Re: hack spacing of triplet against swung 8.+16

[Alexander Kobel]

Correction:

Murphy's law. Still looks okay to me, but (sigh!) just the error message 
for ill-formed duration strings missed the "not" in "not a valid duration".


Cheers,
Alexander

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% applyRhythm
%%
%% 2009, Alexander Kobel (www.a-kobel.de)
%%
%% This program is free software. It comes without any warranty, to
%% the extent permitted by applicable law. You can redistribute it
%% and/or modify it under the terms of the Do What The Fuck You Want
%% To Public License, Version 2, as published by Sam Hocevar. See
%% http://sam.zoy.org/wtfpl/COPYING for more details.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% inspired by: http://lsr.dsi.unimi.it/LSR/Item?id=390
%% Thanks to the unknown contributor!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Version 1.1
%%
%% Changes to http://lsr.dsi.unimi.it/LSR/Item?id=390:
%%
%% - \makeRhythm => \applyRhythm
%% - reversed order of arguments for \applyRhythm
%% - name changes in the backend (no more camel case, e.g.)
%% - checking well-formedness of duration strings
%% - support *num/den arguments
%% - support rests and skips
%% - support additional (arbitrary) whitespace in the rhythm string
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%% This should also work with older version,
%% probably up to <= 2.10.
%% Please report if this is the case.
\version "2.12.2"

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Parsing single duration strings, like "4..*2/3"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(use-modules (ice-9 regex))

#(define duration-string-pattern "^[0-9]+\\.*(\\*[0-9]+)?(/[0-9]+)?$")

#(define (string->duration str)
        (if (not (string-match duration-string-pattern str))
         (begin
                (display (string-append "warning: `" str "' does not denote a 
valid duration. "
                                                        "Using `128...*256' 
instead.")
                 (current-error-port))
                (ly:make-duration 7 3 256 1))
         
         (let* (
                 (dot-index (string-index str #\.))
                 (nom-index (string-index str #\*))
                 (den-index (string-index str #\/))

                 (end-of-nom    (or den-index (string-length str)))
                 (end-of-dots   (or nom-index end-of-nom))
                 (end-of-length (or dot-index end-of-dots))
                 
                 (length (ly:intlog2 (string->number (substring str 0 
end-of-length))))
                 (dot-count (if dot-index
                                                                 (- end-of-dots 
dot-index)
                                                                 0))
                 (nom (if nom-index
                                         ;; get rid of the "*"
                                         (string->number (substring str (1+ 
nom-index) end-of-nom))
                                         1))
                 (den (if den-index
                                         ;; get rid of the "/"
                                         (string->number (substring str (1+ 
den-index) (string-length str)))
                                         1)))
                
                (ly:make-duration length dot-count nom den))))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Parsing rhythm strings, like "4. 8 4 8.*8/9 16*4/3"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (string->duration-vector rhythm)
        (let ((duration-string-list (string-tokenize rhythm)))
         (list->vector (map string->duration duration-string-list))))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Replace the duration of a chord by a duration
%% given as a specific element of a vector of durations
%%
%% Only apply to certain types of events (in particular,
%% not to multi measure rests)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (replace-chord-duration chord duration-vector index)
        (begin
         (if (or
                                (eq? 'NoteEvent (ly:music-property chord 'name))
                                (eq? 'RestEvent (ly:music-property chord 'name))
                                (eq? 'SkipEvent (ly:music-property chord 'name))
                        )
                (set! (ly:music-property chord 'duration) (vector-ref 
duration-vector index)))
         
         chord))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Apply the rhythm scheme of duration-vector at index
%% if music is a chord event; do nothing otherwise
%% Returns:
%% The transformed event and the index of the next duration
%% in the rhythm vector
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#(define (replace-event-duration event duration-vector index)
        (begin
         (if (eq? 'EventChord (ly:music-property event 'name))
                (begin
                 (map (lambda (chord) (replace-chord-duration chord 
duration-vector index))
                        (ly:music-property event 'elements))
                 (set! index (modulo (1+ index) (vector-length 
duration-vector)))))
         (cons event index)))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% The end-user function:
%% Apply rhythm (given as string) to music.
%%
%% If music has more chords than rhythm has entries,
%% repeat the rhythm as often as necessary.
%%
%% Example usage:
%% \applyRhythm "4 8 8 4 8.*8/9 16*4/3" { c d e f g a | a g f e d c }
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
applyRhythm =
#(define-music-function (parser location rhythm music) (string? ly:music?)
        (let (
                (duration-vector (string->duration-vector rhythm))
                (index 0)
        )
         (music-map
                (lambda (event)
                 (let ((result (replace-event-duration event duration-vector 
index)))
                        (begin
                         (set! index (cdr result))
                         (car result))))
                        music)))


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Test
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
applyRhythmTestCaseString = "
        4...                32
        8. 16 8.*8/9 16*4/3   "
applyRhythmTestCase = \new Score {
        <<
                \new Staff \applyRhythm \applyRhythmTestCaseString \relative c' 
{ <c e> c <c e> c c c | R1 | c r r c r c }
                \new Staff \repeat unfold 3 { \repeat unfold 4 \times 2/3 { 
c''8 c'' c'' } \break }
        >>
}

%% \score { \applyRhythmTestCase }