ClickHouse/dbms/include/DB/Functions/FunctionsHigherOrder.h

#pragma once

#include <DB/DataTypes/DataTypeArray.h>
#include <DB/DataTypes/DataTypeExpression.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>

#include <DB/Columns/ColumnArray.h>
#include <DB/Columns/ColumnExpression.h>

#include <DB/Functions/IFunction.h>
#include <DB/Functions/FunctionsMiscellaneous.h>


namespace DB
{

namespace ErrorCodes
{
	extern const int SIZES_OF_ARRAYS_DOESNT_MATCH;
}

/** Функции высшего порядка для массивов:
  *
  * arrayMap(x1,...,xn -> expression, array1,...,arrayn) - применить выражение к каждому элементу массива (или набора параллельных массивов).
  * arrayFilter(x -> predicate, array) - оставить в массиве только элементы, для которых выражение истинно.
  * arrayCount(x1,...,xn -> expression, array1,...,arrayn) - для скольки элементов массива выражение истинно.
  * arrayExists(x1,...,xn -> expression, array1,...,arrayn) - истинно ли выражение для хотя бы одного элемента массива.
  * arrayAll(x1,...,xn -> expression, array1,...,arrayn) - истинно ли выражение для всех элементов массива.
  *
  * Для функций arrayCount, arrayExists, arrayAll доступна еще перегрузка вида f(array), которая работает так же, как f(x -> x, array).
  */

struct ArrayMapImpl
{
	/// true, если выражение (для перегрузки f(expression, arrays)) или массив (для f(array)) должно быть булевым.
	static bool needBoolean() { return false; }
	/// true, если перегрузка f(array) недоступна.
	static bool needExpression() { return true; }
	/// true, если массив должен быть ровно один.
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeArray>(expression_return);
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		return mapped->isConst()
			? std::make_shared<ColumnArray>(dynamic_cast<const IColumnConst &>(*mapped).convertToFullColumn(), array.getOffsetsColumn())
			: std::make_shared<ColumnArray>(mapped, array.getOffsetsColumn());
	}
};

struct ArrayFilterImpl
{
	static bool needBoolean() { return true; }
	static bool needExpression() { return true; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeArray>(array_element);
	}

	/// Если массивов несколько, сюда передается первый.
	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const ColumnUInt8 * column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
				return array.clone();
			else
				return std::make_shared<ColumnArray>(
					array.getDataPtr()->cloneEmpty(),
					std::make_shared<ColumnArray::ColumnOffsets_t>(array.size(), 0));
		}

		const IColumn::Filter & filter = column_filter->getData();
		ColumnPtr filtered = array.getData().filter(filter, -1);

		const IColumn::Offsets_t & in_offsets = array.getOffsets();
		auto column_offsets = std::make_shared<ColumnArray::ColumnOffsets_t>(in_offsets.size());
		ColumnPtr column_offsets_ptr = column_offsets;
		IColumn::Offsets_t & out_offsets = column_offsets->getData();

		size_t in_pos = 0;
		size_t out_pos = 0;
		for (size_t i = 0; i < in_offsets.size(); ++i)
		{
			for (; in_pos < in_offsets[i]; ++in_pos)
			{
				if (filter[in_pos])
					++out_pos;
			}
			out_offsets[i] = out_pos;
		}

		return std::make_shared<ColumnArray>(filtered, column_offsets_ptr);
	}
};

struct ArrayCountImpl
{
	static bool needBoolean() { return true; }
	static bool needExpression() { return false; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeUInt32>();
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const ColumnUInt8 * column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
			{
				const IColumn::Offsets_t & offsets = array.getOffsets();
				auto out_column = std::make_shared<ColumnUInt32>(offsets.size());
				ColumnUInt32::Container_t & out_counts = out_column->getData();

				size_t pos = 0;
				for (size_t i = 0; i < offsets.size(); ++i)
				{
					out_counts[i] = offsets[i] - pos;
					pos = offsets[i];
				}

				return out_column;
			}
			else
				return std::make_shared<ColumnConstUInt32>(array.size(), 0);
		}

		const IColumn::Filter & filter = column_filter->getData();
		const IColumn::Offsets_t & offsets = array.getOffsets();
		auto out_column = std::make_shared<ColumnUInt32>(offsets.size());
		ColumnUInt32::Container_t & out_counts = out_column->getData();

		size_t pos = 0;
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			size_t count = 0;
			for (; pos < offsets[i]; ++pos)
			{
				if (filter[pos])
					++count;
			}
			out_counts[i] = count;
		}

		return out_column;
	}
};

struct ArrayExistsImpl
{
	static bool needBoolean() { return true; }
	static bool needExpression() { return false; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeUInt8>();
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const ColumnUInt8 * column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
			{
				const IColumn::Offsets_t & offsets = array.getOffsets();
				auto out_column = std::make_shared<ColumnUInt8>(offsets.size());
				ColumnUInt8::Container_t & out_exists = out_column->getData();

				size_t pos = 0;
				for (size_t i = 0; i < offsets.size(); ++i)
				{
					out_exists[i] = offsets[i] - pos > 0;
					pos = offsets[i];
				}

				return out_column;
			}
			else
				return std::make_shared<ColumnConstUInt8>(array.size(), 0);
		}

		const IColumn::Filter & filter = column_filter->getData();
		const IColumn::Offsets_t & offsets = array.getOffsets();
		auto out_column = std::make_shared<ColumnUInt8>(offsets.size());
		ColumnUInt8::Container_t & out_exists = out_column->getData();

		size_t pos = 0;
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			UInt8 exists = 0;
			for (; pos < offsets[i]; ++pos)
			{
				if (filter[pos])
				{
					exists = 1;
					pos = offsets[i];
					break;
				}
			}
			out_exists[i] = exists;
		}

		return out_column;
	}
};

struct ArrayAllImpl
{
	static bool needBoolean() { return true; }
	static bool needExpression() { return false; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeUInt8>();
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const ColumnUInt8 * column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
				return std::make_shared<ColumnConstUInt8>(array.size(), 1);
			else
			{
				const IColumn::Offsets_t & offsets = array.getOffsets();
				auto out_column = std::make_shared<ColumnUInt8>(offsets.size());
				ColumnUInt8::Container_t & out_all = out_column->getData();

				size_t pos = 0;
				for (size_t i = 0; i < offsets.size(); ++i)
				{
					out_all[i] = offsets[i] == pos;
					pos = offsets[i];
				}

				return out_column;
			}
		}

		const IColumn::Filter & filter = column_filter->getData();
		const IColumn::Offsets_t & offsets = array.getOffsets();
		auto out_column = std::make_shared<ColumnUInt8>(offsets.size());
		ColumnUInt8::Container_t & out_all = out_column->getData();

		size_t pos = 0;
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			UInt8 all = 1;
			for (; pos < offsets[i]; ++pos)
			{
				if (!filter[pos])
				{
					all = 0;
					pos = offsets[i];
					break;
				}
			}
			out_all[i] = all;
		}

		return out_column;
	}
};

struct ArraySumImpl
{
	static bool needBoolean() { return false; }
	static bool needExpression() { return false; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		if (typeid_cast<const DataTypeUInt8 *>(&*expression_return) ||
			typeid_cast<const DataTypeUInt16 *>(&*expression_return) ||
			typeid_cast<const DataTypeUInt32 *>(&*expression_return) ||
			typeid_cast<const DataTypeUInt64 *>(&*expression_return))
			return std::make_shared<DataTypeUInt64>();

		if (typeid_cast<const DataTypeInt8 *>(&*expression_return) ||
			typeid_cast<const DataTypeInt16 *>(&*expression_return) ||
			typeid_cast<const DataTypeInt32 *>(&*expression_return) ||
			typeid_cast<const DataTypeInt64 *>(&*expression_return))
			return std::make_shared<DataTypeInt64>();

		if (typeid_cast<const DataTypeFloat32 *>(&*expression_return) ||
			typeid_cast<const DataTypeFloat64 *>(&*expression_return))
			return std::make_shared<DataTypeFloat64>();

		throw Exception("arraySum cannot add values of type " + expression_return->getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
	}

	template <class Element, class Result>
	static bool executeType(const ColumnPtr & mapped, const ColumnArray::Offsets_t & offsets, ColumnPtr & res_ptr)
	{
		const ColumnVector<Element> * column = typeid_cast<const ColumnVector<Element> *>(&*mapped);

		if (!column)
		{
			const ColumnConst<Element> * column_const = typeid_cast<const ColumnConst<Element> *>(&*mapped);

			if (!column_const)
				return false;

			const Element x = column_const->getData();

			auto res_column = std::make_shared<ColumnVector<Result>>(offsets.size());
			res_ptr = res_column;
			typename ColumnVector<Result>::Container_t & res = res_column->getData();

			size_t pos = 0;
			for (size_t i = 0; i < offsets.size(); ++i)
			{
				res[i] = x * (offsets[i] - pos);
				pos = offsets[i];
			}

			return true;
		}

		const typename ColumnVector<Element>::Container_t & data = column->getData();
		auto res_column = std::make_shared<ColumnVector<Result>>(offsets.size());
		res_ptr = res_column;
		typename ColumnVector<Result>::Container_t & res = res_column->getData();

		size_t pos = 0;
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			Result s = 0;
			for (; pos < offsets[i]; ++pos)
			{
				s += data[pos];
			}
			res[i] = s;
		}

		return true;
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const IColumn::Offsets_t & offsets = array.getOffsets();
		ColumnPtr res;

		if (executeType< UInt8 , UInt64>(mapped, offsets, res) ||
			executeType< UInt16, UInt64>(mapped, offsets, res) ||
			executeType< UInt32, UInt64>(mapped, offsets, res) ||
			executeType< UInt64, UInt64>(mapped, offsets, res) ||
			executeType<  Int8 ,  Int64>(mapped, offsets, res) ||
			executeType<  Int16,  Int64>(mapped, offsets, res) ||
			executeType<  Int32,  Int64>(mapped, offsets, res) ||
			executeType<  Int64,  Int64>(mapped, offsets, res) ||
			executeType<Float32,Float64>(mapped, offsets, res) ||
			executeType<Float64,Float64>(mapped, offsets, res))
			return res;
		else
			throw Exception("Unexpected column for arraySum: " + mapped->getName());
	}
};

struct ArrayFirstImpl
{
	static bool needBoolean() { return false; }
	static bool needExpression() { return true; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return array_element;
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		auto column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
			{
				const auto & offsets = array.getOffsets();
				const auto & data = array.getData();
				ColumnPtr out{data.cloneEmpty()};

				size_t pos{};
				for (size_t i = 0; i < offsets.size(); ++i)
				{
					if (offsets[i] - pos > 0)
						out->insert(data[pos]);
					else
						out->insertDefault();

					pos = offsets[i];
				}

				return out;
			}
			else
			{
				ColumnPtr out{array.getData().cloneEmpty()};
				out->insertDefault();
				return out->replicate(IColumn::Offsets_t(1, array.size()));
			}
		}

		const auto & filter = column_filter->getData();
		const auto & offsets = array.getOffsets();
		const auto & data = array.getData();
		ColumnPtr out{data.cloneEmpty()};

		size_t pos{};
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			auto exists = false;
			for (; pos < offsets[i]; ++pos)
			{
				if (filter[pos])
				{
					out->insert(data[pos]);
					exists = true;
					pos = offsets[i];
					break;
				}
			}

			if (!exists)
				out->insertDefault();
		}

		return out;
	}
};

struct ArrayFirstIndexImpl
{
	static bool needBoolean() { return false; }
	static bool needExpression() { return true; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeUInt32>();
	}

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		auto column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);

		if (!column_filter)
		{
			const ColumnConstUInt8 * column_filter_const = typeid_cast<const ColumnConstUInt8 *>(&*mapped);

			if (!column_filter_const)
				throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);

			if (column_filter_const->getData())
			{
				const auto & offsets = array.getOffsets();
				auto out_column = std::make_shared<ColumnUInt32>(offsets.size());
				auto & out_index = out_column->getData();

				size_t pos{};
				for (size_t i = 0; i < offsets.size(); ++i)
				{
					out_index[i] = offsets[i] - pos > 0;
					pos = offsets[i];
				}

				return out_column;
			}
			else
				return std::make_shared<ColumnConstUInt32>(array.size(), 0);
		}

		const auto & filter = column_filter->getData();
		const auto & offsets = array.getOffsets();
		auto out_column = std::make_shared<ColumnUInt32>(offsets.size());
		auto & out_index = out_column->getData();

		size_t pos{};
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			UInt32 index{};
			for (size_t idx{1}; pos < offsets[i]; ++pos, ++idx)
			{
				if (filter[pos])
				{
					index = idx;
					pos = offsets[i];
					break;
				}
			}

			out_index[i] = index;
		}

		return out_column;
	}
};


/** Sort arrays, by values of its elements, or by values of corresponding elements of calculated expression (known as "schwartzsort").
  */
template <bool positive>
struct ArraySortImpl
{
	static bool needBoolean() { return false; }
	static bool needExpression() { return false; }
	static bool needOneArray() { return false; }

	static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
	{
		return std::make_shared<DataTypeArray>(array_element);
	}

	struct Less
	{
		const IColumn & column;

		Less(const IColumn & column) : column(column) {}

		bool operator()(size_t lhs, size_t rhs) const
		{
			if (positive)
				return column.compareAt(lhs, rhs, column, 1) < 0;
			else
				return column.compareAt(lhs, rhs, column, -1) > 0;
		}
	};

	static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
	{
		const ColumnArray::Offsets_t & offsets = array.getOffsets();

		size_t size = offsets.size();
		size_t nested_size = array.getData().size();
		IColumn::Permutation permutation(nested_size);

		for (size_t i = 0; i < nested_size; ++i)
			permutation[i] = i;

		ColumnArray::Offset_t current_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			auto next_offset = offsets[i];
			std::sort(&permutation[current_offset], &permutation[next_offset], Less(*mapped));
			current_offset = next_offset;
		}

		return std::make_shared<ColumnArray>(array.getData().permute(permutation, 0), array.getOffsetsColumn());
	}
};


template <typename Impl, typename Name>
class FunctionArrayMapped : public IFunction
{
public:
	static constexpr auto name = Name::name;
	static FunctionPtr create(const Context & context) { return std::make_shared<FunctionArrayMapped>(); };

	/// Получить имя функции.
	String getName() const override
	{
		return name;
	}

	bool isVariadic() const override { return true; }
	size_t getNumberOfArguments() const override { return 0; }

	/// Вызывается, если хоть один агрумент функции - лямбда-выражение.
	/// Для аргументов-лямбда-выражений определяет типы аргументов этих выражений.
	void getLambdaArgumentTypesImpl(DataTypes & arguments) const override
	{
		if (arguments.size() < 1)
			throw Exception("Function " + getName() + " needs at least one argument; passed "
							+ toString(arguments.size()) + ".",
							ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

		if (arguments.size() == 1)
			throw Exception("Function " + getName() + " needs at least one array argument.",
							ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

		DataTypes nested_types(arguments.size() - 1);
		for (size_t i = 0; i < nested_types.size(); ++i)
		{
			const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(&*arguments[i + 1]);
			if (!array_type)
				throw Exception("Argument " + toString(i + 2) + " of function " + getName() + " must be array. Found "
								+ arguments[i + 1]->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
			nested_types[i] = array_type->getNestedType();
		}

		const DataTypeExpression * expression_type = typeid_cast<const DataTypeExpression *>(&*arguments[0]);
		if (!expression_type || expression_type->getArgumentTypes().size() != nested_types.size())
			throw Exception("First argument for this overload of " + getName() + " must be an expression with "
							+ toString(nested_types.size()) + " arguments. Found "
							+ arguments[0]->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

		arguments[0] = std::make_shared<DataTypeExpression>(nested_types);
	}

	void getReturnTypeAndPrerequisitesImpl(const ColumnsWithTypeAndName & arguments,
										DataTypePtr & out_return_type,
										ExpressionActions::Actions & out_prerequisites) override
	{
		size_t min_args = Impl::needExpression() ? 2 : 1;
		if (arguments.size() < min_args)
			throw Exception("Function " + getName() + " needs at least "
							+ toString(min_args) + " argument; passed "
							+ toString(arguments.size()) + ".",
							ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

		if (arguments.size() == 1)
		{
			const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(&*arguments[0].type);

			if (!array_type)
				throw Exception("The only argument for function " + getName() + " must be array. Found "
								+ arguments[0].type->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			DataTypePtr nested_type = array_type->getNestedType();

			if (Impl::needBoolean() && !typeid_cast<const DataTypeUInt8 *>(&*nested_type))
				throw Exception("The only argument for function " + getName() + " must be array of UInt8. Found "
								+ arguments[0].type->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			out_return_type = Impl::getReturnType(nested_type, nested_type);
		}
		else
		{
			if (arguments.size() > 2 && Impl::needOneArray())
				throw Exception("Function " + getName() + " needs one array argument.",
					ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

			if (!arguments[0].column)
				throw Exception("Type of first argument for function " + getName() + " must be an expression.",
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			const ColumnExpression * column_expression = typeid_cast<const ColumnExpression *>(arguments[0].column.get());

			if (!column_expression)
				throw Exception("Column of first argument for function " + getName() + " must be an expression.",
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			/// Типы остальных аргументов уже проверены в getLambdaArgumentTypes.

			/// Попросим добавить в блок все столбцы, упоминаемые в выражении, размноженные в массив, параллельный обрабатываемому.
			const ExpressionActions & expression = *column_expression->getExpression();
			Names required_columns = expression.getRequiredColumns();

			Names argument_name_vector = column_expression->getArgumentNames();
			NameSet argument_names(argument_name_vector.begin(), argument_name_vector.end());

			for (size_t i = 0; i < required_columns.size(); ++i)
			{
				if (argument_names.count(required_columns[i]))
					continue;
				Names replicate_arguments;
				replicate_arguments.push_back(required_columns[i]);
				replicate_arguments.push_back(arguments[1].name);
				out_prerequisites.push_back(ExpressionAction::applyFunction(std::make_shared<FunctionReplicate>(), replicate_arguments));
			}

			DataTypePtr return_type = column_expression->getReturnType();
			if (Impl::needBoolean() && !typeid_cast<const DataTypeUInt8 *>(&*return_type))
				throw Exception("Expression for function " + getName() + " must return UInt8, found "
								+ return_type->getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			const DataTypeArray * first_array_type = typeid_cast<const DataTypeArray *>(&*arguments[1].type);

			out_return_type = Impl::getReturnType(return_type, first_array_type->getNestedType());
		}
	}

	/// Выполнить функцию над блоком.
	void executeImpl(Block & block, const ColumnNumbers & arguments, const ColumnNumbers & prerequisites, size_t result) override
	{
		if (arguments.size() == 1)
		{
			ColumnPtr column_array_ptr = block.safeGetByPosition(arguments[0]).column;
			const ColumnArray * column_array = typeid_cast<const ColumnArray *>(&*column_array_ptr);

			if (!column_array)
			{
				const ColumnConstArray * column_const_array = typeid_cast<const ColumnConstArray *>(&*column_array_ptr);
				if (!column_const_array)
					throw Exception("Expected array column, found " + column_array_ptr->getName(), ErrorCodes::ILLEGAL_COLUMN);
				column_array_ptr = column_const_array->convertToFullColumn();
				column_array = static_cast<const ColumnArray *>(&*column_array_ptr);
			}

			block.safeGetByPosition(result).column = Impl::execute(*column_array, column_array->getDataPtr());
		}
		else
		{
			const auto & column_with_type_and_name = block.safeGetByPosition(arguments[0]);

			if (!column_with_type_and_name.column)
				throw Exception("First argument for function " + getName() + " must be an expression.",
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

			ColumnExpression * column_expression = typeid_cast<ColumnExpression *>(column_with_type_and_name.column.get());

			ColumnPtr offsets_column;

			Block temp_block;
			const ExpressionActions & expression = *column_expression->getExpression();
			NamesAndTypes expression_arguments = column_expression->getArguments();
			NameSet argument_names;

			ColumnPtr column_first_array_ptr;
			const ColumnArray * column_first_array = nullptr;

			/// Положим в блок аргументы выражения.

			for (size_t i = 0; i < expression_arguments.size(); ++i)
			{
				const std::string & argument_name = expression_arguments[i].name;
				DataTypePtr argument_type = expression_arguments[i].type;

				ColumnPtr column_array_ptr = block.safeGetByPosition(arguments[i + 1]).column;
				const ColumnArray * column_array = typeid_cast<const ColumnArray *>(&*column_array_ptr);

				if (!column_array)
				{
					const ColumnConstArray * column_const_array = typeid_cast<const ColumnConstArray *>(&*column_array_ptr);
					if (!column_const_array)
						throw Exception("Expected array column, found " + column_array_ptr->getName(), ErrorCodes::ILLEGAL_COLUMN);
					column_array_ptr = column_const_array->convertToFullColumn();
					column_array = typeid_cast<const ColumnArray *>(&*column_array_ptr);
				}

				if (!offsets_column)
				{
					offsets_column = column_array->getOffsetsColumn();
				}
				else
				{
					/// Первое условие - оптимизация: не сравнивать данные, если указатели равны.
					if (column_array->getOffsetsColumn() != offsets_column
						&& column_array->getOffsets() != typeid_cast<const ColumnArray::ColumnOffsets_t &>(*offsets_column).getData())
						throw Exception("Arrays passed to " + getName() + " must have equal size", ErrorCodes::SIZES_OF_ARRAYS_DOESNT_MATCH);
				}

				if (i == 0)
				{
					column_first_array_ptr = column_array_ptr;
					column_first_array = column_array;
				}

				temp_block.insert(ColumnWithTypeAndName(
					column_array->getDataPtr(),
					argument_type,
					argument_name));

				argument_names.insert(argument_name);
			}

			/// Положим в блок все нужные столбцы, размноженные по размерам массивов.

			Names required_columns = expression.getRequiredColumns();
			size_t prerequisite_index = 0;

			for (size_t i = 0; i < required_columns.size(); ++i)
			{
				const String & name = required_columns[i];

				if (argument_names.count(name))
					continue;

				ColumnWithTypeAndName replicated_column = block.safeGetByPosition(prerequisites[prerequisite_index]);

				replicated_column.name = name;
				replicated_column.column = typeid_cast<ColumnArray &>(*replicated_column.column).getDataPtr();
				replicated_column.type = typeid_cast<const DataTypeArray &>(*replicated_column.type).getNestedType(),
				temp_block.insert(std::move(replicated_column));

				++prerequisite_index;
			}

			expression.execute(temp_block);

			block.safeGetByPosition(result).column = Impl::execute(*column_first_array, temp_block.getByName(column_expression->getReturnName()).column);
		}
	}
};


struct NameArrayMap			{ static constexpr auto name = "arrayMap"; };
struct NameArrayFilter		{ static constexpr auto name = "arrayFilter"; };
struct NameArrayCount		{ static constexpr auto name = "arrayCount"; };
struct NameArrayExists		{ static constexpr auto name = "arrayExists"; };
struct NameArrayAll			{ static constexpr auto name = "arrayAll"; };
struct NameArraySum			{ static constexpr auto name = "arraySum"; };
struct NameArrayFirst		{ static constexpr auto name = "arrayFirst"; };
struct NameArrayFirstIndex	{ static constexpr auto name = "arrayFirstIndex"; };
struct NameArraySort		{ static constexpr auto name = "arraySort"; };
struct NameArrayReverseSort	{ static constexpr auto name = "arrayReverseSort"; };

using FunctionArrayMap = FunctionArrayMapped<ArrayMapImpl, NameArrayMap>;
using FunctionArrayFilter = FunctionArrayMapped<ArrayFilterImpl, NameArrayFilter>;
using FunctionArrayCount = FunctionArrayMapped<ArrayCountImpl, NameArrayCount>;
using FunctionArrayExists = FunctionArrayMapped<ArrayExistsImpl, NameArrayExists>;
using FunctionArrayAll = FunctionArrayMapped<ArrayAllImpl, NameArrayAll>;
using FunctionArraySum = FunctionArrayMapped<ArraySumImpl, NameArraySum>;
using FunctionArrayFirst = FunctionArrayMapped<ArrayFirstImpl, NameArrayFirst>;
using FunctionArrayFirstIndex = FunctionArrayMapped<ArrayFirstIndexImpl, NameArrayFirstIndex>;
using FunctionArraySort = FunctionArrayMapped<ArraySortImpl<true>, NameArraySort>;
using FunctionArrayReverseSort = FunctionArrayMapped<ArraySortImpl<false>, NameArrayReverseSort>;

}