add function to retrive femmesh edges by a TopoDS_Edge

src/Mod/Fem/App/FemMesh.cpp

@@ -633,6 +633,34 @@ std::list<int> FemMesh::getFacesByFace(const TopoDS_Face &face) const
     return result;
 }
 
+std::list<int> FemMesh::getEdgesByEdge(const TopoDS_Edge &edge) const
+{
+    std::list<int> result;
+    std::set<int> nodes_on_edge = getNodesByEdge(edge);
+
+    SMDS_EdgeIteratorPtr edge_iter = myMesh->GetMeshDS()->edgesIterator();
+    while (edge_iter->more()) {
+        const SMDS_MeshEdge* edge = static_cast<const SMDS_MeshEdge*>(edge_iter->next());
+        int numNodes = edge->NbNodes();
+
+        std::set<int> edge_nodes;
+        for (int i=0; i<numNodes; i++) {
+            edge_nodes.insert(edge->GetNode(i)->GetID());
+        }
+
+        std::vector<int> element_edge_nodes;
+        std::set_intersection(nodes_on_edge.begin(), nodes_on_edge.end(), edge_nodes.begin(), edge_nodes.end(),
+            std::back_insert_iterator<std::vector<int> >(element_edge_nodes));
+
+        if (element_edge_nodes.size() == static_cast<std::size_t>(numNodes)) {
+            result.push_back(edge->GetID());
+        }
+    }
+
+    result.sort();
+    return result;
+}
+
 /*! That function returns map containing volume ID and face number
  * as per CalculiX definition for tetrahedral elements. See CalculiX
  * documentation for the details.

src/Mod/Fem/App/FemMesh.h

@@ -101,6 +101,8 @@ public:
     std::list<int> getElementNodes(int id) const;
     /// retrieving face IDs number by face
     std::list<int> getFacesByFace(const TopoDS_Face &face) const;
+    /// retrieving edge IDs number by edge
+    std::list<int> getEdgesByEdge(const TopoDS_Edge &edge) const;
     /// retrieving volume IDs and face IDs number by face
     std::list<std::pair<int, int> > getVolumesByFace(const TopoDS_Face &face) const;
     /// retrieving volume IDs and CalculiX face number by face

src/Mod/Fem/App/FemMeshPy.xml

@@ -93,6 +93,11 @@
                 <UserDocu>Return a list of face IDs which belong to a TopoFace</UserDocu>
             </Documentation>
         </Methode>
+        <Methode Name="getEdgesByEdge" Const="true">
+            <Documentation>
+                <UserDocu>Return a list of edge IDs which belong to a TopoEdge</UserDocu>
+            </Documentation>
+        </Methode>
         <Methode Name="getVolumesByFace" Const="true">
             <Documentation>
                 <UserDocu>Return a dict of volume IDs and face IDs which belong to a TopoFace</UserDocu>

src/Mod/Fem/App/FemMeshPyImp.cpp

@@ -711,6 +711,40 @@ PyObject* FemMeshPy::getFacesByFace(PyObject *args)
     }
 }
 
+
+PyObject* FemMeshPy::getEdgesByEdge(PyObject *args)
+{
+    PyObject *pW;
+    if (!PyArg_ParseTuple(args, "O!", &(Part::TopoShapeEdgePy::Type), &pW))
+         return 0;
+
+    try {
+        const TopoDS_Shape& sh = static_cast<Part::TopoShapeEdgePy*>(pW)->getTopoShapePtr()->getShape();
+        if (sh.IsNull()) {
+            PyErr_SetString(Base::BaseExceptionFreeCADError, "Edge is empty");
+            return 0;
+        }
+
+        const TopoDS_Edge& fc = TopoDS::Edge(sh);
+
+        Py::List ret;
+        std::list<int> resultSet = getFemMeshPtr()->getEdgesByEdge(fc);
+        for (std::list<int>::const_iterator it = resultSet.begin();it!=resultSet.end();++it) {
+#if PY_MAJOR_VERSION >= 3
+            ret.append(Py::Long(*it));
+#else
+            ret.append(Py::Int(*it));
+#endif
+        }
+
+        return Py::new_reference_to(ret);
+    }
+    catch (Standard_Failure& e) {
+        PyErr_SetString(Base::BaseExceptionFreeCADError, e.GetMessageString());
+        return 0;
+    }
+}
+
 PyObject* FemMeshPy::getVolumesByFace(PyObject *args)
 {
     PyObject *pW;