generalized versions of plc configuration utilities

[myplc.git] / plc_config.py

diff --git a/plc_config.py b/plc_config.py
index c9382d2..45805b9 100644 (file)
--- a/plc_config.py
+++ b/plc_config.py
@@ -11,6 +11,7 @@
 #
 
 import xml.dom.minidom
+from xml.parsers.expat import ExpatError
 from StringIO import StringIO
 import time
 import re
@@ -20,6 +21,8 @@ import os
 import types
 
 
+class ConfigurationException(Exception): pass
+
 class PLCConfiguration:
     """
     Configuration file store. Optionally instantiate with a file path
@@ -187,7 +190,11 @@ class PLCConfiguration:
         Merge file into configuration store.
         """
 
-        dom = xml.dom.minidom.parse(file)
+        try:
+            dom = xml.dom.minidom.parse(file)
+        except ExpatError, e:
+            raise ConfigurationException, e
+
         if type(file) in types.StringTypes:
             self._files.append(os.path.abspath(file))
 
@@ -235,6 +242,44 @@ class PLCConfiguration:
 
         fileobj.close()
 
+    def verify(self, default, read, verify_variables={}):
+        """ Confirm that the existing configuration is consistent
+            according to the checks below.
+
+            It looks for filled-in values in the order of, local object (self),
+            followed by cread (read values), and finally default values.
+
+        Arguments: 
+
+            default configuration
+            site configuration
+            list of category/variable tuples to validate in these configurations
+
+        Returns:
+
+            dict of values for the category/variables passed in
+            If an exception is found, ConfigurationException is raised.
+
+        """
+
+        validated_variables = {}
+        for category_id, variable_id in verify_variables.iteritems():
+            category_id = category_id.lower()
+            variable_id = variable_id.lower()
+            variable_value = None
+            sources = (self, read, default)
+            for source in sources:
+                (category_value, variable_value) = source.get(category_id,variable_id)
+                if variable_value <> None:
+                    entry = validated_variables.get(category_id,[])
+                    entry.append(variable_value['value'])
+                    validated_variables["%s_%s"%(category_id.upper(),variable_id.upper())]=entry
+                    break
+            if variable_value == None:
+                raise ConfigurationException("Cannot find %s_%s)" % \
+                                             (category_id.upper(),
+                                              variable_id.upper()))
+        return validated_variables
 
     def get(self, category_id, variable_id):
         """