+ Spanner *sp = dynamic_cast<Spanner*> (me);
+ SCM cache_symbol = begin
+ ? ly_symbol2scm ("begin-of-line-pure-height")
+ : ly_symbol2scm ("rest-of-line-pure-height");
+ SCM cached = sp->get_cached_pure_property (cache_symbol, start, end);
+ if (scm_is_pair (cached))
+ return robust_scm2interval (cached, Interval (0, 0));
+