+ Grob *me = unsmob_grob (smobbed_me);
+ SCM first_elt = me->get_grob_property ("elements");
+
+ // compute common refpoint of elements
+ Grob *refp = me;
+ for (SCM elts = first_elt; gh_pair_p (elts); elts = ly_cdr (elts))
+ {
+ SCM smobbed_staff_bar = ly_car (elts);
+ Grob *staff_bar = unsmob_grob (smobbed_staff_bar);
+ refp = staff_bar->common_refpoint (refp, Y_AXIS);
+ }
+
+ Span_bar::evaluate_glyph(me);
+ SCM glyph = me->get_grob_property ("glyph");
+
+ /*
+ glyph may not be a string, when ME is killed by Hara Kiri in
+ between.
+ */
+ if (!gh_string_p (glyph))
+ return SCM_EOL;
+
+ String glyph_str = ly_scm2string (glyph);
+
+ // compose span_bar_mol
+ Molecule span_bar_mol;
+
+ Interval prev_extent;
+ for (SCM elts = first_elt; gh_pair_p (elts); elts = ly_cdr (elts))
+ {
+ SCM smobbed_staff_bar = ly_car (elts);
+ Grob *staff_bar = unsmob_grob (smobbed_staff_bar);
+ Interval ext = staff_bar->extent (refp, Y_AXIS);
+ if (ext.empty_b ())
+ continue;
+
+ if (!prev_extent.empty_b ())
+ {
+ Interval l(prev_extent [UP],
+ ext[DOWN]);
+
+ Molecule interbar
+ = Bar::compound_barline (staff_bar, glyph_str, l.length());
+ interbar.translate_axis (l.center (), Y_AXIS);
+ span_bar_mol.add_molecule (interbar);
+ }
+ prev_extent = ext;
+ }
+
+ span_bar_mol.translate_axis (- me->relative_coordinate (refp, Y_AXIS), Y_AXIS);
+
+ return span_bar_mol.smobbed_copy ();