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 54 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< RColumnElementBase >	Generate (EColumnType onDiskType)

template<>
std::unique_ptr< ROOT::Experimental::Internal::RColumnElementBase >	Generate (EColumnType onDiskType)

template<typename CppT = void>
static std::unique_ptr< RColumnElementBase >	Generate (EColumnType type)
	If CppT == void, use the default C++ type for the given column type.

static const char *	GetColumnTypeName (EColumnType type)

static std::pair< std::uint16_t, std::uint16_t >	GetValidBitRange (EColumnType 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::Experimental::Internal::RColumnElementBase::RColumnElementBase	(	std::size_t	size,
		std::size_t	bitsOnStorage = `0`
	)

inlineexplicitprotected

Definition at line 62 of file RColumnElementBase.hxx.

◆ RColumnElementBase() [2/3]

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

default

◆ RColumnElementBase() [3/3]

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

default

◆ ~RColumnElementBase()

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

virtualdefault

Member Function Documentation

◆ Generate() [1/3]

template<>

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

static

◆ Generate() [2/3]

template<>

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

static

Definition at line 70 of file RColumnElement.cxx.

◆ Generate() [3/3]

template<typename CppT >

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

static

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

Definition at line 144 of file RColumnElementBase.hxx.

◆ GetBitsOnStorage()

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

inline

Definition at line 128 of file RColumnElementBase.hxx.

◆ GetColumnTypeName()

const char * ROOT::Experimental::Internal::RColumnElementBase::GetColumnTypeName ( EColumnType type )

static

Definition at line 70 of file RColumnElement.cxx.

◆ GetIdentifier()

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

pure virtual

◆ GetPackedSize()

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

inline

Definition at line 130 of file RColumnElementBase.hxx.

◆ GetSize()

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

inline

Definition at line 127 of file RColumnElementBase.hxx.

◆ GetValidBitRange()

std::pair< std::uint16_t, std::uint16_t > ROOT::Experimental::Internal::RColumnElementBase::GetValidBitRange ( EColumnType 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 29 of file RColumnElement.cxx.

◆ GetValueRange()

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

inline

Definition at line 129 of file RColumnElementBase.hxx.

◆ IsMappable()

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

inlinevirtual

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

Definition at line 98 of file RColumnElementBase.hxx.

◆ operator=() [1/2]

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

delete

◆ operator=() [2/2]

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

default

◆ Pack()

virtual void ROOT::Experimental::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 116 of file RColumnElementBase.hxx.

◆ SetBitsOnStorage()

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

inlinevirtual

Definition at line 104 of file RColumnElementBase.hxx.

◆ SetValueRange()

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

inlinevirtual

Definition at line 110 of file RColumnElementBase.hxx.

◆ Unpack()

virtual void ROOT::Experimental::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 122 of file RColumnElementBase.hxx.

Member Data Documentation

◆ fBitsOnStorage

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

protected

Definition at line 58 of file RColumnElementBase.hxx.

◆ fSize

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

protected

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

Definition at line 57 of file RColumnElementBase.hxx.

◆ fValueRange

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

protected

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

Definition at line 60 of file RColumnElementBase.hxx.

Libraries for ROOT::Experimental::Internal::RColumnElementBase:

[legend]

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

tree/ntuple/v7/inc/ROOT/RColumnElementBase.hxx
tree/ntuple/v7/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