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[Anders Logg <logg@xxxxxxxxx>]

I added a utility function get_node() for this.

I suggest we use this at the top of all read() functions in the XMLFoo
files. That way one can easily reuse code for nested data and we get a
uniform error message.

--
Anders



On Wed, Sep 14, 2011 at 11:51:14PM +0200, Anders Logg wrote:
> I need some advice on how to implement the XML parsing for
> MeshDomains. I have this:
>
> <mesh>
>   <domains dim="3">
>     <mesh_value_collection type="uint" dim="0" />
>       stuff
>     </mesh_value_collection>
>     <mesh_value_collection type="uint" dim="1" />
>       stuff
>     </mesh_value_collection>
>     <mesh_value_collection type="uint" dim="2" />
>       stuff
>     </mesh_value_collection>
>   </domains>
> </mesh>
>
> The parsing of MeshValueCollection is implemented in
> XMLMeshValueCollection.cpp and I want to reuse that inside
> XMLMesh.cpp.
>
> So I've tried something like this:
>
>   // Check if we have any domains
>   const pugi::xml_node xml_domains = mesh_node.child("domains");
>   if (!xml_domains)
>     return;
>
>   // Iterate over data
>   for (pugi::xml_node_iterator it = xml_domains.begin();
>        it != xml_domains.end(); ++it)
>   {
>     // Check that node is <mesh_value_collection>
>     const std::string node_name = it->name();
>     if (node_name != "mesh_value_collection")
>       error("Expecting XML node <mesh_value_collection> but got
>       <%s>.",
>             node_name.c_str());
>
>     // Get attributes
>     const std::string type = it->attribute("type").value();
>     const uint dim = it->attribute("dim").as_uint();
>
>     // Check that the type is uint
>     if (type != "uint")
>     {
>       dolfin_error("XMLMesh.cpp",
>                    "read DOLFIN mesh from XML file",
>                    "Mesh domains must be marked as uint, not %s",
>                    type.c_str());
>     }
>
>     // Read MeshValueCollection
>     XMLMeshValueCollection::read(domains.markers(dim), type, *it);
>   }
>
> The problem here is that the node *it sent to XMLMeshValueCollection
> is already the node for the MeshValueCollection but that parser
> expects to get the parent node. But I can't really send it the parent
> node since the parent may have more than one child.
>
> Any ideas?
>