TRawByteStringStream

TRawByteStringStream

  TRawByteStringStream = class(TStream)
  protected
    fDataString: RawByteString;
    fPosition: Integer;
    procedure SetSize(NewSize: Longint); override;
  public
    constructor Create(const aString: RawByteString = ''); overload;
    function Read(var Buffer; Count: Longint): Longint; override;
    function Seek(Offset: Longint; Origin: Word): Longint; override;
    function Write(const Buffer; Count: Longint): Longint; override;
    property DataString: RawByteString read fDataString write fDataString;
  end;
{ TRawByteStringStream }

constructor TRawByteStringStream.Create(const aString: RawByteString);
begin
  fDataString := aString;
end;

function TRawByteStringStream.Read(var Buffer; Count: Integer): Longint;
begin
  if Count <= 0 then
    Result := 0
  else
  begin
    Result := Length(fDataString) - fPosition;
    if Result > Count then
      Result := Count;
    Move(PByteArray(fDataString)[fPosition], Buffer, Result);
    inc(fPosition, Result);
  end;
end;

function TRawByteStringStream.Seek(Offset: Integer; Origin: Word): Longint;
begin
  case Origin of
    soFromBeginning:
      fPosition := Offset;
    soFromCurrent:
      fPosition := fPosition + Offset;
    soFromEnd:
      fPosition := Length(fDataString) - Offset;
  end;
  if fPosition > Length(fDataString) then
    fPosition := Length(fDataString)
  else if fPosition < 0 then
    fPosition := 0;
  result := fPosition;
end;

procedure TRawByteStringStream.SetSize(NewSize: Integer);
begin
  SetLength(fDataString, NewSize);
  if fPosition > NewSize then
    fPosition := NewSize;
end;

function TRawByteStringStream.Write(const Buffer; Count: Integer): Longint;
begin
  if Count <= 0 then
    Result := 0
  else
  begin
    Result := Count;
    SetLength(fDataString, fPosition + Result);
    Move(Buffer, PByteArray(fDataString)[fPosition], Result);
    inc(FPosition, Result);
  end;
end;