X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=scm%2Ftranslation-functions.scm;h=a535497962c07b9ae8ca5d79d1faf3901d1b7e10;hb=d11dbf277719c0179c5520154c925839d969a535;hp=d373da0eebcc0079c2e0c8d0e76a747ceba38742;hpb=9203eadca5bcb79415060f8488889706a9c8e62a;p=lilypond.git

diff --git a/scm/translation-functions.scm b/scm/translation-functions.scm
index d373da0eeb..a535497962 100644
--- a/scm/translation-functions.scm
+++ b/scm/translation-functions.scm
@@ -276,6 +276,10 @@ dot placement entries."
 along with @var{minimum-fret}, @var{maximum-stretch}, and
 @var{tuning}.  Returns a list of @code{(string fret finger) lists."
 
+
+    (define restrain-open-strings (ly:context-property context
+						       'restrainOpenStrings
+					               #f))
     (define specified-frets '())
     (define free-strings (iota (length tuning) 1))
 
@@ -326,7 +330,8 @@ if no string-number is present."
 	  #t
 	  (map (lambda (specced-fret)
 		 (or (eq? 0 specced-fret)
-                     (eq? 0 fret)
+		     (and (not restrain-open-strings)
+		     (eq? 0 fret))
 		     (>= maximum-stretch (abs (- fret specced-fret)))))
 	       specified-frets))))
 
@@ -334,7 +339,9 @@ if no string-number is present."
       "Can @var{pitch} be played on @var{string}, given already placed
 notes?"
       (let* ((fret (calc-fret pitch string tuning)))
-	(and (or (eq? fret 0) (>= fret minimum-fret))
+	(and (or (and (not restrain-open-strings)
+		      (eq? fret 0))
+		 (>= fret minimum-fret))
 	     (close-enough fret))))
 
     (define (open-string string pitch)
@@ -658,3 +665,39 @@ only ~a fret labels provided")
   (= 0 (modulo count n)))
 
 (define-public (all-repeat-counts-visible count context) #t)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; make-engraver helper macro
+
+(defmacro-public make-engraver forms
+  "Helper macro for creating Scheme engravers.
+
+The usual form for an engraver is an association list (or alist)
+mapping symbols to either anonymous functions or to another such
+alist.
+
+@code{make-engraver} accepts forms where the first element is either
+an argument list starting with the respective symbol, followed by the
+function body (comparable to the way @code{define} is used for
+defining functions), or a single symbol followed by subordinate forms
+in the same manner.  You can also just make an alist pair
+literally (the @samp{car} is quoted automatically) as long as the
+unevaluated @samp{cdr} is not a pair.  This is useful if you already
+have defined your engraver functions separately.
+
+Symbols mapping to a function would be @code{initialize},
+@code{start-translation-timestep}, @code{process-music},
+@code{process-acknowledged}, @code{stop-translation-timestep}, and
+@code{finalize}.  Symbols mapping to another alist specified in the
+same manner are @code{listeners} with the subordinate symbols being
+event classes, and @code{acknowledgers} and @code{end-acknowledgers}
+with the subordinate symbols being interfaces."
+  (let loop ((forms forms))
+    (if (cheap-list? forms)
+	`(list
+	  ,@(map (lambda (form)
+		   (if (pair? (car form))
+		       `(cons ',(caar form) (lambda ,(cdar form) ,@(cdr form)))
+		       `(cons ',(car form) ,(loop (cdr form)))))
+		 forms))
+	forms)))