markup to string function?

[Reinhold Kainhofer]

I'm currently implementing PDF metadata (DOCINFO extracted from the \header 
fields) as well as PDF hyperlinks to given labels in the score. For both I 
would need to extract a pure-string representation of a given markup. E.g., 
the title header field might be a markup:

\header{
  title = \markup { \italic "Title of " \bold \concat {"the" " " "piece"} }
}

Now, given that markup, I need a function that extracts only the text (in this 
case "Title of the piece"). Is there anything like that already available in 
lilypond? 

If not, do you have any idea about the easiest way to implement this? It's 
safe to ignore all graphical markup functions, but there are so many text 
markup functions that I can not easily handle each of them manually...

Any ideas?

Thanks,
Reinhold
-- 
------------------------------------------------------------------
Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org