BUG: Fix bug in python for casting of XdmfGridCollections

Since XdmfGridCollection inherit from XdmfDomain, the typemap for XdmfItem
should attempt a dynamic cast to XdmfGridCollection before XdmfDomain.
Added a python test to ensure that these typemap changes will continue to
work in the future.

Xdmf.i

@@ -68,15 +68,15 @@ swig -v -c++ -python -o XdmfPython.cpp Xdmf.i
     else if(shared_ptr<XdmfCurvilinearGrid> value = shared_dynamic_cast<XdmfCurvilinearGrid>($1)) {
         *(shared_ptr< XdmfCurvilinearGrid > **)&($result) = value ? new shared_ptr< XdmfCurvilinearGrid >(value) : 0;
     }
+    else if(shared_ptr<XdmfGridCollection> value = shared_dynamic_cast<XdmfGridCollection>($1)) {
+        *(shared_ptr< XdmfGridCollection > **)&($result) = value ? new shared_ptr< XdmfGridCollection >(value) : 0;
+    }
     else if(shared_ptr<XdmfDomain> value = shared_dynamic_cast<XdmfDomain>($1)) {
         *(shared_ptr< XdmfDomain > **)&($result) = value ? new shared_ptr< XdmfDomain >(value) : 0;
     }
     else if(shared_ptr<XdmfGeometry> value = shared_dynamic_cast<XdmfGeometry>($1)) {
         *(shared_ptr< XdmfGeometry > **)&($result) = value ? new shared_ptr< XdmfGeometry >(value) : 0;
     }
-    else if(shared_ptr<XdmfGridCollection> value = shared_dynamic_cast<XdmfGridCollection>($1)) {
-        *(shared_ptr< XdmfGridCollection > **)&($result) = value ? new shared_ptr< XdmfGridCollection >(value) : 0;
-    }
     else if(shared_ptr<XdmfInformation> value = shared_dynamic_cast<XdmfInformation>($1)) {
         *(shared_ptr< XdmfInformation > **)&($result) = value ? new shared_ptr< XdmfInformation >(value) : 0;
     }
@@ -190,6 +190,9 @@ swig -v -c++ -python -o XdmfPython.cpp Xdmf.i
         else if(shared_ptr<XdmfCurvilinearGrid> gridCurvilinear = shared_dynamic_cast<XdmfCurvilinearGrid>(obj)) {
             result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfCurvilinearGrid>(gridCurvilinear)), SWIGTYPE_p_boost__shared_ptrT_XdmfCurvilinearGrid_t, SWIG_POINTER_OWN);
         }
+        else if(shared_ptr<XdmfGridCollection> gridCollection = shared_dynamic_cast<XdmfGridCollection>(obj)) {
+            result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfGridCollection>(gridCollection)), SWIGTYPE_p_boost__shared_ptrT_XdmfGridCollection_t, SWIG_POINTER_OWN);
+        }
         else if(shared_ptr<XdmfDomain> domain = shared_dynamic_cast<XdmfDomain>(obj)) {
             result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfDomain>(domain)), SWIGTYPE_p_boost__shared_ptrT_XdmfDomain_t, SWIG_POINTER_OWN);
         }
@@ -199,9 +202,6 @@ swig -v -c++ -python -o XdmfPython.cpp Xdmf.i
         else if(shared_ptr<XdmfGraph> graph = shared_dynamic_cast<XdmfGraph>(obj)) {
             result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfGraph>(graph)), SWIGTYPE_p_boost__shared_ptrT_XdmfGraph_t, SWIG_POINTER_OWN);
         }
-        else if(shared_ptr<XdmfGridCollection> gridCollection = shared_dynamic_cast<XdmfGridCollection>(obj)) {
-            result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfGridCollection>(gridCollection)), SWIGTYPE_p_boost__shared_ptrT_XdmfGridCollection_t, SWIG_POINTER_OWN);
-        }
         else if(shared_ptr<XdmfInformation> information = shared_dynamic_cast<XdmfInformation>(obj)) {
             result = SWIG_NewPointerObj(SWIG_as_voidptr(new shared_ptr<XdmfInformation>(information)), SWIGTYPE_p_boost__shared_ptrT_XdmfInformation_t, SWIG_POINTER_OWN);
         }

tests/Python/CMakeLists.txt

@@ -16,6 +16,7 @@ ADD_TEST_PYTHON_PYTHONPATH("")
 # -----------------------
 ADD_TEST_PYTHON(TestXdmfEquals)
 ADD_TEST_PYTHON(TestXdmfHDF5Writer)
+ADD_TEST_PYTHON(TestXdmfRead)
 ADD_TEST_PYTHON(TestXdmfSet)
 ADD_TEST_PYTHON(TestXdmfWriter)
 
@@ -28,6 +29,8 @@ ADD_TEST_PYTHON(TestXdmfWriter)
 CLEAN_TEST_PYTHON(TestXdmfEquals)
 CLEAN_TEST_PYTHON(TestXdmfHDF5Writer
   hdf5WriterPythonTest.h5)
+CLEAN_TEST_PYTHON(TestXdmfRead
+  TestXdmfRead.xmf)
 CLEAN_TEST_PYTHON(TestXdmfSet)
 CLEAN_TEST_PYTHON(TestXdmfWriter
   output.h5

tests/Python/TestXdmfRead.py

+from Xdmf import *
+
+if __name__ == "__main__":
+
+    fileName ="TestXdmfRead.xmf"
+
+    # create a simple empty file
+    domain = XdmfDomain.New()
+    collection = XdmfGridCollection.New()
+    grid = XdmfUnstructuredGrid.New()
+    attribute1 = XdmfAttribute.New()
+    attribute2 = XdmfAttribute.New()
+    information = XdmfInformation.New()
+
+    domain.insert(collection)
+    collection.insert(grid)
+    grid.insert(attribute1)
+    grid.insert(attribute2)
+    grid.insert(information)
+    
+    writer = XdmfWriter.New(fileName)
+    domain.accept(writer)
+
+    # read file using XPaths and verify downcasts to appropriate XdmfItems
+    reader = XdmfReader.New()
+
+    domain = reader.read(fileName, "/Xdmf/Domain")
+    assert(len(domain) == 1)
+    assert(isinstance(domain[0], XdmfDomain))
+
+    collection = reader.read(fileName, "/Xdmf/Domain/Grid")
+    assert(len(collection) == 1)
+    assert(isinstance(collection[0], XdmfGridCollection))
+    
+    grid = reader.read(fileName, "/Xdmf/Domain/Grid/Grid")
+    assert(len(grid) == 1)
+    assert(isinstance(grid[0], XdmfUnstructuredGrid))
+
+    attributes = reader.read(fileName, "/Xdmf/Domain/Grid/Grid/Attribute")
+    assert(len(attributes) == 2)
+    assert(isinstance(attributes[0], XdmfAttribute))
+    assert(isinstance(attributes[1], XdmfAttribute))
+
+    information = reader.read(fileName, "/Xdmf/Domain/Grid/Grid/Information")
+    assert(len(information) == 1)
+    assert(isinstance(information[0], XdmfInformation))
+