Re: Texinfo XML support in Emacs Info browser

[Juri Linkov <juri@jurta.org>]

> () Juri Linkov <juri@jurta.org>
> () Sun, 03 Jun 2007 02:03:03 +0300
>
>    [info-xml.el]
>
> interesting.  i had to modify `Info-xml-select-node' like so:
>
> 	;; Add a new unique history item to full history list
> 	(let ((new-history (list Info-current-file Info-current-node)))
> 	  (setq Info-history-list
> 		(cons new-history (delete new-history Info-history-list)))
> 	  (setq Info-history-forward nil))

Sorry, this part contained function calls for speed optimization of
displaying large index nodes.  I'll post a separate patch for info.el.

> i think ad-hoc regexp-based approach is likely to be troublesome in the long
> run.  so, question: since we have xml.el, why not build a tree immediately?
> one answer is that: well, makeinfo --xml output is not always valid.  :-(
>
> e.g.: makeinfo --xml -o edb.info.xml edb.texi
>       (xml-parse-file "edb.info.xml")
>       => error
>
> (in edb.info.xml, element `detailedmenu' is not properly nested.  this is
> seen using "makeinfo (GNU texinfo) 4.8".)

This is the exact reason why I leaned toward using regexps instead of
xml-parse-file.  In my first attempt to use xml-parse-file I discovered
that `makeinfo --xml' sometimes produces non-wellformed XML, so we can't
parse it with xml-parse-file.  Even if this will be fixed in the future
releases of makeinfo, old versions still produce invalid XML output.

With regexp-based approach, the Info browser would be more permissive to
invalid XML, in the same way as most HTML browsers are permissive to invalid
markup on HTML pages.  It can simply ignore invalid elements, either
removing them or leaving on display which doesn't make much harm.

-- 
Juri Linkov
http://www.jurta.org/emacs/