Input parser

[Hans Kieserman]

I am interested in working on importing Lilypond files into a 
sequencer/graphical notation editor.  The task is somewhat daunting : )

In the opinions of experts, is this possible within reasonable 
expectations?  Is there a recommended mode of attack, i.e. somehow reuse 
the lilypond parser vs. attempt to maintain a "parallel" codebase?  (How 
closely tied to output is the input processor?)  Or is it complicated 
enough that lilypond->MIDI->Import is the recommended path?

A related question is if anyone could give an estimation as to how much 
of the complexity is display-specific notation (vs. simply encoding 
notes and their characteristics).  This application does not 
particularly depend on pretty-printing, so is it possible to discard any 
meaningfully-large parts of the syntax in hopes of easier coding?

I have written a very simple C++ parser as an exercise, but as with most 
things, the first step is significantly easier than the "usual case".

Thanks,
Hans