TFPCustomHashTable¶

Hash class.

Declaration¶

Source position: contnrs.pp line 371

type

  TFPCustomHashTable = class(TObject)
  public
    constructor Create;
    constructor CreateWith;
    destructor Destroy;
    procedure ChangeTableSize;
    procedure Clear;
    procedure Delete;
    function Find : THTCustomNode;
    function IsEmpty : Boolean;
    property HashFunction: THashFunction; {rw}
    property Count: LongWord; {r}
    property HashTableSize: LongWord; {rw}
    property HashTable: TFPObjectList; {r}
    property VoidSlots: LongWord; {r}
    property LoadFactor: Double; {r}
    property AVGChainLen: Double; {r}
    property MaxChainLength: LongWord; {r}
    property NumberOfCollisions: LongWord; {r}
    property Density: LongWord; {r}
  end;

Inheritance¶

Description¶

TFPCustomHashTable is a general-purpose hashing class. It can store string keys and pointers associated with these strings. The hash mechanism is configurable and can be optionally be specified when a new instance of the class is created; A default hash mechanism is implemented in RSHash.

The TFPHashList can also be used when fast lookup of data based on some key is required. It is slightly faster than the TFPCustomHashTable implementation, but the keys are limited to a length of 256 characters, and it is not suitable for re-use: it is a one-time fill, many times search object. TFPCustomHashTable is slower, but handles re-use better.

Properties¶

Member	Visibility	Description
AVGChainLen read only	public	Average chain length.
Count read only	public	Number of items in the hash table.
Density read only	public	Number of filled slots.
HashFunction	public	Hash function currently in use.
HashTable read only	public	Hash table instance.
HashTableSize	public	Size of the hash table.
LoadFactor read only	public	Fraction of count versus size.
MaxChainLength read only	public	Maximum chain length.
NumberOfCollisions read only	public	Number of extra items.
VoidSlots read only	public	Number of empty slots in the hash table.

See all Properties

Methods¶

Member	Visibility	Description
ChangeTableSize	public	Change the table size of the hash table.
Clear	public	Clear the hash table.
Create	public	Instantiate a new TFPCustomHashTable instance using the default hash mechanism.
CreateWith	public	Instantiate a new TFPCustomHashTable instance with given algorithm and size.
Delete	public	Delete a key from the hash list.
Destroy	public	Free the hash table.
Find	public	Search for an item with a certain key value.
IsEmpty	public	Check if the hash table is empty.

See all Methods

Name	Description
THTCustomNode	Single item in the hash table.
TFPObjectList	TFPList descendent which manages objects.
RSHash	Standard hash value calculating function.