ng_repeat: use undirected_graph

src/nfagraph/ng_repeat.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2017, Intel Corporation
+ * Copyright (c) 2015-2018, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -48,6 +48,7 @@
 #include "util/dump_charclass.h"
 #include "util/graph_range.h"
 #include "util/graph_small_color_map.h"
+#include "util/graph_undirected.h"
 #include "util/report_manager.h"
 #include "util/unordered.h"
 
@@ -73,40 +74,41 @@ namespace ue2 {
 
 namespace {
 
-/** \brief Filter that retains only edges between vertices with the same
- * reachability. */
+/**
+ * \brief Filter that retains only edges between vertices with the same
+ * reachability. Special vertices are dropped.
+ */
 template<class Graph>
 struct ReachFilter {
-    ReachFilter() {}
+    ReachFilter() = default;
     explicit ReachFilter(const Graph *g_in) : g(g_in) {}
 
     // Convenience typedefs.
-    typedef typename boost::graph_traits<Graph> Traits;
-    typedef typename Traits::vertex_descriptor VertexDescriptor;
-    typedef typename Traits::edge_descriptor EdgeDescriptor;
+    using Traits = typename boost::graph_traits<Graph>;
+    using VertexDescriptor = typename Traits::vertex_descriptor;
+    using EdgeDescriptor = typename Traits::edge_descriptor;
+
+    bool operator()(const VertexDescriptor &v) const {
+        assert(g);
+        // Disallow special vertices, as otherwise we will try to remove them
+        // later.
+        return !is_special(v, *g);
+    }
 
     bool operator()(const EdgeDescriptor &e) const {
         assert(g);
-
-        VertexDescriptor u = source(e, *g), v = target(e, *g);
-
-        // Disallow special vertices, as otherwise we will try to remove them
-        // later.
-        if (is_special(u, *g) || is_special(v, *g)) {
-            return false;
-        }
-
         // Vertices must have the same reach.
+        auto u = source(e, *g), v = target(e, *g);
         const CharReach &cr_u = (*g)[u].char_reach;
         const CharReach &cr_v = (*g)[v].char_reach;
-
         return cr_u == cr_v;
     }
 
     const Graph *g = nullptr;
 };
 
-typedef boost::filtered_graph<NGHolder, ReachFilter<NGHolder>> RepeatGraph;
+using RepeatGraph = boost::filtered_graph<NGHolder, ReachFilter<NGHolder>,
+                                          ReachFilter<NGHolder>>;
 
 struct ReachSubgraph {
     vector<NFAVertex> vertices;
@@ -300,10 +302,9 @@ void splitSubgraph(const NGHolder &g, const deque<NFAVertex> &verts,
     unordered_map<NFAVertex, NFAVertex> verts_map; // in g -> in verts_g
     fillHolder(&verts_g, g, verts, &verts_map);
 
-    unordered_map<NFAVertex, NFAUndirectedVertex> old2new;
-    auto ug = createUnGraph(verts_g, true, true, old2new);
+    const auto ug = make_undirected_graph(verts_g);
 
-    unordered_map<NFAUndirectedVertex, u32> repeatMap;
+    unordered_map<NFAVertex, u32> repeatMap;
 
     size_t num = connected_components(ug, make_assoc_property_map(repeatMap));
     DEBUG_PRINTF("found %zu connected repeat components\n", num);
@@ -312,7 +313,8 @@ void splitSubgraph(const NGHolder &g, const deque<NFAVertex> &verts,
     vector<ReachSubgraph> rs(num);
 
     for (auto v : verts) {
-        NFAUndirectedVertex vu = old2new.at(verts_map.at(v));
+        assert(!is_special(v, g));
+        auto vu = verts_map.at(v);
         auto rit = repeatMap.find(vu);
         if (rit == repeatMap.end()) {
             continue; /* not part of a repeat */
@@ -323,8 +325,14 @@ void splitSubgraph(const NGHolder &g, const deque<NFAVertex> &verts,
     }
 
     for (const auto &rsi : rs) {
+        if (rsi.vertices.empty()) {
+            // Empty elements can happen when connected_components finds a
+            // subgraph consisting entirely of specials (which aren't added to
+            // ReachSubgraph in the loop above). There's nothing we can do with
+            // these, so we skip them.
+            continue;
+        }
         DEBUG_PRINTF("repeat with %zu vertices\n", rsi.vertices.size());
-        assert(!rsi.vertices.empty());
         if (rsi.vertices.size() >= minNumVertices) {
             DEBUG_PRINTF("enqueuing\n");
             q.push(rsi);
@@ -1023,17 +1031,16 @@ static
 void buildReachSubgraphs(const NGHolder &g, vector<ReachSubgraph> &rs,
                          const u32 minNumVertices) {
     const ReachFilter<NGHolder> fil(&g);
-    const RepeatGraph rg(g, fil);
+    const RepeatGraph rg(g, fil, fil);
 
     if (!isCompBigEnough(rg, minNumVertices)) {
         DEBUG_PRINTF("component not big enough, bailing\n");
         return;
     }
 
-    unordered_map<RepeatGraph::vertex_descriptor, NFAUndirectedVertex> old2new;
-    auto ug = createUnGraph(rg, true, true, old2new);
+    const auto ug = make_undirected_graph(rg);
 
-    unordered_map<NFAUndirectedVertex, u32> repeatMap;
+    unordered_map<NFAVertex, u32> repeatMap;
 
     unsigned int num;
     num = connected_components(ug, make_assoc_property_map(repeatMap));
@@ -1045,8 +1052,7 @@ void buildReachSubgraphs(const NGHolder &g, vector<ReachSubgraph> &rs,
     rs.resize(num);
 
     for (auto v : topoOrder) {
-        NFAUndirectedVertex vu = old2new[v];
-        auto rit = repeatMap.find(vu);
+        auto rit = repeatMap.find(v);
         if (rit == repeatMap.end()) {
             continue; /* not part of a repeat */
         }