Method compute

src/main/java/pascal/taie/util/graph/SCC.java:62–106

(Graph<N> graph)

    }

    private void compute(Graph<N> graph) {
        // use iterative (non-recursive) algorithm to avoid stack overflow
        // for large graph
        int index = 0;
        Map<N, Integer> indexes = Maps.newMap(graph.getNumberOfNodes());
        Map<N, Integer> lows = Maps.newMap(graph.getNumberOfNodes());
        Deque<N> stack = new ArrayDeque<>();
        Set<N> inStack = Sets.newSet();
        for (N curr : graph) {
            if (indexes.containsKey(curr)) {
                continue;
            }
            Deque<N> workStack = new ArrayDeque<>();
            workStack.push(curr);
            while (!workStack.isEmpty()) {
                N node = workStack.peek();
                if (!indexes.containsKey(node)) {
                    indexes.put(node, index);
                    lows.put(node, index);
                    ++index;
                    stack.push(node);
                    inStack.add(node);
                }
                boolean hasUnvisitedSucc = false;
                for (N succ : graph.getSuccsOf(node)) {
                    if (!indexes.containsKey(succ)) {
                        workStack.push(succ);
                        hasUnvisitedSucc = true;
                        break;
                    } else if (indexes.get(node) < indexes.get(succ)) {
                        // node->succ is a forward edge
                        lows.put(node, Math.min(lows.get(node), lows.get(succ)));
                    } else if (inStack.contains(succ)) {
                        lows.put(node, Math.min(lows.get(node), indexes.get(succ)));
                    }
                }
                if (!hasUnvisitedSucc) {
                    if (lows.get(node).equals(indexes.get(node))) {
                        collectSCC(node, stack, inStack, graph);
                    }
                    workStack.pop();
                }
            }
        }
    }

    private void collectSCC(N node, Deque<N> stack, Set<N> inStack, Graph<N> graph) {
        List<N> scc = new ArrayList<>();