/**
* Verify that some non-looping paths from {@code a} to {@code b} pass through at least one node
* where {@code nodePredicate} is true.
*/
private boolean checkSomePathsWithoutBackEdges(DiGraphNode<N, E> a, DiGraphNode<N, E> b) {
if (nodePredicate.apply(a.getValue()) && (inclusive || (a != start && a != end))) {
return true;
}
if (a == b) {
return false;
}
for (DiGraphEdge<N, E> e : a.getOutEdges()) {
// Once we visited that edge once, we no longer need to
// re-visit it again.
if (e.getAnnotation() == VISITED_EDGE) {
continue;
}
e.setAnnotation(VISITED_EDGE);
if (ignoreEdge(e)) {
continue;
}
if (e.getAnnotation() == BACK_EDGE) {
continue;
}
DiGraphNode<N, E> next = e.getDestination();
if (checkSomePathsWithoutBackEdges(next, b)) {
return true;
}
}
return false;
}
/**
* Gets all the edges of the graph.
*/
private static List<DiGraphEdge<Node, Branch>> getAllEdges(
ControlFlowGraph<Node> cfg) {
List<DiGraphEdge<Node, Branch>> edges = new ArrayList<>();
for (DiGraphNode<Node, Branch> n : cfg.getDirectedGraphNodes()) {
edges.addAll(cfg.getOutEdges(n.getValue()));
}
return edges;
}
/** @return true if all paths from block must exit with an explicit return. */
private boolean allPathsReturn(Node function) {
// Computes the control flow graph.
ControlFlowAnalysis cfa = new ControlFlowAnalysis(compiler, false, false);
cfa.process(null, function);
ControlFlowGraph<Node> cfg = cfa.getCfg();
Node returnPathsParent = cfg.getImplicitReturn().getValue();
for (DiGraphNode<Node, Branch> pred : cfg.getDirectedPredNodes(returnPathsParent)) {
Node n = pred.getValue();
if (!n.isReturn()) {
return false;
}
}
return true;
}
@Override
public void process(Node externs, Node root) {
this.root = root;
astPositionCounter = 0;
astPosition = Maps.newHashMap();
nodePriorities = Maps.newHashMap();
cfg = new AstControlFlowGraph(computeFallThrough(root), nodePriorities);
NodeTraversal.traverse(compiler, root, this);
astPosition.put(null, ++astPositionCounter); // the implicit return is last.
// Now, generate the priority of nodes by doing a depth-first
// search on the CFG.
priorityCounter = 0;
DiGraphNode<Node, Branch> entry = cfg.getEntry();
prioritizeFromEntryNode(entry);
if (shouldTraverseFunctions) {
// If we're traversing inner functions, we need to rank the
// priority of them too.
for (DiGraphNode<Node, Branch> candidate : cfg.getDirectedGraphNodes()) {
Node value = candidate.getValue();
if (value != null && value.getType() == Token.FUNCTION) {
Preconditions.checkState(!nodePriorities.containsKey(candidate) || candidate == entry);
prioritizeFromEntryNode(candidate);
}
}
}
// At this point, all reachable nodes have been given a priority, but
// unreachable nodes have not been given a priority. Put them last.
// Presumably, it doesn't really matter what priority they get, since
// this shouldn't happen in real code.
for (DiGraphNode<Node, Branch> candidate : cfg.getDirectedGraphNodes()) {
if (!nodePriorities.containsKey(candidate)) {
nodePriorities.put(candidate, ++priorityCounter);
}
}
// Again, the implicit return node is always last.
nodePriorities.put(cfg.getImplicitReturn(), ++priorityCounter);
}
private void discoverBackEdges(DiGraphNode<N, E> u) {
u.setAnnotation(GRAY);
for (DiGraphEdge<N, E> e : u.getOutEdges()) {
if (ignoreEdge(e)) {
continue;
}
DiGraphNode<N, E> v = e.getDestination();
if (v.getAnnotation() == WHITE) {
discoverBackEdges(v);
} else if (v.getAnnotation() == GRAY) {
e.setAnnotation(BACK_EDGE);
}
}
u.setAnnotation(BLACK);
}
@Override
public int compare(DiGraphNode<Node, Branch> a, DiGraphNode<Node, Branch> b) {
return astPosition.get(a.getValue()) - astPosition.get(b.getValue());
}