Logo ROOT   6.19/01
Reference Guide
THashTable Class Reference

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...
 
TObjectFindObject (const char *name) const
 Find object using its name. More...
 
TObjectFindObject (const TObject *obj) const
 Find object using its hash value (returned by its Hash() member). More...
 
const TListGetListForObject (const char *name) const
 Return the TList corresponding to object's name based hash value. More...
 
const TListGetListForObject (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
 Return the capacity of the collection, i.e. More...
 
TIteratorMakeIterator (Bool_t dir=kIterForward) const
 Returns a hash table iterator. More...
 
void Print (Option_t *option, Int_t recurse) const
 Print the collection header and its elements. More...
 
virtual void Print (Option_t *option="") const
 Default print for collections, calls Print(option, 1). 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 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...
 
void Rehash (Int_t newCapacity, Bool_t checkObjValidity=kTRUE)
 Rehash the hashtable. More...
 
TObjectRemove (TObject *obj)
 Remove object from the hashtable. More...
 
TObjectRemoveSlow (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 ()
 TNamed destructor. More...
 
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 TObjectClone (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
 
R__ALWAYS_INLINE Bool_t IsUsingRWLock () const
 
virtual void ls (Option_t *option="") const
 List (ls) all objects in this collection. More...
 
virtual TIteratorMakeReverseIterator () const
 
virtual Bool_t Notify ()
 'Notify' all objects in this collection. More...
 
TObjectoperator() (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, 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 bool UseRWLock ()
 Set this collection to use a RW lock upon access, making it thread safe. 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...
 
ULong_t CheckedHash ()
 Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object. 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 TObjectDrawClone (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_tGetDrawOption () 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_tGetOption () 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...
 
Bool_t HasInconsistentHash () const
 Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e. 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...
 
R__ALWAYS_INLINE Bool_t IsOnHeap () const
 
R__ALWAYS_INLINE 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...
 
voidoperator new (size_t sz)
 
voidoperator new (size_t sz, void *vp)
 
voidoperator new[] (size_t sz)
 
voidoperator new[] (size_t sz, void *vp)
 
TObjectoperator= (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...
 
R__ALWAYS_INLINE 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 &)
 
void AddImpl (Int_t slot, TObject *object)
 Helper function doing the actual add to the table give a slot and object. More...
 
Int_t GetCheckedHashValue (TObject *obj) const
 
Int_t GetHashValue (const TObject *obj) const
 
Int_t GetHashValue (TString &s) const
 
Int_t GetHashValue (const char *str) const
 
THashTableoperator= (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, kInconsistent = 0x08000000,
  kBitMask = 0x00ffffff
}
 
enum  { kSingleKey = BIT(0), kOverwrite = BIT(1), kWriteDelete = BIT(2) }
 
enum  EDeprecatedStatusBits { kObjInCanvas = BIT(3) }
 
enum  EStatusBits {
  kCanDelete = BIT(0), kMustCleanup = 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 TCollectionGetCurrentCollection ()
 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  EStatusBits { kIsOwner = BIT(14), kUseRWLock = BIT(16) }
 
- 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 43 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 65 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 92 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 138 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 112 of file THashTable.cxx.

◆ AddImpl()

void THashTable::AddImpl ( Int_t  slot,
TObject obj 
)
inlineprivate

Helper function doing the actual add to the table give a slot and object.

This does not take any lock.

Definition at line 78 of file THashTable.cxx.

◆ AverageCollisions()

Float_t THashTable::AverageCollisions ( ) const
inline

Definition at line 84 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 167 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 191 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 205 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 220 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 238 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 251 of file THashTable.cxx.

◆ GetCheckedHashValue()

Int_t THashTable::GetCheckedHashValue ( TObject obj) const
inlineprivate

Definition at line 92 of file THashTable.h.

◆ GetHashValue() [1/3]

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

Definition at line 98 of file THashTable.h.

◆ GetHashValue() [2/3]

Int_t THashTable::GetHashValue ( TString s) const
inlineprivate

Definition at line 47 of file THashTable.h.

◆ GetHashValue() [3/3]

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

Definition at line 48 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 265 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 279 of file THashTable.cxx.

◆ GetObjectRef()

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

Return address of pointer to obj.

Implements TCollection.

Definition at line 293 of file THashTable.cxx.

◆ GetRehashLevel()

Int_t THashTable::GetRehashLevel ( ) const
inline

Definition at line 71 of file THashTable.h.

◆ GetSize()

Int_t THashTable::GetSize ( ) const
inlinevirtual

Return the capacity of the collection, i.e.

the current total amount of space that has been allocated so far. Same as Capacity. Use GetEntries to get the number of elements currently in the collection.

Reimplemented from TCollection.

Definition at line 72 of file THashTable.h.

◆ MakeIterator()

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

Returns a hash table iterator.

Implements TCollection.

Definition at line 308 of file THashTable.cxx.

◆ operator=()

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

◆ Print() [1/5]

void THashTable::Print ( Option_t option,
Int_t  recurse 
) const
virtual

Print the collection header and its elements.

If recurse is non-zero, descend into printing of collection-entries with recurse - 1. This means, if recurse is negative, the recursion is infinite.

If option contains "details", Print will show the content of each of the hash-slots.

Option is passed recursively.

Reimplemented from TCollection.

Definition at line 325 of file THashTable.cxx.

◆ Print() [2/5]

void TCollection::Print

Print the collection header and its elements that match the wildcard.

If recurse is non-zero, descend into printing of collection-entries with recurse - 1. This means, if recurse is negative, the recursion is infinite.

Option is passed recursively, but wildcard is only used on the first level.

Definition at line 515 of file TCollection.cxx.

◆ Print() [3/5]

void TCollection::Print

Default print for collections, calls Print(option, 1).

This will print the collection header and Print() methods of all the collection entries.

If you want to override Print() for a collection class, first see if you can accomplish it by overriding the following protected methods:

void PrintCollectionHeader(Option_t* option) const;
const char* GetCollectionEntryName(TObject* entry) const;
void PrintCollectionEntry(TObject* entry, Option_t* option, Int_t recurse) const;

Otherwise override the Print(Option_t *option, Int_t) variant. Remember to declare:

somewhere close to the method declaration.

Definition at line 474 of file TCollection.cxx.

◆ Print() [4/5]

void TCollection::Print

Print the collection header and its elements that match the regexp.

If recurse is non-zero, descend into printing of collection-entries with recurse - 1. This means, if recurse is negative, the recursion is infinite.

Option is passed recursively, but regexp is only used on the first level.

Definition at line 548 of file TCollection.cxx.

◆ Print() [5/5]

void TCollection::Print

Print the collection header and its elements.

If recurse is non-zero, descend into printing of collection-entries with recurse - 1. This means, if recurse is negative, the recursion is infinite.

Option is passed recursively.

Definition at line 488 of file TCollection.cxx.

◆ 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 362 of file THashTable.cxx.

◆ Remove()

TObject * THashTable::Remove ( TObject obj)
virtual

Remove object from the hashtable.

Implements TCollection.

Definition at line 414 of file THashTable.cxx.

◆ RemoveSlow()

TObject * THashTable::RemoveSlow ( TObject obj)

Remove object from the hashtable without using the hash value.

Definition at line 439 of file THashTable.cxx.

◆ SetRehashLevel()

void THashTable::SetRehashLevel ( Int_t  rehash)
inline

Definition at line 79 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: