Automatic LyricExtenders

lily/extender-engraver.cc

Index: lily/extender-engraver.cc
diff --git a/lily/extender-engraver.cc b/lily/extender-engraver.cc
index f1940083b95a350722cab732eec36a84d1127f3e..1cbad29de4cf092aefb8ac09519bf7e2f159fb03 100644
--- a/lily/extender-engraver.cc
+++ b/lily/extender-engraver.cc
@@ -30,12 +30,15 @@
 #include "warn.hh"
 #include "spanner.hh"
 #include "translator.icc"
+#include "iostream"

[dak, 2017/02/06 19:08:17]

Why?

 
 void completize_extender (Spanner *sp);
 
 class Extender_engraver : public Engraver
 {
-  Stream_event *ev_;
+  Stream_event *syllable_;
+  Stream_event *ex_;
+  Stream_event *hy_;
   Spanner *extender_;
   Spanner *pending_extender_;
 
@@ -43,7 +46,9 @@ public:
   TRANSLATOR_DECLARATIONS (Extender_engraver);
 
 protected:
+  void listen_lyric (Stream_event *);
   void listen_extender (Stream_event *);
+  void listen_hyphen (Stream_event *);
   void listen_completize_extender (Stream_event *);
   void acknowledge_lyric_syllable (Grob_info);
 
@@ -56,15 +61,30 @@ protected:
 Extender_engraver::Extender_engraver (Context *c)
   : Engraver (c)
 {
+  syllable_ = 0;
   extender_ = 0;
   pending_extender_ = 0;
-  ev_ = 0;
+  ex_ = 0;
+  hy_ = 0;
+}
+
+void
+Extender_engraver::listen_lyric (Stream_event *ev)
+{
+  if (robust_scm2string (ev->get_property ("text"), "") != " ")
+    syllable_ = ev;
 }
 
 void
 Extender_engraver::listen_extender (Stream_event *ev)
 {
-  ASSIGN_EVENT_ONCE (ev_, ev);
+  ASSIGN_EVENT_ONCE (ex_, ev);
+}
+
+void
+Extender_engraver::listen_hyphen (Stream_event *ev)
+{
+  ASSIGN_EVENT_ONCE (hy_, ev);

[dak, 2017/02/06 19:08:17]

If we are not the primary engraver for an item, we should not complain about how
often an event is assigned I think.

 }
 
 /*
@@ -86,8 +106,13 @@ Extender_engraver::listen_completize_extender (Stream_event * /* ev */)
 void
 Extender_engraver::process_music ()
 {
-  if (ev_)
-    extender_ = make_spanner ("LyricExtender", ev_->self_scm ());
+  if (ex_ && !hy_)

[dak, 2017/02/06 19:08:17]

Why check for hy_ here?  If there is an explicit extender event, why would we
mess with it?

+    {
+      extender_ = make_spanner ("LyricExtender", ex_->self_scm ());
+      extender_->set_property ("force-extender", SCM_BOOL_T);

[dak, 2017/02/06 19:08:17]

I think it might make more sense to have, if at all, a property for implicitly
generated extenders so that any extender generated by a user-created engraver
sounds as forced.  We could probably could just look up the event_cause and see
whether it is a lyric-event, but when user-created extenders are expected at
all, it might probably be advisable to have a more explicit property one can set
to switch between explicit and implicit behavior.

+    }
+  else if (syllable_ && !hy_)
+    extender_ = make_spanner ("LyricExtender", syllable_->self_scm ());
 }
 
 void
@@ -143,7 +168,9 @@ Extender_engraver::stop_translation_timestep ()
         }
     }
 
-  ev_ = 0;
+  ex_ = 0;
+  hy_ = 0;
+  syllable_ = 0;
 }
 
 void
@@ -163,18 +190,12 @@ Extender_engraver::finalize ()
   if (extender_)
     {
       completize_extender (extender_);
-
-      if (!extender_->get_bound (RIGHT))
-        extender_->warning (_ ("unterminated extender"));
       extender_ = 0;
     }
 
   if (pending_extender_)
     {
       completize_extender (pending_extender_);
-
-      if (!pending_extender_->get_bound (RIGHT))
-        pending_extender_->warning (_ ("unterminated extender"));
       pending_extender_ = 0;
     }
 }
@@ -182,7 +203,9 @@ Extender_engraver::finalize ()
 void
 Extender_engraver::boot ()
 {
+  ADD_LISTENER (Extender_engraver, lyric);
   ADD_LISTENER (Extender_engraver, extender);
+  ADD_LISTENER (Extender_engraver, hyphen);
   ADD_LISTENER (Extender_engraver, completize_extender);
   ADD_ACKNOWLEDGER (Extender_engraver, lyric_syllable);
 }