[Help-source-highlight] regexp for scheme blocks in lilypond language

[Federico Bruni]

Hi,

lilypond files can contain blocks of scheme code in several ways.
The main challenge is handling conflicts between single and multiline 
and especially blocks where the number of parentheses cannot be known in 
advance (there's a way to match balanced parentheses?).

Scheme strings can be single line. 4 examples:

\applyMusic #unfold-repeats \bottom
\Score tempoWholesPerMinute = #(ly:make-moment 120 4)

system-system-spacing #'padding = #8
tagline = \markup { \override #'(box-padding . 1.0) \override 
#'(baseline-skip . 2.7) { "Hello" } }

Strings that should be highlighted:

#unfold-repeats
#(ly:make-moment 120 4)

#'padding
any #'(\.) occurence in that single line


There are also two kinds of scheme blocks (I can match the first not the 
second, because I cannot guess the number of parentheses):

#'((basic-distance . 12)
   (minimum-distance . 6)
   (padding . 1)
   (stretchability . 12))



#(define (naturalize-pitch p)
   (let ((o (ly:pitch-octave p))
         (a (* 4 (ly:pitch-alteration p)))
         ;; alteration, a, in quarter tone steps,
         ;; for historical reasons
         (n (ly:pitch-notename p)))
     (cond
      ((and (> a 1) (or (eq? n 6) (eq? n 2)))
       (set! a (- a 2))
       (set! n (+ n 1)))
      ((and (< a -1) (or (eq? n 0) (eq? n 3)))
       (set! a (+ a 2))
       (set! n (- n 1))))
     (cond
      ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
      ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
     (if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
     (if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
     (ly:make-pitch o n (/ a 4))))


This is very problematic because this kind of block is placed at the 
beginning of a lilypond file and many snippets in the LilyPond 
documentation have such blocks.
My current lilypond.lang can't handle it and all the highlighting gets 
messed, see:
http://lists.gnu.org/archive/html/lilypond-user/2012-01/msg00013.html

(see also my reply to that email)

I attach also an example file.
Sorry for the confusion, I'm in a hurry.

Thanks in advance for your help,
Federico

test.ly
Description: Text document