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

  1  """NDG XACML ElementTree based generic reader for subject, resource, action and 
  2  environment match types 
  3   
  4  NERC DataGrid 
  5  """ 
  6  __author__ = "P J Kershaw" 
  7  __date__ = "16/03/10" 
  8  __copyright__ = "(C) 2010 Science and Technology Facilities Council" 
  9  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
 10  __license__ = "BSD - see LICENSE file in top-level directory" 
 11  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
 12  __revision__ = "$Id: matchreader.py 8028 2012-02-27 14:38:01Z rwilkinson $" 
 13  from ndg.xacml.core.attributevalue import AttributeValue 
 14  from ndg.xacml.core.attributeselector import AttributeSelector 
 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 MatchReaderBase(ETreeAbstractReader): 
 22      '''ElementTree based XACML generic Match parser for subject, resource,  
 23      action and environment match types 
 24       
 25      @cvar ATTRIBUTE_DESIGNATOR_TYPE: type for attribute designator sub-elements: 
 26      derived class should set to relevant type e.g. for SubjectMatch, 
 27      SubjectAttributeDesignator 
 28      @type ATTRIBUTE_DESIGNATOR_TYPE: NoneType 
 29      ''' 
 30      ATTRIBUTE_DESIGNATOR_TYPE = None 
 31       
 32 -    def __init__(self): 
 33          """Virtual method 
 34           
 35          @raise NotImplementedError: ATTRIBUTE_DESIGNATOR_TYPE must be set in a  
 36          derived class 
 37          """ 
 38          if self.__class__.ATTRIBUTE_DESIGNATOR_TYPE is None: 
 39              raise NotImplementedError('Extend this class setting the ' 
 40                                        '"ATTRIBUTE_DESIGNATOR_TYPE" class ' 
 41                                        'variable') 
 42               
 43          super(MatchReaderBase, self).__init__() 
 44           
 45 -    def __call__(self, obj, common): 
 46          """Parse *Match object (where * = Subject, Resource, Environment or 
 47          Action 
 48           
 49          @param obj: input object to parse 
 50          @type obj: ElementTree Element, or stream object 
 51          @return: new XACML match instance 
 52          @rtype: ndg.xacml.core.matchreader.MatchReaderBase derived type  
 53          @raise XMLParseError: error reading element                  
 54          """ 
 55          elem = super(MatchReaderBase, self)._parse(obj) 
 56           
 57          xacmlType = self.__class__.TYPE 
 58          match = xacmlType() 
 59           
 60          localName = QName.getLocalPart(elem.tag) 
 61          if localName != xacmlType.ELEMENT_LOCAL_NAME: 
 62              raise XMLParseError("No \"%s\" element found" %  
 63                                  xacmlType.ELEMENT_LOCAL_NAME) 
 64           
 65          # Unpack *required* attributes from top-level element 
 66          attributeValues = [] 
 67          for attributeName in (xacmlType.MATCH_ID_ATTRIB_NAME, ): 
 68              attributeValue = elem.attrib.get(attributeName) 
 69              if attributeValue is None: 
 70                  raise XMLParseError('No "%s" attribute found in "%s" ' 
 71                                      'element' % (attributeName, 
 72                                                   xacmlType.ELEMENT_LOCAL_NAME)) 
 73                   
 74              attributeValues.append(attributeValue)  
 75                      
 76          match.matchId, = attributeValues 
 77            
 78          # Assign specific attribute designator type from derived class 
 79          attributeDesignatorType = self.__class__.ATTRIBUTE_DESIGNATOR_TYPE 
 80          attributeDesignatorReaderType = ReaderFactory.getReader( 
 81                                                          attributeDesignatorType) 
 82        
 83          # Parse match elements 
 84          for childElem in getElementChildren(elem): 
 85              localName = QName.getLocalPart(childElem.tag) 
 86               
 87              if localName == xacmlType.ATTRIBUTE_VALUE_ELEMENT_LOCAL_NAME: 
 88                  AttributeValueReader = ReaderFactory.getReader(AttributeValue) 
 89                  match.attributeValue = AttributeValueReader.parse(childElem, 
 90                                                                    common) 
 91                   
 92              elif localName == attributeDesignatorType.ELEMENT_LOCAL_NAME: 
 93                  if match.attributeSelector is not None: 
 94                      raise XMLParseError("XACML %r child element may only be " 
 95                                          "either a %r or %r element NOT both" % 
 96                              (xacmlType.ELEMENT_LOCAL_NAME, 
 97                               attributeDesignatorType.ELEMENT_LOCAL_NAME, 
 98                               AttributeSelector.ELEMENT_LOCAL_NAME)) 
 99                       
100                  match.attributeDesignator = attributeDesignatorReaderType.parse( 
101                                                              childElem, common) 
102                           
103              elif localName == AttributeSelector.ELEMENT_LOCAL_NAME: 
104                  if match.attributeDesignator is not None: 
105                      raise XMLParseError("XACML %r child element may only be " 
106                                          "either a %r or %r element NOT both" % 
107                              (xacmlType.ELEMENT_LOCAL_NAME, 
108                               attributeDesignatorType.ELEMENT_LOCAL_NAME, 
109                               AttributeSelector.ELEMENT_LOCAL_NAME)) 
110                       
111                  AttributeSelectorReader = ReaderFactory.getReader( 
112                                                              AttributeSelector) 
113                   
114                  match.attributeSelector = AttributeSelectorReader.parse( 
115                                                              childElem, common) 
116              else: 
117                  raise XMLParseError("XACML %r child element name %r not " 
118                                      "recognised" %  
119                                      (xacmlType.MATCH_TYPE.ELEMENT_LOCAL_NAME, 
120                                       localName)) 
121                       
122          return match 
123