--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/configurationengine/source/cone/validation/common.py	Tue Aug 10 14:29:28 2010 +0300
@@ -0,0 +1,84 @@
+#
+# Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
+# All rights reserved.
+# This component and the accompanying materials are made available
+# under the terms of "Eclipse Public License v1.0"
+# which accompanies this distribution, and is available
+# at the URL "http://www.eclipse.org/legal/epl-v10.html".
+#
+# Initial Contributors:
+# Nokia Corporation - initial contribution.
+#
+# Contributors:
+#
+# Description: 
+#
+
+import sys
+import logging
+import inspect
+
+def load_plugin_classes(entry_point_group, base_class):
+    """
+    Load plugin classes from plug-in entry points.
+    
+    @param entry_point_group: Entry point group from which to load
+        classes. Each entry point is expected to be an iterable of
+        plugin class instances.
+    @param base_class: The base class that every loaded class must inherit.
+    @return: List of loaded plugin classes.
+    """
+    log = logging.getLogger('cone')
+    log.setLevel(logging.DEBUG)
+    validator_classes = []
+    
+    import pkg_resources
+    working_set = pkg_resources.WorkingSet(sys.path)
+    for entry_point in working_set.iter_entry_points(entry_point_group):
+        class_list = entry_point.load()
+        
+        # Make sure that the class list is a list
+        try:
+            class_list = [c for c in class_list]
+        except:
+            log.warn("Entry point %s:%s is not iterable (%r)" % (entry_point_group, entry_point.name, class_list))
+            continue
+        
+        for i, cls in enumerate(class_list):
+            if not inspect.isclass(cls):
+                log.warn("Object %d from entry point %s:%s is not a class (%r)" % (i, entry_point_group, entry_point.name, cls))
+            elif not issubclass(cls, base_class):
+                log.warn("Object %d from entry point %s:%s is not a sub-class of %s.%s (%r)" \
+                         % (i, entry_point, entry_point.name,
+                            base_class.__module__,
+                            base_class.__name__,
+                            cls))
+            else:
+                msg = "Validator class %r loaded from egg entry point %s:%s, item %d" % (cls, entry_point_group, entry_point.name, i)
+                log.debug(msg)
+                #print msg
+                validator_classes.append(cls)
+            
+    return validator_classes
+
+def filter_classes(classes, filter):
+    """
+    Filter the given list of validator by the given ProblemTypeFilter object.
+    
+    @param classes: The class list for filter. Each 
+        class is assumed to have a PROBLEM_TYPES attribute that defines
+        an iterable of the types of problems that the problem yields.
+    @param filter: The filter object to use. Can be None, in which case
+        the class list is simply returned back.
+    @return: The filtered list.
+    """
+    if filter == None:
+        return classes
+    else:
+        result = []
+        for klass in classes:
+            for problem_type in klass.PROBLEM_TYPES:
+                if filter.match(problem_type):
+                    result.append(klass)
+                    break
+        return result