TDoubleLinkedBufIndex¶

Implements an index using a doubly-linked list.

Declaration¶

Source position: bufdataset.pas line 202

type

  TDoubleLinkedBufIndex = class(TBufIndex)
  public
    FLastRecBuf: PBufRecLinkItem = ^TBufRecLinkItem;
    FFirstRecBuf: PBufRecLinkItem = ^TBufRecLinkItem;
    FNeedScroll: Boolean;
    function ScrollBackward : TGetResult;
    function ScrollForward : TGetResult;
    function GetCurrent : TGetResult;
    function ScrollFirst : TGetResult;
    procedure ScrollLast;
    function GetRecord : TGetResult;
    procedure SetToFirstRecord;
    procedure SetToLastRecord;
    procedure StoreCurrentRecord;
    procedure RestoreCurrentRecord;
    function CanScrollForward : Boolean;
    procedure DoScrollForward;
    procedure StoreCurrentRecIntoBookmark;
    procedure StoreSpareRecIntoBookmark;
    procedure GotoBookmark;
    function CompareBookmarks : Integer;
    function SameBookmarks : Boolean;
    procedure InitialiseIndex;
    procedure InitialiseSpareRecord;
    procedure ReleaseSpareRecord;
    procedure BeginUpdate;
    procedure AddRecord;
    procedure InsertRecordBeforeCurrentRecord;
    procedure RemoveRecordFromIndex;
    procedure OrderCurrentRecord;
    procedure EndUpdate;
  end;

Inheritance¶

Description¶

TDoubleLinkedBufIndex is a TBufIndex descendant that implements an index using a doubly-linked list. Nodes in the doubly-linked list are implemented using the TBufRecLinkItem record type and the PBufRecLinkItem pointer type. TDoubleLinkedBufIndex provides two sentinel nodes that represent the first and last items in the linked list.

TDoubleLinkedBufIndex is the type used to implement the default index ('DEFAULT_ORDER') in TBufDataset.

Methods¶

Member	Visibility	Description
AddRecord	public	Adds a record to the index.
BeginUpdate	public
CanScrollForward	public	Indicates if the index can be scrolled towards the end of the index.
CompareBookmarks	public
DoScrollForward	public	Implements actions needed to scroll forward using the index.
EndUpdate	public
GetCurrent	public
GetRecord	public
GotoBookmark	public	Navigates the index to the specified Bookmark.
InitialiseIndex	public	Initializes the index.
InitialiseSpareRecord	public	Initializes the spare record in the index.
InsertRecordBeforeCurrentRecord	public	Inserts a record prior to the current record in the index.
OrderCurrentRecord	public
ReleaseSpareRecord	public	Releases the spare record in the index.
RemoveRecordFromIndex	public	Removes the record at the specified Bookmark from the index.
RestoreCurrentRecord	public
SameBookmarks	public	Compares Bookmark values for ordering in the index.
ScrollBackward	public	Scrolls the index toward the beginning of the index.
ScrollFirst	public	Scrolls to the first entry in the index.
ScrollForward	public	Scrolls the index towards the end of the index.
ScrollLast	public	Scrolls to the last entry in the index.
SetToFirstRecord	public
SetToLastRecord	public
StoreCurrentRecIntoBookmark	public
StoreCurrentRecord	public
StoreSpareRecIntoBookmark	public

See all Methods

Fieldss¶

Member	Visibility	Description
FFirstRecBuf	public
FLastRecBuf	public
FNeedScroll	public

See all Fieldss

Name	Description
TBufIndex	Defines the interface used to implement indexes in TBufDataset.
TBufRecLinkItem	Stores bookmarks to the previous and next records in a linked list.
PBufRecLinkItem	Pointer to a TBufRecLinkItem type.
TBufDataset	Implements a database-aware buffered dataset.