+static void
+set_column_rods (vector<Grob*> const &cols, Real padding)
+{
+ /* distances[i] will be the minimum distance between column i and column i+1 */
+ vector<Real> distances;
+
+ for (vsize i = 1; i < cols.size (); i++)
+ {
+ assert (distances.size () == i-1);
+
+ Item *r = dynamic_cast<Item*> (cols[i]);
+ Item *rb = r->find_prebroken_piece (LEFT);
+
+ if (Separation_item::is_empty (r) && (!rb || Separation_item::is_empty (rb)))
+ {
+ distances.push_back (0);
+ continue;
+ }
+
+ Skyline_pair *skys = Skyline_pair::unsmob (r->get_property ("horizontal-skylines"));
+ Real right_stickout = skys ? (*skys)[LEFT].max_height () : 0.0;
+
+ /* min rather than max because right-stickout will be negative if the right-hand column
+ sticks out a lot to the left */
+ right_stickout = min (right_stickout,
+ Separation_item::conditional_skyline (r, cols[i-1]).max_height ());
+
+ Drul_array<Item*> r_cols (r, rb);
+ Drul_array<Real> cur_dist (0.0, 0.0);
+
+ /* This is an inner loop and hence it is potentially quadratic. However, we only continue
+ as long as there is a rod to insert. Therefore, this loop will usually only execute
+ a constant number of times per iteration of the outer loop. */
+ for (vsize j = i; j--;)
+ {
+ Item *l = dynamic_cast<Item*> (cols[j]);
+ Item *lb = l->find_prebroken_piece (RIGHT);
+ Skyline_pair *skys = Skyline_pair::unsmob (l->get_property ("horizontal-skylines"));
+ Real left_stickout = skys ? (*skys)[RIGHT].max_height () : 0.0;
+ bool done = true;
+
+ Direction d = LEFT;
+ do
+ {
+ if (j < i-1)
+ cur_dist[d] += distances[j];
+
+ Item *r_col = r_cols[d];
+ bool touches = right_stickout - left_stickout + cur_dist[d] < 0.0;
+ Real dist = 0.0;
+
+ /* we set a distance for the line-starter column even if it's non-broken counterpart
+ doesn't touch the right column. */
+ if (lb)
+ Separation_item::set_distance (lb, r_col, padding);
+
+ if (touches || j == i-1)
+ dist = Separation_item::set_distance (l, r_col, padding);
+
+ if (j == i-1 && d == LEFT)
+ distances.push_back (dist);
+
+ if (j == i-1)
+ cur_dist[d] = distances[j];
+
+ done = done && !touches;
+ }
+ while (flip (&d) != LEFT && rb);
+
+ /* we need the empty check for gregorian notation, where there are a lot of
+ extraneous paper-columns that we need to skip over */
+ if (done && !Separation_item::is_empty (l))
+ break;
+ }
+ }
+}
+
+