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

 1  """NDG XACML ElementTree based Target 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: conditionreader.py 8028 2012-02-27 14:38:01Z rwilkinson $" 
12  from ndg.xacml.core.condition import Condition 
13  from ndg.xacml.parsers import XMLParseError 
14  from ndg.xacml.parsers.etree import QName, getElementChildren 
15  from ndg.xacml.parsers.etree.reader import ETreeAbstractReader 
16  from ndg.xacml.parsers.etree.applyreader import ApplyReader 
17   
18   
19 -class ConditionReader(ETreeAbstractReader): 
20      '''ElementTree based XACML 2.0 Condition parser.  Note the difference to 
21      XACML 1.0: the Condition element is its own type and not an Apply type. 
22      It expects a single Expression derived type child element 
23       
24      @cvar TYPE: XACML type to instantiate from parsed object 
25      @type TYPE: type 
26      ''' 
27      TYPE = Condition 
28       
29 -    def __call__(self, obj, common): 
30          """Parse condition object 
31           
32          @param obj: input object to parse 
33          @type obj: ElementTree Element, or stream object 
34          @return: new XACML condition instance 
35          @rtype: ndg.xacml.core.condition.Condition 
36          @raise XMLParseError: error reading sub-elements 
37          """ 
38          elem = super(ConditionReader, self)._parse(obj) 
39           
40          xacmlType = self.__class__.TYPE 
41          condition = 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          # Parse sub-elements 
49          nSubElem = 0 
50          for childElem in getElementChildren(elem): 
51              nSubElem += 1 
52              subElem = childElem 
53   
54          # Parse expression sub-element 
55          if nSubElem != 1: 
56              raise XMLParseError('XACML 2.0 policy schema expects only one ' 
57                                  'expression sub-element in the Condition ' 
58                                  'element; policy file has %d' % nSubElem) 
59           
60          subElemlocalName = QName.getLocalPart(subElem.tag) 
61          if subElemlocalName == xacmlType.APPLY_ELEMENT_LOCAL_NAME: 
62              condition.expression = ApplyReader.parse(subElem, common) 
63          else: 
64              raise XMLParseError('Expecting %r Condition sub-element not ' 
65                                  'recognised' % 
66                                  xacmlType.EXPRESSION_ELEMENT_LOCAL_NAME) 
67               
68           
69      
70          return condition 
71