Re: Best way to label hierarchical sections with their depths

Hello!

> I have a document that looks something like this:

> (define doc2
>   '(article
>      (section (title "T1") (para "text")
>        (section (title "T1.1") (para "text")
> 	 (section (title "T1.1.1") (para "text"))
> 	 (section (title "T1.1.2") (para "text")))
>        (section (title "T1.2") (para "text")))
>      (section (title "T2") (para "text"))))
>
> How to convert into something like this:
>
>     (*section 1 (title "T1")
>       ...
>       (*section 2 (title "T1.1")
>         ...
>         (*section 3 (title "T1.1.1")
>           ...
>           )))

When information flows only up-and-down the branches (but not from a
node to its sibling), simple solutions are possible. For example, the
following. Note that we effectively "modify" the stylesheet to
incorporate the level number into the handler of the 'section'
element. My favorite trick: viral infection, which pushes the virus
deeper and deeper into the tree as the computation progresses.


(define my-ss
  (letrec
    ((make-section-handler
       (lambda (level)
	 (lambda (tag . elems)
	   (pre-post-order 
	     `(*section ,level ,@elems)
	     (cons `(section *preorder* . 
		      ,(make-section-handler (+ 1 level)))
	       my-ss))))))
    `((article *macro*
	. ,(lambda (tag . elems)
	     `(*article ,@elems)))
     (section *preorder* . ,(make-section-handler 1))
     (*default* . ,(lambda x x))
     (*text* . ,(lambda (tag str) str)))))

(pp (pre-post-order doc2 my-ss))

The code seems to print the desired result.



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