CentrED

(*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License, Version 1.0 only

 * (the "License").  You may not use this file except in compliance

 * with the License.

 *

 * You can obtain a copy of the license at

 * http://www.opensource.org/licenses/cddl1.php.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at

 * http://www.opensource.org/licenses/cddl1.php.  If applicable,

 * add the following below this CDDL HEADER, with the fields enclosed

 * by brackets "[]" replaced with your own identifying * information:

 *      Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 *

 *

 *      Portions Copyright 2007 Andreas Schneider

 *)

unit ULinkedList;

interface

uses

  SysUtils;

type

  PLinkedItem = ^TLinkedItem;

  TLinkedItem = record

    ID: Integer;

    Data: Pointer;

    Next: PLinkedItem;

  end;

  TLinkedList = class(TObject)

    constructor Create; virtual;

    destructor Destroy; override;

  protected

    FFirst: PLinkedItem;

    FLast: PLinkedItem;

  public

    procedure Clear; virtual;

    function Iterate(var ALinkedItem: PLinkedItem): Boolean; virtual;

    function Add(AID: Integer; AData: Pointer): PLinkedItem; virtual;

    procedure Delete(AData: Pointer); overload; virtual;

    procedure Delete(AID: Integer); overload; virtual;

    function Get(AID: Integer): Pointer; virtual;

    property Last: PLinkedItem read FLast;

  end;

implementation

{ TBlockList }

function TLinkedList.Add(AID: Integer; AData: Pointer): PLinkedItem;

var

  current: PLinkedItem;

begin

  New(current);

  current^.ID := AID;

  current^.Data := AData;

  current^.Next := nil;

  if FFirst = nil then FFirst := current;

  if FLast <> nil then FLast^.Next := current;

  FLast := current;

  Result := current;

end;

procedure TLinkedList.Clear;

var

  current, next: PLinkedItem;

begin

  current := FFirst;

  while current <> nil do

  begin

    next := current^.Next;

    Dispose(current);

    current := next;

  end;

  FFirst := nil;

  FLast := nil;

end;

constructor TLinkedList.Create;

begin

  inherited Create;

  FFirst := nil;

  FLast := nil;

end;

procedure TLinkedList.Delete(AData: Pointer);

var

  currentItem, lastItem, nextItem: PLinkedItem;

begin

  lastItem := nil;

  currentItem := FFirst;

  while currentItem <> nil do

  begin

    if currentItem^.Data = AData then

    begin

      if FFirst = currentItem then FFirst := currentItem^.Next;

      if FLast = currentItem then FLast := lastItem;

      if lastItem <> nil then lastItem^.Next := currentItem^.Next;

      Dispose(currentItem);

      nextItem := nil;

    end else

      nextItem := currentItem^.Next;

    lastItem := currentItem;

    currentItem := nextItem;

  end;

end;

procedure TLinkedList.Delete(AID: Integer);

var

  currentItem, lastItem, nextItem: PLinkedItem;

begin

  lastItem := nil;

  currentItem := FFirst;

  while currentItem <> nil do

  begin

    if currentItem^.ID = AID then

    begin

      if FFirst = currentItem then FFirst := currentItem^.Next;

      if FLast = currentItem then FLast := lastItem;

      if lastItem <> nil then lastItem^.Next := currentItem^.Next;

      Dispose(currentItem);

      nextItem := nil;

    end else

      nextItem := currentItem^.Next;

    lastItem := currentItem;

    currentItem := nextItem;

  end;

end;

destructor TLinkedList.Destroy;

begin

  Clear;

  inherited Destroy;

end;

function TLinkedList.Get(AID: Integer): Pointer;

var

  item: PLinkedItem;

begin

  Result := nil;

  item := nil;

  while Iterate(item) and (Result = nil) do

    if item^.ID = AID then

      Result := item^.Data;

end;

function TLinkedList.Iterate(var ALinkedItem: PLinkedItem): Boolean;

begin

  if ALinkedItem = nil then

    ALinkedItem := FFirst

  else

    ALinkedItem := ALinkedItem^.Next;

  Result := ALinkedItem <> nil;

end;

end.