1 ;;;; fret-diagrams.scm --
3 ;;;; source file of the GNU LilyPond music typesetter
5 ;;;; (c) 2004--2005 Carl D. Sorensen <c_sorensen@byu.edu>
7 (define (fret-parse-marking-list marking-list fret-count)
8 (let* ((fret-range (list 1 fret-count))
13 (let parse-item ((mylist marking-list))
14 (if (not (null? mylist))
15 (let* ((my-item (car mylist)) (my-code (car my-item)))
17 ((or (eq? my-code 'open)(eq? my-code 'mute))
18 (set! xo-list (cons* my-item xo-list)))
20 (set! barre-list (cons* (cdr my-item) barre-list)))
21 ((eq? my-code 'place-fret)
22 (set! dot-list (cons* (cdr my-item) dot-list))))
23 (parse-item (cdr mylist)))))
24 ; calculate fret-range
25 (let ((maxfret 0) (minfret 99))
26 (let updatemax ((fret-list dot-list))
29 (let ((fretval (second (car fret-list))))
30 (if (> fretval maxfret) (set! maxfret fretval))
31 (if (< fretval minfret) (set! minfret fretval))
32 (updatemax (cdr fret-list)))))
33 (if (> maxfret fret-count)
34 (set! fret-range (list minfret
35 (let ((upfret (- (+ minfret fret-count) 1)))
36 (if (> maxfret upfret) maxfret upfret)))))
37 ; subtract fret from dots
38 (set! dot-list (subtract-base-fret (- (car fret-range) 1) dot-list)))
39 (acons 'fret-range fret-range
40 (acons 'barre-list barre-list
41 (acons 'dot-list dot-list
42 (acons 'xo-list xo-list '()))))))
44 (define (subtract-base-fret base-fret dot-list)
45 "Subtract @var{base-fret} from every fret in @var{dot-list}"
48 (let ((this-list (car dot-list)))
49 (cons* (list (car this-list) (- (second this-list) base-fret) (if (null? (cddr this-list))
52 (subtract-base-fret base-fret (cdr dot-list))))))
54 (define (sans-serif-stencil layout props mag text)
55 "create a stencil in sans-serif font based on @var{layout} and @var{props}
56 with magnification @varr{mag} of the string @var{text}."
57 (let* ((my-props (prepend-alist-chain 'font-size (stepmag mag)
58 (prepend-alist-chain 'font-family 'sans props))))
59 (interpret-markup layout my-props text)))
61 (define (sans-serif-stencil-white layout props mag text)
62 "create a stencil with white text in sans-serif font based on @var{layout} and @var{props}
63 with magnification @varr{mag} of the string @var{text}."
64 (let* ((text-stencil (sans-serif-stencil layout props mag text))
65 (x-extent (ly:stencil-extent text-stencil X))
66 (y-extent (ly:stencil-extent text-stencil Y))
67 (c `(white-text ,(* 2 mag) ,text))) ;urg -- workaround for using ps font
68 (ly:make-stencil c x-extent y-extent))) ;urg -- extent is not from ps font, but we hope it's close
71 (define (draw-strings string-count fret-range th size)
72 "Draw the strings (vertical lines) for a fret diagram with @var{string-count} strings and frets as indicated
73 in @var{fret-range}. Line thickness is given by @var{th}, fret & string spacing by @var{size}. "
74 (let* ((fret-count (+ (- (cadr fret-range) (car fret-range)) 1))
75 (sl (* (+ fret-count 1) size))
77 (half-thickness (* sth 0.5))
79 (string-stencil (ly:make-stencil (list 'draw-line sth 0 0 0 sl)
80 (cons (- half-thickness) half-thickness)
81 (cons (- half-thickness) (+ sl half-thickness)))))
82 (if (= string-count 1)
84 (ly:stencil-combine-at-edge
85 (draw-strings (- string-count 1) fret-range th size) X RIGHT
89 (define (draw-fret-lines fret-count string-count th size)
90 "Draw @var{fret-count} frets (horizontal lines) for a fret diagram with @var{string-count} strings.
91 Line thickness is given by @var{th}, fret & string spacing by @var{size}. "
92 (let* ((fret-length (* (- string-count 1) size))
94 (half-thickness (* sth 0.5))
96 (fret-line (ly:make-stencil (list 'draw-line sth half-thickness size (- fret-length half-thickness) size)
98 (cons (- size half-thickness) (+ size half-thickness)))))
101 (ly:stencil-combine-at-edge fret-line Y UP
102 (draw-fret-lines (- fret-count 1) string-count th size)
105 (define (draw-thick-top-fret props string-count th size)
106 "Draw a thick top fret for a fret diagram whose base fret is not 1."
107 (let* ((sth (* th size))
108 ; (top-fret-thick (* sth (chain-assoc-get 'top-fret-thickness props 3.0)))
109 (top-fret-thick (* sth 3.0))
110 ; (top-half-thick (* top-fret-thick 0.5))
111 (half-thick (* sth 0.5))
113 (x2 (+ half-thick (* size (- string-count 1))))
115 (y2 (+ top-fret-thick half-thick))
116 (x-extent (cons (- x1) x2))
117 (y-extent (cons 0 y2)))
118 (ly:make-stencil (list 'round-filled-box x1 x2 y1 y2 sth)
122 (define (draw-frets layout props fret-range string-count th size)
123 "Draw the frets (horizontal lines) for a fret diagram with @var{string-count} strings and frets as indicated
124 in @var{fret-range}. Line thickness is given by @var{th}, fret & string spacing by @var{size}. "
125 (let* ((fret-count (+ (- (cadr fret-range) (car fret-range)) 1))
126 (fret-length (* (- string-count 1) size))
127 (half-thickness (* th 0.5))
128 (base-fret (car fret-range)))
129 (ly:stencil-combine-at-edge
130 (draw-fret-lines fret-count string-count th size) Y UP
132 (draw-thick-top-fret props string-count th size)
133 (draw-fret-lines 1 string-count th size))
137 (define (draw-dots layout props string-count fret-range size finger-code dot-position dot-radius dot-list)
138 "Make dots for fret diagram."
139 (let* ((scale-dot-radius (* size dot-radius))
140 (dot-color (chain-assoc-get 'dot-color props 'black))
141 ; (finger-xoffset (chain-assoc-get 'finger-xoffset props -0.25))
142 ; (finger-yoffset (chain-assoc-get 'finger-yoffset props (- size)))
143 (finger-xoffset -0.25)
144 (finger-yoffset (- size))
145 ; (dot-label-font-mag (* scale-dot-radius (chain-assoc-get 'dot-label-font-mag props 1.0)))
146 (dot-label-font-mag scale-dot-radius)
147 ; (string-label-font-mag (* size (chain-assoc-get 'label-font-mag props 0.7)))
148 (string-label-font-mag (* size 0.7))
149 (fret-count (+ (- (cadr fret-range) (car fret-range) 1)))
150 (mypair (car dot-list))
151 (restlist (cdr dot-list))
152 (xpos (* size (- string-count (car mypair))))
153 ;TODO -- figure out what 4 is and get rid of it
155 (ypos (* size (+ 4 (- fret-count (cadr mypair) dot-position ))))
156 (extent (cons (- scale-dot-radius) scale-dot-radius))
157 (finger (caddr mypair))
158 (finger (if (number? finger) (number->string finger) finger))
159 (dotstencil (if (eq? dot-color 'white)
161 (ly:make-stencil (list 'white-dot 0 0 scale-dot-radius) extent extent))
162 (ly:make-stencil (list 'dot 0 0 scale-dot-radius ) extent extent)))
163 (positioned-dot (ly:stencil-translate-axis
164 (ly:stencil-translate-axis dotstencil xpos X)
167 (if (or (eq? finger '())(eq? finger-code 'none))
169 (if (eq? finger-code 'in-dot)
170 (let* ((dot-proc (if (eq? dot-color 'white) 'white-dot 'dot)))
172 (ly:stencil-translate-axis
173 (ly:stencil-translate-axis
174 (if (eq? dot-color 'white)
175 (centered-stencil (sans-serif-stencil layout props dot-label-font-mag finger))
176 (centered-stencil (sans-serif-stencil-white layout props
177 dot-label-font-mag finger)))
180 (ly:stencil-translate-axis
181 (ly:stencil-translate-axis
182 (ly:make-stencil (list dot-proc 0 0 scale-dot-radius) extent extent)
185 (if (eq? finger-code 'below-string)
188 (ly:stencil-translate-axis
189 (ly:stencil-translate-axis
190 (centered-stencil (sans-serif-stencil layout props
191 string-label-font-mag finger)) xpos X)
192 (* size finger-yoffset) Y))
198 (draw-dots layout props string-count fret-range size finger-code
199 dot-position dot-radius restlist)
200 labeled-dot-stencil))))
202 (define (draw-xo layout props string-count fret-range size xo-list)
203 "Put open and mute string indications on diagram, as contained in @var{xo-list}."
204 (let* ((fret-count (+ (- (cadr fret-range) (car fret-range) 1)))
205 ; (xo-font-mag (* size (chain-assoc-get 'xo-font-magnification props 0.5)))
206 (xo-font-mag (* size 0.5))
207 ; (xo-horizontal-offset (* size (chain-assoc-get 'xo-horizontal-offset props -0.35)))
208 (xo-horizontal-offset (* size -0.35))
209 (mypair (car xo-list))
210 (restlist (cdr xo-list))
211 (glyph-string (if (eq? (car mypair) 'mute) "X" "O"))
212 (xpos (+ (* (- string-count (cadr mypair)) size) xo-horizontal-offset ))
213 (glyph-stencil (ly:stencil-translate-axis
214 (sans-serif-stencil layout props (* size xo-font-mag) glyph-string) xpos X)))
218 (draw-xo layout props string-count fret-range size restlist)
221 (define (make-bezier-sandwich-list left right bottom height thickness)
222 " Make the argument list for a horizontal bezier sandwich from @var{left} to @var{right} with a bottom at @var{bottom},
223 a height of @var{height}, and a thickness of @var{thickness}."
224 (let* ((width (+ (- right left) 1))
225 (x1 (+ (* width thickness) left))
226 (x2 (- right (* width thickness)))
227 (bottom-control-point-height (+ bottom (- height thickness)))
228 (top-control-point-height (+ bottom height)))
229 ; order of points is: left cp low, right cp low, right end low, left end low
230 ; right cp high, left cp high, left end high, right end high.
231 (list (cons x1 bottom-control-point-height) (cons x2 bottom-control-point-height) (cons right bottom) (cons left bottom)
232 (cons x2 top-control-point-height) (cons x1 top-control-point-height) (cons left bottom) (cons right bottom))))
234 (define (draw-barre layout props string-count fret-range size finger-code dot-position dot-radius barre-list)
235 "Create barre indications for a fret diagram"
236 (if (not (null? barre-list))
237 (let* ((string1 (caar barre-list))
238 (string2 (cadar barre-list))
239 (fret (caddar barre-list))
240 (barre-type (chain-assoc-get 'barre-type props 'curved))
241 (scale-dot-radius (* size dot-radius))
242 (barre-vertical-offset (chain-assoc-get 'barre-vertical-offset props 0.5))
243 ;; 2 is 1 for empty fret at bottom of figure + 1 for interval (top-fret - fret + 1) -- not an arbitrary constant
244 (dot-center-y (* size
245 (- (+ 2 (- (cadr fret-range) fret)) dot-position)))
246 (bottom (+ dot-center-y (* barre-vertical-offset scale-dot-radius)))
247 (left (* size (- string-count string1)))
248 (right (* size (- string-count string2)))
249 ;; (bezier-thick (chain-assoc-get 'bezier-thickness props 0.1))
251 ;; (bezier-height (chain-assoc-get 'bezier-height props 0.5))
253 (bezier-list (make-bezier-sandwich-list left right bottom (* size bezier-height) (* size bezier-thick)))
254 (barre-stencil (if (eq? barre-type 'straight)
255 (ly:make-stencil (list 'draw-line (* size dot-radius) left dot-center-y right dot-center-y)
257 (cons (- dot-center-y scale-dot-radius) (+ dot-center-y scale-dot-radius)))
258 (ly:make-stencil (list 'bezier-sandwich `(quote ,bezier-list) (* size bezier-thick))
260 (cons bottom (+ bottom (* size bezier-height)))))))
261 (if (not (null? (cdr barre-list)))
262 (ly:stencil-add barre-stencil
263 (draw-barre layout props string-count fret-range size finger-code
264 dot-position dot-radius (cdr barre-list)))
268 (define (stepmag mag)
269 "Calculate the font step necessary to get a desired magnification"
270 (* 6 (/ (log mag) (log 2))))
272 (define (label-fret layout props string-count fret-range size)
273 "Label the base fret on a fret diagram"
274 (let* ((base-fret (car fret-range))
275 ; (label-font-mag (chain-assoc-get 'label-font-mag props 0.7))
277 ; (label-vertical-offset (chain-assoc-get 'fret-label-vertical-offset props -0.2))
278 (label-vertical-offset -0.2)
279 (number-type (chain-assoc-get 'number-type props 'roman-lower))
280 (fret-count (+ (- (cadr fret-range) (car fret-range)) 1))
283 ((equal? number-type 'roman-lower) (format #f "~(~:@r~)" base-fret))
284 ((equal? number-type 'roman-upper) (format #f "~:@r" base-fret))
285 ((equal? 'arabic number-type) (format #f "~d" base-fret))
286 (else (format #f "~(~:@r~)" base-fret)))))
287 (ly:stencil-translate-axis
288 (sans-serif-stencil layout props (* size label-font-mag) label-text)
289 (* size (+ fret-count label-vertical-offset)) Y)))
291 (def-markup-command (fret-diagram-verbose layout props marking-list)
293 "Make a fret diagram containing the symbols indicated in @var{marking-list}
298 \\markup \\fret-diagram #'((mute 6) (mute 5) (open 4)
299 (place-fret 3 2) (place-fret 2 3) (place-fret 1 2))
302 will produce a standard D chord diagram without fingering indications.
304 Possible elements in @var{marking-list}:
306 @item (mute string-number)
307 Place a small 'x' at the top of string @var{string-number}
309 @item (open string-number)
310 Place a small 'o' at the top of string @var{string-number}
312 @item (barre start-string end-string fret-number)
313 Place a barre indicator (much like a tie) from string @var{start-string}to string @var{end-string} at fret @var{fret-number}
315 @item (place-fret string-number fret-number finger-value)
316 Place a fret playing indication on string @var{string-number} at fret @var{fret-number} with an optional
317 fingering label @var{finger-value}. By default, the fret playing indicator is a solid dot. This can be
318 changed by setting the value of the variable @var{dot-color}. If the @var{finger}
319 part of the place-fret element is present, @var{finger-value} will be displayed according to the setting of the variable
320 @var{finger-code}. There is no limit to the number of fret indications per string.
323 (make-fret-diagram layout props marking-list))
325 (define (make-fret-diagram layout props marking-list)
326 " Make a fret diagram markup"
328 ; note: here we get items from props that are needed in this routine, or that are needed in more than one
329 ; of the procedures called from this routine. If they're only used in one of the sub-procedure, they're
330 ; obtained in that procedure
332 (size (chain-assoc-get 'size props 1.0)) ; needed for everything
333 ;TODO -- get string-count directly from length of stringTunings; requires FretDiagram engraver, which is not yet available
334 ;TODO -- adjust padding for fret label? it appears to be too close to dots
335 (string-count (chain-assoc-get 'string-count props 6)) ; needed for everything
336 (fret-count (chain-assoc-get 'fret-count props 4)) ; needed for everything
337 (finger-code (chain-assoc-get 'finger-code props 'none)) ; needed for both draw-dots and draw-barre
338 (default-dot-radius (if (eq? finger-code 'in-dot) 0.425 0.25)) ; bigger dots if labeled
339 (default-dot-position (if (eq? finger-code 'in-dot) (- 0.95 default-dot-radius) 0.6)) ; move up to make room for bigger if labeled
340 (dot-radius (chain-assoc-get 'dot-radius props default-dot-radius)) ; needed for both draw-dots and draw-barre
341 (dot-position (chain-assoc-get 'dot-position props default-dot-position)) ; needed for both draw-dots and draw-barre
342 (th (* (ly:output-def-lookup layout 'linethickness)
343 (chain-assoc-get 'thickness props 0.5))) ; needed for both draw-frets and draw-strings
345 (alignment (chain-assoc-get 'align-dir props -0.4)) ; needed only here
346 ; (xo-padding (* th (chain-assoc-get 'padding props 2))) ; needed only here
348 (xo-padding (* th 2))
349 (label-dir (chain-assoc-get 'label-dir props RIGHT))
350 (parameters (fret-parse-marking-list marking-list fret-count))
351 (dot-list (cdr (assoc 'dot-list parameters)))
352 (xo-list (cdr (assoc 'xo-list parameters)))
353 (fret-range (cdr (assoc 'fret-range parameters)))
354 (barre-list (cdr (assoc 'barre-list parameters)))
355 (fret-diagram-stencil (ly:stencil-add
356 (draw-strings string-count fret-range th size)
357 (draw-frets layout props fret-range string-count th size))))
358 (if (not (null? barre-list))
359 (set! fret-diagram-stencil (ly:stencil-add
360 (draw-barre layout props string-count fret-range size finger-code
361 dot-position dot-radius barre-list)
362 fret-diagram-stencil)))
363 (if (not (null? dot-list))
364 (set! fret-diagram-stencil (ly:stencil-add
365 (draw-dots layout props string-count fret-range size finger-code
366 dot-position dot-radius dot-list)
367 fret-diagram-stencil)))
368 (if (not (null? xo-list))
369 (set! fret-diagram-stencil (ly:stencil-combine-at-edge
370 fret-diagram-stencil Y UP
371 (draw-xo layout props string-count fret-range size xo-list) xo-padding 0)))
372 (if (> (car fret-range) 1)
373 (set! fret-diagram-stencil
374 (ly:stencil-combine-at-edge fret-diagram-stencil X label-dir
375 (label-fret layout props string-count fret-range size) label-space 0)))
376 (ly:stencil-aligned-to fret-diagram-stencil X alignment)
379 (def-markup-command (fret-diagram layout props definition-string)
385 \\markup \\fret-diagram #\"s:0.75;6-x;5-x;4-o;3-2;2-3;1-2;\"
388 for fret spacing 3/4 of staff space, D chord diagram
390 Syntax rules for @var{definition-string}:
394 Diagram items are separated by semicolons.
401 s:number -- set the fret spacing of the diagram (in staff spaces). Default 1
404 t:number -- set the line thickness (in staff spaces). Default 0.05
407 h:number -- set the height of the diagram in frets. Default 4
410 w:number -- set the width of the diagram in strings. Default 6
413 f:number -- set fingering label type (0 = none, 1 = in circle on string, 2 = below string) Default 0
416 d:number -- set radius of dot, in terms of fret spacing. Default 0.25
419 p:number -- set the position of the dot in the fret space. 0.5 is centered; 1 is on lower fret bar,
420 0 is on upper fret bar. Default 0.6
423 c:string1-string2-fret -- include a barre mark from string1 to string2 on fret
426 string-fret -- place a dot on string at fret. If fret is o, string is identified
427 as open. If fret is x, string is identified as muted.
430 string-fret-fingering -- place a dot on string at fret, and label with fingering as
436 Note: There is no limit to the number of fret indications per string.
440 (let ((definition-list (fret-parse-definition-string props definition-string)))
441 (make-fret-diagram layout (car definition-list) (cdr definition-list))))
443 (define (fret-parse-definition-string props definition-string)
444 "parse a fret diagram string and return a pair containing:
445 props, modified as necessary by the definition-string
446 a fret-indication list with the appropriate values"
447 (let* ((fret-count 4)
449 (fret-range (list 1 fret-count))
455 (items (string-split definition-string #\;)))
456 (let parse-item ((myitems items))
457 (if (not (null? (cdr myitems)))
458 (let ((test-string (car myitems)))
459 (case (car (string->list (substring test-string 0 1)))
460 ((#\s) (let ((size (get-numeric-from-key test-string)))
461 (set! new-props (acons 'size size new-props))))
462 ((#\f) (let* ((finger-code (get-numeric-from-key test-string))
463 (finger-id (case finger-code
466 ((2) 'below-string))))
468 (acons 'finger-code finger-id new-props))))
469 ((#\c) (set! output-list (cons-fret (cons 'barre (numerify (string-split (substring test-string 2) #\-)))
471 ((#\h) (let ((fret-count (get-numeric-from-key test-string)))
472 (set! new-props (acons 'fret-count fret-count new-props))))
473 ((#\w) (let ((string-count (get-numeric-from-key test-string)))
474 (set! new-props (acons 'string-count string-count new-props))))
475 ((#\d) (let ((dot-size (get-numeric-from-key test-string)))
476 (set! new-props (acons 'dot-radius dot-size new-props))))
477 ((#\p) (let ((dot-position (get-numeric-from-key test-string)))
478 (set! new-props (acons 'dot-position dot-position new-props))))
480 (let ((this-list (string-split test-string #\-)))
481 (if (string->number (cadr this-list))
482 (set! output-list (cons-fret (cons 'place-fret (numerify this-list)) output-list))
483 (if (equal? (cadr this-list) "x" )
484 (set! output-list (cons-fret (list 'mute (string->number (car this-list))) output-list))
485 (set! output-list (cons-fret (list 'open (string->number (car this-list))) output-list)))))))
486 (parse-item (cdr myitems)))))
487 (if (eq? new-props '())
488 `(,props . ,output-list)
489 `(,(cons new-props props) . ,output-list))))
491 (define (cons-fret new-value old-list)
492 " Put together a fret-list in the format desired by parse-string "
493 (if (eq? old-list '())
495 (cons* new-value old-list)))
497 (define (get-numeric-from-key keystring)
498 "Get the numeric value from a key of the form k:val"
499 (string->number (substring keystring 2 (string-length keystring))))
501 (define (numerify mylist)
502 "Convert string values to numeric or character"
505 (let ((numeric-value (string->number (car mylist))))
507 (cons* numeric-value (numerify (cdr mylist)))
508 (cons* (car (string->list (car mylist))) (numerify (cdr mylist)))))))
510 (def-markup-command (fret-diagram-terse layout props definition-string)
512 "Make a fret diagram markup using terse string-based syntax.
516 \\markup \\fret-diagram-terse #\"x;x;o;2;3;2;\"
518 for a D chord diagram.
520 Syntax rules for @var{definition-string}:
524 Strings are terminated by semicolons; the number of semicolons
525 is the number of strings in the diagram.
528 Mute strings are indicated by \"x\".
531 Open strings are indicated by \"o\".
534 A number indicates a fret indication at that fret.
537 If there are multiple fret indicators desired on a string, they
538 should be separated by spaces.
541 Fingerings are given by following the fret number with a \"-\",
542 followed by the finger indicator, e.g. 3-2 for playing the third
543 fret with the second finger.
546 Where a barre indicator is desired, follow the fret (or fingering) symbol
547 with \"-(\" to start a barre and \"-)\" to end the barre.
549 ;TODO -- change syntax to fret\string-finger
550 (let ((definition-list (fret-parse-terse-definition-string props definition-string)))
551 (make-fret-diagram layout (car definition-list) (cdr definition-list))))
553 (define (fret-parse-terse-definition-string props definition-string)
554 "parse a fret diagram string that uses terse syntax; return a pair containing:
555 props, modified to include the string-count determined by the definition-string
556 a fret-indication list with the appropriate values"
557 ;TODO -- change syntax to fret\string-finger
558 (let* ((barre-start-list '())
561 (items (string-split definition-string #\;))
562 (string-count (- (length items) 1)))
563 (let parse-item ((myitems items))
564 (if (not (null? (cdr myitems)))
565 (let* ((test-string (car myitems))
566 (current-string (- (length myitems) 1))
567 (indicators (string-split test-string #\ )))
568 (let parse-indicators ((myindicators indicators))
569 (if (not (eq? '() myindicators))
570 (let* ((this-list (string-split (car myindicators) #\-))
571 (max-element-index (- (length this-list) 1))
572 (last-element (car (list-tail this-list max-element-index)))
573 (fret (if (string->number (car this-list)) (string->number (car this-list)) (car this-list))))
574 (if (equal? last-element "(")
576 (set! barre-start-list (cons-fret (list current-string fret) barre-start-list))
577 (set! this-list (list-head this-list max-element-index))))
578 (if (equal? last-element ")")
579 (let* ((this-barre (get-sub-list fret barre-start-list))
580 (insert-index (- (length this-barre) 1)))
581 (set! output-list (cons-fret (cons* 'barre (car this-barre) current-string (cdr this-barre))
583 (set! this-list (list-head this-list max-element-index))))
585 (set! output-list (cons-fret (cons* 'place-fret current-string (drop-paren (numerify this-list))) output-list))
586 (if (equal? (car this-list) "x" )
587 (set! output-list (cons-fret (list 'mute current-string) output-list))
588 (set! output-list (cons-fret (list 'open current-string) output-list))))
589 (parse-indicators (cdr myindicators)))))
590 (parse-item (cdr myitems)))))
591 (set! new-props (acons 'string-count string-count new-props))
593 `(,(cons new-props props) . ,output-list)))
595 (define (drop-paren item-list)
596 " drop a final parentheses from a fret indication list resulting from a terse string specification of barre."
597 (if (> (length item-list) 0)
598 (let* ((max-index (- (length item-list) 1))
599 (last-element (car (list-tail item-list max-index))))
600 (if (or (equal? last-element ")") (equal? last-element "("))
601 (list-head item-list max-index)
605 (define (get-sub-list value master-list)
606 " Get a sub-list whose cadr is equal to @var{value} from @var{master-list}"
607 (if (eq? master-list '())
609 (let ((sublist (car master-list)))
610 (if (equal? (cadr sublist) value)
612 (get-sub-list value (cdr master-list))))))