First prototype

class2layer.inx

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+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+  <name>IfcClasses to Layers</name>
+  <id>effect.class2layer</id>
+
+  <label>New layers will be created from IfcClasses.</label>
+
+  <effect needs-live-preview="false">
+    <object-type>all</object-type>
+    <effects-menu>
+     <submenu name="IFC"/>
+    </effects-menu>
+  </effect>
+  <script>
+    <command location="inx" interpreter="python">class2layer.py</command>
+  </script>
+</inkscape-extension>

class2layer.py

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+#!/usr/bin/env python
+
+import inkex
+from inkex import Group
+
+global layer_list
+global layer
+layer_list = []
+
+class CreateLayersFromClasses(inkex.EffectExtension):
+    def effect(self):
+        svg = self.svg
+        for g in svg.xpath('//svg:g'):
+            g_class = g.get('class')
+            check_str = 'Ifc'
+            if g_class:
+                for class_name in g_class.split():
+                    if check_str in class_name:
+                        if class_name not in layer_list:
+                            layer = svg.add(Group(id=class_name))
+                            layer.set('inkscape:groupmode', 'layer')
+                            layer.set('inkscape:label', class_name)                          
+                            layer_list.append(class_name)
+                        else:
+                            layer = svg.getElementById(class_name)
+                        layer.add(g)
+
+if __name__ == '__main__':
+    CreateLayersFromClasses().run()