TTreeReaderValue< T > Class Template Reference

template<typename T>
class TTreeReaderValue< T >

An interface for reading values stored in ROOT columnar datasets.

The TTreeReaderValue is a type-safe tool to be used in association with a TTreeReader to access the values stored in TTree, TNtuple and TChain datasets. TTreeReaderValue can be also used to access collections such as std::vectors or TClonesArray stored in columnar datasets but it is recommended to use TTreeReaderArray instead as it offers several advantages.

See the documentation of TTreeReader for more details and examples.

Definition at line 140 of file TTreeReaderValue.h.

Public Types
using	NonConstT_t = typename std::remove_const< T >::type
Public Types inherited from ROOT::Internal::TTreeReaderValueBase
typedef Bool_t(ROOT::Detail::TBranchProxy::*	BranchProxyRead_t) ()
enum	EReadStatus { kReadSuccess = 0 , kReadNothingYet , kReadError }
enum	ESetupStatus {   kSetupNotSetup = -7 , kSetupTreeDestructed = -8 , kSetupMakeClassModeMismatch = -7 , kSetupMissingCounterBranch = -6 ,   kSetupMissingBranch = -5 , kSetupInternalError = -4 , kSetupMissingDictionary = -3 , kSetupMismatch = -2 ,   kSetupNotACollection = -1 , kSetupMatch = 0 , kSetupMatchBranch = 0 , kSetupNoCheck = 5 ,   kSetupMatchLeaf = 6 }

Public Member Functions
	TTreeReaderValue ()=delete
	TTreeReaderValue (TTreeReader &tr, const char *branchname)
T *	Get ()
	Return a pointer to the value of the current entry. More...
T &	operator* ()
	Return a reference to the value of the current entry. More...
T *	operator-> ()
	Return a pointer to the value of the current entry. More...
Public Member Functions inherited from ROOT::Internal::TTreeReaderValueBase
virtual	~TTreeReaderValueBase ()
	Unregister from tree reader, cleanup. More...
void *	GetAddress ()
	Returns the memory address of the object being read. More...
const char *	GetBranchName () const
TLeaf *	GetLeaf ()
	If we are reading a leaf, return the corresponding TLeaf. More...
virtual EReadStatus	GetReadStatus () const
ESetupStatus	GetSetupStatus () const
Bool_t	IsValid () const
EReadStatus	ProxyRead ()
EReadStatus	ProxyReadDefaultImpl ()
template<BranchProxyRead_t Func>
ROOT::Internal::TTreeReaderValueBase::EReadStatus	ProxyReadTemplate ()
	Try to read the value from the TBranchProxy, returns the status of the read. More...

Protected Member Functions
virtual const char *	GetDerivedTypeName () const
	Get the template argument as a string. More...
Protected Member Functions inherited from ROOT::Internal::TTreeReaderValueBase
	TTreeReaderValueBase (const TTreeReaderValueBase &)
	Copy-construct. More...
	TTreeReaderValueBase (TTreeReader *reader, const char *branchname, TDictionary *dict)
	Construct a tree value reader and register it with the reader object. More...
virtual void	CreateProxy ()
	Create the proxy object for our branch. More...
virtual const char *	GetDerivedTypeName () const =0
Detail::TBranchProxy *	GetProxy () const
void	MarkTreeReaderUnavailable ()
void	NotifyNewTree (TTree *newTree)
	The TTreeReader has switched to a new TTree. Update the leaf. More...
TTreeReaderValueBase &	operator= (const TTreeReaderValueBase &)
	Copy-assign. More...
void	RegisterWithTreeReader ()
	Register with tree reader. More...
TBranch *	SearchBranchWithCompositeName (TLeaf *&myleaf, TDictionary *&branchActualType, std::string &err)
	Search a branch the name of which contains a ".". More...

Additional Inherited Members
Protected Types inherited from ROOT::Internal::TTreeReaderValueBase
typedef EReadStatus(TTreeReaderValueBase::*	Read_t) ()
Static Protected Member Functions inherited from ROOT::Internal::TTreeReaderValueBase
static const char *	GetBranchDataType (TBranch *branch, TDictionary *&dict, TDictionary const *curDict)
	Retrieve the type of data stored by branch; put its dictionary into dict, return its type name. More...
static std::string	GetElementTypeName (const std::type_info &ti)
	Stringify the template argument. More...
Protected Attributes inherited from ROOT::Internal::TTreeReaderValueBase
TString	fBranchName
TDictionary *	fDict
int	fHaveLeaf: 1
int	fHaveStaticClassOffsets: 1
TLeaf *	fLeaf = nullptr
TString	fLeafName
Detail::TBranchProxy *	fProxy = nullptr
Read_t	fProxyReadFunc = &TTreeReaderValueBase::ProxyReadDefaultImpl
	! Pointer to the Read implementation to use. More...
EReadStatus	fReadStatus: 2
ESetupStatus	fSetupStatus = kSetupNotSetup
std::vector< Long64_t >	fStaticClassOffsets
TTreeReader *	fTreeReader

#include <TTreeReaderValue.h>

Inheritance diagram for TTreeReaderValue< T >:

Member Typedef Documentation

NonConstT_t

template<typename T >

using TTreeReaderValue< T >::NonConstT_t = typename std::remove_const<T>::type

Definition at line 144 of file TTreeReaderValue.h.

Constructor & Destructor Documentation

TTreeReaderValue() [1/2]

template<typename T >

TTreeReaderValue< T >::TTreeReaderValue ( )

delete

TTreeReaderValue() [2/2]

template<typename T >

TTreeReaderValue< T >::TTreeReaderValue ( TTreeReader &  tr, const char *  branchname  )

inline

Definition at line 146 of file TTreeReaderValue.h.

Member Function Documentation

Get()

template<typename T >

T * TTreeReaderValue< T >::Get ( )

inline

Return a pointer to the value of the current entry.

Return a nullptr and print an error if no entry has been loaded yet. The returned address is guaranteed to stay constant while a given TTree is being read from a given file, unless the branch addresses are manipulated directly (e.g. through TTree::SetBranchAddress()). The address might also change when the underlying TTree/TFile is switched, e.g. when a TChain switches files.

Definition at line 155 of file TTreeReaderValue.h.

GetDerivedTypeName()

template<typename T >

virtual const char * TTreeReaderValue< T >::GetDerivedTypeName ( ) const

inlineprotectedvirtual

Get the template argument as a string.

Implements ROOT::Internal::TTreeReaderValueBase.

Definition at line 173 of file TTreeReaderValue.h.

operator*()

template<typename T >

T & TTreeReaderValue< T >::operator* ( )

inline

Return a reference to the value of the current entry.

Equivalent to dereferencing the pointer returned by Get(). Behavior is undefined if no entry has been loaded yet. Most likely a crash will occur.

Definition at line 168 of file TTreeReaderValue.h.

operator->()

template<typename T >

T * TTreeReaderValue< T >::operator-> ( )

inline

Return a pointer to the value of the current entry.

Equivalent to Get().

Definition at line 164 of file TTreeReaderValue.h.

Libraries for TTreeReaderValue< T >:

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