Hello,

I have the following variable that I need to initialize:

yyinput: Text;

I searched, but I can't find anything that explains what this is, or how to initialize it. Is the Text type the same as TextFile?

I would like to set this variables to the contents of a file, so I tryed the following, but it crashes with runtime error 123 ( 'No medium found' ) and no error message.

  AssignFile(lexlib.yyinput, AFileName);
  Reset(lexlib.yyinput) ;
  fmlscan.yylex();
  CloseFile(lexlib.yyinput) ;

thanks,

Hello Felipe,

Yes, Text is the same as TextFile.

Use:
Rewrite for create a new file for writing.
Reset for open a file already created for reading. Append for open a file already created for writing.

Yes (although more the other way around: Text is a standard Pascal type, while TextFile is an alias for Text introduced in Delphi).

Normally, you would use plain assign() with Text files, but AssignFile maps through to that.

Same remark as for assign() here (close vs closefile)

So your error is unrelated to the use of assign(file)/close(file), it is something else.

Jonas

Ok, thanks, the initial problem was that the filename calculation logic was wrong.

thanks,

Is it possible to set a Text file to nowhere? I mean, lexlib has a textfile called yyoutput, where it will throw output. I don't want to have this output at all, and lexlib doesn't allow me to choose that.

yyoutput is declared simply as Text

I would initially try setting it to zero, but that's StdIO.

thanks,

Michael Van Canneyt wrote

Assign yyoutput to a dummy stream, which simply skips output.

Could you explain better how can this be implemented?

The only think I know about streams is TStream.

thanks,

Assign yyoutput to a dummy stream, which simply skips output.

Michael.

Exactly:

-----------------------------------------------------------------------

uses lexlib, Classes, StreamIO;
Type
  TNullStream = Class(TStream)
    function Read(var Buffer; Count : LongInt) : Longint; override;
    function Write(const Buffer; Count : LongInt) : LongInt; override;
    function Seek(Offset: Longint; Origin: Word): Longint; override;
  end;
Function TNullStream.Read(var Buffer; Count : LongInt) : Longint;
begin
  Result:=Count;
end;
Function TNullStream.Write(const Buffer; Count : LongInt) : LongInt;
begin
  Result:=Count;
end;
function TNullStream.Seek(Offset: Longint; Origin: Word): Longint;
begin
  Result:=0;
end;
Var
  Null : TNullStream;
begin
  Null:=TNullstream.Create;
  assignstream(yyoutput,Null);
  // blah blah
  FreeAndNil(Null);
end.
-----------------------------------------------------------------------

That's it. Come to think of it,I may add TNullStream to the streamex unit or so.

Michael.

I'm not sure if mixing lexlib (which is AFAIK written using procedural TP style code) with streams is a good idea. Depending on your platform, you could probably simply assign the text file name of 'NUL' or '/dev/nul'. Admittedly, I don't know whether this kind of device exists for all platforms (e.g. Symbian ;-) ).

Tomas

Find the definition of the "text" type and see that it contains pointers to read and write functions.

They need replacing in yor instance to pointers to functions that do nothing.

The original Pascal file access is object oriented after all!

Sam