/* Merge the nodes of a min, max, or same rank set. */
void collapse_rankset(graph_t *g, graph_t *subg, int kind)
{
node_t *u,*v;
u = v = agfstnode(subg);
if (u) {
ND_ranktype(u) = kind;
while ((v = agnxtnode(subg,v))) {
UF_union(u,v);
ND_ranktype(v) = ND_ranktype(u);
}
switch (kind) {
case MINRANK: case SOURCERANK:
if (GD_minset(g) == NULL) GD_minset(g) = u;
else GD_minset(g) = UF_union(GD_minset(g),u);
break;
case MAXRANK: case SINKRANK:
if (GD_maxset(g) == NULL) GD_maxset(g) = u;
else GD_maxset(g) = UF_union(GD_maxset(g),u);
break;
}
switch (kind) {
case SOURCERANK: GD_minset(g)->u.ranktype = kind; break;
case SINKRANK: GD_maxset(g)->u.ranktype = kind; break;
}
}
}
/* To ensure that min and max rank nodes always have the intended rank
* assignment, reverse any incompatible edges.
*/
static point
minmax_edges(graph_t * g)
{
node_t *n;
edge_t *e;
point slen;
slen.x = slen.y = 0;
if ((GD_maxset(g) == NULL) && (GD_minset(g) == NULL))
return slen;
if (GD_minset(g) != NULL)
GD_minset(g) = UF_find(GD_minset(g));
if (GD_maxset(g) != NULL)
GD_maxset(g) = UF_find(GD_maxset(g));
if ((n = GD_maxset(g))) {
slen.y = (ND_ranktype(GD_maxset(g)) == SINKRANK);
while ((e = ND_out(n).list[0])) {
assert(aghead(e) == UF_find(aghead(e)));
reverse_edge(e);
}
}
if ((n = GD_minset(g))) {
slen.x = (ND_ranktype(GD_minset(g)) == SOURCERANK);
while ((e = ND_in(n).list[0])) {
assert(agtail(e) == UF_find(agtail(e)));
reverse_edge(e);
}
}
return slen;
}
static int
minmax_edges2(graph_t * g, point slen)
{
node_t *n;
edge_t *e = 0;
if ((GD_maxset(g)) || (GD_minset(g))) {
for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
if (n != UF_find(n))
continue;
if ((ND_out(n).size == 0) && GD_maxset(g) && (n != GD_maxset(g))) {
e = virtual_edge(n, GD_maxset(g), NULL);
ED_minlen(e) = slen.y;
}
if ((ND_in(n).size == 0) && GD_minset(g) && (n != GD_minset(g))) {
e = virtual_edge(GD_minset(g), n, NULL);
ED_minlen(e) = slen.x;
}
}
}
return (e != 0);
}
