ROOT::RNTupleViewBase< T > Class Template Reference

template<typename T>
class ROOT::RNTupleViewBase< T >

An RNTupleView provides read-only access to a single field of an RNTuple.

Template Parameters

T	The type of the object that will be read by the view; can be void if unknown at compile time.

The view owns a field and its underlying columns in order to fill an RField::RValue object with data. Data can be accessed by index. For top-level fields, the index refers to the entry number. Fields that are part of nested collections have global index numbers that are derived from their parent indexes (

See also

GetFieldRange()).

View can only be created by a reader or by a collection view.

Example: read an RNTuple's field with a view**

auto reader = RNTupleReader::Open("myNtuple", "myntuple.root");
auto viewFoo = reader->GetView<float>("foo");
for (auto idx : reader->GetEntryRange()) {
   float foo = viewFoo(idx); // read field "foo" of the `idx`-th entry
   std::cout << foo << "\n";
}

Example: read an RNTuple's collection subfield with a view**

auto reader = RNTupleReader::Open("myNtuple", "myntuple.root");
// Assuming "v" is a std::vector<int>:
auto view = reader->GetView<int>("v._0");
// Effectively flattens all fields "v" in all entries and reads their elements.
for (auto idx : view.GetFieldRange()) {
   int x = view(idx);
   std::cout << x << "\n";
}

Definition at line 85 of file RNTupleView.hxx.

Public Member Functions
	RNTupleViewBase (const RNTupleViewBase &other)=delete
	RNTupleViewBase (RNTupleViewBase &&other)=default
	~RNTupleViewBase ()=default
void	Bind (std::shared_ptr< T > objPtr)
void	BindRawPtr (T *rawPtr)
ROOT::RFieldBase::RBulk	CreateBulk ()
void	EmplaceNew ()
const ROOT::RFieldBase &	GetField () const
ROOT::RNTupleGlobalRange	GetFieldRange () const
	Returns the global field range of this view.
const ROOT::RFieldBase::RValue &	GetValue () const
RNTupleViewBase &	operator= (const RNTupleViewBase &other)=delete
RNTupleViewBase &	operator= (RNTupleViewBase &&other)=default

Protected Member Functions
	RNTupleViewBase (std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range)
	RNTupleViewBase (std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range, std::shared_ptr< T > objPtr)
	RNTupleViewBase (std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range, T *rawPtr)

Static Protected Member Functions
static std::unique_ptr< ROOT::RFieldBase >	CreateField (ROOT::DescriptorId_t fieldId, ROOT::Experimental::Internal::RPageSource &pageSource)

Protected Attributes
std::unique_ptr< ROOT::RFieldBase >	fField
ROOT::RNTupleGlobalRange	fFieldRange
ROOT::RFieldBase::RValue	fValue

#include <ROOT/RNTupleView.hxx>

Inheritance diagram for ROOT::RNTupleViewBase< T >:

Constructor & Destructor Documentation

RNTupleViewBase() [1/5]

template<typename T >

ROOT::RNTupleViewBase< T >::RNTupleViewBase ( std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range )

inlineprotected

Definition at line 109 of file RNTupleView.hxx.

RNTupleViewBase() [2/5]

template<typename T >

ROOT::RNTupleViewBase< T >::RNTupleViewBase ( std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range, std::shared_ptr< T > objPtr )

inlineprotected

Definition at line 114 of file RNTupleView.hxx.

RNTupleViewBase() [3/5]

template<typename T >

ROOT::RNTupleViewBase< T >::RNTupleViewBase ( std::unique_ptr< ROOT::RFieldBase > field, ROOT::RNTupleGlobalRange range, T * rawPtr )

inlineprotected

Definition at line 119 of file RNTupleView.hxx.

RNTupleViewBase() [4/5]

template<typename T >

ROOT::RNTupleViewBase< T >::RNTupleViewBase ( const RNTupleViewBase< T > & other )

delete

RNTupleViewBase() [5/5]

template<typename T >

ROOT::RNTupleViewBase< T >::RNTupleViewBase ( RNTupleViewBase< T > && other )

default

~RNTupleViewBase()

template<typename T >

ROOT::RNTupleViewBase< T >::~RNTupleViewBase ( )

default

Member Function Documentation

Bind()

template<typename T >

void ROOT::RNTupleViewBase< T >::Bind ( std::shared_ptr< T > objPtr )

inline

Definition at line 150 of file RNTupleView.hxx.

BindRawPtr()

template<typename T >

void ROOT::RNTupleViewBase< T >::BindRawPtr ( T * rawPtr )

inline

Definition at line 151 of file RNTupleView.hxx.

CreateBulk()

template<typename T >

ROOT::RFieldBase::RBulk ROOT::RNTupleViewBase< T >::CreateBulk ( )

inline

Definition at line 134 of file RNTupleView.hxx.

CreateField()

template<typename T >

static std::unique_ptr< ROOT::RFieldBase > ROOT::RNTupleViewBase< T >::CreateField ( ROOT::DescriptorId_t fieldId, ROOT::Experimental::Internal::RPageSource & pageSource )

inlinestaticprotected

Definition at line 92 of file RNTupleView.hxx.

EmplaceNew()

template<typename T >

void ROOT::RNTupleViewBase< T >::EmplaceNew ( )

inline

Definition at line 152 of file RNTupleView.hxx.

GetField()

template<typename T >

const ROOT::RFieldBase & ROOT::RNTupleViewBase< T >::GetField ( ) const

inline

Definition at line 133 of file RNTupleView.hxx.

GetFieldRange()

template<typename T >

ROOT::RNTupleGlobalRange ROOT::RNTupleViewBase< T >::GetFieldRange ( ) const

inline

Returns the global field range of this view.

This may differ from the RNTuple's entry range in case of subfields and can be used to iterate over all the concatenated elements of the subfield without caring which entry they belong to. Throws an RException if the underlying field of this view is empty, i.e. if it's a class or record field with no associated columns.

Definition at line 142 of file RNTupleView.hxx.

GetValue()

template<typename T >

const ROOT::RFieldBase::RValue & ROOT::RNTupleViewBase< T >::GetValue ( ) const

inline

Definition at line 136 of file RNTupleView.hxx.

operator=() [1/2]

template<typename T >

RNTupleViewBase & ROOT::RNTupleViewBase< T >::operator= ( const RNTupleViewBase< T > & other )

delete

operator=() [2/2]

template<typename T >

RNTupleViewBase & ROOT::RNTupleViewBase< T >::operator= ( RNTupleViewBase< T > && other )

default

Member Data Documentation

fField

template<typename T >

std::unique_ptr<ROOT::RFieldBase> ROOT::RNTupleViewBase< T >::fField

protected

Definition at line 87 of file RNTupleView.hxx.

fFieldRange

template<typename T >

ROOT::RNTupleGlobalRange ROOT::RNTupleViewBase< T >::fFieldRange

protected

Definition at line 88 of file RNTupleView.hxx.

fValue

template<typename T >

ROOT::RFieldBase::RValue ROOT::RNTupleViewBase< T >::fValue

protected

Definition at line 89 of file RNTupleView.hxx.