- bool have_slur = false;
- // Check if we already have a slur with the same spanner-id.
- // In that case, don't create a new slur, but print a warning
- for (vsize i = 0; i < slurs_.size (); i++)
- have_slur = have_slur || (id == robust_scm2string (slurs_[i]->get_property ("spanner-id"), ""));
-
- if (have_slur)
- ev->origin ()->warning (_ ("already have phrasing slur"));
- else
+ Direction updown = to_dir (ev->get_property ("direction"));
+
+ bool completed;
+ for (vsize j = 0; !(completed = (j == slurs_.size ())); j++)
+ {
+ // Check if we already have a slur with the same spanner-id.
+ if (id == robust_scm2string (slurs_[j]->get_property ("spanner-id"), ""))
+ {
+ if (j < old_slurs)
+ {
+ // We already have an old slur, so give a warning
+ // and completely ignore the new slur.
+ ev->origin ()->warning (_ ("already have phrasing slur"));
+ start_events_.erase (start_events_.begin () + i);
+ break;
+ }
+
+ // If this slur event has no direction, it will not
+ // contribute anything new to the existing slur(s), so
+ // we can ignore it. This is not entirely accurate:
+ // tweaks or context properties like those set with
+ // \slurUp can still override a neutral direction, so
+ // when encountering a slur event with "opposite"
+ // direction first, then one with neutral direction, we
+ // only let the "opposite" direction remain, while if
+ // the order is the other way round, a double slur
+ // results since the direction of the first slur is no
+ // longer attributable to a "neutral" slur event. A
+ // mixture of neutral and directed events is nothing
+ // that the partcombiner should crank out, and it would
+ // be decidedly strange for manual input.
+
+ if (!updown)
+ break;
+
+ // If the existing slur does not have a direction yet,
+ // give it ours
+
+ Direction slur_dir = to_dir (slurs_[j]->get_property ("direction"));
+
+ if (!slur_dir)
+ {
+ set_grob_direction (slurs_[j], updown);
+ break;
+ }
+
+ // If the existing slur has the same direction as ours, drop ours
+
+ if (slur_dir == updown)
+ break;
+ }
+ }
+ // If the loop completed, our slur is new
+ if (completed)