TSortedCollection

[Properties (by Name)][Methods (by Name)][Events (by Name)]

Abstract sorted collection.

Declaration

Source position: objects.pp line 466

Type
  TSortedCollection = object (TCollection)
    Duplicates : Boolean;
    constructor Init(ALimit: Sw_Integer; ADelta: Sw_Integer);
    constructor Load(var S: TStream);
    function KeyOf(Item: Pointer) : Pointer;  Virtual;
    function IndexOf(Item: Pointer) : Sw_Integer;  Virtual;
    function Compare(Key1: Pointer; Key2: Pointer) : Sw_Integer;  Virtual;
    function Search(Key: Pointer; var Index: Sw_Integer) : Boolean;  Virtual;
    procedure Insert(Item: Pointer);  Virtual;
    procedure Store(var S: TStream);
  end
  ;

Description

TSortedCollection is an abstract class, implementing a sorted collection. You should never use an instance of TSortedCollection directly, instead you should declare a descendent type, and override the Compare method.

Because the collection is ordered, TSortedCollection overrides some TCollection methods, to provide faster routines for lookup.

The Compare method decides how elements in the collection should be ordered. Since TCollection has no way of knowing how to order pointers, you must override the compare method.

Additionally, TCollection provides a means to filter out duplicates. if you set Duplicates to False (the default) then duplicates will not be allowed.

The example below defines a descendent of TSortedCollection which is used in the examples.

Members

Member	Type	Visibility	Description
Compare	Method	default	Compare two items in the collection.
Duplicates	Field	default	If True duplicate strings are allowed in the collection.
IndexOf	Method	default	Return index of an item in the collection.
Init	Method	default	Instantiates a new instance of a TSortedCollection
Insert	Method	default	Insert new item in collection.
KeyOf	Method	default	Return the key of an item
Load	Method	default	Instantiates a new instance of a TSortedCollection and loads it from stream.
Search	Method	default	Search for item with given key.
Store	Method	default	Write the collection to the stream.

Inheritance

Class	Description
TSortedCollection	Abstract sorted collection.

Example

Unit MySortC;
Interface
Uses Objects;
Type
  PMySortedCollection = ^TMySortedCollection;
  TMySortedCollection = Object(TSortedCollection)
       Function Compare (Key1,Key2 : Pointer): Sw_integer; virtual;
       end;
Implementation
Uses MyObject;
Function TMySortedCollection.Compare (Key1,Key2 : Pointer) :sw_integer;
begin
  Compare:=PMyobject(Key1)^.GetField - PMyObject(Key2)^.GetField;
end;
end.

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