\version "2.19.53"

\paper { ragged-right = ##f }

\pointAndClickOff

#(set-global-staff-size 16)


#(define (has-hyphen? event)
   (let* ((art (ly:music-property event 'articulations))
          (is-hyphen? (lambda (ev) (eq? (ly:music-property ev 'name) 'HyphenEvent))))
      (find is-hyphen? art)))


#(define (add-extender! event)
   (ly:music-set-property! event 'articulations
     (append (ly:music-property event 'articulations) (list (make-music (quote ExtenderEvent)))))
   event)

add-lyric-extenders =
#(define-music-function (parser location lyrics) (ly:music?)
   (music-map
    (lambda (event)
      (if (and (eq? (ly:music-property event 'name) 'LyricEvent)
               ; do not add extenders below hyphens
               (not (has-hyphen? event))
               ; do not add additional extenders after _ (internally equivalent to " ")
               ; to avoid killed extenders
               (not (string=? (ly:music-property event 'text) " ")))
          (add-extender! event))
      event)
    lyrics))

\markup { "no extenders"} 

<<
    { c''2. 4 ~ 4 2. ~ 2. 4 ~ \break 2. 4 2 ~ 2 \bar "|." }
    \addlyrics {  foo -- bar foo -- bar foo -- bar }
>>

\markup { "automatic extenders"} 

<<
    { c''2. 4 ~ 4 2. ~ 2. 4 ~ \break 2. 4 2 ~ 2 \bar "|." }
    \addlyrics { \add-lyric-extenders \repeat unfold 3 { foo -- bar }}
>>

<<
    { c''2. 4 ~ 4 2. ~ 2. 4 ~ \break 2. 4 1 \bar "|." }
    \addlyrics { \add-lyric-extenders \repeat unfold 3 { foo -- bar }}
>>

\markup { "automatic extenders, extender on last note forced"} 

<<
    { c''2. 4 ~ 4 2. ~ 2. 4 ~ \break 2. 4 1 \bar "|." }
    \addlyrics { \add-lyric-extenders { foo -- bar foo -- bar foo -- 
    \override Lyrics.LyricExtender.minimum-length = #30 
    \override Lyrics.LyricExtender.force-extender = ##t bar }}
>>

\markup { "automatic extenders, minimum-length 8 "} 
<<
    { c''1 2 ~ 2 2 4 ~ 4 4 8 ~ 8 8  16 ~ 16 4 1  \bar "|." }
    \addlyrics { \add-lyric-extenders { \override Lyrics.LyricExtender.minimum-length = #8
                 \repeat unfold 10 {  foo -- bar }}}
>>

\markup { "automatic extenders, minimum-length 4 "} 
<<
    { c''1 2 ~ 2 2 4 ~ 4 4 8 ~ 8 8  16 ~ 16 4 1  \bar "|." }
    \addlyrics { \add-lyric-extenders { \override Lyrics.LyricExtender.minimum-length = #4
                 \repeat unfold 10 {  foo -- bar }}}
>>

\markup { "automatic extenders, minimum-length 2 "} 
<<
    { c''1 2 ~ 2 2 4 ~ 4 4 8 ~ 8 8  16 ~ 16 4 1  \bar "|." }
    \addlyrics { \add-lyric-extenders { \override Lyrics.LyricExtender.minimum-length = #2
                 \repeat unfold 10 {  foo -- bar }}}
>>

\markup { "automatic extenders, minimum-length 1 "} 
<<
    { c''1 2 ~ 2 2 4 ~ 4 4 8 ~ 8 8  16 ~ 16 4 1  \bar "|." }
    \addlyrics { \add-lyric-extenders { \override Lyrics.LyricExtender.minimum-length = #1
                 \repeat unfold 10 {  foo -- bar }}}
>>

\markup { "automatic extenders, mixed manual and automatic melismata, extender on last note forced "} 
<<
    { \autoBeamOff
      c''2 2 4\( 4 4 4\)
      4 4 4\( 4( 4) 8[ 8] 8\)
      16\(\melisma 16\melismaEnd 4\) 1
      \bar "|." }
    \addlyrics {
      \add-lyric-extenders {
        \override Lyrics.LyricExtender.minimum-length = #8
        \repeat unfold 2 {  foo -- _ bar _ _ _ }
        foo -- _ \override Lyrics.LyricExtender.force-extender = ##t bar _ _ _ } }
>>

\layout {}