A column element encapsulates the translation between basic C++ types and their column representation.

Usually the on-disk element should map bitwise to the in-memory element. Sometimes that's not the case though, for instance on big endian platforms or for bools.

There is a template specialization for every valid pair of C++ type and column representation. These specialized child classes are responsible for overriding Pack() / Unpack() for packing / unpacking elements as appropriate.

Definition at line 51 of file RColumnElementBase.hxx.

Classes
struct	RIdentifier
	Every concrete RColumnElement type is identified by its on-disk type (column type) and the in-memory C++ type, given by a type index. More...

Public Member Functions
	RColumnElementBase (const RColumnElementBase &other)=default
	RColumnElementBase (RColumnElementBase &&other)=default
virtual	~RColumnElementBase ()=default
std::size_t	GetBitsOnStorage () const
virtual RIdentifier	GetIdentifier () const =0
std::size_t	GetPackedSize (std::size_t nElements=1U) const
std::size_t	GetSize () const
std::optional< std::pair< double, double > >	GetValueRange () const
virtual bool	IsMappable () const
	Derived, typed classes tell whether the on-storage layout is bitwise identical to the memory layout.
RColumnElementBase &	operator= (const RColumnElementBase &other)=delete
RColumnElementBase &	operator= (RColumnElementBase &&other)=default
virtual void	Pack (void destination, const void source, std::size_t count) const
	If the on-storage layout and the in-memory layout differ, packing creates an on-disk page from an in-memory page.
virtual void	SetBitsOnStorage (std::size_t bitsOnStorage)
virtual void	SetValueRange (double, double)
virtual void	Unpack (void destination, const void source, std::size_t count) const
	If the on-storage layout and the in-memory layout differ, unpacking creates a memory page from an on-storage page.

Static Public Member Functions
template<>
std::unique_ptr< ROOT::Internal::RColumnElementBase >	Generate (ENTupleColumnType onDiskType)
template<>
std::unique_ptr< RColumnElementBase >	Generate (ROOT::ENTupleColumnType onDiskType)
template<typename CppT = void>
static std::unique_ptr< RColumnElementBase >	Generate (ROOT::ENTupleColumnType type)
	If CppT == void, use the default C++ type for the given column type.
static const char *	GetColumnTypeName (ROOT::ENTupleColumnType type)
static std::pair< std::uint16_t, std::uint16_t >	GetValidBitRange (ROOT::ENTupleColumnType type)
	Most types have a fixed on-disk bit width.

Protected Member Functions
	RColumnElementBase (std::size_t size, std::size_t bitsOnStorage=0)

Protected Attributes
std::size_t	fBitsOnStorage
std::size_t	fSize
	Size of the C++ value that corresponds to the on-disk element.
std::optional< std::pair< double, double > >	fValueRange = std::nullopt
	This is only meaningful for column elements that support it (e.g. Real32Quant).

#include <ROOT/RColumnElementBase.hxx>

Constructor & Destructor Documentation

◆ RColumnElementBase() [1/3]

ROOT::Internal::RColumnElementBase::RColumnElementBase	(	std::size_t	size,
		std::size_t	bitsOnStorage = 0 )

inlineexplicitprotected

Definition at line 59 of file RColumnElementBase.hxx.

◆ RColumnElementBase() [2/3]

ROOT::Internal::RColumnElementBase::RColumnElementBase ( const RColumnElementBase & other )

default

◆ RColumnElementBase() [3/3]

ROOT::Internal::RColumnElementBase::RColumnElementBase ( RColumnElementBase && other )

default

◆ ~RColumnElementBase()

virtual ROOT::Internal::RColumnElementBase::~RColumnElementBase ( )

virtualdefault

Member Function Documentation

◆ Generate() [1/3]

template<>

std::unique_ptr< ROOT::Internal::RColumnElementBase > ROOT::Internal::RColumnElementBase::Generate ( ENTupleColumnType onDiskType )

static

Definition at line 69 of file RColumnElement.cxx.

◆ Generate() [2/3]

template<>

std::unique_ptr< RColumnElementBase > ROOT::Internal::RColumnElementBase::Generate ( ROOT::ENTupleColumnType onDiskType )

static

◆ Generate() [3/3]

template<typename CppT>

std::unique_ptr< RColumnElementBase > ROOT::Internal::RColumnElementBase::Generate ( ROOT::ENTupleColumnType type )

static

If CppT == void, use the default C++ type for the given column type.

Definition at line 142 of file RColumnElementBase.hxx.

◆ GetBitsOnStorage()

std::size_t ROOT::Internal::RColumnElementBase::GetBitsOnStorage ( ) const

inline

Definition at line 125 of file RColumnElementBase.hxx.

◆ GetColumnTypeName()

const char * ROOT::Internal::RColumnElementBase::GetColumnTypeName ( ROOT::ENTupleColumnType type )

static

Definition at line 69 of file RColumnElement.cxx.

◆ GetIdentifier()

virtual RIdentifier ROOT::Internal::RColumnElementBase::GetIdentifier ( ) const

pure virtual

◆ GetPackedSize()

std::size_t ROOT::Internal::RColumnElementBase::GetPackedSize ( std::size_t nElements = 1U ) const

inline

Definition at line 127 of file RColumnElementBase.hxx.

◆ GetSize()

std::size_t ROOT::Internal::RColumnElementBase::GetSize ( ) const

inline

Definition at line 124 of file RColumnElementBase.hxx.

◆ GetValidBitRange()

std::pair< std::uint16_t, std::uint16_t > ROOT::Internal::RColumnElementBase::GetValidBitRange ( ROOT::ENTupleColumnType type )

static

Most types have a fixed on-disk bit width.

Some low-precision column types have a range of possible bit widths. Return the minimum and maximum allowed bit size per type.

Definition at line 28 of file RColumnElement.cxx.

◆ GetValueRange()

std::optional< std::pair< double, double > > ROOT::Internal::RColumnElementBase::GetValueRange ( ) const

inline

Definition at line 126 of file RColumnElementBase.hxx.

◆ IsMappable()

virtual bool ROOT::Internal::RColumnElementBase::IsMappable ( ) const

inlinevirtual

Derived, typed classes tell whether the on-storage layout is bitwise identical to the memory layout.

Definition at line 95 of file RColumnElementBase.hxx.

◆ operator=() [1/2]

RColumnElementBase & ROOT::Internal::RColumnElementBase::operator= ( const RColumnElementBase & other )

delete

◆ operator=() [2/2]

RColumnElementBase & ROOT::Internal::RColumnElementBase::operator= ( RColumnElementBase && other )

default

◆ Pack()

virtual void ROOT::Internal::RColumnElementBase::Pack	(	void *	destination,
		const void *	source,
		std::size_t	count ) const

inlinevirtual

If the on-storage layout and the in-memory layout differ, packing creates an on-disk page from an in-memory page.

Definition at line 113 of file RColumnElementBase.hxx.

◆ SetBitsOnStorage()

virtual void ROOT::Internal::RColumnElementBase::SetBitsOnStorage ( std::size_t bitsOnStorage )

inlinevirtual

Definition at line 101 of file RColumnElementBase.hxx.

◆ SetValueRange()

virtual void ROOT::Internal::RColumnElementBase::SetValueRange	(	double	,
		double	)

inlinevirtual

Definition at line 107 of file RColumnElementBase.hxx.

◆ Unpack()

virtual void ROOT::Internal::RColumnElementBase::Unpack	(	void *	destination,
		const void *	source,
		std::size_t	count ) const

inlinevirtual

If the on-storage layout and the in-memory layout differ, unpacking creates a memory page from an on-storage page.

Definition at line 119 of file RColumnElementBase.hxx.

Member Data Documentation

◆ fBitsOnStorage

std::size_t ROOT::Internal::RColumnElementBase::fBitsOnStorage

protected

Definition at line 55 of file RColumnElementBase.hxx.

◆ fSize

std::size_t ROOT::Internal::RColumnElementBase::fSize

protected

Size of the C++ value that corresponds to the on-disk element.

Definition at line 54 of file RColumnElementBase.hxx.

◆ fValueRange

std::optional<std::pair<double, double> > ROOT::Internal::RColumnElementBase::fValueRange = std::nullopt

protected

This is only meaningful for column elements that support it (e.g. Real32Quant).

Definition at line 57 of file RColumnElementBase.hxx.

The documentation for this class was generated from the following files:

tree/ntuple/inc/ROOT/RColumnElementBase.hxx
tree/ntuple/src/RColumnElement.cxx

Classes

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Constructor & Destructor Documentation

◆ RColumnElementBase() [1/3]

◆ RColumnElementBase() [2/3]

◆ RColumnElementBase() [3/3]

◆ ~RColumnElementBase()

Member Function Documentation

◆ Generate() [1/3]

◆ Generate() [2/3]

◆ Generate() [3/3]

◆ GetBitsOnStorage()

◆ GetColumnTypeName()

◆ GetIdentifier()

◆ GetPackedSize()

◆ GetSize()

◆ GetValidBitRange()

◆ GetValueRange()

◆ IsMappable()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ Pack()

◆ SetBitsOnStorage()

◆ SetValueRange()

◆ Unpack()

Member Data Documentation

◆ fBitsOnStorage

◆ fSize

◆ fValueRange