ClickHouse/dbms/src/Functions/FunctionHelpers.h
2018-11-20 23:09:20 +03:00

98 lines
2.4 KiB
C++

#pragma once
#include <Common/typeid_cast.h>
#include <DataTypes/IDataType.h>
#include <Columns/IColumn.h>
#include <Columns/ColumnConst.h>
#include <Core/Block.h>
#include <Core/ColumnNumbers.h>
#include <Core/callOnTypeIndex.h>
namespace DB
{
/// Methods, that helps dispatching over real column types.
template <typename Type>
const Type * checkAndGetDataType(const IDataType * data_type)
{
return typeid_cast<const Type *>(data_type);
}
template <typename Type>
const Type * checkAndGetColumn(const IColumn * column)
{
return typeid_cast<const Type *>(column);
}
template <typename Type>
bool checkColumn(const IColumn * column)
{
return checkAndGetColumn<Type>(column);
}
template <typename Type>
const ColumnConst * checkAndGetColumnConst(const IColumn * column)
{
if (!column || !column->isColumnConst())
return {};
const ColumnConst * res = static_cast<const ColumnConst *>(column);
if (!checkColumn<Type>(&res->getDataColumn()))
return {};
return res;
}
template <typename Type>
const Type * checkAndGetColumnConstData(const IColumn * column)
{
const ColumnConst * res = checkAndGetColumnConst<Type>(column);
if (!res)
return {};
return static_cast<const Type *>(&res->getDataColumn());
}
template <typename Type>
bool checkColumnConst(const IColumn * column)
{
return checkAndGetColumnConst<Type>(column);
}
/// Returns non-nullptr if column is ColumnConst with ColumnString or ColumnFixedString inside.
const ColumnConst * checkAndGetColumnConstStringOrFixedString(const IColumn * column);
/// Transform anything to Field.
template <typename T>
inline std::enable_if_t<!IsDecimalNumber<T>, Field> toField(const T & x)
{
return Field(NearestFieldType<T>(x));
}
template <typename T>
inline std::enable_if_t<IsDecimalNumber<T>, Field> toField(const T & x, UInt32 scale)
{
return Field(NearestFieldType<T>(x, scale));
}
Columns convertConstTupleToConstantElements(const ColumnConst & column);
/// Returns the copy of a given block in which each column specified in
/// the "arguments" parameter is replaced with its respective nested
/// column if it is nullable.
Block createBlockWithNestedColumns(const Block & block, const ColumnNumbers & args);
/// Similar function as above. Additionally transform the result type if needed.
Block createBlockWithNestedColumns(const Block & block, const ColumnNumbers & args, size_t result);
}