The container field for an ntuple model, which itself has no physical representation.

Therefore, the zero field must not be connected to a page source or sink.

Definition at line 655 of file RField.hxx.

Public Member Functions
	RFieldZero ()

void	AcceptVisitor (Detail::RFieldVisitor &visitor) const final

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.

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 ()

RSchemaIterator	begin ()

RValue	BindValue (void *where)
	Creates a value from a memory location with an already constructed object.

RConstSchemaIterator	cbegin () const

RConstSchemaIterator	cend () const

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.

void	CommitCluster ()
	Flushes data from active columns to disk and calls CommitClusterImpl.

void	ConnectPageSink (RPageSink &pageSink, NTupleSize_t firstEntry=0)
	Fields and their columns live in the void until connected to a physical page storage.

void	ConnectPageSource (RPageSource &pageSource)

RSchemaIterator	end ()

RBulk	GenerateBulk ()
	The returned bulk is initially empty; RBulk::ReadBulk will construct the array of values.

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

EState	GetState () const

ENTupleStructure	GetStructure () const

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

int	GetTraits () const

std::string	GetType () const

std::string	GetTypeAlias () const

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

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

void	SetDescription (std::string_view description)

void	SetOnDiskId (DescriptorId_t id)

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

Protected Member Functions
std::unique_ptr< Detail::RFieldBase >	CloneImpl (std::string_view newName) const override
	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 &) final
	Creates the backing columns corresponsing to the field type for reading.

void	GenerateValue (void *) const final
	Constructs value in a given location of size at least GetValueSize(). Called by the base class' GenerateValue().

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.

std::size_t	Append (const void *from)
	Write the given value into columns.

virtual std::size_t	AppendImpl (const void *from)
	Operations on values of complex types, e.g.

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

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 void	CommitClusterImpl ()

virtual void	DestroyValue (void *objPtr, bool dtorOnly=false) const
	Releases the resources acquired during GenerateValue (memory and constructor) This implementation works for types with a trivial destructor and should be overwritten otherwise.

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

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.

void	Read (const RClusterIndex &clusterIndex, void *to)

void	Read (NTupleSize_t globalIndex, void *to)
	Populate a single value with data from the field.

std::size_t	ReadBulk (const RBulkSpec &bulkSpec)
	Returns the number of newly available values, that is the number of bools in bulkSpec.fMaskAvail that flipped from false to true.

virtual std::size_t	ReadBulkImpl (const RBulkSpec &bulkSpec)
	General implementation of bulk read.

virtual void	ReadGlobalImpl (NTupleSize_t globalIndex, void *to)

virtual void	ReadInClusterImpl (const RClusterIndex &clusterIndex, void *to)

void	RemoveReadCallback (size_t idx)

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

enum class	EState { kUnconnected , kConnectedToSink , kConnectedToSource }
	During its lifetime, a field undergoes the following possible state transitions: More...

using	RConstSchemaIterator = RSchemaIteratorTemplate< true >

using	RSchemaIterator = RSchemaIteratorTemplate< false >

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.

Static Protected Member Functions inherited from ROOT::Experimental::Detail::RFieldBase
static std::size_t	CallAppendOn (RFieldBase &other, const void *from)
	Allow derived classes to call Append and Read on other (sub) fields.

static void	CallDestroyValueOn (const RFieldBase &other, void *objPtr, bool dtorOnly=false)

static void	CallGenerateValueOn (const RFieldBase &other, void *where)
	Allow derived classes to call GenerateValue(void *) and DestroyValue on other (sub) fields.

static void	CallReadOn (RFieldBase &other, const RClusterIndex &clusterIndex, void *to)

static void	CallReadOn (RFieldBase &other, NTupleSize_t globalIndex, void *to)

static RResult< std::unique_ptr< RFieldBase > >	Create (const std::string &fieldName, const std::string &canonicalType, const std::string &typeAlias)
	Factory method to resurrect a field from the stored on-disk type information.

static RColumn *	GetPrincipalColumnOf (const RFieldBase &other)
	Fields may need direct access to the principal column of their sub fields, e.g. in RRVecField::ReadBulk.

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.

std::string	fTypeAlias
	A typedef or using name that was used when creating the field.