unit dpgrtl.tokenqueue;

interface
uses
   System.Classes,
   dpgrtl.types;

type
   TTokenQueue = class( TInterfacedObject)
      private
         fItems   : TInterfaceList;

      private
         function    GetCount : integer;
         function    GetItem(i:integer): IToken;
         procedure   SetItem(i:integer;value:IToken);

      public
         procedure   Clear;
         procedure   Add( Item: IToken);
         procedure   Remove( Num: integer=1);

      public
         procedure   AfterConstruction; override;
         procedure   BeforeDestruction; override;

      public
         property    Count             : integer   read  GetCount;
         property    Items[i:integer]  : IToken    read  GetItem  write SetItem;
   end;

implementation
uses
   System.SysUtils;

{ TTokenQueue }

// @@@: Construction/destruction ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
//                                   Construction/destruction
//
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ================================================================================================
// After Construction
// ================================================================================================
procedure TTokenQueue.AfterConstruction;
begin
   inherited;

   fItems := TInterfaceList.Create;
end;

// ================================================================================================
// Before Destruction
// ================================================================================================
procedure TTokenQueue.BeforeDestruction;
begin
   FreeAndNil(fItems);
   inherited;
end;



// @@@: Interface +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
//                                           Interface
//
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ================================================================================================
// Clear
// ================================================================================================
procedure TTokenQueue.Clear;
begin
   fItems.Clear;
end;

// ================================================================================================
// Add
// ================================================================================================
procedure TTokenQueue.Add(Item: IToken);
begin
   if Assigned(Item) then
      fItems.Add(Item)
end;

// ================================================================================================
// Remove
// ================================================================================================
procedure TTokenQueue.Remove(Num: integer);
var
   i: integer;

begin
   if Num > 0 then
   begin
      if Num >= fItems.Count then
         fItems.Clear

      else
         for i:=0 to Num -1 do
            fItems.Delete(0)
   end
end;



// @@@: Property Handlers +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
//                                       Property Handlers
//
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// ================================================================================================
// Get Count
// ================================================================================================
function TTokenQueue.GetCount: integer;
begin
   result := fItems.Count
end;

// ================================================================================================
// Get Item
// ================================================================================================
function TTokenQueue.GetItem(i: integer): IToken;
begin
   // -------------------------------------------------------------------------
   // Check for valid index value.
   // -------------------------------------------------------------------------
   if i > fItems.Count  then raise ERangeError.CreateFmt( 'Index "%d" is too big', [i]);
   if i < 0             then raise ERangeError.CreateFmt( 'Index is less than 0', []);

   result := fItems[i] as IToken
end;

// ================================================================================================
// Set Item
// ================================================================================================
procedure TTokenQueue.SetItem(i: integer; value: IToken);
begin
   if i > fItems.Count  then raise ERangeError.CreateFmt( 'Index "%d" is too big', [i]);
   if i < 0             then raise ERangeError.CreateFmt( 'Index is less than 0', []);

   fItems.Items[i] := value
end;

end.