[climacs-devel] Can syntax classes handle text overlays? (Evaluating from buffer)

[Derek Peschel]

Hi everybody,

I've been looking through the syntax classes but it's a lot to learn
at once (especially when I'm learning about CLOS and brushing up on my
LISP at the same time).

I know that display-parse-tree gets called for every node in the tree.
Can that handle anything like Emacs's text properties or overlays?
In the most general case, they apply to characters and not parse-tree items,
so the character-by-character formatting of the overlay would have to be
mixed with the formatting of the parse item.

Right now, the only thing on the screen that has X-Y coordinates derived
from a text location seems to be the cursor.  And I've edited LISP files
with strings (displayed in a larger italic font) and the cursor can go to
the wrong place in the window, so I suspect the syntax machinery is not
being used.

Ultimately I'm dreaming of an evaluation package that would replace the
teletype mentality of the traditional top-level loop.  With my package,
the user would highlight text to act on (evaluate, macro expand, etc.),
either using unstructured commands (move by character and line) or
structured ones (mark defun around point).  The results might be substituted
for the original text or the package might keep a history of the computation.
I can't decide much more about the design until I have a prototype.  (I tried
a few experiments with Emacs and its structured navigation functions are
far too inaccurate to be useful.)

Thanks,

-- Derek