TFPCustomHashTable class

In unit Contnrs

Hash class.

Declaration

pascal

TFPCustomHashTable = class(TObject)

Inheritance

TFPCustomHashTable
TObject

Descends from it: TFPDataHashTable TFPObjectHashTable TFPStringHashTable TLazFPGHashTable

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

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

Methods

`Chain`	protected
`CreateNewNode`	protected
`AddNode`	protected
`ChainLength`	protected
`FindOrCreateNew`	protected
`SetHashFunction`	protected
`FindChainForAdd`	protected
`Create`	public	Instantiate a new TFPCustomHashTable instance using the default hash mechanism.
`CreateWith`	public	Instantiate a new TFPCustomHashTable instance with given algorithm and size.
`Destroy`	public	Free the hash table.
`ChangeTableSize`	public	Change the table size of the hash table.
`Clear`	public	Clear the hash table.
`Delete`	public	Delete a key from the hash list.
`Find`	public	Search for an item with a certain key value.
`IsEmpty`	public	Check if the hash table is empty.

Fields

FHashTableSize protected

Inherited

From TObject (40)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf Equals FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.