%%%% -*- Mode: Scheme -*-

%%%% This file is part of LilyPond, the GNU music typesetter.
%%%%
%%%% Copyright (C) 2003--2023 Han-Wen Nienhuys <hanwen@xs4all.nl>
%%%%                          Jan Nieuwenhuizen <janneke@gnu.org>
%%%%
%%%% LilyPond is free software: you can redistribute it and/or modify
%%%% it under the terms of the GNU General Public License as published by
%%%% the Free Software Foundation, either version 3 of the License, or
%%%% (at your option) any later version.
%%%%
%%%% LilyPond is distributed in the hope that it will be useful,
%%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%%%% GNU General Public License for more details.
%%%%
%%%% You should have received a copy of the GNU General Public License
%%%% along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.

\version "2.21.0"


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% this file is alphabetically sorted.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%% need SRFI-1 for filter; optargs for lambda*
#(use-modules (srfi srfi-1)
              (ice-9 optargs))

absolute =
#(define-music-function (music) (ly:music?)
   (_i "Make @var{music} absolute.

This does not actually change the music itself but rather hides it from
surrounding @code{\\relative} and @code{\\fixed} commands.")
   (make-music 'RelativeOctaveMusic 'element music))

acciaccatura =
#(def-grace-function startAcciaccaturaMusic stopAcciaccaturaMusic
   (_i "Create an acciaccatura from @var{music}."))

%% keep these two together
instrument-definitions = #'()
addInstrumentDefinition =
#(define-void-function
   (name lst) (string? list?)
   (_i "Create instrument @var{name} with properties @var{lst}.

This function is deprecated.")
   (set! instrument-definitions (acons name lst instrument-definitions)))

addQuote =
#(define-void-function (name music) (string? ly:music?)
   (_i "Define @var{music} as a quotable music expression named @var{name}.")
   (add-quotable name music))

after =
#(define-music-function (delta ev mus) (ly:duration? ly:music? ly:music?)
  (_i "Add music @var{ev} with a delay of @var{delta} after the onset of
@var{mus}.

@var{ev} is usually a post-event.")
  (define (empty-chord? m)
     "Checks whether m is an empty chord <>."
     (and (music-is-of-type? m 'event-chord)
          (null? (ly:music-property m 'elements))
          (null? (ly:music-property m 'duration))))
  (if (and (not (empty-chord? mus))
           (ly:moment<?
            (ly:music-length mus)
            (+ (ly:music-length ev) (ly:duration-length delta))))
      (ly:warning (G_ "\\after expression longer than main music argument.")))
  #{ \context Bottom << { \skip $delta <> $ev } #mus >> #})

%% keep these two together
afterGraceFraction = 3/4
afterGrace =
#(define-music-function (fraction main grace) ((scale?) ly:music? ly:music?)
   (_i "Create @var{grace} as grace notes after a @var{main} music expression.

The musical position of the grace expression is after a given fraction of the
main note's duration has passed.  If optional argument @var{fraction} is
omitted, the fraction value is taken from @code{afterGraceFraction}, defaulting
to@tie{}3/4.")
   (let* ((factor
            (scale->factor (or fraction
                               (ly:parser-lookup 'afterGraceFraction))))
          (delta
            (* factor (ly:moment-main (ly:music-length main))))
          (grace-music
            (make-music 'GraceMusic 'element grace)))
     (if (> factor 1)
         (ly:warning (G_ "\\afterGrace exceeds duration of main argument.")))
     ;;; Despite the similarity of definitions, don't reduce this to
     ;;; an application of \after. For \afterGrace, the arguments are
     ;;; input in visual order, hence they should be used in that order
     ;;; to ensure
     ;;;   \relative \afterGrace c'2 d8
     ;;; gives the expected result.
     #{
       \context Bottom << #main { \skip 1*$delta #grace-music } >>
     #}))

%% music identifiers not allowed at top-level,
%% so this is a music-function instead.
allowPageTurn =
#(define-music-function () ()
   (_i "Allow a page turn.

May be used at top level (i.e., between scores or markups), or inside a score.")
   (make-music 'EventChord
               'page-marker #t
               'page-turn-permission 'allow
               'elements (list (make-music 'PageTurnEvent
                                           'break-permission 'allow))))

alterBroken =
#(define-music-function (property arg target)
  (key-list-or-symbol? list? key-list-or-music?)
  (_i "Override @var{property} for pieces of broken spanner @var{target} with
@var{arg}.

@var{target} may either be music in the form of a starting spanner event, or a
symbol list of the form @code{@var{Context}@/.@var{Grob}} or just
@code{@var{Grob}}.  If @var{target} is in the form of a spanner event,
@var{property} may also have the form @code{@var{Grob}@/.@var{property}} for
specifying a directed tweak.

@var{arg} is a list of values, one for each broken piece.")
  (if (ly:music? target)
      (if (or (eqv? (ly:music-property target 'span-direction) START)
              (music-is-of-type? target 'tie-event))
          (tweak property (value-for-spanner-piece property arg) target)
          (begin
            (ly:music-warning target (G_ "not a spanner"))
            target))
      (propertyOverride (append target (if (symbol? property)
                                           (list property)
                                           property))
                        (value-for-spanner-piece property arg))))

appendToTag =
#(define-music-function (tag more music) (symbol? ly:music? ly:music?)
   (_i "Append @var{more} to @var{music} tagged with @var{tag}.

A post-event can be added to the articulations of rhythmic events or chords;
other expressions may be added to chords, sequential or simultaneous music.")
   (define (add-right m more)
     (cond
      ((or (music-is-of-type? m 'sequential-music)
           (music-is-of-type? m 'simultaneous-music))
       (if (ly:event? more)
           (begin
             (ly:music-warning m (G_ "\\appendToTag cannot append post-event"))
             (ly:music-message m (G_ "to this music")))
           (set! (ly:music-property m 'elements)
                 (append! (ly:music-property m 'elements) (list more)))))
      ((music-is-of-type? m 'event-chord)
       (cond ((ly:event? more)
              (set! (ly:music-property m 'elements)
                    (append! (ly:music-property m 'elements (list more)))))
             ((music-is-of-type? more 'rhythmic-event)
              (set! (ly:music-property m 'elements)
                    (call-with-values (lambda ()
                                        (break! ly:event?
                                                (ly:music-property m 'elements)))
                      (lambda (elts posts)
                        (append! elts (cons more posts))))))
             (else
              (ly:music-warning more (G_ "\\appendToTag cannot append this"))
              (ly:music-message m (G_ "to this event-chord")))))
      ((music-is-of-type? m 'rhythmic-event)
       (if (ly:event? more)
           (set! (ly:music-property m 'articulations)
                 (append! (ly:music-property m 'articulations) (list more)))
           (begin
             (ly:music-warning more (G_ "\\appendToTag cannot append this music"))
             (ly:music-message m (G_ "to this rhythmic-event")))))
      ((music-is-of-type? m 'music-wrapper-music)
       (add-right (ly:music-property m 'element) more))
      (else
       (ly:input-warning (*location*) (G_ "\\appendToTag failed:"))
       (ly:music-message m (G_ "No \\appendToTag destination")))))
   (music-map (lambda (m)
                (if (memq tag (ly:music-property m 'tags))
                    (add-right m more))
                m)
              music))

applyContext =
#(define-music-function (proc) (procedure?)
   (_i "Modify context properties with Scheme procedure @var{proc}.")
   (make-music 'ApplyContext
               'procedure proc))

applyMusic =
#(define-music-function (func music) (procedure? ly:music?)
   (_i "Apply procedure @var{func} to @var{music}.")
   (func music))

applyOutput =
#(define-music-function (target proc) (symbol-list-or-symbol? procedure?)
   (_i "Apply function @code{proc} to every layout object matched by
@var{target}.

@var{target} takes the form @code{@var{Context}} or
@code{@var{Context}@/.@var{Grob}}.")
   (let ((p (check-grob-path target #:max 2)))
     (if p
         (make-music 'ApplyOutputEvent
                     'procedure proc
                     'context-type (car p)
                     (if (pair? (cdr p))
                         (list (cons 'symbol (cadr p)))
                         '()))
         (make-music 'Music))))

appoggiatura =
#(def-grace-function startAppoggiaturaMusic stopAppoggiaturaMusic
   (_i "Create an appoggiatura from @var{music}."))

% for regression testing purposes.
assertBeamQuant =
#(define-music-function (l r) (pair? pair?)
   (_i "Testing function: check whether the beam quants @var{l} and @var{r} are
correct.")
   (make-grob-property-override 'Beam 'positions (check-quant-callbacks l r)))

% for regression testing purposes.
assertBeamSlope =
#(define-music-function (comp) (procedure?)
   (_i "Testing function: check whether the slope of the beam is the same as
@var{comp}.")
   (make-grob-property-override 'Beam 'positions (check-slope-callbacks comp)))

autoChange =
#(define-music-function (pitch clef-1 clef-2 music)
  ((ly:pitch?) (ly:context-mod?) (ly:context-mod?) ly:music?)
  (_i "Make voices for @var{music} that switch between staves automatically.

The optional argument @var{pitch} specifies where to switch staves; the default
is @code{c'}.  Optional arguments @var{clef-1} and @var{clef-2} specify which
clefs to use; this only works for implicitly instantiated staves.

Example:

@example
\\autoChange d' \\with @{ \\clef alto @} @{ g4 d' g' @}
@end example
")
  (let ;; keep the contexts alive for the full duration
       ((skip (make-duration-of-length (ly:music-length music)))
        (clef-1 (or clef-1 #{ \with { \clef "treble" } #}))
        (clef-2 (or clef-2 #{ \with { \clef "bass" } #})))
    (make-simultaneous-music
     (list
      (descend-to-context (make-autochange-music music pitch) 'Staff
                          "up" clef-1)
      (context-spec-music (make-skip-music skip) 'Staff
                          "up" clef-1)
      (context-spec-music (make-skip-music skip) 'Staff
                          "down" clef-2)))))



balloonGrobText =
#(define-music-function (grob-name offset text)
   (symbol? number-pair? markup?)
   (_i "Attach @var{text} to @var{grob-name} at offset @var{offset} (use like
@code{\\once}).")
   (make-event-chord
    (list
     (make-music 'AnnotateOutputEvent
                 'symbol grob-name
                 'X-offset (car offset)
                 'Y-offset (cdr offset)
                 'text text))))

balloonText =
#(define-event-function (offset text) (number-pair? markup?)
   (_i "Attach @var{text} at @var{offset} (use like @code{\\tweak}).")
   (make-music 'AnnotateOutputEvent
               'X-offset (car offset)
               'Y-offset (cdr offset)
               'text text))

bar =
#(define-music-function (type) (string?)
   (_i "Insert a bar line of type @var{type}, overriding any automatic bar
lines.")
   (make-music 'BarEvent 'bar-type type))

barNumberCheck =
#(define-music-function (n) (integer?)
   (_i "Print a warning if the current bar number is not @var{n}.")
   (make-music 'ApplyContext
               'procedure
               (lambda (c)
                 (if (not (ly:context-property c 'ignoreBarNumberChecks #f))
                     (let ((cbn (ly:context-property c 'currentBarNumber)))
                       (if (and (number? cbn) (not (= cbn n)))
                           (ly:input-warning (*location*)
                                             "Bar number is ~a; expected ~a"
                                             cbn n)))))))

beamExceptions =
#(define-scheme-function (music) (ly:music?)
   (_i "Set beam exceptions.

This function extracts a value suitable for setting @code{Timing.beamExceptions}
from the given pattern with explicit beams in @var{music}.  A bar check @samp{|}
has to be used between bars of patterns in order to reset the timing.")
   (extract-beam-exceptions music))

bendAfter =
#(define-event-function (delta) (real?)
   (_i "Create a fall or doit of pitch interval @var{delta}.")
   (make-music 'BendAfterEvent
               'delta-step delta))

%% BendSpanner convenience event functions
bendStartLevel =
#(define-event-function (idx mus)(index? ly:music?)
   (_i "Set @code{Bendspanner.details.successive-level} to @var{idx} for
@var{mus}.")
#{
  \tweak details.successive-level $idx
  $mus
#})

bendHold =
#(define-event-function (mus)(ly:music?)
   (_i "Set @code{BendSpanner.style} to @code{'hold} for @var{mus}.")
#{
  \tweak style #'hold
  \tweak details.head-text-break-visibility ##(#t #t #f)
  $mus
#})

preBend =
#(define-event-function (mus)(ly:music?)
   (_i "Set @code{BendSpanner.style} to @code{'pre-bend} for @var{mus}.")
#{
  \tweak style #'pre-bend
  \tweak details.head-text-break-visibility ##(#t #t #f)
  $mus
#})

preBendHold =
#(define-event-function (mus)(ly:music?)
   (_i "Set @code{BendSpanner.style} to @code{'pre-bend-hold} for @var{mus}.")
#{
  \tweak style #'pre-bend-hold
  \tweak details.head-text-break-visibility ##(#t #t #f)
  $mus
#})

bookOutputName =
#(define-void-function (newfilename) (string?)
   (_i "Direct output for the current book block to @var{newfilename}.

This is equivalent to setting @code{output-filename} in the current book's
@code{\\paper} block.")
   (set! (paper-variable #f 'output-filename) newfilename))

bookOutputSuffix =
#(define-void-function (newsuffix) (string?)
   (_i "Set the output file name suffix for the current book block to
@var{newsuffix}.

This is equivalent to setting @code{output-suffix} in the current book's
@code{\\paper} block.")
   (set! (paper-variable #f 'output-suffix) newsuffix))

%% \breathe is defined as a music function rather than an event identifier to
%% ensure it gets useful input location information: as an event identifier,
%% it would have to be wrapped in an EventChord to prevent it from being
%% treated as a post_event by the parser
breathe =
#(define-music-function () ()
   (_i "Insert a breath mark.")
   (make-music 'BreathingEvent))



%% \caesura is defined as a music function rather than an event identifier to
%% ensure it gets useful input location information: as an event identifier,
%% it would have to be wrapped in an EventChord to prevent it from being
%% treated as a post_event by the parser
caesura =
#(define-music-function () ()
   (_i "Insert a caesura.")
   (make-music 'CaesuraEvent))

clef =
#(define-music-function (type) (string?)
   (_i "Set the current clef to @var{type}.")
   (make-clef-set type))

codaMark =
#(define-music-function (num) ((index?))
   (_i "Create a coda mark.

@var{num} may be 1@tie{}for the first mark, 2@tie{}for the second, etc., or it
may be @code{\\default} to use the next number in sequence automatically.")
   (if num
       (make-music 'CodaMarkEvent 'label num)
       (make-music 'CodaMarkEvent)))

compoundMeter =
#(define-music-function (args) (pair?)
  (_i "Create a compound time signature.

The argument @var{args} is a Scheme list of lists.  Each list represents one
fraction, where all entries but the last hold the summands in the enumerator,
and the last entry is the denominator.  If the time signature consists of just
one fraction, the list can be given directly, i.e., not as a list containing a
single list.  For example, a time signature of (3+1)/8 + 2/4 can be created with
@code{\\compoundMeter #'((3 1 8) (2 4))}, and a time signature of (3+2)/8 with
either @code{\\compoundMeter #'((3 2 8))} or the shorter version
@code{\\compoundMeter #'(3 2 8)}.")
  (let* ((mlen (calculate-compound-measure-length args))
         (beat (calculate-compound-base-beat args))
         (beatGrouping (calculate-compound-beat-grouping args))
         (timesig (cons (ly:moment-main-numerator mlen)
                        (ly:moment-main-denominator mlen))))
  #{
    \once \override Timing.TimeSignature.stencil = #(lambda (grob)
      (grob-interpret-markup grob (make-compound-meter-markup args)))
    \set Timing.timeSignatureFraction = #timesig
    \set Timing.baseMoment = #beat
    \set Timing.beatStructure = #beatGrouping
    \set Timing.beamExceptions = #'()
    \set Timing.measureLength = #mlen
  #} ))

compressMMRests =
#(define-music-function (music) (ly:music?)
   (_i "Convert empty bars to multi-measure rests in @var{music}.")
   (music-map
    (lambda (m)
      (if (eq? 'MultiMeasureRestMusic (ly:music-property m 'name))
          #{ \once \set Score.skipBars = ##t #m #}
          #{ #m #} ))
    music))

crossStaff =
#(define-music-function (notes) (ly:music?)
  (_i "Create cross-staff stems for @var{notes}.")
  #{
  \temporary \override Stem.cross-staff = #cross-staff-connect
  \temporary \override Flag.style = #'no-flag
  #notes
  \revert Stem.cross-staff
  \revert Flag.style
#})

cueClef =
#(define-music-function (type) (string?)
  (_i "Set the current cue clef to @var{type}.")
  (make-cue-clef-set type))

cueClefUnset =
#(define-music-function () ()
  (_i "Unset the current cue clef.")
  (make-cue-clef-unset))

cueDuring =
#(define-music-function (what dir main-music)
   (string? ly:dir? ly:music?)
   (_i "Create a cue.

This function inserts the contents of quote @var{what} corresponding to
@var{main-music}, in a @code{CueVoice} context called @code{cue} oriented by
@var{dir}.")
   (make-music 'QuoteMusic
               'element main-music
               'quoted-context-type 'CueVoice
               'quoted-context-id "cue"
               'quoted-music-name what
               'quoted-voice-direction dir))

cueDuringWithClef =
#(define-music-function (what dir clef main-music)
   (string? ly:dir? string? ly:music?)
   (_i "Create a cue with clef.

This function inserts the contents of quote @var{what} corresponding to
@var{main-music}, in a @code{CueVoice} context called @code{cue} oriented by
@var{dir} and using clef @var{clef}.")
   (make-music 'QuoteMusic
               'element main-music
               'quoted-context-type 'CueVoice
               'quoted-context-id "cue"
               'quoted-music-name what
               'quoted-music-clef clef
               'quoted-voice-direction dir))



displayLilyMusic =
#(define-music-function (port music) ((output-port?) ly:music?)
   (_i "Write LilyPond's input representation of @var{music}.

If @var{port} is omitted, the output defaults to the console (stdout).")
   (let ((port (or port (current-output-port))))
     (newline port)
     (display-lily-music music port))
   music)

displayMusic =
#(define-music-function (port music) ((output-port?) ly:music?)
   (_i "Write the internal representation of @var{music}.

If @var{port} is omitted, the output defaults to the console (stdout).")
   (let ((port (or port (current-output-port))))
     (newline port)
     (display-scheme-music music port))
   music)

displayScheme =
#(define-scheme-function (port expr) ((output-port?) scheme?)
   (_i "Write the internal Scheme representation of @var{expr}.

If @var{port} is omitted, the output defaults to the console (stdout).")
   (let ((port (or port (current-output-port))))
     (newline port)
     (display-scheme-music expr port))
   expr)

dropNote =
#(define-music-function (num music) (integer? ly:music?)
   (_i "@q{Drop} the @var{num}-th note in each chord of @var{music}.

This function moves the affected notes down (usually by an octave) to be lower
than the other notes of the chord.  The position in a chord is counted downwards
from the top.

The opposite function is @code{\\raiseNote}.")
   (music-map (move-chord-note (- num) DOWN) music))



endSpanners =
#(define-music-function (music) (ly:music?)
   (_i "Terminate spanners.

This function prematurely ends all spanners in @var{music} by inserting an
end-spanner event at the end of the argument, without the need of specific
end-spanner commands.")
   (let* ((start-span-evs (filter (lambda (ev)
                                    (equal? (ly:music-property ev 'span-direction)
                                            START))
                                  (extract-typed-music music 'span-event)))
          (stop-span-evs
           (map (lambda (m)
                  (music-clone m 'span-direction STOP))
                start-span-evs))
          (end-ev-chord (make-music 'EventChord
                                    'elements stop-span-evs))
          (total (make-music 'SequentialMusic
                             'elements (list music
                                             end-ev-chord))))
     total))

eventChords =
#(define-music-function (music) (ly:music?)
   (_i "Compatibility function: Handle isolated rhythmic events in @var{music}.

Use this to wrap @code{EventChord} around isolated rhythmic events occuring
since version 2.15.28, after expanding repeat chords @samp{q}.

Not needed for new code.")
   (event-chord-wrap! music))



featherDurations=
#(define-music-function (scale music) (scale? ly:music?)
   (_i "Adjust feathered beam durations in @var{music} by @var{scale}.")
   (let ((orig-duration (ly:music-length music))
         (factor (scale->factor scale))
         (multiplier 1))
     (for-each
      (lambda (mus)
        (if (< 0 (ly:moment-main-denominator (ly:music-length mus)))
            (begin
              (ly:music-compress mus multiplier)
              (set! multiplier (* factor multiplier)))))
      (extract-named-music music '(EventChord NoteEvent RestEvent SkipEvent)))
     (ly:music-compress
      music
      (ly:moment-div orig-duration (ly:music-length music)))))

finger =
#(define-event-function (finger) (index-or-markup?)
   (_i "Apply @var{finger} as a fingering indication.")

   (make-music
            'FingeringEvent
            (if (index? finger) 'digit 'text) finger))

fixed =
#(define-music-function (pitch music) (ly:pitch? ly:music?)
   (_i "Use the octave of @var{pitch} as the default octave for @var{music}.")
   (let ((octave-marks (1+ (ly:pitch-octave pitch))))
     (cond ((not (= 0 octave-marks))
            (ly:music-transpose music (ly:make-pitch octave-marks 0 0))
            ;;In order to leave unchanged the notes in any enclosed
            ;; \absolute or \fixed or \relative, make a cancelling shift
            (map (lambda (m)
                   (ly:music-transpose m (ly:make-pitch (- octave-marks) 0 0)))
                 (extract-named-music music 'RelativeOctaveMusic)))))
   (make-music 'RelativeOctaveMusic 'element music))

footnote =
#(define-music-function (mark offset footnote item)
   ((markup?) number-pair? markup? symbol-list-or-music?)
   (_i "Make the markup @var{footnote} a footnote on @var{item}.

The footnote is marked with a markup @var{mark} moved by @var{offset} with
respect to the marked music.

If @var{mark} is not given or specified as @code{\\default}, it is replaced by
an automatically generated sequence number.  If @var{item} is a symbol list of
form @code{@var{Grob}} or @code{@var{Context}@/.@var{Grob}}, then grobs of that
type are marked at the current time step in the given context (default
@code{Bottom}).

If @var{item} is music, the music gets a footnote attached to a grob immediately
attached to the event, like @code{\\tweak} does.  For attaching a footnote to an
@emph{indirectly} caused grob, write @code{\\single\\footnote}, use @var{item}
to specify the grob, and follow it with the music to annotate.

Like with @code{\\tweak}, if you use a footnote on a following post-event, the
@code{\\footnote} command itself needs to be attached to the preceding note or
rest as a post-event with @samp{-}.")
   (let ((mus (make-music
               'FootnoteEvent
               'X-offset (car offset)
               'Y-offset (cdr offset)
               'automatically-numbered (not mark)
               'text (or mark (make-null-markup))
               'footnote-text footnote)))
     (once (propertyTweak 'footnote-music mus item))))



grace =
#(def-grace-function startGraceMusic stopGraceMusic
   (_i "Insert @var{music} as grace notes."))

grobdescriptions =
#(define-scheme-function (descriptions) (list?)
   (_i "Create a context modification from @var{descriptions}.

The argument is a list
in the format of @code{all-grob-descriptions}.")
   (ly:make-context-mod `((grob-descriptions ,descriptions))))



harmonicByFret =
#(define-music-function (fret music) (number? ly:music?)
   (_i "Convert @var{music} into mixed harmonics.

The resulting notes resemble harmonics played on a fretted instrument by
touching the strings at @var{fret}.")
  #{
    \set harmonicDots = ##t
    \temporary \override TabNoteHead.stencil = #(tab-note-head::print-custom-fret-label (number->string fret))
    \temporary \override NoteHead.Y-extent = #grob::always-Y-extent-from-stencil
    \temporary \override NoteHead.stencil = #(lambda (grob) (ly:grob-set-property! grob 'style 'harmonic-mixed)
                                            (ly:note-head::print grob))
    #(make-harmonic
       (calc-harmonic-pitch (fret->pitch (number->string fret)) music))
    \unset harmonicDots
    \revert TabNoteHead.stencil
    \revert NoteHead.Y-extent
    \revert NoteHead.stencil
  #})

harmonicByRatio =
#(define-music-function (ratio music) (number? ly:music?)
   (_i "Convert @var{music} into mixed harmonics.

The resulting notes resemble harmonics played on a fretted instrument by
touching the strings at the point given through @var{ratio}.")
  #{
    \set harmonicDots = ##t
    \temporary \override TabNoteHead.stencil =
      #(tab-note-head::print-custom-fret-label (ratio->fret ratio))
    \temporary \override NoteHead.Y-extent =
      #(ly:make-unpure-pure-container ly:grob::stencil-height)
    \temporary \override NoteHead.stencil =
      #(lambda (grob) (ly:grob-set-property! grob 'style 'harmonic-mixed)
               (ly:note-head::print grob))
    #(make-harmonic
      (calc-harmonic-pitch (ratio->pitch ratio) music))
    \unset harmonicDots
    \revert TabNoteHead.stencil
    \revert NoteHead.Y-extent
    \revert NoteHead.stencil
  #})

hide =
#(define-music-function (item) (symbol-list-or-music?)
   (_i "Make @var{item} invisible while still retaining its dimensions.

If @var{item} is a symbol list of form @code{@var{GrobName}} or
@code{@var{Context}@/.@var{GrobName}}, the result is an override for the grob
name specified by it.  If @var{item} is a music expression, the result is the
same music expression with an appropriate tweak applied to it.

This function sets @var{item}'s @code{transparent} property to @code{#t}.")
   (propertyTweak 'transparent #t item))

initialContextFrom =
#(define-music-function (music) (ly:music?)
   (_i "Enter the initial context of @var{music} and ignore the rest of it.

This is useful for prepending music while preserving the influence of the
original music on the context.

Example:

@example
@{
  \\initialContextFrom \\originalMusic
  \\prependedMusic
  \\originalMusic
  \\appendedMusic
@}
@end example
")
   (make-initial-context-music music))



inStaffSegno =
#(define-music-function () ()
   (_i "Put the segno variant @code{varsegno} at this position into the staff.

This is compatible with the repeat command.")
   #{
     {
       \once \set Timing.segnoStyle = #'bar-line
       \segnoMark \default
     }
   #})

instrumentSwitch =
#(define-music-function (name) (string?)
   (_i "Switch instrument to @var{name}.

@var{name} must have been predefined with function
@code{\\addInstrumentDefinition}.

This function is deprecated.")
   (let* ((handle (assoc name instrument-definitions))
          (instrument-def (if handle (cdr handle) '())))

     (if (not handle)
         (ly:input-warning (*location*) "No such instrument: ~a" name))
     (context-spec-music
      (make-music 'SimultaneousMusic
                  'elements
                  (map (lambda (kv)
                         (make-property-set
                          (car kv)
                          (cdr kv)))
                       instrument-def))
      'Staff)))

inversion =
#(define-music-function (around to music) (ly:pitch? ly:pitch? ly:music?)
   (_i "Invert @var{music} about @var{around} and transpose from @var{around} to
@var{to}.")
   (music-invert around to music))

invertChords =
#(define-music-function (num music) (integer? ly:music?)
   (_i "Invert any chords in @var{music} into their @var{num}-th position.

Chord inversions may be directed downwards using negative integers.")
   (let loop ((num num) (music music))
     (cond ((zero? num) music)
       ((negative? num) (loop (1+ num) (dropNote 1 music)))
       (else (loop (1- num) (raiseNote 1 music))))))



jump =
#(define-music-function (text) (markup?)
   (_i "Use @var{text} to mark a point of departure, e.g.,
@q{Gavotte@tie{}I D.C.}.")
   (make-music 'AdHocJumpEvent 'text text))



keepWithTag =
#(define-music-function (tags music) (symbol-list-or-symbol? ly:music?)
   (_i "Keep tagged music.

This function only includes elements of @var{music} that are tagged with one of
the tags in @var{tags}.  @var{tags} may be either a single symbol or a list of
symbols.

Each tag may be declared as a member of at most one tag group (defined with
@code{\\tagGroup}).  If none of a @var{music} element's tags share a tag group
with one of the specified @var{tags}, the element is retained.")
   (music-filter
    (tags-keep-predicate tags)
    music))

key =
#(define-music-function (tonic pitch-alist)
   ((ly:pitch? '()) (number-pair-list? '()))
   (_i "Set key to @var{tonic} and scale @var{pitch-alist}.

If both arguments are omitted (i.e., replaced by @code{\\default}), just
generate a @code{KeyChangeEvent}, which prints the current key signature again.")
   (cond ((null? tonic) (make-music 'KeyChangeEvent))
         ((null? pitch-alist)
          (ly:parser-error (G_ "second argument must be pitch list")
                           (*location*))
          (make-music 'SequentialMusic 'void #t))
         (else
          (ly:music-transpose
           (make-music 'KeyChangeEvent
                'tonic (ly:make-pitch 0 0 0)
                'pitch-alist pitch-alist)
           tonic))))

killCues =
#(define-music-function (music) (ly:music?)
   (_i "Remove cue notes from @var{music}.")
   (music-map
    (lambda (mus)
      (if (and (string? (ly:music-property mus 'quoted-music-name))
               (string=? (ly:music-property mus 'quoted-context-id "") "cue"))
          (ly:music-property mus 'element)
          mus))
    music))



label =
#(define-music-function (label) (symbol?)
   (_i "Create @var{label} as a referrable label.

The value stored in @var{label} is the page number, which can be extracted with
the @code{\\page-ref} markup command later on.")
   (make-music 'EventChord
               'page-marker #t
               'page-label label
               'elements (list (make-music 'LabelEvent
                                           'page-label label))))

previous-pitchnames = #'()

language =
#(define-void-function (language) (string?)
   (_i "Set note names for language @var{language}.

The value is stored in the @code{pitchnames} alist.")
   (note-names-language language))

languageSaveAndChange =
#(define-void-function (language) (string?)
  (_i "Save current @code{pitchnames} alist and change note names to
@var{language}.")
  (set! previous-pitchnames pitchnames)
  (note-names-language language))

languageRestore =
#(define-void-function () ()
   (_i "Restore the previously-saved @code{pitchnames} alist.")
   (if previous-pitchnames
       (begin
        (set! pitchnames previous-pitchnames)
        (ly:parser-set-note-names pitchnames))
      (ly:input-warning (*location*) (G_ "No other language was defined previously. Ignoring."))))



magnifyMusic =
#(define-music-function (mag music) (positive-number? ly:music?)
   (_i "Magnify the size of @var{music} by factor @var{mag}.

This doesn't change the staff size.  Stems, beams, slurs, ties, and horizontal
spacing are adjusted automatically.")

   ;; these props are NOT allowed to shrink below default size
   (define unshrinkable-props
     '(
       ;; stems
       (Stem thickness)

       ;; slurs
       (Slur line-thickness)
       (Slur thickness)
       (PhrasingSlur line-thickness)
       (PhrasingSlur thickness)

       ;; ties
       (Tie line-thickness)
       (Tie thickness)
       (LaissezVibrerTie line-thickness)
       (LaissezVibrerTie thickness)
       (RepeatTie line-thickness)
       (RepeatTie thickness)
       ))

   ;; these props ARE allowed to shrink below default size
   (define shrinkable-props
     (let ((baseline-skip-props
             (find-named-props 'baseline-skip all-grob-descriptions))
           (word-space-props
             (find-named-props 'word-space all-grob-descriptions)))
       (append
         baseline-skip-props
         word-space-props
         '(
           ;; TODO: uncomment spacing-increment here once Issue 3987 is fixed
           ;; override at the 'Score level
           ;(SpacingSpanner spacing-increment)

           ;; lengths and heights
           (Beam length-fraction)
           (Stem length-fraction)
           (Stem beamlet-default-length)
           (Stem double-stem-separation)
           (Slur height-limit)
           (Slur minimum-length)
           (PhrasingSlur height-limit)
           (PhrasingSlur minimum-length)

           ;; Beam.beam-thickness is dealt with separately below
           ))))
   #{
     \context Bottom {
       %% TODO: uncomment \newSpacingSection once Issue 3990 is fixed
       %\newSpacingSection
       #(scale-fontSize 'magnifyMusic mag)
       #(scale-props    'magnifyMusic mag #f unshrinkable-props)
       #(scale-props    'magnifyMusic mag #t shrinkable-props)
       #(scale-beam-thickness mag)

       #music

       %% TODO: uncomment \newSpacingSection once Issue 3990 is fixed
       %\newSpacingSection
       %% reverse engineer the former fontSize value instead of using \unset
       #(revert-fontSize 'magnifyMusic mag)
       #(revert-props    'magnifyMusic mag (append unshrinkable-props
                                                   shrinkable-props
                                                   '((Beam beam-thickness))))
     }
   #})

magnifyStaff =
#(define-music-function (mag) (positive-number?)
   (_i "Change the staff size by factor @var{mag}.

This adjusts notation size and horizontal spacing automatically.")

   ;; these props are NOT allowed to shrink below default size
   (define unshrinkable-props
     '((StaffSymbol thickness)))

   ;; these props ARE allowed to shrink below default size
   (define shrinkable-props
     (let* ((baseline-skip-props
              (find-named-props 'baseline-skip all-grob-descriptions))
            (word-space-props
              (find-named-props 'word-space all-grob-descriptions))
            (space-alist-props
              (find-named-props 'space-alist all-grob-descriptions)))
       (append
         baseline-skip-props
         word-space-props
         space-alist-props
         '(
           ;; override at the 'Score level
           (SpacingSpanner spacing-increment)

           (StaffSymbol staff-space)
           (BarLine kern)
           (BarLine segno-kern)
           (BarLine hair-thickness)
           (BarLine thick-thickness)
           (Stem beamlet-default-length)
           (Stem double-stem-separation)
           ))))

   #{
     \stopStaff

     %% revert settings from last time
     %% (but only if \magnifyStaff has already been used
     %% and the staff magnification is changing)
     #(revert-fontSize 'magnifyStaff mag)
     #(revert-props    'magnifyStaff mag (append unshrinkable-props
                                                 shrinkable-props))

     %% scale settings
     %% (but only if staff magnification is changing
     %% and does not equal 1)
     #(scale-fontSize 'magnifyStaff mag)
     #(scale-props    'magnifyStaff mag #f unshrinkable-props)
     #(scale-props    'magnifyStaff mag #t shrinkable-props)

     %% this might cause problems until Issue 3990 is fixed
     \newSpacingSection

     \startStaff
     \set Staff.magnifyStaffValue = #mag
   #})

makeClusters =
#(define-music-function (arg) (ly:music?)
   (_i "Display chords in @var{arg} as clusters.")
   (music-map note-to-cluster arg))

mark =
#(define-music-function (label) ((index-or-markup?))
   (_i "Create a rehearsal mark.

If @var{label} is an integer, create the rehearsal mark for the given sequence
number.  If @var{label} is @code{\\default}, create the next sequential
rehearsal mark.  If @var{label} is markup, use it for the mark.")
   (cond ((not label)
          (make-music 'RehearsalMarkEvent))
         ((index? label)
          (make-music 'RehearsalMarkEvent 'label label))
         (else
          (make-music 'AdHocMarkEvent 'text label))))

markupMap =
#(define-music-function (path markupfun music)
   (symbol-list-or-symbol? markup-function? ly:music?)
   (_i "Apply @var{markupfun} to property @var{path} in @var{music}.

Argument @var{path} is either of the form @code{@var{property}} or
@code{@var{MusicExpression}@/.@var{property}}.  If @code{@var{MusicExpression}}
is not given, @var{markupfun} gets applied to all properties called
@code{@var{property}}, otherwise it is restricted to
@code{@var{MusicExpression}} events.  If @code{@var{property}} is not a markup,
it is ignored.

In the following example, both the tempo indication and the bowing instruction
are printed in red.  If you replace @code{text} with
@code{TempoChangeEvent@/.text}, only the tempo indication changes the color.

@example
\\markupMap
  text
  \\markup \\with-color #red \\etc
  @{ \\tempo \"Largo\" g'2_\"arco\" c'' @}
@end example
")
   (let* ((p (check-music-path path))
          (name (and p (car p)))
          (prop (and p (cadr p))))
     (if p
         (for-some-music
          (lambda (m)
            (if (or (not name) (eq? (ly:music-property m 'name) name))
                (let ((text (ly:music-property m prop)))
                  (if (markup? text)
                      (set! (ly:music-property m prop)
                            (list markupfun text)))))
            #f)
          music)))
   music)

modalInversion =
#(define-music-function (around to scale music)
    (ly:pitch? ly:pitch? ly:music? ly:music?)
    (_i "Invert @var{music} about @var{around} using @var{scale} and transpose
from @var{around} to @var{to}.")
    (let ((inverter (make-modal-inverter around to scale)))
      (change-pitches music inverter)
      music))

modalTranspose =
#(define-music-function (from to scale music)
    (ly:pitch? ly:pitch? ly:music? ly:music?)
    (_i "Transpose @var{music} from pitch @var{from} to pitch @var{to} using
@var{scale}.")
    (let ((transposer (make-modal-transposer from to scale)))
      (change-pitches music transposer)
      music))

musicLength =
#(define-scheme-function (music) (ly:music?)
   (_i "Return the length of @var{music} as a moment.")
   (ly:music-length music))

musicMap =
#(define-music-function (proc mus) (procedure? ly:music?)
   (_i "Apply @var{proc} to @var{mus} and all of the music it contains.")
   (music-map proc mus))



%% noPageBreak and noPageTurn are music functions (not music identifiers),
%% because music identifiers are not allowed at top-level.
noPageBreak =
#(define-music-function () ()
   (_i "Forbid a page break.

May be used at top level (i.e., between scores or markups), or inside a score.")
   (make-music 'EventChord
               'page-marker #t
               'page-break-permission 'forbid
               'elements (list (make-music 'PageBreakEvent
                                           'break-permission '()))))

noPageTurn =
#(define-music-function () ()
   (_i "Forbid a page turn.

May be used at top level (i.e., between scores or markups), or inside a score.")
   (make-music 'EventChord
               'page-marker #t
               'page-turn-permission 'forbid
               'elements (list (make-music 'PageTurnEvent
                                           'break-permission '()))))



octaveCheck =
#(define-music-function (pitch) (ly:pitch?)
   (_i "Do an octave check.

This prints a warning if the interval between the previous note and @var{pitch}
is not within a fourth.")
   (make-music 'RelativeOctaveCheck
               'pitch pitch))

offset =
#(define-music-function (property offsets item)
  (symbol-list-or-symbol? scheme? key-list-or-music?)
   (_i "Offset the default value of @var{property} of @var{item} by
@var{offsets}.

If @var{item} is a string, the result is an override for the specified grob
type.  If @var{item} is a music expression, the result is the same music
expression with an appropriate tweak applied to it.")
  (if (ly:music? item)
      ; In case of a tweak, grob property path is Grob.property
      (let ((prop-path (check-grob-path
                         (if (symbol? property)
                             (list property)
                             property)
                         #:start 1 #:default #t #:min 2 #:max 2)))
        (if prop-path
            ; If the head of the grob property path is a symbol--i.e.,
            ; a grob name, produce a directed tweak.  Otherwise, create
            ; an ordinary tweak.
            (if (symbol? (car prop-path))
                (tweak prop-path (offsetter (second prop-path) offsets) item)
                (tweak (second prop-path)
                       (offsetter (second prop-path) offsets)
                       item))
            item))
      ; In case of an override, grob property path is Context.Grob.property.
      (let ((prop-path (check-grob-path
                         (append item
                                 (if (symbol? property)
                                     (list property)
                                     property))
                         #:default 'Bottom #:min 3 #:max 3)))
        (if prop-path
            (propertyOverride prop-path (offsetter (third prop-path) offsets))
            (make-music 'Music)))))

omit =
#(define-music-function (item) (symbol-list-or-music?)
   (_i "Omit @var{item} without taking up space.

If @var{item} is a symbol list of form @code{@var{GrobName}} or
@code{@var{Context}@/.@var{GrobName}}, the result is an override for the grob
name specified by it.  If @var{item} is a music expression, the result is the
same music expression with an appropriate tweak applied to it.

This function sets @var{item}'s @code{stencil} property to @code{#f}.")
   (propertyTweak 'stencil #f item))

once =
#(define-music-function (music) (ly:music?)
   (_i "Set property @code{once} to @code{#t} on all layout instruction events
in @var{music}.")
   (for-each
    (lambda (m)
      (ly:music-set-property! m 'once #t))
    (extract-typed-music music 'layout-instruction-event))
   music)

ottava =
#(define-music-function (octave) (integer?)
   (_i "Set the octavation to @var{octave}.

A positive value@tie{}@var{n} indicates @var{n}@tie{}octaves higher; a negative
value @var{n}@tie{}octaves lower, and value@tie{}0 means no octavation.")
   (make-music 'OttavaEvent
               'ottava-number octave))

overrideTimeSignatureSettings =
#(define-music-function
   (time-signature base-moment beat-structure beam-exceptions)
   (boolean-or-fraction? fraction? list? list?)
   (_i "Override time signature settings.

This function sets @code{timeSignatureSettings} for time signatures equal to
@var{time-signature} to have settings of @var{base-moment},
@var{beat-structure}, and @var{beam-exceptions}.")

   ;; TODO -- add warning if largest value of grouping is
   ;;       greater than time-signature.
  (let ((setting (make-setting base-moment beat-structure beam-exceptions)))
    (override-time-signature-setting time-signature setting)))

overrideProperty =
#(define-music-function (grob-property-path value)
   (key-list? scheme?)
   (_i "Set the grob property specified by @var{grob-property-path} to
@var{value}.

@var{grob-property-path} is a symbol list of the form
@code{@var{Context}@/.@var{GrobName}@/.@var{property}} or
@code{@var{GrobName}@/.@var{property}}, possibly with subproperties given as
well.

As opposed to @code{\\override}, which overrides the context-dependent defaults
with which a grob is created, this command uses @code{Output_property_engraver}
at the grob acknowledge stage.  This may be necessary for overriding values set
after the initial grob creation.")
   (let ((p (check-grob-path grob-property-path
                             #:default 'Bottom
                             #:min 3)))
     (if p
         (make-music 'ApplyOutputEvent
                     'context-type (first p)
                     'symbol (second p)
                     'procedure
                     (lambda (grob orig-context context)
                       (ly:grob-set-nested-property! grob (cddr p) value)))
         (make-music 'Music))))



%% pageBreak and pageTurn are music functions (iso music identifiers),
%% because music identifiers are not allowed at top-level.
pageBreak =
#(define-music-function () ()
   (_i "Force a page break.

May be used at top-level (i.e., between scores or markups), or inside a score.")
   (make-music 'EventChord
               'page-marker #t
               'line-break-permission 'force
               'page-break-permission 'force
               'elements (list (make-music 'LineBreakEvent
                                           'break-permission 'force)
                               (make-music 'PageBreakEvent
                                           'break-permission 'force))))

pageTurn =
#(define-music-function () ()
   (_i "Force a page turn.

May be used at top-level (i.e., between scores or markups), or inside a score.")
   (make-music 'EventChord
               'page-marker #t
               'line-break-permission 'force
               'page-break-permission 'force
               'page-turn-permission 'force
               'elements (list (make-music 'LineBreakEvent
                                           'break-permission 'force)
                               (make-music 'PageBreakEvent
                                           'break-permission 'force)
                               (make-music 'PageTurnEvent
                                           'break-permission 'force))))

parallelMusic =
#(define-void-function (voice-ids music) (list? ly:music?)
   (_i "Define parallel music sequences.

Within @var{music}, parallel music sequences are separated by @samp{|}
characters.  The sequences are assigned to the LilyPond music identifiers
provided in @var{voice-ids}.

For example, this code

@example
\\parallelMusic A,B,C @{
  c c | d d | e e |
  d d | e e | f f |
@}
@end example

@noindent
is equivalent to

@example
A = @{ c c | d d @}
B = @{ d d | e e @}
C = @{ e e | f f @}
@end example

The last bar checks in a sequence are not copied to the result in order to
facilitate ending the last entry at non-bar boundaries.
")
   (define voice-count (length voice-ids))
   (define (bar-check? m)
     "Checks whether m is a bar check."
     (eq? (ly:music-property m 'name) 'BarCheckEvent))
   (define (recurse-and-split-list lst)
     "Return either a list of music lists split along bar checks, or @code{#f}."
     (if (any bar-check? lst)
         (let* ((voices (apply circular-list (make-list voice-count '())))
                (current-voices voices)
                (current-sequence '()))
           ;;
           ;; utilities
           (define (push-music m)
             "Push the music expression into the current sequence"
             (set! current-sequence (cons m current-sequence)))
           (define (change-voice)
             "Store the previously built sequence into the current voice and
change to the following voice."
             (set-car! current-voices
                       (cons current-sequence
                             (car current-voices)))
             (set! current-sequence '())
             (set! current-voices (cdr current-voices)))
           (for-each (lambda (m)
                       (let ((split? (recurse-and-split m)))
                         (if split?
                             (for-each
                              (lambda (m)
                                (push-music m)
                                (change-voice))
                              split?)
                             (begin
                               (push-music m)
                               (if (bar-check? m) (change-voice))))))
                     lst)
           (if (pair? current-sequence) (change-voice))
           ;; Un-circularize voices
           (set! voices (list-head voices voice-count))

           ;; Remove trailing bar checks to facilitate ending a
           ;; sequence on a non-bar, reverse partial sequences and sequences
           (set! voices (map!
                         (lambda (l)
                           (map! reverse!
                                 (reverse!
                                  (if (and (pair? l) (pair? (car l))
                                           (bar-check? (caar l)))
                                      (cons (cdar l) (cdr l))
                                      l))))
                         voices))

           ;; check sequence length
           (apply for-each (lambda seqs
                             (define (seq-len seq)
                               (reduce ly:moment-add
                                       (ly:make-moment 0)
                                       (map ly:music-length seq)))
                             (let ((moment-reference (seq-len (car seqs))))
                               (for-each (lambda (seq)
                                           (if (not (equal? (seq-len seq)
                                                            moment-reference))
                                               (ly:music-warning
                                                (if (pair? seq)
                                                    (last seq)
                                                    (caar seqs))
                                                (G_ "Bars in parallel music don't have the same length"))))
                                         seqs)))
                  voices)
           (map concatenate! voices))
         (let ((deeper (map recurse-and-split lst)))
           (and (any pair? deeper)
                (apply zip (map
                            (lambda (m split)
                              (or split
                                  (ly:music-deep-copy (make-list voice-count m))))
                            lst deeper))))))
   (define (recurse-and-split music)
     "This returns either a list of music split along bar checks, or
@code{#f}."
     (let* ((elt (ly:music-property music 'element))
            (elts (ly:music-property music 'elements))
            (split-elt (and (ly:music? elt) (recurse-and-split elt)))
            (split-elts (and (pair? elts) (recurse-and-split-list elts))))
       (and (or split-elt split-elts)
            (map
             (lambda (e es)
               (let ((m (ly:music-deep-copy music
                       ;;; reassigning the origin of the parent only
                       ;;; makes sense if the first expression in the
                       ;;; result is from a distributed origin
                                            (or (and (ly:music? e) e)
                                                (and (pair? es) (car es))))))
                 (if (ly:music? e)
                     (set! (ly:music-property m 'element) e))
                 (if (pair? es)
                     (set! (ly:music-property m 'elements) es))
                 m))
             (or split-elt (circular-list #f))
             (or split-elts (circular-list #f))))))
   (let ((voices (recurse-and-split music)))
     (if voices
         ;;
         ;; bind voice identifiers to the voices
         (for-each (lambda (voice-id voice)
                     (ly:parser-define! voice-id voice))
                   voice-ids voices)
         (ly:music-warning music
                           (G_ "ignoring parallel music without bar checks")))))

parenthesize =
#(define-music-function (arg) (symbol-list-or-music?)
   (_i "Tag @var{arg} to be parenthesized.

@var{arg} may be either a music event or a grob path.")
   (let ((maybe-with-id (if (and (ly:music? arg)
                                 (music-is-of-type? arg 'event-chord))
                            (tweak 'parenthesis-id
                                   (gensym "unique-parenthesis-id")
                                   arg)
                            arg)))
     (once (propertyTweak 'parenthesized #t maybe-with-id))))

#(define (make-directed-part-combine-music direction chord-range part1 part2
          one-context-settings
          two-context-settings
          shared-context-settings)

   (let* ((pc-music (make-music 'PartCombineMusic))
          (listener (ly:parser-lookup 'partCombineListener))
          (evs2 (recording-group-emulate
                 (context-spec-music (make-non-relative-music part2)
                                     'Voice "two")
                 listener))
          (evs1 (recording-group-emulate
                 (context-spec-music (make-non-relative-music part1)
                                     'Voice "one")
                 listener))
          (split-list
           (determine-split-list (reverse! (assoc-get "one" evs1 '()) '())
                                 (reverse! (assoc-get "two" evs2 '()) '())
                                 chord-range))
          (L1 (ly:music-length part1))
          (L2 (ly:music-length part2))
          ;; keep the contexts alive for the full duration
          (skip (make-skip-music (make-duration-of-length
                                  (if (ly:moment<? L1 L2) L2 L1)))))

     ;; \partCombine depends on Simultaneous_music_iterator's
     ;; processing its children in order (at each timestep) so that
     ;; context changes occur before notation events.  If
     ;; Simultaneous_music_iterator's behavior is ever changed, this
     ;; will need to be changed too.
     (define (make-part-music initial-voice-name changes notation)
       (context-spec-music
        ;; TODO: Is non-relative music necessary here, or only for the
        ;; analysis above?
        (make-music 'SimultaneousMusic
                    'elements (list changes (make-non-relative-music notation))
                    'tags '($partCombine))
        'Voice initial-voice-name))

     (set! (ly:music-property pc-music 'elements)
           (list (make-part-music
                  "one"
                  (make-part-combine-context-changes
                   default-part-combine-context-change-state-machine-one
                   split-list)
                  part1)
                 (make-part-music
                  "two"
                  (make-part-combine-context-changes
                   default-part-combine-context-change-state-machine-two
                   split-list)
                  part2)))

     (set! (ly:music-property pc-music 'direction) direction)

     #{ \context Staff <<
          \context Voice = "one" \with #one-context-settings { #skip }
          \context Voice = "two" \with #two-context-settings { #skip }
          \context Voice = "shared" \with #shared-context-settings { #skip }
          \context Voice = "solo" { #skip }
          \context NullVoice = "null" { #skip }
          #pc-music
          #(make-part-combine-marks
            default-part-combine-mark-state-machine split-list)
        >> #} ))

partCombine =
#(define-music-function (chord-range part1 part2)
   ((number-pair? '(0 . 8)) ly:music? ly:music?)
   (_i "Combine two parts into a single staff.

This takes the music in @var{part1} and @var{part2} and returns a music
expression containing simultaneous @code{Voice} contexts (called @code{one} for
the upper and @code{two} for the lower voice).  Where appropriate, @var{part1}
and @var{part2} are combined into a single voice (called @code{shared} or
@code{solo}, depending on context).

Optional argument @var{chord-range} is a pair @code{(@var{start} . @var{stop})}
that defines the range in which the two voices are printed as chords (or
unison); the default value is @code{(0 . 8)}, which means that intervals up to
and including a ninth are unified.")
   (make-directed-part-combine-music #f chord-range part1 part2
    #{ \with { \voiceOne \override DynamicLineSpanner.direction = #UP } #}
    #{ \with { \voiceTwo \override DynamicLineSpanner.direction = #DOWN } #}
    #{ #} ))

partCombineUp =
#(define-music-function (chord-range part1 part2)
   ((number-pair? '(0 . 8)) ly:music? ly:music?)
   (_i "Combine two parts into a single staff with all stems upwards.

See function @code{\\partCombine} for details.")
   (make-directed-part-combine-music UP chord-range part1 part2
    #{ \with { \voiceOne \override DynamicLineSpanner.direction = #UP } #}
    #{ \with { \voiceThree \override DynamicLineSpanner.direction = #UP } #}
    #{ \with { \voiceOne \override DynamicLineSpanner.direction = #UP } #} ))

partCombineDown =
#(define-music-function (chord-range part1 part2)
   ((number-pair? '(0 . 8)) ly:music? ly:music?)
   (_i "Combine two parts into a single staff with all stems downwards.

See function @code{\\partCombine} for details.")
   (make-directed-part-combine-music DOWN chord-range part1 part2
    #{ \with { \voiceFour \override DynamicLineSpanner.direction = #DOWN } #}
    #{ \with { \voiceTwo \override DynamicLineSpanner.direction = #DOWN } #}
    #{ \with { \voiceTwo \override DynamicLineSpanner.direction = #DOWN } #} ))

%% Part combine forcing to be found in ly/property-init.ly

partial =
#(define-music-function (dur) (ly:duration?)
  (_i "Make a partial measure of duration @var{dur}.")
  (context-spec-music (make-music 'PartialSet
                                  'origin (*location*)
                                  'duration dur)
                      'Timing))

pitchedTrill =
#(define-music-function (main-note secondary-note) (ly:music? ly:music?)
   (_i "Print a pitched trill.

@var{main-note} is the main note of the trill; @var{secondary-note} gets printed
as a stemless note head in parentheses.")
   (let* ((get-notes (lambda (ev-chord)
                       (extract-named-music ev-chord 'NoteEvent)))
          (sec-note-events (get-notes secondary-note))
          (trill-events (extract-named-music main-note 'TrillSpanEvent)))
     (if (pair? sec-note-events)
         (begin
           (let* ((trill-pitch (ly:music-property (car sec-note-events) 'pitch))
                  (forced (ly:music-property (car sec-note-events) 'force-accidental)))

             (if (ly:pitch? trill-pitch)
                 (for-each (lambda (m)
                             (ly:music-set-property! m 'pitch trill-pitch)) trill-events)
                 (begin
                   (ly:input-warning (*location*) (G_ "Second argument of \\pitchedTrill should be single note: "))
                   (display sec-note-events)))

             (if (eq? forced #t)
                 (for-each (lambda (m)
                             (ly:music-set-property! m 'force-accidental forced))
                           trill-events)))))
     main-note))

propertyOverride =
#(define-music-function (grob-property-path value) (key-list? scheme?)
   (_i "Set the grob property specified by @var{grob-property-path} to
@var{value}.

@var{grob-property-path} is a symbol list of the form
@code{@var{Context}@/.@var{GrobName}@/.@var{property}} or
@code{@var{GrobName}@/.@var{property}}, possibly with subproperties given as
well.  This music function is mostly intended for use from Scheme as a
substitute for the built-in @code{\\override} command.")
   (let ((p (check-grob-path grob-property-path
                             #:default 'Bottom
                             #:min 3)))
     (if p
         (context-spec-music
          (make-music 'OverrideProperty
                      'symbol (cadr p)
                      'origin (*location*)
                      'grob-value value
                      'grob-property-path (cddr p)
                      'pop-first #t)
          (car p))
         (make-music 'Music))))

propertyRevert =
#(define-music-function (grob-property-path) (key-list?)
   (_i "Revert the grob property specified by @var{grob-property-path} to its
previous value.

@var{grob-property-path} is a symbol list of the form
@code{@var{Context}@/.@var{GrobName}@/.@var{property}} or
@code{@var{GrobName}@/.@var{property}}, possibly with subproperties given as
well.  This music function is mostly intended for use from Scheme as a
substitute for the built-in @code{\\revert} command.")
   (let ((p (check-grob-path grob-property-path
                             #:default 'Bottom
                             #:min 3)))
     (if p
         (context-spec-music
          (make-music 'RevertProperty
                      'symbol (cadr p)
                      'origin (*location*)
                      'grob-property-path (cddr p))
          (car p))
         (make-music 'Music))))

propertySet =
#(define-music-function (property-path value) (symbol-list-or-symbol? scheme?)
   (_i "Set the context property specified by @var{property-path} to
@var{value}.

This music function is mostly intended for use from Scheme as a substitute for
the built-in @code{\\set} command.")
   (let ((p (check-context-path property-path)))
     (if p
         (context-spec-music
          (make-music 'PropertySet
                      'symbol (cadr p)
                      'value value
                      'origin (*location*))
          (car p))
         (make-music 'Music))))

propertyTweak =
#(define-music-function (prop value item)
   (key-list-or-symbol? scheme? key-list-or-music?)
   (_i "Add a tweak to @var{item}, usually music.

This function sets the value of property @var{prop} to @var{value}; it generally
behaves like @code{\\tweak} but will turn into an @code{\\override} when
@var{item} is a symbol list.  In that case, @var{item} specifies the grob path
to override.  This is mainly useful when using @code{\\propertyTweak} as as a
component for building other functions like @code{\\omit}.  It is not the
default behavior for @code{\\tweak} since many input strings in
@code{\\lyricmode} can serve equally as music or as symbols, which causes
surprising behavior when tweaking lyrics using the less specific semantics of
@code{\\propertyTweak}.

@var{prop} can contain additional elements in which case a nested
property (inside of an alist) is tweaked.")
   ;; Why not instead make the parser treat strings preferably as
   ;; music in lyrics mode rather than as symbol?  Because then
   ;;
   ;; \tweak text "whatever" mylyrics
   ;;
   ;; will try putting a lyric event with text "whatever" in the text
   ;; property of lyrics.  So we want expressions allowing both
   ;; strings and lyrics to deliver strings: more complex conversions
   ;; should only be attempted when the simple uses don't match the
   ;; given predicate.
   (if (ly:music? item)
       (if (music-is-of-type? item 'context-specification)
           ;; This is essentially dealing with the case
           ;; \propertyTweak color #red \propertyTweak font-size #3 NoteHead
           ;; namely when stacked tweaks end in a symbol list
           ;; rather than a music expression.
           ;;
           ;; We have a tweak here to convert into an override,
           ;; so we need to know the grob to apply it to.  That's
           ;; easy if we have a directed tweak, and otherwise we
           ;; need to find the symbol in the expression itself.
           (let* ((p (check-grob-path prop
                                      #:start 1
                                      #:default #t
                                      #:min 2))
                  (elt (ly:music-property item 'element))
                  (seq (if (music-is-of-type? elt 'sequential-music)
                           elt
                           (make-sequential-music (list elt))))
                  (elts (ly:music-property seq 'elements))
                  (symbol (if (symbol? (car p))
                              (car p)
                              (and (pair? elts)
                                   (ly:music-property (car elts)
                                                      'symbol)))))
             (if (symbol? symbol)
                 (begin
                   (set! (ly:music-property seq 'elements)
                         (cons (make-music 'OverrideProperty
                                           'symbol symbol
                                           'grob-property-path (cdr p)
                                           'pop-first #t
                                           'grob-value value
                                           'origin (*location*))
                               elts))
                   (set! (ly:music-property item 'element) seq))
                 (begin
                   (ly:parser-error (G_ "Cannot \\propertyTweak")
                                    (*location*))
                   (ly:music-message item (G_ "untweakable"))))
             item)
           (tweak prop value item))
       (propertyOverride (append item (if (symbol? prop) (list prop) prop))
                         value)))

propertyUnset =
#(define-music-function (property-path) (symbol-list-or-symbol?)
   (_i "Unset the context property specified by @var{property-path}.

This music function is mostly intended for use from Scheme as a substitute for
the built-in @code{\\unset} command.")
   (let ((p (check-context-path property-path)))
     (if p
         (context-spec-music
          (make-music 'PropertyUnset
                      'symbol (cadr p)
                      'origin (*location*))
          (car p))
         (make-music 'Music))))

pushToTag =
#(define-music-function (tag more music) (symbol? ly:music? ly:music?)
   (_i "Add @var{more} to the front of @var{music} tagged with @var{tag}.

A post-event can be added to the articulations of rhythmic events or chords;
other expressions may be added to chords, sequential or simultaneous music.")
   (define (add-left m more)
     (cond
      ((or (music-is-of-type? m 'sequential-music)
           (music-is-of-type? m 'simultaneous-music))
       (if (ly:event? more)
           (begin
             (ly:music-warning more (G_ "\\pushToTag cannot push post-event"))
             (ly:music-message m (G_ "to this music")))
           (set! (ly:music-property m 'elements)
                 (cons more (ly:music-property m 'elements)))))
      ((music-is-of-type? m 'event-chord)
       (cond ((ly:event? more)
              (set! (ly:music-property m 'elements)
                    (call-with-values (lambda ()
                                        (break! ly:event?
                                                (ly:music-property m 'elements)))
                      (lambda (elts posts)
                        (append! elts (cons more posts))))))
             ((music-is-of-type? more 'rhythmic-event)
              (set! (ly:music-property m 'elements)
                    (cons more (ly:music-property m 'elements))))
             (else
              (ly:music-warning more (G_ "\\pushToTag cannot push this"))
              (ly:music-message m (G_ "to this event-chord")))))
      ((music-is-of-type? m 'rhythmic-event)
       (if (ly:event? more)
           (set! (ly:music-property m 'articulations)
                 (cons more (ly:music-property m 'articulations)))
           (begin
             (ly:music-warning more (G_ "\\pushToTag cannot push this music"))
             (ly:music-message m (G_ "to this rhythmic-event")))))
      ((music-is-of-type? m 'music-wrapper-music)
       (add-left (ly:music-property m 'element) more))
      (else
       (ly:input-warning (*location*) (G_ "\\pushToTag failed:"))
       (ly:music-message m (G_ "No \\pushToTag destination")))))
   (music-map (lambda (m)
                (if (memq tag (ly:music-property m 'tags))
                    (add-left m more))
                m)
              music))



quoteDuring =
#(define-music-function (what main-music) (string? ly:music?)
   (_i "Indicate a section of music to be quoted.

@var{what} indicates the name of the quoted voice, as specified in an
@code{\\addQuote} command.  @var{main-music} is used to indicate the length of
music to be quoted; it usually contains spacers or multi-measure rests.")
   (make-music 'QuoteMusic
               'element main-music
               'quoted-music-name what))



raiseNote =
#(define-music-function (num music) (integer? ly:music?)
   (_i "@q{Raise} the @var{num}-th note in each chord of @var{music}.

This function moves the affected notes up (usually by an octave) to be higher
than the other notes of the chord.  The position in a chord is counted upwards
from the bottom.

The opposite function is @code{\\dropNote}.")
   (music-map (move-chord-note (1- num) UP) music))

reduceChords =
#(define-music-function (music) (ly:music?)
   (_i "Reduce chords contained in @var{music} to single notes.

This is intended mainly for reusing music in a @code{RhythmicStaff} context.  It
does not reduce simultaneous music.")
   (event-chord-reduce music))

relative =
#(define-music-function (pitch music) ((ly:pitch?) ly:music?)
   (_i "Make @var{music} relative to @var{pitch}.

If @var{pitch} is omitted, the first note in @var{music} is given in absolute
pitch.")
   ;; When \relative has no clear decision (can only happen with
   ;; scales with an even number of steps), it goes down (see
   ;; pitch.cc).  The following formula puts out f for both the normal
   ;; 7-step scale as well as for a "shortened" scale missing the
   ;; final b.  In either case, a first note of c will end up as c,
   ;; namely pitch (-1, 0, 0).
   (ly:make-music-relative! music
                            (or pitch
                                (ly:make-pitch
                                 -1
                                 (quotient
                                  ;; size of current scale:
                                  (ly:pitch-steps (ly:make-pitch 1 0))
                                  2))))
   (make-music 'RelativeOctaveMusic
               'element music))

removeWithTag =
#(define-music-function (tags music) (symbol-list-or-symbol? ly:music?)
   (_i "Remove elements of @var{music} that are tagged with one of the tags in
@var{tags}.

@var{tags} may be either a single symbol or a list of symbols.")
   (music-filter
    (tags-remove-predicate tags)
    music))

resetRelativeOctave =
#(define-music-function (pitch) (ly:pitch?)
   (_i "Set the octave inside a @code{\\relative} section to @var{pitch}.")

   (make-music 'SequentialMusic
               'to-relative-callback
               (lambda (music last-pitch) pitch)))

retrograde =
#(define-music-function (music) (ly:music?)
    (_i "Return @var{music} in reverse order.")
    (retrograde-music
     (expand-repeat-notes!
      (expand-repeat-chords!
       (cons 'rhythmic-event
             (ly:parser-lookup '$chord-repeat-events))
       music))))

revertTimeSignatureSettings =
#(define-music-function (time-signature) (pair?)
   (_i "Revert @code{timeSignatureSettings} for time signatures equal to
@var{time-signature}.")
   (revert-time-signature-setting time-signature))

rightHandFinger =
#(define-event-function (finger) (index-or-markup?)
   (_i "Apply @var{finger} as a right-hand fingering indication.")

   (make-music
            'StrokeFingerEvent
            (if (index? finger) 'digit 'text) finger))



scaleDurations =
#(define-music-function (fraction music) (scale? ly:music?)
   (_i "Multiply the duration of events in @var{music} by @var{fraction}.")
   (ly:music-compress music fraction))

sectionLabel =
#(define-music-function (text) (markup?)
   (_i "Mark the beginning of a named passage with @var{text}, e.g., @qq{Coda}.

This is well suited for use at a section division created with @code{\\section},
but it does not imply @code{\\section} and may be used alone.")
   (make-music 'SectionLabelEvent 'text text))

segnoMark =
#(define-music-function (num) ((index?))
   (_i "Create a segno mark (or bar line).

@var{num} may be 1@tie{}for the first segno, 2@tie{}for the second, etc., or it
may be @code{\\default} to use the next number in sequence automatically.

If the @code{segnoStyle} context property is @code{'bar-line}, a segno bar line
is created instead of a segno mark.")
   (if num
       (make-music 'SegnoMarkEvent 'label num)
       (make-music 'SegnoMarkEvent)))

settingsFrom =
#(define-scheme-function (ctx music)
   ((symbol?) ly:music?)
   (_i "Translate layout instructions into a context modification.

This function takes the layout instruction events from @var{music} (i.e.,
@code{\\set}, @code{\\unset}, @code{\\override}, @code{\\revert}), optionally
restricted to those applying to context type @var{ctx}, and returns
a context modification duplicating their effect.")
   (context-mod-from-music m ctx))

shape =
#(define-music-function (offsets item) (list? key-list-or-music?)
   (_i "Offset control points of @var{item} by @var{offsets}.

@var{offsets} is a list of number pairs @code{(@var{x} . @var{y})} or a list of
such lists.  Each pair represents an offset to a control point.  The @samp{y}
value of each pair is scaled by staff space.

If @var{item} is a string, the result is @code{\\once@/\\override} for the
specified grob type.  If @var{item} is a music expression, the result is the
same music expression with an appropriate tweak applied.")
   (define (shape-curve grob coords)
     (let* ((orig (ly:grob-original grob))
            (siblings (if (ly:spanner? grob)
                          (ly:spanner-broken-into orig) '()))
            (total-found (length siblings))
            (staff-space (ly:staff-symbol-staff-space grob))
            (scaled-offsets
              (map
                (lambda (offset)
                  (if (number-pair? offset)
                      (cons (car offset) (* (cdr offset) staff-space))
                      offset))
                offsets)))

       (define (offset-control-points offsets)
         (if (null? offsets)
             coords
             (map coord-translate coords offsets)))

       (define (helper sibs offs)
         (if (pair? offs)
             (if (eq? (car sibs) grob)
                 (offset-control-points (car offs))
                 (helper (cdr sibs) (cdr offs)))
             coords))

       ;; we work with lists of lists
       (if (or (null? scaled-offsets)
               (not (list? (car scaled-offsets))))
           (set! scaled-offsets (list scaled-offsets)))

       (if (>= total-found 2)
           (helper siblings scaled-offsets)
           (offset-control-points (car scaled-offsets)))))

   (once (propertyTweak 'control-points
                        (grob-transformer 'control-points shape-curve)
                        item)))

shiftDurations =
#(define-music-function (dur dots arg) (integer? integer? ly:music?)
   (_i "Change duration of @var{arg}.

This function walks over all durations and dot counts in @var{arg}, adding
@var{dur} to the durations and @var{dots} to the dot counts.")
   (shift-duration-log arg dur dots))

single =
#(define-music-function (overrides music) (ly:music? ly:music?)
   (_i "Convert @var{overrides} to tweaks and apply them to @var{music}.

This does not convert @code{\\revert}, @code{\\set} or @code{\\unset}.")
   (fold-some-music
    (lambda (m) (eq? (ly:music-property m 'name)
                     'OverrideProperty))
    (lambda (m music)
      (tweak (cons (ly:music-property m 'symbol) ;grob name
                   (cond
                    ((ly:music-property m 'grob-property #f) => list)
                    (else
                     (ly:music-property m 'grob-property-path))))
             (ly:music-property m 'grob-value) music))
    music
    overrides))

skip =
#(define-music-function (arg) (duration-or-music?)
  (_i "Skip over @var{arg}, which may be music or a duration.")
  (if (ly:duration? arg)
      (make-music 'SkipMusic
                  'duration arg)
      (make-music 'SkippedMusic
                  'element arg)))

slashedGrace =
#(def-grace-function startSlashedGraceMusic stopSlashedGraceMusic
   (_i "Create slashed graces from @var{music}.

This produces slashes through stems, but no slur."))

styledNoteHeads =
#(define-music-function (style heads music)
   (symbol? symbol-list-or-symbol? ly:music?)
   (_i "Set @var{heads} in @var{music} to @var{style}.")
   (style-note-heads heads style music))



tag =
#(define-music-function (tags music) (symbol-list-or-symbol? ly:music?)
   (_i "Tag @var{music} with @var{tags}.

This function adds the single symbol or symbol list @var{tags} to the
@code{tags} property of @var{music} and returns the result.")
   (set!
    (ly:music-property music 'tags)
    ((if (symbol? tags) cons append)
     tags
     (ly:music-property music 'tags)))
   music)

tagGroup =
#(define-void-function (tags) (symbol-list?)
   (_i "Define a tag group comprising the symbols in the symbol list @var{tags}.

Tag groups must not overlap.")
   (let ((err (define-tag-group tags)))
     (if err (ly:parser-error err (*location*)))))

temporary =
#(define-music-function (music) (ly:music?)
   (_i "Make @code{\\override} reversible with @code{\\revert}.

This function makes any @code{\\override} in @var{music} replace an existing
grob property value only temporarily, restoring the old value when a
corresponding @code{\\revert} is executed.  This is achieved by clearing the
@code{pop-first} property normally set on @code{\\override}s.

An @code{\\override}/@/@code{\\revert} sequence created by using
@code{\\temporary} and @code{\\undo} on the same music containing overrides will
cancel out perfectly or cause a warning.

Non-property-related music is ignored, warnings are generated for any
property-changing music that isn't an @code{\\override}.")
   (define warned #f)
   (for-some-music
    (lambda (m)
      (and (or (music-is-of-type? m 'layout-instruction-event)
               (music-is-of-type? m 'context-specification)
               (music-is-of-type? m 'apply-context)
               (music-is-of-type? m 'time-signature-music))
           (case (ly:music-property m 'name)
             ((OverrideProperty)
              (if (ly:music-property m 'pop-first #f)
                  (set! (ly:music-property m 'pop-first) '()))
              (if (ly:music-property m 'once #f)
                  (set! (ly:music-property m 'once) '()))
              #t)
             ((ContextSpeccedMusic)
              #f)
             (else
              (if (not warned)
                  (begin
                    (ly:input-warning (*location*) (G_ "Cannot make ~a revertible")
                                      (ly:music-property m 'name))
                    (set! warned #t)))
              #t))))
    music)
   music)

%% The reasoning behind using RIGHT for \textMark and LEFT for \textEndMark
%% is that we may want to generalize horizontal-direction to be also a grob
%% property and apply to more items, and this way it is similar to the break
%% status direction of an item.

textMark =
#(define-music-function (text) (markup?)
   (_i "Create a (left-aligned) text mark using @var{text}.")
   (make-music 'TextMarkEvent 'text text 'horizontal-direction RIGHT))

textEndMark =
#(define-music-function (text) (markup?)
   (_i "Create a right-aligned text mark using @var{text}.")
   (make-music 'TextMarkEvent 'text text 'horizontal-direction LEFT))

time =
#(define-music-function (beat-structure fraction)
   ((number-list? '()) fraction?)
   (_i "Set @var{fraction} as a time signature.

The optional number list @var{beat-structure} additionally sets a beat
structure.")
  (make-music 'TimeSignatureMusic
              'numerator (car fraction)
              'denominator (cdr fraction)
              'beat-structure beat-structure))

times =
#(define-music-function (fraction music) (fraction? ly:music?)
   (_i "Scale @var{music} in time by @var{fraction}.")
  (make-music 'TimeScaledMusic
              'element (ly:music-compress music (ly:make-moment (car fraction) (cdr fraction)))
              'numerator (car fraction)
              'denominator (cdr fraction)))

transpose =
#(define-music-function (from to music) (ly:pitch? ly:pitch? ly:music?)
   (_i "Transpose @var{music} from pitch @var{from} to pitch @var{to}.")
   (make-music 'TransposedMusic
               'element (ly:music-transpose music (- to from))))

transposedCueDuring =
#(define-music-function (what dir pitch main-music)
   (string? ly:dir? ly:pitch? ly:music?)
   (_i "Create a transposed cue.

This function inserts notes from the part @var{what} into a @code{CueVoice}
context called @code{cue}, using the transposition defined by @var{pitch}.  This
happens simultaneously with @var{main-music}, which is usually a rest.  The
argument @var{dir} determines whether the cue notes should be notated as a first
or second voice.")
   (make-music 'QuoteMusic
               'element main-music
               'quoted-context-type 'CueVoice
               'quoted-context-id "cue"
               'quoted-music-name what
               'quoted-voice-direction dir
               ;; following is inverse of instrumentTransposition for
               ;; historical reasons
               'quoted-transposition pitch))

transposition =
#(define-music-function (pitch) (ly:pitch?)
   (_i "Set instrument transposition to @var{pitch}.")
   (context-spec-music
    (make-property-set 'instrumentTransposition pitch)
    'Staff))

tuplet =
#(define-music-function (ratio tuplet-span music)
   (fraction? (ly:duration? '()) ly:music?)
   (_i "Scale the given @var{music} to tuplets.

@var{ratio} is a fraction that specifies how many notes are played in place of
the nominal value: it will be 3/2 for triplets, namely three notes being played
in place of two.

If the optional duration @var{tuplet-span} is specified, it is used instead of
@code{tupletSpannerDuration} for grouping the tuplets.  For example,

@example
\\tuplet 3/2 4 @{ c8 c c c c c @}
@end example

@noindent
results in two groups of three tuplets, each group lasting for a quarter note.")
   (make-music 'TimeScaledMusic
               'element (ly:music-compress
                         music
                         (ly:make-moment (cdr ratio) (car ratio)))
               'numerator (cdr ratio)
               'denominator (car ratio)
               'duration tuplet-span))

tupletSpan =
#(define-music-function (tuplet-span) ((ly:duration?))
   (_i "Set @code{tupletSpannerDuration} to the duration @var{tuplet-span}.

This context property is the length into which @code{\\tuplet} without an
explicit tuplet span argument of its own will group its tuplets.  To revert to
the default of not subdividing the contents of a @code{\\tuplet} command without
an explicit tuplet span argument, use

@example
\\tupletSpan \\default
@end example
")
   (if tuplet-span
       #{ \set tupletSpannerDuration = #(ly:duration-length tuplet-span) #}
       #{ \unset tupletSpannerDuration #}))

tweak =
#(define-music-function (prop value music)
   (key-list-or-symbol? scheme? ly:music?)
   (_i "Add a tweak to @var{music}.

Layout objects created by @var{music} get their property @var{prop} set to
@var{value}.  If @var{prop} has the form @code{@var{Grob}@/.@var{property}},
like with

@example
\\tweak Accidental.color #red cis'
@end example

@noindent
an indirectly created grob (@code{Accidental} is caused by @code{NoteHead}) can
be tweaked; otherwise only directly created grobs are affected.

@var{prop} can contain additional elements in which case a nested
property (inside of an alist) is tweaked.

If @var{music} is an @code{event-chord}, every contained @code{rhythmic-event}
is tweaked instead.")
   (let ((p (check-grob-path prop
                             #:start 1
                             #:default #t
                             #:min 2)))
     (define (tweak-this music)
       (set! (ly:music-property music 'tweaks)
             (acons (cond ((pair? (cddr p)) p)
                          ((symbol? (car p))
                           (cons (car p) (cadr p)))
                          (else (cadr p)))
                    value
                    (ly:music-property music 'tweaks))))
     (if p
         ;; p now contains at least two elements.  The first
         ;; element is #t when no grob has been explicitly
         ;; specified, otherwise it is a grob name.
         (for-each tweak-this (get-tweakable-music music)))
     music))



undo =
#(define-music-function (music) (ly:music?)
   (_i "Convert @code{\\override} and @code{\\set} in @var{music} to
@code{\\revert} and @code{\\unset}, respectively.

Any reverts and unsets already in @var{music} cause a warning.
Non-property-related music is ignored.")
   (define warned #f)
   (let loop
       ((music music))
     (let
         ((lst
           (fold-some-music
            (music-type-predicate '(layout-instruction-event
                                    context-specification
                                    apply-context
                                    time-signature-music))
            (lambda (m overrides)
              (case (ly:music-property m 'name)
                ((OverrideProperty)
                 (cons
                  (make-music 'RevertProperty
                              'symbol (ly:music-property m 'symbol)
                              'grob-property-path
                              (cond
                               ((ly:music-property m 'grob-property #f) => list)
                               (else
                                (ly:music-property m 'grob-property-path))))
                  overrides))
                ((PropertySet)
                 (cons
                  (make-music 'PropertyUnset
                              'symbol (ly:music-property m 'symbol))
                  overrides))
                ((ContextSpeccedMusic)
                 (cons
                  (make-music 'ContextSpeccedMusic
                              'element (loop (ly:music-property m 'element))
                              'context-type (ly:music-property m 'context-type))
                  overrides))
                (else
                 (if (not warned)
                     (begin
                       (ly:input-warning (*location*) (G_ "Cannot revert ~a")
                                         (ly:music-property m 'name))
                       (set! warned #t)))
                 overrides)))
            '()
            music)))
       (cond
        ((null? lst) (make-music 'Music))
        ((null? (cdr lst)) (car lst))
        (else (make-sequential-music lst))))))

unfolded =
#(define-music-function (music) (ly:music?)
   (_i "Mask @var{music} until the innermost enclosing repeat is unfolded.")
   (make-music 'UnfoldedSpeccedMusic
               'element music))

unfoldRepeats =
#(define-music-function (types music)
   ((symbol-list-or-symbol? '()) ly:music?)
   (_i "Unfold @code{\\repeat}.

This forces @code{\\repeat volta}, @code{\\repeat tremolo} or @code{\\repeat
percent} commands in @var{music} to be interpreted as @code{\\repeat unfold}, if
specified in the optional symbol-list @var{types}.  The default for @var{types}
is an empty list, which forces any of those commands in @var{music} to be
interpreted as @code{\\repeat unfold}.  Possible entries are @code{volta},
@code{tremolo} or @code{percent}.  Multiple entries are possible.")
   (unfold-repeats types music))



voices =
#(define-music-function (ids music) (key-list? ly:music?)
   (_i "Specify voice order in simultaneous music.

This takes the key list @var{ids} of numbers (indicating the use of
@samp{\\voiceOne}@dots{}) or symbols (indicating voice names, typically
converted from strings by argument list processing) and assign the following
@code{\\\\}-separated music in @var{music} to contexts according to that list.
Named rather than numbered contexts can be used for continuing one voice (for
the sake of spanners and lyrics), usually requiring a @code{\\voiceOne}-style
override at the beginning of the passage and a @code{\\oneVoice} override at its
end.

The default

@example
<< @dots{} \\\\ @dots{} \\\\ @dots{} >>
@end example

@noindent
construct would correspond to

@example
\\voices 1,2,3 << @dots{} \\\\ @dots{} \\\\ @dots{} >>
@end example
")
   (voicify-music music ids))

void =
#(define-void-function (arg) (scheme?)
   (_i "Accept a Scheme argument @var{arg} and return a void expression.

Use this if you want to have a Scheme expression evaluated because of its side
effects but its return value being ignored."))

volta =
#(define-music-function (volta-numbers music) (number-list? ly:music?)
   (_i "Mark @var{music} as being limited to the volte given in
@var{volta-numbers}.

This gets used when the innermost enclosing repeat is unfolded.  Volta number
begins at@tie{}1 and increases by@tie{}1 with each repetition.")
   (volta-spec-music volta-numbers music))

vshape =
#(define-music-function (offsets item) (list? key-list-or-music?)
   (_i "Like @code{\\shape}, but additionally show control points for ease of
tweaking.")
   (once (propertyTweak 'show-control-points #t (shape offsets item))))



withMusicProperty =
#(define-music-function (sym val music)
   (symbol? scheme? ly:music?)
   (_i "Set music property @var{sym} to @var{val} in @var{music}.")

   (set! (ly:music-property music sym) val)
   music)

withRelativeDir =
#(define-scheme-function (file-name) (string?)
   (_i "Prepend directory of current input file to string @var{file-name}.

Use this for markup commands that include files, and where such files
should be found relative to the input file.  Example:

@example
\\markup @{ \\image #X #3 \\withRelativeDir \"test.png\" @}
@end example
")
   (let* ((input-file (car (ly:input-file-line-char-column (*location*))))
          (input-dir (dirname input-file)))
     (string-append input-dir file-name-separator-string file-name)))
