diff --git a/CMakeLists.txt b/CMakeLists.txt
index 56f17c5b..30adff52 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1014,6 +1014,7 @@ SET (hs_compile_SRCS
     src/util/graph.h
     src/util/graph_range.h
     src/util/graph_small_color_map.h
+    src/util/graph_undirected.h
     src/util/hash.h
     src/util/hash_dynamic_bitset.h
     src/util/insertion_ordered.h
diff --git a/src/nfagraph/ng_calc_components.cpp b/src/nfagraph/ng_calc_components.cpp
index 65574b50..3e9454ee 100644
--- a/src/nfagraph/ng_calc_components.cpp
+++ b/src/nfagraph/ng_calc_components.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:
@@ -53,11 +53,11 @@
 #include "ng_depth.h"
 #include "ng_holder.h"
 #include "ng_prune.h"
-#include "ng_undirected.h"
 #include "ng_util.h"
 #include "grey.h"
 #include "ue2common.h"
 #include "util/graph_range.h"
+#include "util/graph_undirected.h"
 #include "util/make_unique.h"
 
 #include <map>
@@ -310,28 +310,19 @@ void splitIntoComponents(unique_ptr<NGHolder> g,
         return;
     }
 
-    unordered_map<NFAVertex, NFAUndirectedVertex> old2new;
-    auto ug = createUnGraph(*g, true, true, old2new);
+    auto ug = make_undirected_graph(*g);
 
-    // Construct reverse mapping.
-    unordered_map<NFAUndirectedVertex, NFAVertex> new2old;
-    for (const auto &m : old2new) {
-        new2old.emplace(m.second, m.first);
-    }
+    // Filter specials and shell vertices from undirected graph.
+    unordered_set<NFAVertex> bad_vertices(
+        {g->start, g->startDs, g->accept, g->acceptEod});
+    bad_vertices.insert(head_shell.begin(), head_shell.end());
+    bad_vertices.insert(tail_shell.begin(), tail_shell.end());
 
-    // Filter shell vertices from undirected graph.
-    unordered_set<NFAUndirectedVertex> shell_undir_vertices;
-    for (auto v : head_shell) {
-        shell_undir_vertices.insert(old2new.at(v));
-    }
-    for (auto v : tail_shell) {
-        shell_undir_vertices.insert(old2new.at(v));
-    }
     auto filtered_ug = boost::make_filtered_graph(
-        ug, boost::keep_all(), make_bad_vertex_filter(&shell_undir_vertices));
+        ug, boost::keep_all(), make_bad_vertex_filter(&bad_vertices));
 
     // Actually run the connected components algorithm.
-    map<NFAUndirectedVertex, u32> split_components;
+    map<NFAVertex, u32> split_components;
     const u32 num = connected_components(
         filtered_ug, boost::make_assoc_property_map(split_components));
 
@@ -348,10 +339,8 @@ void splitIntoComponents(unique_ptr<NGHolder> g,
 
     // Collect vertex lists per component.
     for (const auto &m : split_components) {
-        NFAUndirectedVertex uv = m.first;
+        NFAVertex v = m.first;
         u32 c = m.second;
-        assert(contains(new2old, uv));
-        NFAVertex v = new2old.at(uv);
         verts[c].push_back(v);
         DEBUG_PRINTF("vertex %zu is in comp %u\n", (*g)[v].index, c);
     }
diff --git a/src/util/graph_undirected.h b/src/util/graph_undirected.h
new file mode 100644
index 00000000..049964ab
--- /dev/null
+++ b/src/util/graph_undirected.h
@@ -0,0 +1,501 @@
+/*
+ * Copyright (c) 2018, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ * \brief Adaptor that presents an undirected view of a bidirectional BGL graph.
+ *
+ * Analogous to the reverse_graph adapter. You can construct one of these for
+ * bidirectional graph g with:
+ *
+ *          auto ug = make_undirected_graph(g);
+ *
+ * The vertex descriptor type is the same as that of the underlying graph, but
+ * the edge descriptor is different.
+ */
+
+#ifndef GRAPH_UNDIRECTED_H
+#define GRAPH_UNDIRECTED_H
+
+#include "util/operators.h"
+
+#include <boost/graph/adjacency_iterator.hpp>
+#include <boost/graph/graph_traits.hpp>
+#include <boost/graph/properties.hpp>
+#include <boost/iterator/iterator_facade.hpp>
+
+#include <type_traits>
+#include <utility>
+
+namespace ue2 {
+
+struct undirected_graph_tag {};
+
+template <class BidirectionalGraph, class GraphRef>
+class undirected_graph;
+
+namespace undirected_detail {
+
+template <typename BidirectionalGraph>
+class undirected_graph_edge_descriptor
+    : totally_ordered<undirected_graph_edge_descriptor<BidirectionalGraph>> {
+    using base_graph_type = BidirectionalGraph;
+    using base_graph_traits = typename boost::graph_traits<base_graph_type>;
+    using base_edge_type = typename base_graph_traits::edge_descriptor;
+    using base_vertex_type = typename base_graph_traits::vertex_descriptor;
+
+    base_edge_type underlying_edge;
+    const base_graph_type *g;
+    bool reverse; // if true, reverse vertices in source() and target()
+
+    inline std::pair<base_vertex_type, base_vertex_type>
+    canonical_edge() const {
+        auto u = std::min(source(underlying_edge, *g),
+                          target(underlying_edge, *g));
+        auto v = std::max(source(underlying_edge, *g),
+                          target(underlying_edge, *g));
+        return std::make_pair(u, v);
+    }
+
+    template <class BidiGraph, class GraphRef>
+    friend class ::ue2::undirected_graph;
+
+public:
+    undirected_graph_edge_descriptor() = default;
+
+    undirected_graph_edge_descriptor(base_edge_type edge,
+                                     const base_graph_type &g_in,
+                                     bool reverse_in)
+        : underlying_edge(std::move(edge)), g(&g_in), reverse(reverse_in) {}
+
+    bool operator==(const undirected_graph_edge_descriptor &other) const {
+        return canonical_edge() == other.canonical_edge();
+    }
+
+    bool operator<(const undirected_graph_edge_descriptor &other) const {
+        return canonical_edge() < other.canonical_edge();
+    }
+
+    base_vertex_type get_source() const {
+        return reverse ? target(underlying_edge, *g)
+                       : source(underlying_edge, *g);
+    }
+
+    base_vertex_type get_target() const {
+        return reverse ? source(underlying_edge, *g)
+                       : target(underlying_edge, *g);
+    }
+};
+
+} // namespace undirected_detail
+
+template <class BidirectionalGraph, class GraphRef = const BidirectionalGraph &>
+class undirected_graph {
+private:
+    using Self = undirected_graph<BidirectionalGraph, GraphRef>;
+    using Traits = boost::graph_traits<BidirectionalGraph>;
+
+public:
+    using base_type = BidirectionalGraph;
+    using base_ref_type = GraphRef;
+
+    explicit undirected_graph(GraphRef g_in) : g(g_in) {}
+
+    // Graph requirements
+    using vertex_descriptor = typename Traits::vertex_descriptor;
+    using edge_descriptor =
+        undirected_detail::undirected_graph_edge_descriptor<base_type>;
+    using directed_category = boost::undirected_tag;
+    using edge_parallel_category = boost::disallow_parallel_edge_tag;
+    using traversal_category = typename Traits::traversal_category;
+
+    // IncidenceGraph requirements
+
+    /**
+     * \brief Templated iterator used for out_edge_iterator and
+     * in_edge_iterator, depending on the value of Reverse.
+     */
+    template <bool Reverse>
+    class adj_edge_iterator
+        : public boost::iterator_facade<
+              adj_edge_iterator<Reverse>, edge_descriptor,
+              boost::forward_traversal_tag, edge_descriptor> {
+        vertex_descriptor u;
+        const base_type *g;
+        typename Traits::in_edge_iterator in_it;
+        typename Traits::out_edge_iterator out_it;
+        bool done_in = false;
+    public:
+        adj_edge_iterator() = default;
+
+        adj_edge_iterator(vertex_descriptor u_in, const base_type &g_in,
+                          bool end_iter)
+            : u(std::move(u_in)), g(&g_in) {
+            auto pi = in_edges(u, *g);
+            auto po = out_edges(u, *g);
+            if (end_iter) {
+                in_it = pi.second;
+                out_it = po.second;
+                done_in = true;
+            } else {
+                in_it = pi.first;
+                out_it = po.first;
+                if (in_it == pi.second) {
+                    done_in = true;
+                    find_first_valid_out();
+                }
+            }
+        }
+
+    private:
+        friend class boost::iterator_core_access;
+
+        void find_first_valid_out() {
+            auto out_end = out_edges(u, *g).second;
+            for (; out_it != out_end; ++out_it) {
+                auto v = target(*out_it, *g);
+                if (!edge(v, u, *g).second) {
+                    break;
+                }
+            }
+        }
+
+        void increment() {
+            if (!done_in) {
+                auto in_end = in_edges(u, *g).second;
+                assert(in_it != in_end);
+                ++in_it;
+                if (in_it == in_end) {
+                    done_in = true;
+                    find_first_valid_out();
+                }
+            } else {
+                ++out_it;
+                find_first_valid_out();
+            }
+        }
+        bool equal(const adj_edge_iterator &other) const {
+            return in_it == other.in_it && out_it == other.out_it;
+        }
+        edge_descriptor dereference() const {
+            if (done_in) {
+                return edge_descriptor(*out_it, *g, Reverse);
+            } else {
+                return edge_descriptor(*in_it, *g, !Reverse);
+            }
+        }
+    };
+
+    using out_edge_iterator = adj_edge_iterator<false>;
+    using in_edge_iterator = adj_edge_iterator<true>;
+
+    using degree_size_type = typename Traits::degree_size_type;
+
+    // AdjacencyGraph requirements
+    using adjacency_iterator =
+        typename boost::adjacency_iterator_generator<Self, vertex_descriptor,
+                                                     out_edge_iterator>::type;
+    using inv_adjacency_iterator =
+        typename boost::inv_adjacency_iterator_generator<
+            Self, vertex_descriptor, in_edge_iterator>::type;
+
+    // VertexListGraph requirements
+    using vertex_iterator = typename Traits::vertex_iterator;
+
+    // EdgeListGraph requirements
+    enum {
+        is_edge_list = std::is_convertible<traversal_category,
+                                      boost::edge_list_graph_tag>::value
+    };
+
+    /** \brief Iterator used for edges(). */
+    class edge_iterator
+        : public boost::iterator_facade<edge_iterator, edge_descriptor,
+                                        boost::forward_traversal_tag,
+                                        edge_descriptor> {
+        const base_type *g;
+        typename Traits::edge_iterator it;
+    public:
+        edge_iterator() = default;
+
+        edge_iterator(typename Traits::edge_iterator it_in,
+                      const base_type &g_in)
+            : g(&g_in), it(std::move(it_in)) {
+            find_first_valid_edge();
+        }
+
+    private:
+        friend class boost::iterator_core_access;
+
+        void find_first_valid_edge() {
+            const auto end = edges(*g).second;
+            for (; it != end; ++it) {
+                const auto &u = source(*it, *g);
+                const auto &v = target(*it, *g);
+                if (!edge(v, u, *g).second) {
+                    break; // No reverse edge, we must visit this one
+                }
+                if (u <= v) {
+                    // We have a reverse edge, but we'll return this one (and
+                    // skip the other). Note that (u, u) shouldn't be skipped.
+                    break;
+                }
+            }
+        }
+
+        void increment() {
+            assert(it != edges(*g).second);
+            ++it;
+            find_first_valid_edge();
+        }
+        bool equal(const edge_iterator &other) const {
+            return it == other.it;
+        }
+        edge_descriptor dereference() const {
+            return edge_descriptor(*it, *g, false);
+        }
+    };
+
+    using vertices_size_type = typename Traits::vertices_size_type;
+    using edges_size_type = typename Traits::edges_size_type;
+
+    using graph_tag = undirected_graph_tag;
+
+    using vertex_bundle_type =
+        typename boost::vertex_bundle_type<base_type>::type;
+    using edge_bundle_type = typename boost::edge_bundle_type<base_type>::type;
+
+    vertex_bundle_type &operator[](const vertex_descriptor &d) {
+        return const_cast<base_type &>(g)[d];
+    }
+    const vertex_bundle_type &operator[](const vertex_descriptor &d) const {
+        return g[d];
+    }
+
+    edge_bundle_type &operator[](const edge_descriptor &d) {
+        return const_cast<base_type &>(g)[d.underlying_edge];
+    }
+    const edge_bundle_type &operator[](const edge_descriptor &d) const {
+        return g[d.underlying_edge];
+    }
+
+    static vertex_descriptor null_vertex() { return Traits::null_vertex(); }
+
+    // Accessor free functions follow
+
+    friend std::pair<vertex_iterator, vertex_iterator>
+    vertices(const undirected_graph &ug) {
+        return vertices(ug.g);
+    }
+
+    friend std::pair<edge_iterator, edge_iterator>
+    edges(const undirected_graph &ug) {
+        auto e = edges(ug.g);
+        return std::make_pair(edge_iterator(e.first, ug.g),
+                              edge_iterator(e.second, ug.g));
+    }
+
+    friend std::pair<out_edge_iterator, out_edge_iterator>
+    out_edges(const vertex_descriptor &u, const undirected_graph &ug) {
+        return std::make_pair(out_edge_iterator(u, ug.g, false),
+                              out_edge_iterator(u, ug.g, true));
+    }
+
+    friend vertices_size_type num_vertices(const undirected_graph &ug) {
+        return num_vertices(ug.g);
+    }
+
+    friend edges_size_type num_edges(const undirected_graph &ug) {
+        auto p = edges(ug);
+        return std::distance(p.first, p.second);
+    }
+
+    friend degree_size_type out_degree(const vertex_descriptor &u,
+                                       const undirected_graph &ug) {
+        return degree(u, ug);
+    }
+
+    friend vertex_descriptor vertex(vertices_size_type n,
+                                    const undirected_graph &ug) {
+        return vertex(n, ug.g);
+    }
+
+    friend std::pair<edge_descriptor, bool> edge(const vertex_descriptor &u,
+                                                 const vertex_descriptor &v,
+                                                 const undirected_graph &ug) {
+        auto e = edge(u, v, ug.g);
+        if (e.second) {
+            return std::make_pair(edge_descriptor(e.first, ug.g, false), true);
+        }
+        auto e_rev = edge(v, u, ug.g);
+        if (e_rev.second) {
+            return std::make_pair(edge_descriptor(e_rev.first, ug.g, true),
+                                  true);
+        }
+        return std::make_pair(edge_descriptor(), false);
+    }
+
+    friend std::pair<in_edge_iterator, in_edge_iterator>
+    in_edges(const vertex_descriptor &v, const undirected_graph &ug) {
+        return std::make_pair(in_edge_iterator(v, ug.g, false),
+                              in_edge_iterator(v, ug.g, true));
+    }
+
+    friend std::pair<adjacency_iterator, adjacency_iterator>
+    adjacent_vertices(const vertex_descriptor &u, const undirected_graph &ug) {
+        out_edge_iterator oi, oe;
+        std::tie(oi, oe) = out_edges(u, ug);
+        return std::make_pair(adjacency_iterator(oi, &ug),
+                              adjacency_iterator(oe, &ug));
+    }
+
+    friend std::pair<inv_adjacency_iterator, inv_adjacency_iterator>
+    inv_adjacent_vertices(const vertex_descriptor &v,
+                          const undirected_graph &ug) {
+        in_edge_iterator ei, ee;
+        std::tie(ei, ee) = in_edges(v, ug);
+        return std::make_pair(inv_adjacency_iterator(ei, &ug),
+                              inv_adjacency_iterator(ee, &ug));
+    }
+
+    friend degree_size_type in_degree(const vertex_descriptor &v,
+                                      const undirected_graph &ug) {
+        return degree(v, ug);
+    }
+
+    friend vertex_descriptor source(const edge_descriptor &e,
+                                    const undirected_graph &) {
+        return e.get_source();
+    }
+
+    friend vertex_descriptor target(const edge_descriptor &e,
+                                    const undirected_graph &) {
+        return e.get_target();
+    }
+
+    friend degree_size_type degree(const vertex_descriptor &u,
+                                   const undirected_graph &ug) {
+        auto p = out_edges(u, ug);
+        return std::distance(p.first, p.second);
+    }
+
+    // Property accessors.
+
+    template <typename Property>
+    using prop_map = typename boost::property_map<undirected_graph, Property>;
+
+    template <typename Property>
+    friend typename prop_map<Property>::type
+    get(Property p, undirected_graph &ug) {
+        return get(p, ug.g);
+    }
+
+    template <typename Property>
+    friend typename prop_map<Property>::const_type
+    get(Property p, const undirected_graph &ug) {
+        return get(p, ug.g);
+    }
+
+    template <typename Property, typename Key>
+    friend typename boost::property_traits<
+        typename prop_map<Property>::const_type>::value_type
+    get(Property p, const undirected_graph &ug, const Key &k) {
+        return get(p, ug.g, get_underlying_descriptor(k));
+    }
+
+    template <typename Property, typename Value, typename Key>
+    friend void put(Property p, const undirected_graph &ug,
+                    const Key &k, const Value &val) {
+        put(p, const_cast<BidirectionalGraph &>(ug.g),
+            get_underlying_descriptor(k), val);
+    }
+
+private:
+    // Accessors are here because our free friend functions (above) cannot see
+    // edge_descriptor's private members.
+    static typename base_type::vertex_descriptor
+    get_underlying_descriptor(const vertex_descriptor &v) {
+        return v;
+    }
+    static typename base_type::edge_descriptor
+    get_underlying_descriptor(const edge_descriptor &e) {
+        return e.underlying_edge;
+    }
+
+    // Reference to underlying bidirectional graph
+    GraphRef g;
+};
+
+template <class BidirectionalGraph>
+undirected_graph<BidirectionalGraph>
+make_undirected_graph(const BidirectionalGraph &g) {
+    return undirected_graph<BidirectionalGraph>(g);
+}
+
+} // namespace ue2
+
+namespace boost {
+
+/* Derive all the property map specializations from the underlying
+ * bidirectional graph. */
+
+template <typename BidirectionalGraph, typename GraphRef, typename Property>
+struct property_map<ue2::undirected_graph<BidirectionalGraph, GraphRef>,
+                    Property> {
+    using base_map_type = property_map<BidirectionalGraph, Property>;
+    using type = typename base_map_type::type;
+    using const_type = typename base_map_type::const_type;
+};
+
+template <class BidirectionalGraph, class GraphRef>
+struct vertex_property_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : vertex_property_type<BidirectionalGraph> {};
+
+template <class BidirectionalGraph, class GraphRef>
+struct edge_property_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : edge_property_type<BidirectionalGraph> {};
+
+template <class BidirectionalGraph, class GraphRef>
+struct graph_property_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : graph_property_type<BidirectionalGraph> {};
+
+template <typename BidirectionalGraph, typename GraphRef>
+struct vertex_bundle_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : vertex_bundle_type<BidirectionalGraph> {};
+
+template <typename BidirectionalGraph, typename GraphRef>
+struct edge_bundle_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : edge_bundle_type<BidirectionalGraph> {};
+
+template <typename BidirectionalGraph, typename GraphRef>
+struct graph_bundle_type<ue2::undirected_graph<BidirectionalGraph, GraphRef>>
+    : graph_bundle_type<BidirectionalGraph> {};
+
+} // namespace boost
+
+#endif // GRAPH_UNDIRECTED_H
diff --git a/unit/CMakeLists.txt b/unit/CMakeLists.txt
index 06cddebd..7c39ae90 100644
--- a/unit/CMakeLists.txt
+++ b/unit/CMakeLists.txt
@@ -77,6 +77,7 @@ set(unit_internal_SOURCES
     internal/flat_set.cpp
     internal/flat_map.cpp
     internal/graph.cpp
+    internal/graph_undirected.cpp
     internal/insertion_ordered.cpp
     internal/lbr.cpp
     internal/limex_nfa.cpp
diff --git a/unit/internal/graph_undirected.cpp b/unit/internal/graph_undirected.cpp
new file mode 100644
index 00000000..babc01a6
--- /dev/null
+++ b/unit/internal/graph_undirected.cpp
@@ -0,0 +1,236 @@
+/*
+ * 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:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "gtest/gtest.h"
+#include "util/container.h"
+#include "util/graph.h"
+#include "util/graph_range.h"
+#include "util/graph_undirected.h"
+#include "util/ue2_graph.h"
+
+#include <boost/graph/adjacency_list.hpp>
+
+using namespace std;
+using namespace ue2;
+
+struct SimpleV {
+    size_t index;
+    string test_v = "SimpleV";
+};
+
+struct SimpleE {
+    size_t index;
+    string test_e = "SimpleE";
+};
+
+struct SimpleG : public ue2_graph<SimpleG, SimpleV, SimpleE> {};
+
+using SimpleVertex = SimpleG::vertex_descriptor;
+
+template<typename Graph, typename Range>
+vector<size_t> to_indices(const Range &range, const Graph &g) {
+    vector<size_t> indices;
+    for (const auto &elem : range) {
+        indices.push_back(g[elem].index);
+    }
+    sort(indices.begin(), indices.end());
+    return indices;
+}
+
+template<typename Graph, typename T>
+vector<size_t> to_indices(const std::initializer_list<T> &range,
+                          const Graph &g) {
+    vector<size_t> indices;
+    for (const auto &elem : range) {
+        indices.push_back(g[elem].index);
+    }
+    sort(indices.begin(), indices.end());
+    return indices;
+}
+
+TEST(graph_undirected, simple_ue2_graph) {
+    SimpleG g;
+    auto a = add_vertex(g);
+    ASSERT_NE(SimpleG::null_vertex(), a);
+    auto b = add_vertex(g);
+    ASSERT_NE(SimpleG::null_vertex(), b);
+    auto c = add_vertex(g);
+    ASSERT_NE(SimpleG::null_vertex(), c);
+
+    add_edge(a, b, g);
+    add_edge(b, a, g);
+    add_edge(a, c, g);
+    add_edge(c, b, g);
+    add_edge(c, c, g);
+
+    auto ug = make_undirected_graph(g);
+
+    ASSERT_EQ(3, num_vertices(ug));
+    ASSERT_EQ(4, num_edges(ug));
+
+    // Check adjacencies
+
+    ASSERT_EQ(2, out_degree(a, ug));
+    ASSERT_EQ(to_indices({b, c}, ug),
+              to_indices(adjacent_vertices_range(a, ug), ug));
+
+    ASSERT_EQ(2, out_degree(b, ug));
+    ASSERT_EQ(to_indices({a, c}, ug),
+              to_indices(adjacent_vertices_range(b, ug), ug));
+
+    ASSERT_EQ(3, out_degree(c, ug));
+    ASSERT_EQ(to_indices({a, b, c}, ug),
+              to_indices(adjacent_vertices_range(c, ug), ug));
+
+    ASSERT_EQ(2, in_degree(b, ug));
+    ASSERT_EQ(to_indices({a, c}, ug),
+              to_indices(inv_adjacent_vertices_range(b, ug), ug));
+
+    // Test reverse edge existence
+
+    ASSERT_TRUE(edge(a, b, ug).second);
+    ASSERT_TRUE(edge(b, a, ug).second);
+    ASSERT_TRUE(edge(a, c, ug).second);
+    ASSERT_TRUE(edge(c, a, ug).second); // (a,c) actually exists
+    ASSERT_TRUE(edge(b, c, ug).second); // (c,b) actually exists
+    ASSERT_FALSE(edge(a, a, ug).second);
+
+    // Vertex properties
+
+    g[c].test_v = "vertex c";
+    ASSERT_EQ("vertex c", ug[c].test_v);
+    ASSERT_EQ("vertex c", get(&SimpleV::test_v, ug, c));
+
+    ug[c].test_v = "vertex c again";
+    ASSERT_EQ("vertex c again", g[c].test_v);
+    ASSERT_EQ("vertex c again", get(&SimpleV::test_v, g, c));
+
+    put(&SimpleV::test_v, ug, c, "vertex c once more");
+    ASSERT_EQ("vertex c once more", g[c].test_v);
+
+    const auto &vprops1 = ug[b];
+    ASSERT_EQ(1, vprops1.index);
+
+    const auto &vprops2 = get(boost::vertex_all, ug, b);
+    ASSERT_EQ(1, vprops2.index);
+
+    // Edge Properties
+
+    auto edge_undirected = edge(a, b, ug).first;
+    ug[edge_undirected].test_e = "edge (a,b)";
+    ASSERT_EQ("edge (a,b)", ug[edge_undirected].test_e);
+    ASSERT_EQ("edge (a,b)", get(&SimpleE::test_e, ug, edge_undirected));
+
+    ug[edge_undirected].test_e = "edge (a,b) again";
+    put(&SimpleE::test_e, ug, edge_undirected, "edge (a,b) once more");
+}
+
+TEST(graph_undirected, simple_adjacency_list) {
+    using AdjListG =
+        boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS,
+                              SimpleV, SimpleE>;
+
+    AdjListG g;
+    auto a = add_vertex(g);
+    ASSERT_NE(AdjListG::null_vertex(), a);
+    g[a].index = 0;
+    auto b = add_vertex(g);
+    ASSERT_NE(AdjListG::null_vertex(), b);
+    g[b].index = 1;
+    auto c = add_vertex(g);
+    ASSERT_NE(AdjListG::null_vertex(), c);
+    g[c].index = 2;
+
+    add_edge(a, b, g);
+    add_edge(b, a, g);
+    add_edge(a, c, g);
+    add_edge(c, b, g);
+    add_edge(c, c, g);
+
+    auto ug = make_undirected_graph(g);
+
+    ASSERT_EQ(3, num_vertices(ug));
+    ASSERT_EQ(4, num_edges(ug));
+
+    // Check adjacencies
+
+    ASSERT_EQ(2, out_degree(a, ug));
+    ASSERT_EQ(to_indices({b, c}, ug),
+              to_indices(adjacent_vertices_range(a, ug), ug));
+
+    ASSERT_EQ(2, out_degree(b, ug));
+    ASSERT_EQ(to_indices({a, c}, ug),
+              to_indices(adjacent_vertices_range(b, ug), ug));
+
+    ASSERT_EQ(3, out_degree(c, ug));
+    ASSERT_EQ(to_indices({a, b, c}, ug),
+              to_indices(adjacent_vertices_range(c, ug), ug));
+
+    ASSERT_EQ(2, in_degree(b, ug));
+    ASSERT_EQ(to_indices({a, c}, ug),
+              to_indices(inv_adjacent_vertices_range(b, ug), ug));
+
+    // Test reverse edge existence
+
+    ASSERT_TRUE(edge(a, b, ug).second);
+    ASSERT_TRUE(edge(b, a, ug).second);
+    ASSERT_TRUE(edge(a, c, ug).second);
+    ASSERT_TRUE(edge(c, a, ug).second); // (a,c) actually exists
+    ASSERT_TRUE(edge(b, c, ug).second); // (c,b) actually exists
+    ASSERT_FALSE(edge(a, a, ug).second);
+
+    // Vertex properties
+
+    g[c].test_v = "vertex c";
+    ASSERT_EQ("vertex c", ug[c].test_v);
+    ASSERT_EQ("vertex c", get(&SimpleV::test_v, ug, c));
+
+    ug[c].test_v = "vertex c again";
+    ASSERT_EQ("vertex c again", g[c].test_v);
+    ASSERT_EQ("vertex c again", get(&SimpleV::test_v, g, c));
+
+    put(&SimpleV::test_v, ug, c, "vertex c once more");
+    ASSERT_EQ("vertex c once more", g[c].test_v);
+
+    const auto &vprops1 = ug[b];
+    ASSERT_EQ(1, vprops1.index);
+
+    const auto &vprops2 = get(boost::vertex_all, ug, b);
+    ASSERT_EQ(1, vprops2.index);
+
+    // Edge Properties
+
+    auto edge_undirected = edge(a, b, ug).first;
+    ug[edge_undirected].test_e = "edge (a,b)";
+    ASSERT_EQ("edge (a,b)", ug[edge_undirected].test_e);
+    ASSERT_EQ("edge (a,b)", get(&SimpleE::test_e, ug, edge_undirected));
+
+    ug[edge_undirected].test_e = "edge (a,b) again";
+    put(&SimpleE::test_e, ug, edge_undirected, "edge (a,b) once more");
+}