Edge and vertex descriptors now carry a weakref to their Graphs

This fixes an obvious problem, where the graph gets deleted, and the
descriptors are still lying around. Usage of orphaned descriptors will
now just raise a ValueError.

The __repr__ function of Edge, Vertex, and PropertyMap now give
something more informative about each object.

src/graph/graph.hh

@@ -104,23 +104,12 @@ public:
     //
     // python interface
     //
-    python::object Vertices() const;
-    python::object Vertex(size_t i) const;
-    python::object Edges() const;
-
-    python::object AddVertex();
-    void           RemoveVertex(const python::object& v);
-    python::object AddEdge(const python::object& s, const python::object& t);
-    void           RemoveEdge(const python::object& e);
-
     python::object DegreeMap(string deg) const;
 
     // used for graph properties
     graph_property_tag GetDescriptor() const { return graph_property_tag(); }
     bool CheckValid() const {return true;}
 
-    void ExportPythonInterface() const;
-
     // I/O
     void WriteToFile(string s, python::object pf, string format,
                      python::list properties);

src/graph/graph_bind.cc

@@ -305,13 +305,14 @@ void ungroup_vector_property(GraphInterface& g, boost::any vector_prop,
                              boost::any prop, size_t pos, bool edge);
 void group_vector_property(GraphInterface& g, boost::any vector_prop,
                            boost::any prop, size_t pos, bool edge);
+void export_python_interface();
 
 BOOST_PYTHON_MODULE(libgraph_tool_core)
 {
     // numpy
     import_array();
 
-    GraphInterface().ExportPythonInterface();
+    export_python_interface();
 
     register_exception_translator<GraphException>
         (graph_exception_translator<GraphException>);
@@ -348,13 +349,6 @@ BOOST_PYTHON_MODULE(libgraph_tool_core)
         .def("ShiftVertexProperty",  &GraphInterface::ShiftVertexProperty)
         .def("WriteToFile", &GraphInterface::WriteToFile)
         .def("ReadFromFile",&GraphInterface::ReadFromFile)
-        .def("Vertices", &GraphInterface::Vertices)
-        .def("Vertex", &GraphInterface::Vertex)
-        .def("Edges", &GraphInterface::Edges)
-        .def("AddVertex", &GraphInterface::AddVertex)
-        .def("AddEdge", &GraphInterface::AddEdge)
-        .def("RemoveVertex", &GraphInterface::RemoveVertex)
-        .def("RemoveEdge", &GraphInterface::RemoveEdge)
         .def("DegreeMap", &GraphInterface::DegreeMap)
         .def("Clear", &GraphInterface::Clear)
         .def("ClearEdges", &GraphInterface::ClearEdges)

src/graph/graph_python_interface.cc

@@ -26,26 +26,28 @@ using namespace std;
 using namespace boost;
 using namespace graph_tool;
 
+namespace graph_tool
+{
+
 struct get_vertex_iterator
 {
     template <class Graph>
-    void operator()(Graph& g, GraphInterface& gi,
+    void operator()(Graph& g, python::object& pg,
                     python::object& iter) const
     {
         typedef typename graph_traits<Graph>::vertex_iterator vertex_iterator;
         iter = python::object(PythonIterator<PythonVertex,
-                                             vertex_iterator>(gi, vertices(g)));
+                                             vertex_iterator>(pg, vertices(g)));
     }
 };
 
-python::object
-GraphInterface::Vertices() const
+python::object get_vertices(python::object g)
 {
+    GraphInterface& gi = python::extract<GraphInterface&>(g());
     python::object iter;
-    run_action<>()(const_cast<GraphInterface&>(*this),
-                   bind<void>(get_vertex_iterator(), _1,
-                              ref(const_cast<GraphInterface&>(*this)),
-                              ref(iter)))();
+    run_action<>()(gi, bind<void>(get_vertex_iterator(), _1,
+                                  ref(g),
+                                  ref(iter)))();
     return iter;
 }
 
@@ -53,17 +55,17 @@ struct get_vertex_soft
 {
     template <class Graph>
     void operator()(Graph& g,
-                    GraphInterface& gi,
+                    python::object& pg,
                     size_t i, python::object& v) const
     {
-        v = python::object(PythonVertex(gi, vertex(i, g)));
+        v = python::object(PythonVertex(pg, vertex(i, g)));
     }
 };
 
 struct get_vertex_hard
 {
     template <class Graph>
-    void operator()(Graph& g, GraphInterface& gi, size_t i,
+    void operator()(Graph& g, python::object& pg, size_t i,
                     python::object& v) const
     {
         size_t c = 0;
@@ -72,59 +74,54 @@ struct get_vertex_hard
         {
             if (c == i)
             {
-                v = python::object(PythonVertex(gi, *vi));
+                v = python::object(PythonVertex(pg, *vi));
                 return;
             }
             ++c;
         }
-        v = python::object(PythonVertex(gi,
+        v = python::object(PythonVertex(pg,
                                         graph_traits<Graph>::null_vertex()));
     }
 };
 
-python::object
-GraphInterface::Vertex(size_t i) const
+python::object get_vertex(python::object g, size_t i)
 {
+    GraphInterface& gi = python::extract<GraphInterface&>(g());
     python::object v;
-    if (IsVertexFilterActive())
-        run_action<>()(const_cast<GraphInterface&>(*this),
-                       bind<void>(get_vertex_hard(), _1,
-                                  ref(const_cast<GraphInterface&>(*this)),
-                                  i, ref(v)))();
+    if (gi.IsVertexFilterActive())
+        run_action<>()(gi,
+                       bind<void>(get_vertex_hard(), _1, ref(g), i, ref(v)))();
     else
-        run_action<>()(const_cast<GraphInterface&>(*this),
-                       bind<void>(get_vertex_soft(), _1,
-                                  ref(const_cast<GraphInterface&>(*this)), i,
-                                  ref(v)))();
+        run_action<>()(gi,
+                       bind<void>(get_vertex_soft(), _1, ref(g), i, ref(v)))();
     return v;
 }
 
 struct get_edge_iterator
 {
     template <class Graph>
-    void operator()(Graph& g, GraphInterface& gi,
-                    python::object& iter) const
+    void operator()(Graph& g, const python::object& pg, python::object& iter)
+        const
     {
         typedef typename graph_traits<Graph>::edge_iterator edge_iterator;
         iter = python::object(PythonIterator<PythonEdge<Graph>,
-                                             edge_iterator>(gi, edges(g)));
+                                             edge_iterator>(pg, edges(g)));
     }
 };
 
-python::object
-GraphInterface::Edges() const
+python::object get_edges(python::object g)
 {
+    GraphInterface& gi = python::extract<GraphInterface&>(g());
     python::object iter;
-    run_action<>()(const_cast<GraphInterface&>(*this),
-                   bind<void>(get_edge_iterator(), _1,
-                              ref(const_cast<GraphInterface&>(*this)),
-                              ref(iter)))();
+    run_action<>()(gi,
+                   bind<void>(get_edge_iterator(), _1, ref(g), ref(iter)))();
     return iter;
 }
 
-python::object GraphInterface::AddVertex()
+python::object add_vertex(python::object g)
 {
-    return python::object(PythonVertex(*this, add_vertex(_mg)));
+    GraphInterface& gi = python::extract<GraphInterface&>(g());
+    return python::object(PythonVertex(g, add_vertex(gi.GetGraph())));
 }
 
 struct shift_vertex_property
@@ -143,28 +140,28 @@ struct shift_vertex_property
     }
 };
 
-void GraphInterface::RemoveVertex(const python::object& v)
+void remove_vertex(GraphInterface& gi, const python::object& v)
 {
     PythonVertex& pv = python::extract<PythonVertex&>(v);
     pv.CheckValid();
-    vertex_t dv = pv.GetDescriptor();
+    GraphInterface::vertex_t dv = pv.GetDescriptor();
     pv.SetValid(false);
 
     //remove vertex
-    clear_vertex(dv, _mg);
-    remove_vertex(dv, _mg);
+    clear_vertex(dv, gi.GetGraph());
+    remove_vertex(dv, gi.GetGraph());
 }
 
 struct add_new_edge
 {
     template <class Graph, class EdgeIndexMap>
-    void operator()(Graph& g, GraphInterface& gi, const PythonVertex& s,
-                    const PythonVertex& t, EdgeIndexMap edge_index,
-                    python::object& new_e) const
+    void operator()(Graph& g, python::object& pg, GraphInterface& gi,
+                    const PythonVertex& s, const PythonVertex& t,
+                    EdgeIndexMap edge_index, python::object& new_e) const
     {
         typename graph_traits<Graph>::edge_descriptor e =
             add_edge(s.GetDescriptor(), t.GetDescriptor(), g).first;
-        new_e = python::object(PythonEdge<Graph>(gi, e));
+        new_e = python::object(PythonEdge<Graph>(pg, e));
         gi.AddEdgeIndex(e);
     }
 };
@@ -184,18 +181,17 @@ void GraphInterface::AddEdgeIndex(const edge_t& e)
     _nedges++;
 }
 
-python::object GraphInterface::AddEdge(const python::object& s,
-                                       const python::object& t)
+python::object add_edge(python::object g, const python::object& s,
+                        const python::object& t)
 {
     PythonVertex& src = python::extract<PythonVertex&>(s);
     PythonVertex& tgt = python::extract<PythonVertex&>(t);
     src.CheckValid();
     tgt.CheckValid();
+    GraphInterface& gi = python::extract<GraphInterface&>(g());
     python::object new_e;
-    run_action<>()(*this, bind<void>(add_new_edge(), _1,
-                                     ref(*this), src, tgt,
-                                     _edge_index,
-                                     ref(new_e)))();
+    run_action<>()(gi, bind<void>(add_new_edge(), _1, ref(g), ref(gi), src, tgt,
+                                  gi.GetEdgeIndex(), ref(new_e)))();
     return new_e;
 }
 
@@ -204,8 +200,7 @@ struct get_edge_descriptor
     template <class Graph>
     void operator()(const Graph& g, const python::object& e,
                     typename GraphInterface::edge_t& edge,
-                    bool& found)
-        const
+                    bool& found)  const
     {
         PythonEdge<Graph>& pe = python::extract<PythonEdge<Graph>&>(e);
         pe.CheckValid();
@@ -215,17 +210,15 @@ struct get_edge_descriptor
     }
 };
 
-void GraphInterface::RemoveEdge(const python::object& e)
+void remove_edge(GraphInterface& gi, const python::object& e)
 {
-    edge_t de;
+    GraphInterface::edge_t de;
     bool found = false;
-    run_action<>()(*this,
-                   bind<void>(get_edge_descriptor(), _1,
-                              ref(e), ref(de),
-                              ref(found)))();
+    run_action<>()(gi, bind<void>(get_edge_descriptor(), _1, ref(e), ref(de),
+                                  ref(found)))();
     if (!found)
         throw ValueException("invalid edge descriptor");
-    RemoveEdgeIndex(de);
+    gi.RemoveEdgeIndex(de);
 }
 
 void GraphInterface::RemoveEdgeIndex(const edge_t& e)
@@ -364,8 +357,6 @@ struct export_python_interface
     }
 };
 
-void export_python_properties(GraphInterface&);
-
 PythonPropertyMap<GraphInterface::vertex_index_map_t>
 get_vertex_index(GraphInterface& g)
 {
@@ -380,9 +371,13 @@ get_edge_index(GraphInterface& g)
         (g.GetEdgeIndex());
 }
 
+} // namespace graph_tool
+
 // register everything
 
-void GraphInterface::ExportPythonInterface() const
+void export_python_properties();
+
+void export_python_interface()
 {
     using namespace boost::python;
 
@@ -407,15 +402,23 @@ void GraphInterface::ExportPythonInterface() const
     set<string> v_iterators;
     typedef mpl::transform<graph_tool::detail::all_graph_views,
                            mpl::quote1<add_pointer> >::type graph_views;
-    mpl::for_each<graph_views>(bind<void>(export_python_interface(),
+    mpl::for_each<graph_views>(bind<void>(graph_tool::export_python_interface(),
                                           _1,ref(v_iterators)));
-    export_python_properties(const_cast<GraphInterface&>(*this));
+    export_python_properties();
     def("new_vertex_property",
         &new_property<GraphInterface::vertex_index_map_t>);
     def("new_edge_property", &new_property<GraphInterface::edge_index_map_t>);
     def("new_graph_property",
         &new_property<ConstantPropertyMap<size_t,graph_property_tag> >);
 
+    def("get_vertex", get_vertex);
+    def("get_vertices", get_vertices);
+    def("get_edges", get_edges);
+    def("add_vertex", graph_tool::add_vertex);
+    def("add_edge", graph_tool::add_edge);
+    def("remove_vertex", graph_tool::remove_vertex);
+    def("remove_edge", graph_tool::remove_edge);
+
     def("get_vertex_index", get_vertex_index);
     def("get_edge_index", get_edge_index);
 }

src/graph/graph_python_interface.hh

@@ -47,18 +47,21 @@ template <class Descriptor, class Iterator>
 class PythonIterator
 {
 public:
-    PythonIterator(GraphInterface& gi, std::pair<Iterator,Iterator> e)
-        : _gi(gi), _e(e) {}
+    PythonIterator(const python::object& g, std::pair<Iterator,Iterator> e)
+        : _g(g), _e(e) {}
     Descriptor Next()
     {
         if (_e.first == _e.second)
             python::objects::stop_iteration_error();
-        Descriptor e(_gi, *_e.first);
+        if (_g() == python::object())
+            throw GraphException("The corresponding graph object has been"
+                                 " deleted during iteration!");
+        Descriptor e(_g, *_e.first);
         ++_e.first;
         return e;
     }
 private:
-    GraphInterface& _gi;
+    python::object _g;
     std::pair<Iterator,Iterator> _e;
 };
 
@@ -71,17 +74,20 @@ class PythonEdge;
 class PythonVertex
 {
 public:
-    PythonVertex(GraphInterface& gi, GraphInterface::vertex_t v):
-        _gi(gi), _v(v), _valid(true)
+    PythonVertex(const python::object& g, GraphInterface::vertex_t v):
+        _g(g), _v(v), _valid(true)
     {
         CheckValid();
     }
 
     bool IsValid() const
     {
+        if (_g().ptr() == Py_None)
+            return false;
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         return _valid &&
             (_v != graph_traits<GraphInterface::multigraph_t>::null_vertex()) &&
-            (_v < num_vertices(_gi._mg));
+            (_v < num_vertices(gi._mg));
     }
 
     void SetValid(bool valid)
@@ -115,19 +121,21 @@ public:
     size_t GetInDegree() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         size_t in_deg;
-        run_action<>()(_gi, bind<void>(get_degree<in_degreeS>(),
-                                       _1, _v,
-                                       ref(in_deg)))();
+        run_action<>()(gi, bind<void>(get_degree<in_degreeS>(),
+                                      _1, _v,
+                                      ref(in_deg)))();
         return in_deg;
     }
 
     size_t GetOutDegree() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         size_t out_deg;
-        run_action<>()(_gi, bind<void>(get_degree<out_degreeS>(), _1, _v,
-                                       ref(out_deg)))();
+        run_action<>()(gi, bind<void>(get_degree<out_degreeS>(), _1, _v,
+                                      ref(out_deg)))();
         return out_deg;
     }
 
@@ -136,7 +144,7 @@ public:
     struct get_out_edges
     {
         template<class Graph>
-        void operator()(const Graph& g, GraphInterface& gi,
+        void operator()(const Graph& g, const python::object& pg,
                         typename graph_traits<Graph>::vertex_descriptor v,
                         python::object& iter) const
         {
@@ -144,7 +152,7 @@ public:
                 out_edge_iterator;
             iter = python::object(PythonIterator<PythonEdge<Graph>,
                                                  out_edge_iterator>
-                                  (gi, out_edges(v, g)));
+                                  (pg, out_edges(v, g)));
         }
     };
 
@@ -152,16 +160,17 @@ public:
     OutEdges() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         python::object iter;
-        run_action<>()(_gi, bind<void>(get_out_edges(), _1,
-                                       ref(_gi), _v, ref(iter)))();
+        run_action<>()(gi, bind<void>(get_out_edges(), _1,
+                                      ref(_g), _v, ref(iter)))();
         return iter;
     }
 
     struct get_in_edges
     {
         template<class Graph>
-        void operator()(const Graph& g, GraphInterface& gi,
+        void operator()(const Graph& g, const python::object& pg,
                         typename graph_traits<Graph>::vertex_descriptor v,
                         python::object& iter) const
         {
@@ -169,7 +178,7 @@ public:
                 in_edge_iterator;
             iter = python::object
                 (PythonIterator<PythonEdge<Graph>,in_edge_iterator>
-                 (gi, in_edge_iteratorS<Graph>::get_edges(v, g)));
+                 (pg, in_edge_iteratorS<Graph>::get_edges(v, g)));
         }
     };
 
@@ -177,9 +186,10 @@ public:
     InEdges() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         python::object iter;
-        run_action<>()(_gi, bind<void>(get_in_edges(), _1, ref(_gi),
-                                       _v, ref(iter)))();
+        run_action<>()(gi, bind<void>(get_in_edges(), _1, ref(_g), _v,
+                                      ref(iter)))();
         return iter;
     }
 
@@ -191,12 +201,14 @@ public:
 
     size_t GetHash() const
     {
-        return hash<size_t>()(_gi._vertex_index[_v]);
+        return hash<size_t>()(_v);
     }
 
     size_t GetIndex() const
     {
-        return _gi._vertex_index[_v];
+        CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
+        return gi._vertex_index[_v];
     }
 
     bool operator==(const PythonVertex& other) const
@@ -214,7 +226,7 @@ public:
     }
 
 private:
-    GraphInterface& _gi;
+    python::object _g;
     GraphInterface::vertex_t _v;
     bool _valid;
 };
@@ -226,19 +238,22 @@ class PythonEdge
 {
 public:
     typedef typename graph_traits<Graph>::edge_descriptor edge_descriptor;
-    PythonEdge(GraphInterface& gi, edge_descriptor e)
-        : _gi(gi), _e(e), _valid(true)
+    PythonEdge(const python::object& g, edge_descriptor e)
+        : _g(g), _e(e), _valid(true)
     {
         CheckValid();
     }
 
     bool IsValid() const
     {
+        if (_g().ptr() == Py_None)
+            return false;
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         return _valid &&
-            (_gi._vertex_index[target(_e, _gi._mg)] < num_vertices(_gi._mg)) &&
-            (_gi._vertex_index[source(_e, _gi._mg)] < num_vertices(_gi._mg)) &&
-            (target(_e, _gi._mg) != graph_traits<Graph>::null_vertex()) &&
-            (source(_e, _gi._mg) != graph_traits<Graph>::null_vertex());
+            (gi._vertex_index[target(_e, gi._mg)] < num_vertices(gi._mg)) &&
+            (gi._vertex_index[source(_e, gi._mg)] < num_vertices(gi._mg)) &&
+            (target(_e, gi._mg) != graph_traits<Graph>::null_vertex()) &&
+            (source(_e, gi._mg) != graph_traits<Graph>::null_vertex());
     }
 
     void SetValid(bool valid)
@@ -260,46 +275,47 @@ public:
     struct get_source
     {
         template<class GraphType>
-        void operator()(const GraphType& g, GraphInterface& gi,
+        void operator()(const GraphType& g, const python::object& pg,
                         const edge_descriptor& edge, python::object& vertex)
             const
         {
-            vertex = python::object(PythonVertex(gi, source(edge, g)));
+            vertex = python::object(PythonVertex(pg, source(edge, g)));
         }
     };
 
     python::object GetSource() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         python::object v;
-        run_action<>()(_gi, bind<void>(get_source(), _1, ref(_gi), ref(_e),
-                                       ref(v)))();
+        run_action<>()(gi, bind<void>(get_source(), _1, ref(_g), ref(_e),
+                                      ref(v)))();
         return v;
     }
 
     struct get_target
     {
         template<class GraphType>
-        void operator()(const GraphType& g, GraphInterface& gi,
-                        const edge_descriptor& edge,
-                        python::object& vertex) const
+        void operator()(const GraphType& g, const python::object& pg,
+                        const edge_descriptor& edge, python::object& vertex)
+            const
         {
-            vertex = python::object(PythonVertex(gi, target(edge, g)));
+            vertex = python::object(PythonVertex(pg, target(edge, g)));
         }
     };
 
     python::object GetTarget() const
     {
         CheckValid();
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
         python::object v;
-        run_action<>()(_gi, bind<void>(get_target(), _1, ref(_gi), ref(_e),
-                                       ref(v)))();
+        run_action<>()(gi, bind<void>(get_target(), _1, ref(_g), ref(_e),
+                                      ref(v)))();
         return v;
     }
 
     std::string GetString() const
     {
-        CheckValid();
         PythonVertex src = python::extract<PythonVertex>(GetSource());
         PythonVertex tgt = python::extract<PythonVertex>(GetTarget());
         return "(" + src.GetString() + "," + tgt.GetString() + ")";
@@ -308,23 +324,26 @@ public:
     size_t GetHash() const
     {
         CheckValid();
-        return hash<size_t>()(_gi._edge_index[_e]);
+        GraphInterface& gi = python::extract<GraphInterface&>(_g());
+        return hash<size_t>()(gi._edge_index[_e]);
     }
 
     bool operator==(const PythonEdge& other) const
     {
         CheckValid();
+        other.CheckValid();
         return other._e == _e;
     }
 
     bool operator!=(const PythonEdge& other) const