text.mod/graphviz.mod/graphviz/cmd/gvpr/lib/depath

/* Replace paths a -> b -> ... -> c with a -> c */
BEGIN {
  edge_t  e;
  node_t  n, prv, nxt;
  int to_delete[node_t];
}

N [(indegree == 1) && (outdegree == 1)] {
  e = fstin ($);
  prv = e.tail;
  e = fstout ($);
  nxt = e.head;
  to_delete[$] = 1;

  while ((prv.indegree == 1) && (prv.outdegree == 0)) {
    e = fstin (prv);
    n = e.tail;
    to_delete[prv] = 1;
    prv = n;
  }

  while ((nxt.indegree == 0) && (nxt.outdegree == 1)) {
    e = fstout (nxt);
    n = e.head;
    to_delete[nxt] = 1;
    nxt = n;
  }
 
  if (!isEdge (prv,nxt,""))
    edge (prv,nxt,"");
  
}

END_G {
  for (to_delete[n]) {
    delete($G, n);
  }
}