[Oberon] HOW2 get Token at cursor?

eas lab lab.eas at gmail.com
Mon Jan 28 09:44:46 CET 2013

Please follow and correct my exposed reasoning:

Getting the tokens at the cursor is exactly what must happen with:
      Oberon.Call(S.s, Oberon.Par, FALSE, res);
which is repeated often in severa; *.Mod

Let's morph this to
   Oberon.CaT(TokenAtCursor, ParList, New, Res);

Using 3 colours, which you can't see in the mail, shows, eg :
Texts.OpenScanner(S, Oberon.Par.text, Oberon.Par.pos); Texts.Scan(S);
COPY(S.s, cmd); Oberon.Call(cmd, Oberon.Par, FALSE, res)

Which shows the <signalFlow> as:
cmd <- S.s <- ?? Texts.*

But the <TextScanner> does NOT read the cursor co-ordinates;
which are exported from Oberon.*   via
        Cursor* = RECORD
            marker*: Marker;    (** Cursor marker. *)
            on*: BOOLEAN;       (** Is cursor shown? *)
            X*, Y*: INTEGER     (** Absolute cursor position. *)

So is Cursor.X continually updated, if the mouse moves?

But <Variable:Text> is a list of chars
and <Cursor Position> is an OrderedPair.

So, TextScanner only sees a list of chars.

And It's not clear where the pixelGeometry/OrderedPair
maps to the corresponding char, except at the very low-level
of the display-driver.

Actually I don't want the token at the cursor, which I've
tried to trace above.  I want the more primitive CharAtCursor.

NB. distinguish between cursor and caret.

I'd like to see:
  WHILE CharAtCursorChanges(Ch) DO
      Out.Char(Ch);Out.Ln() END;

   or better:


So the ChangingCharAtTheCursor would scroll in the System.Log

Please advise.

== Chris Glur.

PS. Since Texts does not IMPORT Oberon, it can't
know Oberon.Cursor.X
PSS. Perhaps more is seem from:-
Arrow*, Star*: Marker;
        (** Normal Oberon arrow, and the star marker. *)
No, because the star-marker is not concerned with

More information about the Oberon mailing list