The generic field for std::variant types.

Definition at line 770 of file RField.hxx.

Public Member Functions
	RVariantField (RVariantField &&other)=default

	RVariantField (std::string_view fieldName, const std::vector< Detail::RFieldBase * > &itemFields)

	~RVariantField () override=default

Detail::RFieldValue	CaptureValue (void *where) final
	Creates a value from a memory location with an already constructed object.

void	CommitCluster () final
	Perform housekeeping tasks for global to cluster-local index translation.

void	DestroyValue (const Detail::RFieldValue &value, bool dtorOnly=false) final
	Releases the resources acquired during GenerateValue (memory and constructor) This implementation works for simple types but needs to be overwritten for complex ones.

Detail::RFieldValue	GenerateValue (void *where) override
	Generates a tree value in a given location of size at least GetValueSize().

size_t	GetAlignment () const final
	As a rule of thumb, the alignment is equal to the size of the type.

size_t	GetValueSize () const final
	The number of bytes taken by a value of the appropriate type.

RVariantField &	operator= (RVariantField &&other)=default

Public Member Functions inherited from ROOT::Experimental::Detail::RFieldBase
	RFieldBase (const RFieldBase &)=delete

	RFieldBase (RFieldBase &&)=default

	RFieldBase (std::string_view name, std::string_view type, ENTupleStructure structure, bool isSimple, std::size_t nRepetitions=0)
	The constructor creates the underlying column objects and connects them to either a sink or a source.

virtual	~RFieldBase ()

virtual void	AcceptVisitor (RFieldVisitor &visitor) const

std::size_t	Append (const RFieldValue &value)
	Write the given value into columns.

void	Attach (std::unique_ptr< Detail::RFieldBase > child)
	Add a new subfield to the list of nested fields.

RSchemaIterator	begin ()

virtual RFieldValue	CaptureValue (void *where)=0
	Creates a value from a memory location with an already constructed object.

std::unique_ptr< RFieldBase >	Clone (std::string_view newName) const
	Copies the field and its sub fields using a possibly new name and a new, unconnected set of columns.

virtual void	CommitCluster ()
	Perform housekeeping tasks for global to cluster-local index translation.

void	ConnectPageSink (RPageSink &pageSink)
	Fields and their columns live in the void until connected to a physical page storage.

void	ConnectPageSource (RPageSource &pageSource)

virtual void	DestroyValue (const RFieldValue &value, bool dtorOnly=false)
	Releases the resources acquired during GenerateValue (memory and constructor) This implementation works for simple types but needs to be overwritten for complex ones.

RSchemaIterator	end ()

void	Flush () const
	Ensure that all received items are written from page buffers to the storage.

RFieldValue	GenerateValue ()
	Generates an object of the field type and allocates new initialized memory according to the type.

virtual RFieldValue	GenerateValue (void *where)=0
	Generates a tree value in a given location of size at least GetValueSize().

virtual size_t	GetAlignment () const =0
	As a rule of thumb, the alignment is equal to the size of the type.

const ColumnRepresentation_t &	GetColumnRepresentative () const
	Returns the fColumnRepresentative pointee or, if unset, the field's default representative.

std::string	GetDescription () const
	Get the field's description.

virtual std::uint32_t	GetFieldVersion () const
	Indicates an evolution of the mapping scheme from C++ type to columns.

std::string	GetName () const

NTupleSize_t	GetNElements () const

std::size_t	GetNRepetitions () const

DescriptorId_t	GetOnDiskId () const

std::uint32_t	GetOnDiskTypeVersion () const
	Return the C++ type version stored in the field descriptor; only valid after a call to `ConnectPageSource()`

RFieldBase *	GetParent () const

std::string	GetQualifiedFieldName () const
	Returns the field name and parent field names separated by dots ("grandparent.parent.child")

ENTupleStructure	GetStructure () const

std::vector< RFieldBase * >	GetSubFields () const

int	GetTraits () const

std::string	GetType () const

virtual std::uint32_t	GetTypeVersion () const
	Indicates an evolution of the C++ type itself.

virtual size_t	GetValueSize () const =0
	The number of bytes taken by a value of the appropriate type.

bool	HasDefaultColumnRepresentative () const
	Whether or not an explicit column representative was set.

bool	HasReadCallbacks () const

bool	IsSimple () const

RFieldBase &	operator= (const RFieldBase &)=delete

RFieldBase &	operator= (RFieldBase &&)=default

void	Read (const RClusterIndex &clusterIndex, RFieldValue *value)

void	Read (NTupleSize_t globalIndex, RFieldValue *value)
	Populate a single value with data from the tree, which needs to be of the fitting type.

void	SetColumnRepresentative (const ColumnRepresentation_t &representative)
	Fixes a column representative.

void	SetDescription (std::string_view description)

void	SetOnDiskId (DescriptorId_t id)

virtual std::vector< RFieldValue >	SplitValue (const RFieldValue &value) const
	Creates the list of direct child values given a value for this field.

Protected Member Functions
std::size_t	AppendImpl (const Detail::RFieldValue &value) final
	Operations on values of complex types, e.g.

std::unique_ptr< Detail::RFieldBase >	CloneImpl (std::string_view newName) const final
	Called by Clone(), which additionally copies the on-disk ID.

void	GenerateColumnsImpl () final
	Creates the backing columns corresponsing to the field type for writing.

void	GenerateColumnsImpl (const RNTupleDescriptor &desc) final
	Creates the backing columns corresponsing to the field type for reading.

const RColumnRepresentations &	GetColumnRepresentations () const final
	Implementations in derived classes should return a static RColumnRepresentations object.

void	ReadGlobalImpl (NTupleSize_t globalIndex, Detail::RFieldValue *value) final

Protected Member Functions inherited from ROOT::Experimental::Detail::RFieldBase
size_t	AddReadCallback (ReadCallback_t func)
	Set a user-defined function to be called after reading a value, giving a chance to inspect and/or modify the value object.

virtual std::size_t	AppendImpl (const RFieldValue &value)
	Operations on values of complex types, e.g.

void	AutoAdjustColumnTypes (const RNTupleWriteOptions &options)
	When connecting a field to a page sink, the field's default column representation is subject to adjustment according to the write options.

virtual std::unique_ptr< RFieldBase >	CloneImpl (std::string_view newName) const =0
	Called by Clone(), which additionally copies the on-disk ID.

const ColumnRepresentation_t &	EnsureCompatibleColumnTypes (const RNTupleDescriptor &desc) const
	Returns the on-disk column types found in the provided descriptor for fOnDiskId.

virtual void	GenerateColumnsImpl ()=0
	Creates the backing columns corresponsing to the field type for writing.

virtual void	GenerateColumnsImpl (const RNTupleDescriptor &desc)=0
	Creates the backing columns corresponsing to the field type for reading.

virtual const RColumnRepresentations &	GetColumnRepresentations () const
	Implementations in derived classes should return a static RColumnRepresentations object.

virtual void	OnConnectPageSource ()
	Called by `ConnectPageSource()` only once connected; derived classes may override this as appropriate.

virtual void	ReadGlobalImpl (NTupleSize_t globalIndex, RFieldValue *value)

virtual void	ReadInClusterImpl (const RClusterIndex &clusterIndex, RFieldValue *value)

void	RemoveReadCallback (size_t idx)

Private Member Functions
std::uint32_t	GetTag (void *variantPtr) const
	Extracts the index from an std::variant and transforms it into the 1-based index used for the switch column.

void	SetTag (void *variantPtr, std::uint32_t tag) const

Static Private Member Functions
static std::string	GetTypeList (const std::vector< Detail::RFieldBase * > &itemFields)

Private Attributes
size_t	fMaxAlignment = 1

size_t	fMaxItemSize = 0

std::vector< ClusterSize_t::ValueType >	fNWritten

size_t	fTagOffset = 0
	In the std::variant memory layout, at which byte number is the index stored.

Additional Inherited Members
Public Types inherited from ROOT::Experimental::Detail::RFieldBase
using	ColumnRepresentation_t = std::vector< EColumnType >

Static Public Member Functions inherited from ROOT::Experimental::Detail::RFieldBase
static RResult< std::unique_ptr< RFieldBase > >	Create (const std::string &fieldName, const std::string &typeName)
	Factory method to resurrect a field from the stored on-disk type information.

static RResult< void >	EnsureValidFieldName (std::string_view fieldName)
	Check whether a given string is a valid field name.

Static Public Attributes inherited from ROOT::Experimental::Detail::RFieldBase
static constexpr std::uint32_t	kInvalidTypeVersion = -1U

static constexpr int	kTraitMappable = 0x04
	A field of a fundamental type that can be directly mapped via `RField<T>::Map()`, i.e.

static constexpr int	kTraitTriviallyConstructible = 0x01
	No constructor needs to be called, i.e.

static constexpr int	kTraitTriviallyDestructible = 0x02
	The type is cleaned up just by freeing its memory. I.e. DestroyValue() is a no-op.

static constexpr int	kTraitTrivialType = kTraitTriviallyConstructible \| kTraitTriviallyDestructible
	Shorthand for types that are both trivially constructible and destructible.

Protected Attributes inherited from ROOT::Experimental::Detail::RFieldBase
const ColumnRepresentation_t *	fColumnRepresentative = nullptr
	Points into the static vector GetColumnRepresentations().GetSerializationTypes() when SetColumnRepresentative is called.

std::vector< std::unique_ptr< RColumn > >	fColumns
	The columns are connected either to a sink or to a source (not to both); they are owned by the field.

std::uint32_t	fOnDiskTypeVersion = kInvalidTypeVersion
	C++ type version cached from the descriptor after a call to `ConnectPageSource()`

RFieldBase *	fParent
	Sub fields point to their mother field.

RColumn *	fPrincipalColumn
	Points into fColumns.

std::vector< ReadCallback_t >	fReadCallbacks
	List of functions to be called after reading a value.

std::vector< std::unique_ptr< RFieldBase > >	fSubFields
	Collections and classes own sub fields.

int	fTraits = 0
	Properties of the type that allow for optimizations of collections of that type.

#include <ROOT/RField.hxx>

Inheritance diagram for ROOT::Experimental::RVariantField:

[legend]

Constructor & Destructor Documentation

◆ RVariantField() [1/2]

ROOT::Experimental::RVariantField::RVariantField	(	std::string_view	fieldName,
		const std::vector< Detail::RFieldBase * > &	itemFields
	)

Definition at line 2206 of file RField.cxx.

◆ RVariantField() [2/2]

ROOT::Experimental::RVariantField::RVariantField ( RVariantField && other )

default

◆ ~RVariantField()

ROOT::Experimental::RVariantField::~RVariantField ( )

overridedefault

Member Function Documentation

◆ AppendImpl()

std::size_t ROOT::Experimental::RVariantField::AppendImpl ( const Detail::RFieldValue & value )

finalprotectedvirtual

Operations on values of complex types, e.g.

ones that involve multiple columns or for which no direct column type exists.

Reimplemented from ROOT::Experimental::Detail::RFieldBase.

Definition at line 2250 of file RField.cxx.

◆ CaptureValue()

ROOT::Experimental::Detail::RFieldValue ROOT::Experimental::RVariantField::CaptureValue ( void * where )

finalvirtual

Creates a value from a memory location with an already constructed object.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2316 of file RField.cxx.

◆ CloneImpl()

std::unique_ptr< ROOT::Experimental::Detail::RFieldBase > ROOT::Experimental::RVariantField::CloneImpl ( std::string_view newName ) const

finalprotectedvirtual

Called by Clone(), which additionally copies the on-disk ID.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2227 of file RField.cxx.

◆ CommitCluster()

void ROOT::Experimental::RVariantField::CommitCluster ( )

finalvirtual

Perform housekeeping tasks for global to cluster-local index translation.

Reimplemented from ROOT::Experimental::Detail::RFieldBase.

Definition at line 2326 of file RField.cxx.

◆ DestroyValue()

void ROOT::Experimental::RVariantField::DestroyValue	(	const Detail::RFieldValue &	value,
		bool	dtorOnly = `false`
	)

finalvirtual

Releases the resources acquired during GenerateValue (memory and constructor) This implementation works for simple types but needs to be overwritten for complex ones.

Reimplemented from ROOT::Experimental::Detail::RFieldBase.

Definition at line 2304 of file RField.cxx.

◆ GenerateColumnsImpl() [1/2]

void ROOT::Experimental::RVariantField::GenerateColumnsImpl ( )

finalprotectedvirtual

Creates the backing columns corresponsing to the field type for writing.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2285 of file RField.cxx.

◆ GenerateColumnsImpl() [2/2]

void ROOT::Experimental::RVariantField::GenerateColumnsImpl ( const RNTupleDescriptor & desc )

finalprotectedvirtual

Creates the backing columns corresponsing to the field type for reading.

The method should to check, using the page source and fOnDiskId, if the column types match and throw if they don't.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2290 of file RField.cxx.

◆ GenerateValue()

ROOT::Experimental::Detail::RFieldValue ROOT::Experimental::RVariantField::GenerateValue ( void * where )

overridevirtual

Generates a tree value in a given location of size at least GetValueSize().

Assumes that where has been allocated by malloc().

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2296 of file RField.cxx.

◆ GetAlignment()

size_t ROOT::Experimental::RVariantField::GetAlignment ( ) const

inlinefinalvirtual

As a rule of thumb, the alignment is equal to the size of the type.

There are, however, various exceptions to this rule depending on OS and CPU architecture. So enforce the alignment to be explicitly spelled out.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 803 of file RField.hxx.

◆ GetColumnRepresentations()

const ROOT::Experimental::Detail::RFieldBase::RColumnRepresentations & ROOT::Experimental::RVariantField::GetColumnRepresentations ( ) const

finalprotectedvirtual

Implementations in derived classes should return a static RColumnRepresentations object.

The default implementation does not attach any columns to the field.

Reimplemented from ROOT::Experimental::Detail::RFieldBase.

Definition at line 2279 of file RField.cxx.

◆ GetTag()

std::uint32_t ROOT::Experimental::RVariantField::GetTag ( void * variantPtr ) const

private

Extracts the index from an std::variant and transforms it into the 1-based index used for the switch column.

Definition at line 2238 of file RField.cxx.

◆ GetTypeList()

std::string ROOT::Experimental::RVariantField::GetTypeList ( const std::vector< Detail::RFieldBase * > & itemFields )

staticprivate

Definition at line 2195 of file RField.cxx.

◆ GetValueSize()

size_t ROOT::Experimental::RVariantField::GetValueSize ( ) const

finalvirtual

The number of bytes taken by a value of the appropriate type.

Implements ROOT::Experimental::Detail::RFieldBase.

Definition at line 2321 of file RField.cxx.

◆ operator=()

RVariantField & ROOT::Experimental::RVariantField::operator= ( RVariantField && other )

default

◆ ReadGlobalImpl()

void ROOT::Experimental::RVariantField::ReadGlobalImpl	(	NTupleSize_t	globalIndex,
		Detail::RFieldValue *	value
	)

finalprotectedvirtual

Reimplemented from ROOT::Experimental::Detail::RFieldBase.

Definition at line 2266 of file RField.cxx.

◆ SetTag()

void ROOT::Experimental::RVariantField::SetTag	(	void *	variantPtr,
		std::uint32_t	tag
	)		const

private

Definition at line 2244 of file RField.cxx.

Member Data Documentation

◆ fMaxAlignment

size_t ROOT::Experimental::RVariantField::fMaxAlignment = 1

private

Definition at line 773 of file RField.hxx.

◆ fMaxItemSize

size_t ROOT::Experimental::RVariantField::fMaxItemSize = 0

private

Definition at line 772 of file RField.hxx.

◆ fNWritten

std::vector<ClusterSize_t::ValueType> ROOT::Experimental::RVariantField::fNWritten

private

Definition at line 776 of file RField.hxx.

◆ fTagOffset

size_t ROOT::Experimental::RVariantField::fTagOffset = 0

private

In the std::variant memory layout, at which byte number is the index stored.

Definition at line 775 of file RField.hxx.

Libraries for ROOT::Experimental::RVariantField:

[legend]

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

tree/ntuple/v7/inc/ROOT/RField.hxx
tree/ntuple/v7/src/RField.cxx

Public Member Functions

Protected Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ RVariantField() [1/2]

◆ RVariantField() [2/2]

◆ ~RVariantField()

Member Function Documentation

◆ AppendImpl()

◆ CaptureValue()

◆ CloneImpl()

◆ CommitCluster()

◆ DestroyValue()

◆ GenerateColumnsImpl() [1/2]

◆ GenerateColumnsImpl() [2/2]

◆ GenerateValue()

◆ GetAlignment()

◆ GetColumnRepresentations()

◆ GetTag()

◆ GetTypeList()

◆ GetValueSize()

◆ operator=()

◆ ReadGlobalImpl()

◆ SetTag()

Member Data Documentation

◆ fMaxAlignment

◆ fMaxItemSize

◆ fNWritten

◆ fTagOffset