[tools/rdfwriter] Refactor save_elem usage

To reduce complexity, the RDFWriter.save_elem method
is removed and its usage replaced by the new methods
RDFWriter.save_document, .save_section and .save_property.

Author: mpsonntag

odml/tools/rdf_converter.py

@@ -90,7 +90,7 @@ def convert_to_rdf(self):
                 if isinstance(doc, BaseDocument):
                     # make sure links and includes are resolved before conversion
                     doc.finalize()
-                    self.save_element(doc)
+                    self.save_document(doc)
 
         return self.graph
 
@@ -137,7 +137,12 @@ def save_odml_list(self, odml_list, parent_node, rdf_predicate):
         for curr_item in odml_list:
             node = URIRef(ODML_NS + unicode(curr_item.id))
             self.graph.add((parent_node, rdf_predicate, node))
-            self.save_element(curr_item, node)
+
+            fmt = curr_item.format()
+            if fmt.name == Section.name:
+                self.save_section(curr_item, node)
+            elif fmt.name == Property.name:
+                self.save_property(curr_item, node)
 
     def save_repository_node(self, parent_node, rdf_predicate, leaf_value):
         """
@@ -272,75 +277,6 @@ def save_property(self, prop, curr_node):
                 curr_lit = Literal(curr_val)
                 self.graph.add((curr_node, curr_pred, curr_lit))
 
-    def save_element(self, odml_elem, node=None):
-        """
-        Save the current odml element to the RDF graph and handle all child
-        elements of the current odml element recursively.
-        :param odml_elem: An odml element that should be added to the RDF graph.
-        :param node: An RDF node that is used to append the current odml element
-                     to the RDF graph. If None, a new node will be created and
-                     added to the 'Hub' node of the RDF graph.
-        """
-        fmt = odml_elem.format()
-
-        is_doc = fmt.name == Document.name
-        is_sec = fmt.name == Section.name
-        is_prop = fmt.name == Property.name
-
-        curr_node = node
-        if not curr_node:
-            curr_node = URIRef(ODML_NS + unicode(odml_elem.id))
-
-        # Add type of current node to the RDF graph
-        curr_type = fmt.rdf_type
-        # Handle section subclass types
-        if is_sec:
-            sub_sec = self._get_section_subclass(odml_elem)
-            if sub_sec:
-                curr_type = sub_sec
-        self.graph.add((curr_node, RDF.type, URIRef(curr_type)))
-
-        # Add a new document to the RDF Hub node
-        if is_doc:
-            self.graph.add((self.hub_root, ODML_NS.hasDocument, curr_node))
-
-            # If available, add the documents' filename to the document node
-            # so we can identify where the data came from.
-            if hasattr(odml_elem, "_origin_file_name"):
-                curr_lit = Literal(odml_elem._origin_file_name)
-                self.graph.add((curr_node, ODML_NS.hasFileName, curr_lit))
-
-        for k in fmt.rdf_map_keys:
-            # Ignore "id" and empty values, but make sure the content of "value"
-            # is only accessed via its non deprecated property "values".
-            if k == "id" or k == "value" and not getattr(odml_elem, fmt.map(k)):
-                continue
-            elif k != "value" and not getattr(odml_elem, k):
-                continue
-
-            if (is_doc or is_sec) and k == "repository":
-                self.save_repository_node(curr_node, fmt.rdf_map(k),
-                                          getattr(odml_elem, k))
-
-            # generating nodes for sections and properties
-            elif ((is_doc or is_sec) and k == "sections") or \
-                    (is_sec and k == "properties"):
-                self.save_odml_list(getattr(odml_elem, k), curr_node, fmt.rdf_map(k))
-
-            # generating nodes for Property values
-            elif is_prop and k == "value":
-                # 'value' needs to be mapped to its appropriate odml Property attribute.
-                self.save_odml_values(curr_node, fmt.rdf_map(k),
-                                      getattr(odml_elem, fmt.map(k)))
-
-            elif k == "date":
-                curr_lit = Literal(getattr(odml_elem, k), datatype=XSD.date)
-                self.graph.add((curr_node, fmt.rdf_map(k), curr_lit))
-
-            else:
-                curr_lit = Literal(getattr(odml_elem, k))
-                self.graph.add((curr_node, fmt.rdf_map(k), curr_lit))
-
     def _get_section_subclass(self, elem):
         """
         _get_section_subclass checks whether the current odML element