ENH: Support default attribute values for ArrayType (Float32) and

AttributeType (Scalar). Also enable parsing of deprecated DataStructure
tag, synonym of DataItem.

XdmfAttributeType.cpp

@@ -100,14 +100,8 @@ XdmfAttributeType::New(const std::map<std::string, std::string> & itemProperties
     type = itemProperties.find("AttributeType");
   }
   if(type == itemProperties.end()) {
-    try {
-      XdmfError::message(XdmfError::FATAL, 
-                         "Neither 'Type' nor 'AttributeType' found in "
-                         "itemProperties in XdmfAttributeType::New");
-    }
-    catch (XdmfError e) {
-      throw e;
-    }
+    // to support old xdmf defaults, return Scalar()
+    return Scalar();
   }
   const std::string & typeVal = type->second;
 

core/XdmfArrayType.cpp

@@ -127,15 +127,8 @@ XdmfArrayType::New(const std::map<std::string, std::string> & itemProperties)
     type = itemProperties.find("NumberType");
   }
   if(type == itemProperties.end()) {
-    try {
-      XdmfError::message(XdmfError::FATAL,
-                         "Type unset because neither 'DataType' nor "
-                         "'NumberType' found in itemProperties in "
-                         "XdmfArrayType::New");
-    }
-    catch (XdmfError e) {
-      throw e;
-    }
+    // to support old xdmf defaults, return Float32()
+    return Float32();
   }
   const std::string & typeVal = type->second;
 

core/XdmfCoreItemFactory.cpp

@@ -44,6 +44,10 @@ XdmfCoreItemFactory::createItem(const std::string & itemTag,
   if(itemTag.compare(XdmfArray::ItemTag) == 0) {
     return XdmfArray::New();
   }
+  else if(itemTag.compare("DataStructure") == 0) {
+    // to support old xdmf DataStructure tag
+    return XdmfArray::New();
+  }
   else if (itemTag.compare(XdmfFunction::ItemTag) == 0) {
     std::map<std::string, std::string>::const_iterator type =
       itemProperties.find("ConstructedType");