/** Visit each predecessor of this node applying the given visitor. Breadth first. */
private <Alpha, Beta> void doVisitPredecessors(
Visitor<Alpha, Beta> visitor, Alpha arg1, Beta arg2, Set<GraphNode> seen) {
if (seen.add(this)) {
Collection<GraphNode> allKill = null;
for (Iterator<GraphNode> i = pred.iterator(); i.hasNext(); ) {
GraphNode pred = i.next();
List<GraphNode> kill = visitor.visit(pred, this, arg1, arg2);
if (kill != null) {
if (allKill == null) allKill = new ArrayList<GraphNode>();
allKill.addAll(kill);
}
}
if (allKill != null) pred.removeAll(allKill);
for (Iterator<GraphNode> i = pred.iterator(); i.hasNext(); ) {
GraphNode pred = i.next();
pred.doVisitPredecessors(visitor, arg1, arg2, seen);
}
}
}
/** Visit each predecessor of this node applying the given visitor. */
public <Alpha, Beta> void visitPredecessors(Visitor<Alpha, Beta> visitor, Alpha arg1, Beta arg2) {
List<GraphNode> kill = visitor.visit(this, null, arg1, arg2);
if (kill != null) pred.removeAll(kill);
doVisitPredecessors(visitor, arg1, arg2, new HashSet<GraphNode>());
}