Source Code for Module ndg.xacml.parsers.etree.rulereader

 1  """NDG XACML ElementTree based Rule Element reader  
 2   
 3  NERC DataGrid 
 4  """ 
 5  __author__ = "P J Kershaw" 
 6  __date__ = "16/03/10" 
 7  __copyright__ = "(C) 2010 Science and Technology Facilities Council" 
 8  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
 9  __license__ = "BSD - see LICENSE file in top-level directory" 
10  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
11  __revision__ = "$Id: rulereader.py 8028 2012-02-27 14:38:01Z rwilkinson $" 
12  from ndg.xacml.core.rule import Rule, Effect 
13  from ndg.xacml.core.condition import Condition 
14  from ndg.xacml.core.target import Target 
15  from ndg.xacml.parsers import XMLParseError 
16  from ndg.xacml.parsers.etree import QName, getElementChildren 
17  from ndg.xacml.parsers.etree.reader import ETreeAbstractReader 
18  from ndg.xacml.parsers.etree.factory import ReaderFactory 
19   
20   
21 -class RuleReader(ETreeAbstractReader): 
22      '''ElementTree based XACML Rule parser 
23       
24      @cvar TYPE: XACML type to instantiate from parsed object 
25      @type TYPE: type 
26      ''' 
27      TYPE = Rule 
28       
29 -    def __call__(self, obj, common): 
30          """Parse rule object 
31           
32          @param obj: input object to parse 
33          @type obj: ElementTree Element, or stream object 
34          @return: new XACML expression instance 
35          @rtype: ndg.xacml.core.rule.Rule derived type  
36          @raise XMLParseError: error reading element                
37          """ 
38          elem = super(RuleReader, self)._parse(obj) 
39           
40          xacmlType = RuleReader.TYPE 
41          rule = xacmlType() 
42           
43          localName = QName.getLocalPart(elem.tag) 
44          if localName != xacmlType.ELEMENT_LOCAL_NAME: 
45              raise XMLParseError("No \"%s\" element found" %  
46                                  xacmlType.ELEMENT_LOCAL_NAME) 
47           
48          # Unpack *required* attributes from top-level element 
49          attributeValues = [] 
50          for attributeName in (xacmlType.RULE_ID_ATTRIB_NAME,  
51                                xacmlType.EFFECT_ATTRIB_NAME): 
52              attributeValue = elem.attrib.get(attributeName) 
53              if attributeValue is None: 
54                  raise XMLParseError('No "%s" attribute found in "%s" ' 
55                                          'element' % 
56                                          (attributeName, 
57                                           xacmlType.ELEMENT_LOCAL_NAME)) 
58                   
59              attributeValues.append(attributeValue)  
60           
61          rule.effect = Effect()         
62          rule.id, rule.effect.value = attributeValues 
63               
64          # Parse sub-elements 
65          for childElem in getElementChildren(elem): 
66              localName = QName.getLocalPart(childElem.tag) 
67               
68              if localName == xacmlType.DESCRIPTION_LOCAL_NAME: 
69                  if childElem.text is not None: 
70                      rule.description = childElem.text.strip() 
71                       
72              elif localName == Condition.ELEMENT_LOCAL_NAME: 
73                  ConditionReader = ReaderFactory.getReader(Condition) 
74                  rule.condition = ConditionReader.parse(childElem, common) 
75                                      
76              elif localName == Target.ELEMENT_LOCAL_NAME: 
77                  TargetReader = ReaderFactory.getReader(Target) 
78                  rule.target = TargetReader.parse(childElem, common) 
79               
80              else: 
81                  raise XMLParseError("XACML Rule child element name %r not " 
82                                      "recognised" % localName)                 
83                   
84          return rule 
85