/**
* Add the given CFG node to the node map.
*
* @param nodeMap
* @param cfgNode
*/
private static <N> void registerCfgNode(Map<N, Set<ICFGNode<N>>> nodeMap, ICFGNode<N> cfgNode) {
N astnode = cfgNode.getASTNode();
if (astnode == null) return;
Set<ICFGNode<N>> cfgnodes = nodeMap.get(astnode);
if (cfgnodes == null) {
cfgnodes = new HashSet<ICFGNode<N>>();
nodeMap.put(astnode, cfgnodes);
}
cfgnodes.add(cfgNode);
}
/**
* Builds a post-order comparator for the nodes in the given CFG, in which a node is bigger than
* all of its successors (predecessors) if <code>isForward</code> is <code>true</code> (<code>
* false</code>), and populates a map from AST nodes to all their corresponding nodes in the given
* CFG.
*
* @param cfg
* @param nodeMap Node map to be populated (will not be cleared).
* @param isForward If <code>true</code> the CFG is traversed in the forward direction, meaning
* starting from the {@link IControlFlowGraph#getStartNode() start node} following {@link
* ICFGNode#getOutputs() outgoing edges}; if <code>false</code> the traversal direction is
* reversed, meaning traversal starts from the {@link IControlFlowGraph#getEndNode() end node}
* and follows {@link ICFGNode#getInputs() incoming edges}.
* @return Post-order comparator for the nodes in the given CFG
*/
public static <N> WorklistNodeOrderComparator createPostOrderAndPopulateNodeMap(
final IControlFlowGraph<N> cfg,
final Map<N, Set<ICFGNode<N>>> nodeMap,
final boolean isForward) {
Map<ICFGNode<?>, Integer> order = new HashMap<ICFGNode<?>, Integer>();
// iterative post-order visit / depth-first search (DFS)
// "visits" (numbers) nodes after all their children are
// visited (ie., when nodes become "black")
int cur = 0;
LinkedList<Object> spine = new LinkedList<Object>();
ICFGNode<N> node = isForward ? cfg.getStartNode() : cfg.getEndNode();
order.put(node, null);
spine.addFirst(node);
spine.addFirst((isForward ? node.getOutputs() : node.getInputs()).iterator());
newNode:
while (spine.isEmpty() == false) {
Iterator<ICFGEdge<N>> it = (Iterator<ICFGEdge<N>>) spine.peek();
while (it.hasNext()) {
node = isForward ? it.next().getSink() : it.next().getSource();
if (order.containsKey(node) == false) {
order.put(node, null);
spine.addFirst(node);
spine.addFirst((isForward ? node.getOutputs() : node.getInputs()).iterator());
continue newNode;
}
}
spine.removeFirst();
node = (ICFGNode<N>) spine.removeFirst();
// number nodes in increasing order
if (order.put(node, cur++) != null)
throw new IllegalStateException("Node already visited: " + node);
// also register node so that we can find it given its AST node
registerCfgNode(nodeMap, node);
}
// visitPostOrder(cfg.getStartNode(), order, Integer.MAX_VALUE);
return new WorklistNodeOrderComparator(order);
}