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

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#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 "FunctionsMiscellaneous.h"
namespace DB
{
/** Функции высшего порядка для массивов:
*
* arrayMap(x -> expression, array) - применить выражение к каждому элементу массива.
* arrayFilter(x -> predicate, array) - оставить в массиве только элементы, для которых выражение истинно.
* arrayCount(x -> predicate, array) - для скольки элементов массива выражение истинно.
* arrayExists(x -> predicate, array) - истинно ли выражение для хотя бы одного элемента массива.
*/
struct ArrayMapImpl
{
static bool needBooleanExpression() { return false; }
static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
{
return new DataTypeArray(expression_return);
}
static ColumnPtr execute(const ColumnArray * array, ColumnPtr mapped)
{
return new ColumnArray(mapped, array->getOffsetsColumn());
}
};
struct ArrayFilterImpl
{
static bool needBooleanExpression() { return true; }
static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
{
return new DataTypeArray(array_element);
}
static ColumnPtr execute(const ColumnArray * array, ColumnPtr mapped)
{
ColumnVector<UInt8> * column_filter = dynamic_cast<ColumnVector<UInt8> *>(&*mapped);
if (!column_filter)
throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);
const IColumn::Filter & filter = column_filter->getData();
ColumnPtr filtered = array->getData().filter(filter);
const IColumn::Offsets_t & in_offsets = array->getOffsets();
ColumnArray::ColumnOffsets_t * column_offsets = new 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 new ColumnArray(filtered, column_offsets_ptr);
}
};
struct ArrayCountImpl
{
static bool needBooleanExpression() { return true; }
static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
{
return new DataTypeUInt32;
}
static ColumnPtr execute(const ColumnArray * array, ColumnPtr mapped)
{
ColumnVector<UInt8> * column_filter = dynamic_cast<ColumnVector<UInt8> *>(&*mapped);
if (!column_filter)
throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);
const IColumn::Filter & filter = column_filter->getData();
const IColumn::Offsets_t & offsets = array->getOffsets();
ColumnVector<UInt32> * out_column = new ColumnVector<UInt32>(offsets.size());
ColumnPtr out_column_ptr = out_column;
ColumnVector<UInt32>::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_ptr;
}
};
struct ArrayExistsImpl
{
static bool needBooleanExpression() { return true; }
static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & array_element)
{
return new DataTypeUInt8;
}
static ColumnPtr execute(const ColumnArray * array, ColumnPtr mapped)
{
ColumnVector<UInt8> * column_filter = dynamic_cast<ColumnVector<UInt8> *>(&*mapped);
if (!column_filter)
throw Exception("Unexpected type of filter column", ErrorCodes::ILLEGAL_COLUMN);
const IColumn::Filter & filter = column_filter->getData();
const IColumn::Offsets_t & offsets = array->getOffsets();
ColumnVector<UInt8> * out_column = new ColumnVector<UInt8>(offsets.size());
ColumnPtr out_column_ptr = out_column;
ColumnVector<UInt8>::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 = true;
break;
}
}
out_exists[i] = exists;
}
return out_column_ptr;
}
};
template <typename Impl, typename Name>
class FunctionArrayMapped : public IFunction
{
public:
/// Получить имя функции.
String getName() const
{
return Name::get();
}
void checkTypes(const DataTypes & arguments, const DataTypeExpression *& expression_type, const DataTypeArray *& array_type) const {
if (arguments.size() != 2)
throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
+ Poco::NumberFormatter::format(arguments.size()) + ", should be 2.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
array_type = dynamic_cast<const DataTypeArray *>(&*arguments[1]);
if (!array_type)
throw Exception("Second argument for function " + getName() + " must be array. Found "
+ arguments[1]->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
expression_type = dynamic_cast<const DataTypeExpression *>(&*arguments[0]);
if (!expression_type || expression_type->getArgumentTypes().size() != 1)
throw Exception("First argument for function " + getName() + " must be an expression with one argument. Found "
+ arguments[0]->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
}
/// Вызывается, если хоть один агрумент функции - лямбда-выражение.
/// Для аргументов-лямбда-выражений определяет типы аргументов этих выражений.
void getLambdaArgumentTypes(DataTypes & arguments) const
{
const DataTypeArray * array_type;
const DataTypeExpression * expression_type;
checkTypes(arguments, expression_type, array_type);
arguments[0] = new DataTypeExpression(DataTypes(1, array_type->getNestedType()));
}
void getReturnTypeAndPrerequisites(const ColumnsWithNameAndType & arguments,
DataTypePtr & out_return_type,
ExpressionActions::Actions & out_prerequisites)
{
if (arguments.size() != 2)
throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
+ Poco::NumberFormatter::format(arguments.size()) + ", should be 2.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
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const ColumnExpression * column_expression = dynamic_cast<const ColumnExpression *>(&*arguments[0].column);
const DataTypeArray * array_type = dynamic_cast<const DataTypeArray *>(&*arguments[1].type);
if (!column_expression)
throw Exception("First argument for function " + getName() + " must be an expression with one argument.",
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
if (!array_type)
throw Exception("Second argument for function " + getName() + " must be array. Found "
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+ arguments[1].type->getName() + " instead.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
/// Попросим добавить в блок все столбцы, упоминаемые в выражении, размноженные в массив, параллельный обрабатываемому.
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const ExpressionActions & expression = *column_expression->getExpression();
Names required_columns = expression.getRequiredColumns();
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Names::iterator it = std::find(required_columns.begin(), required_columns.end(), column_expression->getArguments()[0].first);
if (it != required_columns.end())
required_columns.erase(it);
for (size_t i = 0; i < required_columns.size(); ++i)
{
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Names replicate_arguments;
replicate_arguments.push_back(required_columns[i]);
replicate_arguments.push_back(arguments[1].name);
out_prerequisites.push_back(ExpressionActions::Action::applyFunction(new FunctionReplicate, replicate_arguments));
}
DataTypePtr return_type = column_expression->getReturnType();
if (Impl::needBooleanExpression() && !dynamic_cast<const DataTypeUInt8 *>(&*return_type))
throw Exception("Expression for function " + getName() + " must return UInt8, found "
+ return_type->getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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out_return_type = Impl::getReturnType(return_type, array_type->getNestedType());
}
/// Выполнить функцию над блоком.
void execute(Block & block, const ColumnNumbers & arguments, const ColumnNumbers & prerequisites, size_t result)
{
ColumnPtr column_array_ptr = block.getByPosition(arguments[1]).column;
ColumnExpression * column_expression = dynamic_cast<ColumnExpression *>(&*block.getByPosition(arguments[0]).column);
const ColumnArray * column_array = dynamic_cast<const ColumnArray *>(&*column_array_ptr);
ColumnPtr temp_column;
if (!column_array)
{
const ColumnConstArray * column_const_array = dynamic_cast<const ColumnConstArray *>(&*column_array_ptr);
if (!column_const_array)
throw Exception("Expected array column, found " + column_array_ptr->getName(), ErrorCodes::ILLEGAL_COLUMN);
temp_column = column_const_array->convertToFullColumn();
column_array = dynamic_cast<const ColumnArray *>(&*temp_column);
}
Block temp_block;
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const ExpressionActions & expression = *column_expression->getExpression();
String argument_name = column_expression->getArguments()[0].first;
DataTypePtr element_type = column_expression->getArguments()[0].second;
Names required_columns = expression.getRequiredColumns();
Names::iterator it = std::find(required_columns.begin(), required_columns.end(), argument_name);
if (it != required_columns.end())
required_columns.erase(it);
/// Положим в блок аргумент выражения.
temp_block.insert(ColumnWithNameAndType(column_array->getDataPtr(), element_type, argument_name));
/// Положим в блок все нужные столбцы, размноженные по размерам массивов.
for (size_t i = 0; i < required_columns.size(); ++i)
{
const String & name = required_columns[i];
ColumnWithNameAndType replicated_column = block.getByPosition(prerequisites[i]);
const ColumnArray * col = dynamic_cast<const ColumnArray *>(&*replicated_column.column);
const DataTypeArray * type = dynamic_cast<const DataTypeArray *>(&*replicated_column.type);
if (!col || !type)
throw Exception("Unexpected replicated column", ErrorCodes::LOGICAL_ERROR);
replicated_column.name = name;
replicated_column.column = col->getDataPtr();
replicated_column.type = type->getNestedType();
temp_block.insert(replicated_column);
}
expression.execute(temp_block);
block.getByPosition(result).column = Impl::execute(column_array, temp_block.getByName(column_expression->getReturnName()).column);
}
};
struct NameArrayMap { static const char * get() { return "arrayMap"; } };
struct NameArrayFilter { static const char * get() { return "arrayFilter"; } };
struct NameArrayCount { static const char * get() { return "arrayCount"; } };
struct NameArrayExists { static const char * get() { return "arrayExists"; } };
typedef FunctionArrayMapped<ArrayMapImpl, NameArrayMap> FunctionArrayMap;
typedef FunctionArrayMapped<ArrayFilterImpl, NameArrayFilter> FunctionArrayFilter;
typedef FunctionArrayMapped<ArrayCountImpl, NameArrayCount> FunctionArrayCount;
typedef FunctionArrayMapped<ArrayExistsImpl, NameArrayExists> FunctionArrayExists;
}