Re: [Texmacs-dev] Environment at a tree

[Henri Lesourd]

Lionel Elie Mamane wrote:
> Hi,
>
> Given t a value of type tree in TeXmacs's scheme environment, is there
> an easy way to find the value what a certain TeXmacs variable has at
> that point in the document? Roughly, what the tree (value "foo") would
> be if placed at the place of t. I mean, suppose that the tree-type
> value points at the tree (here) in the following document:
>
>  (with "foo" "bar"
>    (document
>      "blah"
>      (with "foo" "baz"
>         (session
>           (document
>             (input "$" "Go! Go!")
>             (input (concat "$" (here) "%") "Back! Back!")
>             (output "No luck here."))))))
>
> I would get "baz". An "easy" way means short of doing tree-up until
> one encounters a (with "foo" . .) or (with . . "foo" . .) or
>  (with . . . . "foo" . .)
> where "." stands for any tree. An easy way includes a library routine
> that would do just that.
The function :
<<
(get-upwards-property path var)
> >

in graphics-utils.scm does exactly what you want. This
function is not currently a 1st class function of the
TeXmacs libraries, thus I would suggest that you extract
it with all its dependencies (i.e., (find-prop), (tm-find-prop),
and especially (tm-upwards-path), which is the one that
performs going up in the tree), and that you put that
in a library of your own. At some point, this code will
probably become deprecated (although perhaps not the API),
but at least, this way you enjoy a simple implementation
of this traversal routine that only relies on the basic
tree primitives [i.e., (tree-label), (tree-ref) and (tree->path)].

There are also some interesting (but a little bit unpolished)
traversal primitives [i.e. (For) and (for@)] that I use
all the time in my code : adieu les fonctions recursives
a la mords-moi-le-noeud qu'on est oblige de tout le temps
se taper juste parce qu'il manque une boucle for pour
parcourir les arbres et les listes !


Best, Henri