ClickHouse/src/Functions/array/arrayPop.h
2020-07-21 16:58:07 +03:00

83 lines
2.6 KiB
C++

#include <Functions/IFunctionImpl.h>
#include <Functions/GatherUtils/GatherUtils.h>
#include <DataTypes/DataTypeArray.h>
#include <Columns/ColumnArray.h>
#include <Common/typeid_cast.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}
class FunctionArrayPop : public IFunction
{
public:
FunctionArrayPop(bool pop_front_, const char * name_) : pop_front(pop_front_), name(name_) {}
String getName() const override { return name; }
bool isVariadic() const override { return false; }
size_t getNumberOfArguments() const override { return 1; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
if (arguments[0]->onlyNull())
return arguments[0];
auto array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
if (!array_type)
throw Exception("First argument for function " + getName() + " must be an array but it has type "
+ arguments[0]->getName() + ".", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
return arguments[0];
}
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) const override
{
const auto & return_type = block.getByPosition(result).type;
if (return_type->onlyNull())
{
block.getByPosition(result).column = return_type->createColumnConstWithDefaultValue(input_rows_count);
return;
}
auto result_column = return_type->createColumn();
const auto & array_column = block.getByPosition(arguments[0]).column;
std::unique_ptr<GatherUtils::IArraySource> source;
size_t size = array_column->size();
if (auto argument_column_array = typeid_cast<const ColumnArray *>(array_column.get()))
source = GatherUtils::createArraySource(*argument_column_array, false, size);
else
throw Exception{"First arguments for function " + getName() + " must be array.", ErrorCodes::LOGICAL_ERROR};
auto sink = GatherUtils::createArraySink(typeid_cast<ColumnArray &>(*result_column), size);
if (pop_front)
GatherUtils::sliceFromLeftConstantOffsetUnbounded(*source, *sink, 1);
else
GatherUtils::sliceFromLeftConstantOffsetBounded(*source, *sink, 0, -1);
block.getByPosition(result).column = std::move(result_column);
}
bool useDefaultImplementationForConstants() const override { return true; }
bool useDefaultImplementationForNulls() const override { return false; }
private:
bool pop_front;
const char * name;
};
}