ClickHouse/dbms/Functions/identity.cpp

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#include <Functions/IFunctionImpl.h>
#include <Functions/FunctionFactory.h>
namespace DB
{
class FunctionIdentity : public IFunction
{
public:
static constexpr auto name = "identity";
static FunctionPtr create(const Context &)
{
return std::make_shared<FunctionIdentity>();
}
String getName() const override
{
return name;
}
size_t getNumberOfArguments() const override
{
return 1;
}
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
return arguments.front();
}
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
{
block.getByPosition(result).column = block.getByPosition(arguments.front()).column;
}
};
void registerFunctionIdentity(FunctionFactory & factory)
{
factory.registerFunction<FunctionIdentity>();
}
}