THashTable implements a hash table to store TObject's.

The hash value is calculated using the value returned by the TObject's Hash() function. Each class inheriting from TObject can override Hash() as it sees fit.

THashTable does not preserve the insertion order of the objects. If the insertion order is important AND fast retrieval is needed use THashList instead.

Definition at line 35 of file THashTable.h.

Public Member Functions
	THashTable (Int_t capacity=TCollection::kInitHashTableCapacity, Int_t rehash=0)
	Create a THashTable object. More...

virtual	~THashTable ()
	Delete a hashtable. More...

void	Add (TObject *obj)
	Add object to the hash table. More...

virtual void	AddAll (const TCollection *col)
	Add all objects from collection col to this collection. More...

void	AddBefore (const TObject before, TObject obj)
	Add object to the hash table. More...

Float_t	AverageCollisions () const

void	Clear (Option_t *option="")
	Remove all objects from the table. More...

Int_t	Collisions (const char *name) const
	Returns the number of collisions for an object with a certain name (i.e. More...

Int_t	Collisions (TObject *obj) const
	Returns the number of collisions for an object (i.e. More...

void	Delete (Option_t *option="")
	Remove all objects from the table AND delete all heap based objects. More...

TObject *	FindObject (const char *name) const
	Find object using its name. More...

TObject *	FindObject (const TObject *obj) const
	Find object using its hash value (returned by its Hash() member). More...

const TList *	GetListForObject (const char *name) const
	Return the TList corresponding to object's name based hash value. More...

const TList *	GetListForObject (const TObject *obj) const
	Return the TList corresponding to object's hash value. More...

TObject **	GetObjectRef (const TObject *obj) const
	Return address of pointer to obj. More...

Int_t	GetRehashLevel () const

Int_t	GetSize () const

TIterator *	MakeIterator (Bool_t dir=kIterForward) const
	Returns a hash table iterator. More...

void	Rehash (Int_t newCapacity, Bool_t checkObjValidity=kTRUE)
	Rehash the hashtable. More...

TObject *	Remove (TObject *obj)
	Remove object from the hashtable. More...

TObject *	RemoveSlow (TObject *obj)
	Remove object from the hashtable without using the hash value. More...

void	SetRehashLevel (Int_t rehash)

Public Member Functions inherited from TCollection
virtual	~TCollection ()

void	AddVector (TObject *obj1,...)
	Add all arguments to the collection. More...

Bool_t	AssertClass (TClass *cl) const
	Make sure all objects in this collection inherit from class cl. More...

TIter	begin () const

void	Browse (TBrowser *b)
	Browse this collection (called by TBrowser). More...

Int_t	Capacity () const

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an collection using the Streamer facility. More...

Int_t	Compare (const TObject *obj) const
	Compare two TCollection objects. More...

Bool_t	Contains (const char *name) const

Bool_t	Contains (const TObject *obj) const

virtual void	Draw (Option_t *option="")
	Draw all objects in this collection. More...

virtual void	Dump () const
	Dump all objects in this collection. More...

TIter	end () const

virtual Int_t	GetEntries () const

virtual const char *	GetName () const
	Return name of this collection. More...

virtual Int_t	GrowBy (Int_t delta) const
	Increase the collection's capacity by delta slots. More...

ULong_t	Hash () const
	Return hash value for this object. More...

Bool_t	IsArgNull (const char where, const TObject obj) const
	Returns true if object is a null pointer. More...

virtual Bool_t	IsEmpty () const

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...

Bool_t	IsOwner () const

Bool_t	IsSortable () const

virtual void	ls (Option_t *option="") const
	List (ls) all objects in this collection. More...

virtual TIterator *	MakeReverseIterator () const

virtual Bool_t	Notify ()
	'Notify' all objects in this collection. More...

TObject *	operator() (const char *name) const
	Find an object in this collection by name. More...

virtual void	Paint (Option_t *option="")
	Paint all objects in this collection. More...

virtual void	Print (Option_t *option="") const
	Default print for collections, calls Print(option, 1). More...

virtual void	Print (Option_t *option, Int_t recurse) const
	Print the collection header and its elements. More...

virtual void	Print (Option_t option, const char wildcard, Int_t recurse=1) const
	Print the collection header and its elements that match the wildcard. More...

virtual void	Print (Option_t *option, TPRegexp &regexp, Int_t recurse=1) const
	Print the collection header and its elements that match the regexp. More...

virtual void	RecursiveRemove (TObject *obj)
	Remove object from this collection and recursively remove the object from all other objects (and collections). More...

virtual void	RemoveAll (TCollection *col)
	Remove all objects in collection col from this collection. More...

void	RemoveAll ()

void	SetCurrentCollection ()
	Set this collection to be the globally accesible collection. More...

void	SetName (const char *name)

virtual void	SetOwner (Bool_t enable=kTRUE)
	Set whether this collection is the owner (enable==true) of its content. More...

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write all objects in this collection. More...

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write all objects in this collection. More...

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor. More...

	TObject (const TObject &object)
	TObject copy ctor. More...

virtual	~TObject ()
	TObject destructor. More...

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad. More...

virtual const char *	ClassName () const
	Returns name of class to which the object belongs. More...

virtual void	Copy (TObject &object) const
	Copy this to obj. More...

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object. More...

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs. More...

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: `gROOT->SetSelectedPad(gPad)`. More...

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message. More...

virtual void	Execute (const char method, const char params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g. More...

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray. More...

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py). More...

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message. More...

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object. More...

virtual const char *	GetIconName () const
	Returns mime type name of object. More...

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py). More...

virtual Option_t *	GetOption () const

virtual const char *	GetTitle () const
	Returns title of object. More...

virtual UInt_t	GetUniqueID () const
	Return the unique object id. More...

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out. More...

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message. More...

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname". More...

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl. More...

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas. More...

void	InvertBit (UInt_t f)

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory). More...

Bool_t	IsOnHeap () const

Bool_t	IsZombie () const

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete. More...

void	operator delete (void *ptr)
	Operator delete. More...

void	operator delete[] (void *ptr)
	Operator delete []. More...

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator. More...

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list. More...

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory. More...

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename. More...

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out". More...

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f. More...

void	SetBit (UInt_t f)

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object. More...

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id. More...

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message. More...

Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message. More...

Private Member Functions
	THashTable (const THashTable &)

Int_t	GetHashValue (const TObject *obj) const

Int_t	GetHashValue (TString &s) const

Int_t	GetHashValue (const char *str) const

THashTable &	operator= (const THashTable &)

Private Attributes
TList **	fCont

Int_t	fEntries

Int_t	fRehashLevel

Int_t	fUsedSlots

Friends
class	THashTableIter

Additional Inherited Members
Public Types inherited from TCollection
enum	{ kInitCapacity = 16, kInitHashTableCapacity = 17 }

Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000, kNotDeleted = 0x02000000, kZombie = 0x04000000, kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0), kOverwrite = BIT(1), kWriteDelete = BIT(2) }

enum	EStatusBits { kCanDelete = BIT(0), kMustCleanup = BIT(3), kObjInCanvas = BIT(3), kIsReferenced = BIT(4), kHasUUID = BIT(5), kCannotPick = BIT(6), kNoContextMenu = BIT(8), kInvalidObject = BIT(13) }

Static Public Member Functions inherited from TCollection
static void	EmptyGarbageCollection ()
	Do the garbage collection. More...

static void	GarbageCollect (TObject *obj)
	Add to the list of things to be cleaned up. More...

static TCollection *	GetCurrentCollection ()
	Return the globally accessible collection. More...

static void	StartGarbageCollection ()
	Set up for garbage collection. More...

Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag. More...

static Bool_t	GetObjectStat ()
	Get status of object stat flag. More...

static void	SetDtorOnly (void *obj)
	Set destructor only flag. More...

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable. More...

Protected Types inherited from TCollection
enum	{ kIsOwner = BIT(14) }

Protected Member Functions inherited from TCollection
	TCollection ()

virtual const char *	GetCollectionEntryName (TObject *entry) const
	For given collection entry return the string that is used to identify the object and, potentially, perform wildcard/regexp filtering on. More...

virtual void	PrintCollectionEntry (TObject entry, Option_t option, Int_t recurse) const
	Print the collection entry. More...

virtual void	PrintCollectionHeader (Option_t *option) const
	Print the collection header. More...

Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected). More...

void	MakeZombie ()

Protected Attributes inherited from TCollection
TString	fName

Int_t	fSize

#include <THashTable.h>

Inheritance diagram for THashTable:

[legend]

Constructor & Destructor Documentation

◆ THashTable() [1/2]

THashTable::THashTable ( const THashTable & )

private

◆ THashTable() [2/2]

THashTable::THashTable	(	Int_t	capacity = `TCollection::kInitHashTableCapacity`,
		Int_t	rehashlevel = `0`
	)

Create a THashTable object.

Capacity is the initial hashtable capacity (i.e. number of slots), by default kInitHashTableCapacity = 17, and rehashlevel is the value at which a rehash will be triggered. I.e. when the average size of the linked lists at a slot becomes longer than rehashlevel then the hashtable will be resized and refilled to reduce the collision rate to about 1. The higher the collision rate, i.e. the longer the linked lists, the longer lookup will take. If rehashlevel=0 the table will NOT automatically be rehashed. Use Rehash() for manual rehashing.

Definition at line 42 of file THashTable.cxx.

◆ ~THashTable()

THashTable::~THashTable ( )

virtual

Delete a hashtable.

Objects are not deleted unless the THashTable is the owner (set via SetOwner()).

Definition at line 64 of file THashTable.cxx.

Member Function Documentation

◆ Add()

void THashTable::Add ( TObject * obj )

virtual

Add object to the hash table.

Its position in the table will be determined by the value returned by its Hash() function.

Implements TCollection.

Definition at line 76 of file THashTable.cxx.

◆ AddAll()

void THashTable::AddAll ( const TCollection * col )

virtual

Add all objects from collection col to this collection.

Implemented for more efficient rehashing.

Reimplemented from TCollection.

Definition at line 122 of file THashTable.cxx.

◆ AddBefore()

void THashTable::AddBefore	(	const TObject *	before,
		TObject *	obj
	)

Add object to the hash table.

Its position in the table will be determined by the value returned by its Hash() function. If and only if 'before' is in the same bucket as obj, obj is added in front of 'before' within the bucket's list.

Definition at line 98 of file THashTable.cxx.

◆ AverageCollisions()

Float_t THashTable::AverageCollisions ( ) const

inline

Definition at line 79 of file THashTable.h.

◆ Clear()

void THashTable::Clear ( Option_t * option = "" )

virtual

Remove all objects from the table.

Does not delete the objects unless the THashTable is the owner (set via SetOwner()).

Implements TCollection.

Definition at line 149 of file THashTable.cxx.

◆ Collisions() [1/2]

Int_t THashTable::Collisions ( const char * name ) const

Returns the number of collisions for an object with a certain name (i.e.

number of objects in same slot in the hash table, i.e. length of linked list).

Definition at line 171 of file THashTable.cxx.

◆ Collisions() [2/2]

Int_t THashTable::Collisions ( TObject * obj ) const

Returns the number of collisions for an object (i.e.

number of objects in same slot in the hash table, i.e. length of linked list).

Definition at line 182 of file THashTable.cxx.

◆ Delete()

void THashTable::Delete ( Option_t * option = "" )

virtual

Remove all objects from the table AND delete all heap based objects.

Implements TCollection.

Definition at line 194 of file THashTable.cxx.

◆ FindObject() [1/2]

TObject * THashTable::FindObject ( const char * name ) const

virtual

Find object using its name.

Uses the hash value returned by the TString::Hash() after converting name to a TString.

Reimplemented from TCollection.

Definition at line 210 of file THashTable.cxx.

◆ FindObject() [2/2]

TObject * THashTable::FindObject ( const TObject * obj ) const

virtual

Find object using its hash value (returned by its Hash() member).

Reimplemented from TCollection.

Definition at line 220 of file THashTable.cxx.

◆ GetHashValue() [1/3]

Int_t THashTable::GetHashValue ( const TObject * obj ) const

inlineprivate

Definition at line 87 of file THashTable.h.

◆ GetHashValue() [2/3]

Int_t THashTable::GetHashValue ( TString & s ) const

inlineprivate

Definition at line 46 of file THashTable.h.

◆ GetHashValue() [3/3]

Int_t THashTable::GetHashValue ( const char * str ) const

inlineprivate

Definition at line 47 of file THashTable.h.

◆ GetListForObject() [1/2]

const TList * THashTable::GetListForObject ( const char * name ) const

Return the TList corresponding to object's name based hash value.

One can iterate this list "manually" to find, e.g. objects with the same name.

Definition at line 234 of file THashTable.cxx.

◆ GetListForObject() [2/2]

const TList * THashTable::GetListForObject ( const TObject * obj ) const

Return the TList corresponding to object's hash value.

One can iterate this list "manually" to find, e.g. identical objects.

Definition at line 244 of file THashTable.cxx.

◆ GetObjectRef()

TObject ** THashTable::GetObjectRef ( const TObject * obj ) const

virtual

Return address of pointer to obj.

Implements TCollection.

Definition at line 253 of file THashTable.cxx.

◆ GetRehashLevel()

Int_t THashTable::GetRehashLevel ( ) const

inline

Definition at line 68 of file THashTable.h.

◆ GetSize()

Int_t THashTable::GetSize ( ) const

inlinevirtual

Reimplemented from TCollection.

Definition at line 69 of file THashTable.h.

◆ MakeIterator()

TIterator * THashTable::MakeIterator ( Bool_t dir = kIterForward ) const

virtual

Returns a hash table iterator.

Implements TCollection.

Definition at line 265 of file THashTable.cxx.

◆ operator=()

THashTable& THashTable::operator= ( const THashTable & )

private

◆ Rehash()

void THashTable::Rehash	(	Int_t	newCapacity,
		Bool_t	checkObjValidity = `kTRUE`
	)

Rehash the hashtable.

If the collision rate becomes too high (i.e. the average size of the linked lists become too long) then lookup efficiency decreases since relatively long lists have to be searched every time. To improve performance rehash the hashtable. This resizes the table to newCapacity slots and refills the table. Use AverageCollisions() to check if you need to rehash. Set checkObjValidity to kFALSE if you know that all objects in the table are still valid (i.e. have not been deleted from the system in the meanwhile).

Definition at line 280 of file THashTable.cxx.

◆ Remove()

TObject * THashTable::Remove ( TObject * obj )

virtual

Remove object from the hashtable.

Implements TCollection.

Definition at line 315 of file THashTable.cxx.

◆ RemoveSlow()

TObject * THashTable::RemoveSlow ( TObject * obj )

Remove object from the hashtable without using the hash value.

Definition at line 335 of file THashTable.cxx.

◆ SetRehashLevel()

void THashTable::SetRehashLevel ( Int_t rehash )

inline

Definition at line 74 of file THashTable.h.

Friends And Related Function Documentation

◆ THashTableIter

friend class THashTableIter

friend

Definition at line 37 of file THashTable.h.

Member Data Documentation

◆ fCont

TList** THashTable::fCont

private

Definition at line 40 of file THashTable.h.

◆ fEntries

Int_t THashTable::fEntries

private

Definition at line 41 of file THashTable.h.

◆ fRehashLevel

Int_t THashTable::fRehashLevel

private

Definition at line 43 of file THashTable.h.

◆ fUsedSlots

Int_t THashTable::fUsedSlots

private

Definition at line 42 of file THashTable.h.

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

core/cont/inc/THashTable.h
core/cont/src/THashTable.cxx

Public Member Functions

Private Member Functions

Private Attributes

Friends

Additional Inherited Members

Constructor & Destructor Documentation

◆ THashTable() [1/2]

◆ THashTable() [2/2]

◆ ~THashTable()

Member Function Documentation

◆ Add()

◆ AddAll()

◆ AddBefore()

◆ AverageCollisions()

◆ Clear()

◆ Collisions() [1/2]

◆ Collisions() [2/2]

◆ Delete()

◆ FindObject() [1/2]

◆ FindObject() [2/2]

◆ GetHashValue() [1/3]

◆ GetHashValue() [2/3]

◆ GetHashValue() [3/3]

◆ GetListForObject() [1/2]

◆ GetListForObject() [2/2]

◆ GetObjectRef()

◆ GetRehashLevel()

◆ GetSize()

◆ MakeIterator()

◆ operator=()

◆ Rehash()

◆ Remove()

◆ RemoveSlow()

◆ SetRehashLevel()

Friends And Related Function Documentation

◆ THashTableIter

Member Data Documentation

◆ fCont

◆ fEntries

◆ fRehashLevel

◆ fUsedSlots