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Reference Guide
ROOT::Experimental::RVariantField Class Reference

The generic field for std::variant types.

Definition at line 563 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. More...
 
void CommitCluster () final
 Perform housekeeping tasks for global to cluster-local index translation. More...
 
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. More...
 
void GenerateColumnsImpl () final
 Creates the backing columns corresponsing to the field type for writing. More...
 
void GenerateColumnsImpl (const RNTupleDescriptor &desc) final
 Creates the backing columns corresponsing to the field type for reading. More...
 
Detail::RFieldValue GenerateValue (void *where) override
 Generates a tree value in a given location of size at least GetValueSize(). More...
 
size_t GetAlignment () const final
 For many types, the alignment requirement is equal to the size; otherwise override. More...
 
size_t GetValueSize () const final
 The number of bytes taken by a value of the appropriate type. More...
 
RVariantFieldoperator= (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. More...
 
virtual ~RFieldBase ()
 
virtual void AcceptVisitor (RFieldVisitor &visitor) const
 
std::size_t Append (const RFieldValue &value)
 Write the given value into columns. More...
 
void Attach (std::unique_ptr< Detail::RFieldBase > child)
 Add a new subfield to the list of nested fields. More...
 
RSchemaIterator begin ()
 
virtual RFieldValue CaptureValue (void *where)=0
 Creates a value from a memory location with an already constructed object. More...
 
std::unique_ptr< RFieldBaseClone (std::string_view newName) const
 Copies the field and its sub fields using a possibly new name and a new, unconnected set of columns. More...
 
virtual void CommitCluster ()
 Perform housekeeping tasks for global to cluster-local index translation. More...
 
void ConnectPageSink (RPageSink &pageSink)
 Fields and their columns live in the void until connected to a physical page storage. More...
 
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. More...
 
RSchemaIterator end ()
 
void Flush () const
 Ensure that all received items are written from page buffers to the storage. More...
 
RFieldValue GenerateValue ()
 Generates an object of the field type and allocates new initialized memory according to the type. More...
 
virtual RFieldValue GenerateValue (void *where)=0
 Generates a tree value in a given location of size at least GetValueSize(). More...
 
virtual size_t GetAlignment () const
 For many types, the alignment requirement is equal to the size; otherwise override. More...
 
std::string GetDescription () const
 Get the field's description. More...
 
virtual std::uint32_t GetFieldVersion () const
 Indicates an evolution of the mapping scheme from C++ type to columns. More...
 
std::string GetName () const
 
NTupleSize_t GetNElements () const
 
std::size_t GetNRepetitions () const
 
DescriptorId_t GetOnDiskId () const
 
RFieldBaseGetParent () const
 
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. More...
 
virtual size_t GetValueSize () const =0
 The number of bytes taken by a value of the appropriate type. More...
 
bool IsSimple () const
 
RFieldBaseoperator= (const RFieldBase &)=delete
 
RFieldBaseoperator= (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. More...
 
void SetDescription (std::string_view description)
 
void SetOnDiskId (DescriptorId_t id)
 
virtual std::vector< RFieldValueSplitValue (const RFieldValue &value) const
 Creates the list of direct child values given a value for this field. More...
 

Protected Member Functions

std::size_t AppendImpl (const Detail::RFieldValue &value) final
 Operations on values of complex types, e.g. More...
 
std::unique_ptr< Detail::RFieldBaseCloneImpl (std::string_view newName) const final
 Called by Clone(), which additionally copies the on-disk ID. More...
 
void ReadGlobalImpl (NTupleSize_t globalIndex, Detail::RFieldValue *value) final
 
- Protected Member Functions inherited from ROOT::Experimental::Detail::RFieldBase
virtual std::size_t AppendImpl (const RFieldValue &value)
 Operations on values of complex types, e.g. More...
 
virtual std::unique_ptr< RFieldBaseCloneImpl (std::string_view newName) const =0
 Called by Clone(), which additionally copies the on-disk ID. More...
 
ROOT::Experimental::EColumnType EnsureColumnType (const std::vector< EColumnType > &requestedTypes, unsigned int columnIndex, const RNTupleDescriptor &desc)
 Throws an exception if the column given by fOnDiskId and the columnIndex in the provided descriptor is not of one of the requested types. More...
 
virtual void GenerateColumnsImpl ()=0
 Creates the backing columns corresponsing to the field type for writing. More...
 
virtual void GenerateColumnsImpl (const RNTupleDescriptor &desc)=0
 Creates the backing columns corresponsing to the field type for reading. More...
 
virtual void ReadGlobalImpl (NTupleSize_t globalIndex, RFieldValue *value)
 
virtual void ReadInClusterImpl (const RClusterIndex &clusterIndex, RFieldValue *value)
 

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

Additional Inherited Members

- 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. More...
 
static RResult< void > EnsureValidFieldName (std::string_view fieldName)
 Check whether a given string is a valid field name. More...
 
- Static Public Attributes inherited from ROOT::Experimental::Detail::RFieldBase
static constexpr int kTraitTriviallyConstructible = 0x01
 No constructor needs to be called, i.e. More...
 
static constexpr int kTraitTriviallyDestructible = 0x02
 The type is cleaned up just by freeing its memory. I.e. DestroyValue() is a no-op. More...
 
static constexpr int kTraitTrivialType = kTraitTriviallyConstructible | kTraitTriviallyDestructible
 Shorthand combining all other shortcut traits. More...
 
- Protected Attributes inherited from ROOT::Experimental::Detail::RFieldBase
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. More...
 
RFieldBasefParent
 Sub fields point to their mother field. More...
 
RColumnfPrincipalColumn
 Points into fColumns. More...
 
std::vector< std::unique_ptr< RFieldBase > > fSubFields
 Collections and classes own sub fields. More...
 
int fTraits = 0
 Properties of the type that allow for optimizations of collections of that type. More...
 

#include <ROOT/RField.hxx>

Inheritance diagram for ROOT::Experimental::RVariantField:
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Constructor & Destructor Documentation

◆ RVariantField() [1/2]

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

Definition at line 1852 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 1896 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 1957 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 1873 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 1967 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 1945 of file RField.cxx.

◆ GenerateColumnsImpl() [1/2]

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

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

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

Definition at line 1924 of file RField.cxx.

◆ GenerateColumnsImpl() [2/2]

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

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 1931 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 1937 of file RField.cxx.

◆ GetAlignment()

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

For many types, the alignment requirement is equal to the size; otherwise override.

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

Definition at line 595 of file RField.hxx.

◆ 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 1884 of file RField.cxx.

◆ GetTypeList()

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

Definition at line 1841 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 1962 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 1912 of file RField.cxx.

◆ SetTag()

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

Definition at line 1890 of file RField.cxx.

Member Data Documentation

◆ fMaxAlignment

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

Definition at line 566 of file RField.hxx.

◆ fMaxItemSize

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

Definition at line 565 of file RField.hxx.

◆ fNWritten

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

Definition at line 569 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 568 of file RField.hxx.

Libraries for ROOT::Experimental::RVariantField:
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The documentation for this class was generated from the following files: