// TTextFileStream class by Chronos 12.9.2005
// Homepage: http://jirihajda.zdechov.net/

unit UTextFileStream;

interface

uses Classes, Dialogs, SysUtils;

type

  TTextFileStream = class(TFileStream)
  private
    FBuffer: string;
  protected

  public
    procedure WriteLn(Text: string);
    function ReadLn: string;
    function Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; override;
    function RowsCount: Integer;
  end;

implementation

{ TTextFileStream }

function TTextFileStream.ReadLn: string;
const
  BufferLength = 10000;
var
  NewBuffer: string;
  Readed: Integer;
begin
  Readed:= 1;
  while (Pos(#13,FBuffer) = 0) and (Readed > 0) do begin
    SetLength(NewBuffer, BufferLength+2);
    Readed:= Read(NewBuffer[1], BufferLength);
    SetLength(NewBuffer, Readed);
    FBuffer:= FBuffer + NewBuffer;
  end;
  if Pos(#13,FBuffer)>0 then begin
    Result:= Copy(FBuffer, 1, Pos(#13,FBuffer)-1);
    Delete(FBuffer, 1, Pos(#13,FBuffer)+1);
  end else begin
    Result:= FBuffer;
    FBuffer:= '';
  end;
end;

function TTextFileStream.RowsCount: Integer;
begin
  Result:= 1;
  FBuffer:= '';
  Seek(0, soBeginning);
  while ReadLn <> '' do Inc(Result);
  Seek(0, soBeginning);
end;

function TTextFileStream.Seek(const Offset: Int64;
  Origin: TSeekOrigin): Int64;
begin
  if Origin = soCurrent then Result:= inherited Seek(Offset - Length(FBuffer), Origin)
  else Result:= inherited Seek(Offset, Origin);
  FBuffer:= '';
end;

procedure TTextFileStream.WriteLn(Text: string);
const
  NewLine = #13#10;
begin
  Seek(0, soCurrent);
  Write(Text[1], Length(Text));
  Write(NewLine, 2);
end;

end.