ClickHouse/dbms/src/Functions/materialize.cpp

#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>


namespace DB
{

/** materialize(x) - materialize the constant
  */
class FunctionMaterialize : public IFunction
{
public:
    static constexpr auto name = "materialize";
    static FunctionPtr create(const Context &)
    {
        return std::make_shared<FunctionMaterialize>();
    }

    /// Get the function name.
    String getName() const override
    {
        return name;
    }

    size_t getNumberOfArguments() const override
    {
        return 1;
    }

    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
    {
        return arguments[0];
    }

    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
    {
        const auto & src = block.getByPosition(arguments[0]).column;
        if (ColumnPtr converted = src->convertToFullColumnIfConst())
            block.getByPosition(result).column = converted;
        else
            block.getByPosition(result).column = src;
    }
};


void registerFunctionMaterialize(FunctionFactory & factory)
{
    factory.registerFunction<FunctionMaterialize>();
}

}