vector<vector<int> > Scc(const Graph &g) {
const int n = g.size();
vector<vector<int> > ret;
Graph revg(n);
for (int i = 0; i < n; i++) {
for (Edges::const_iterator it = g[i].begin(); it != g[i].end(); it++) {
revg[it->dest].push_back(Edge(it->dest, i, it->weight));
}
}
vector<int> st;
vector<int> visit(n, 0);
for (int i = 0; i < n; i++) {
if (visit[i]) { continue; }
SccDfs(g, i, visit, st);
}
visit = vector<int>(n, 0);
for (int i = n - 1; i >= 0; i--) {
int index = st[i];
if (visit[index]) { continue; }
vector<int> nret;
SccDfs(revg, index, visit, nret);
ret.push_back(nret);
}
return ret;
}
/** Remove any vertices that can't be reached by traversing the graph in
* reverse from acceptEod. */
void pruneUnreachable(NGHolder &g) {
deque<NFAVertex> dead;
if (!hasGreaterInDegree(1, g.acceptEod, g) &&
!hasGreaterInDegree(0, g.accept, g) &&
edge(g.accept, g.acceptEod, g).second) {
// Trivial case: there are no in-edges to our accepts (other than
// accept->acceptEod), so all non-specials are unreachable.
for (auto v : vertices_range(g)) {
if (!is_special(v, g)) {
dead.push_back(v);
}
}
} else {
// Walk a reverse graph from acceptEod with Boost's depth_first_visit
// call.
typedef reverse_graph<NFAGraph, NFAGraph&> RevNFAGraph;
RevNFAGraph revg(g.g);
map<NFAVertex, default_color_type> colours;
depth_first_visit(revg, g.acceptEod,
make_dfs_visitor(boost::null_visitor()),
make_assoc_property_map(colours));
DEBUG_PRINTF("color map has %zu entries after DFV\n", colours.size());
// All non-special vertices that aren't in the colour map (because they
// weren't reached) can be removed.
for (auto v : vertices_range(revg)) {
if (is_special(v, revg)) {
continue;
}
if (!contains(colours, v)) {
dead.push_back(v);
}
}
}
if (dead.empty()) {
DEBUG_PRINTF("no unreachable vertices\n");
return;
}
remove_vertices(dead, g, false);
DEBUG_PRINTF("removed %zu unreachable vertices\n", dead.size());
}
flat_set<NFAVertex> execute_graph(const NGHolder &running_g,
const NGHolder &input_dag,
const flat_set<NFAVertex> &input_start_states,
const flat_set<NFAVertex> &initial_states) {
DEBUG_PRINTF("g has %zu vertices, input_dag has %zu vertices\n",
num_vertices(running_g), num_vertices(input_dag));
assert(hasCorrectlyNumberedVertices(running_g));
assert(in_degree(input_dag.acceptEod, input_dag) == 1);
map<NFAVertex, boost::default_color_type> colours;
/* could just a topo order, but really it is time to pull a slightly bigger
* gun: DFS */
RevNFAGraph revg(input_dag.g);
map<NFAVertex, dynamic_bitset<> > dfs_states;
auto info = makeInfoTable(running_g);
auto input_fs = makeStateBitset(running_g, initial_states);
for (auto v : input_start_states) {
dfs_states[v] = input_fs;
}
depth_first_visit(revg, input_dag.accept,
eg_visitor(running_g, info, input_dag, dfs_states),
make_assoc_property_map(colours));
auto states = getVertices(dfs_states[input_dag.accept], info);
#ifdef DEBUG
DEBUG_PRINTF(" output rstates:");
for (const auto &v : states) {
printf(" %u", running_g[v].index);
}
printf("\n");
#endif
return states;
}