ContainerPtrType<UInt8>, ContainerPtrType<UInt16>, ContainerPtrType<UInt32>, ContainerPtrType<UInt64>,
  			ContainerPtrType<Int8>, ContainerPtrType<Int16>, ContainerPtrType<Int32>, ContainerPtrType<Int64>,
  			ContainerPtrType<Float32>, ContainerPtrType<Float64>,
  			ContainerPtrType<StringRef>> arrays;
  		std::unique_ptr<Arena> string_arena;
  	};
  
  	void createAttributes();
  	void loadData();
  
  	template <typename T>
  	void addAttributeSize(const Attribute & attribute);
  
  	void calculateBytesAllocated();
  
  	template <typename T>
  	void createAttributeImpl(Attribute & attribute, const Field & null_value);
  
  	Attribute createAttributeWithType(const AttributeUnderlyingType type, const Field & null_value);
  
  	template <typename OutputType, typename ValueSetter, typename DefaultGetter>
  	void getItemsNumber(
  		const Attribute & attribute,
  		const PaddedPODArray<Key> & ids,
  		ValueSetter && set_value,
  		DefaultGetter && get_default) const;
  
  	template <typename AttributeType, typename OutputType, typename ValueSetter, typename DefaultGetter>
  	void getItemsImpl(
  		const Attribute & attribute,
  		const PaddedPODArray<Key> & ids,
  		ValueSetter && set_value,
  		DefaultGetter && get_default) const;
  
  	template <typename T>
  	void setAttributeValueImpl(Attribute & attribute, const Key id, const T value);
  
  	void setAttributeValue(Attribute & attribute, const Key id, const Field & value);
  
  	const Attribute & getAttribute(const std::string & attribute_name) const;
  
  	template <typename T>
  	void has(const Attribute & attribute, const PaddedPODArray<Key> & ids, PaddedPODArray<UInt8> & out) const;
  
  	const std::string name;
  	const DictionaryStructure dict_struct;
  	const DictionarySourcePtr source_ptr;
  	const DictionaryLifetime dict_lifetime;
  	const bool require_nonempty;
  
  	std::map<std::string, std::size_t> attribute_index_by_name;
  	std::vector<Attribute> attributes;
  	const Attribute * hierarchical_attribute = nullptr;
  
  	std::size_t bytes_allocated = 0;
  	std::size_t element_count = 0;
  	std::size_t bucket_count = 0;
  	mutable std::atomic<std::size_t> query_count{0};
  
  	std::chrono::time_point<std::chrono::system_clock> creation_time;
  
  	std::exception_ptr creation_exception;
  };
  
  }
  