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

  1  """NDG XACML ElementTree based Apply type reader  
  2   
  3  NERC DataGrid 
  4  """ 
  5  __author__ = "P J Kershaw" 
  6  __date__ = "19/03/10" 
  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: applyreader.py 8041 2012-03-16 11:51:01Z rwilkinson $" 
 12  import logging 
 13  log = logging.getLogger(__name__) 
 14   
 15  from ndg.xacml.core.apply import Apply 
 16  from ndg.xacml.core.attributevalue import AttributeValue 
 17  from ndg.xacml.core.condition import Condition 
 18  from ndg.xacml.core.variablereference import VariableReference 
 19  from ndg.xacml.core.attributeselector import AttributeSelector 
 20  from ndg.xacml.core.attributedesignator import (SubjectAttributeDesignator, 
 21                                                  ResourceAttributeDesignator, 
 22                                                  ActionAttributeDesignator, 
 23                                                  EnvironmentAttributeDesignator) 
 24  from ndg.xacml.parsers import XMLParseError 
 25  from ndg.xacml.parsers.etree import QName, getElementChildren 
 26  from ndg.xacml.parsers.etree.reader import ETreeAbstractReader 
 27  from ndg.xacml.parsers.etree.factory import ReaderFactory 
 28   
 29   
 30 -class ApplyReader(ETreeAbstractReader): 
 31      '''ElementTree based XACML Apply type parser 
 32       
 33      @cvar FUNCTION_ELEMENT_LOCAL_NAME: XML local name for function element 
 34      @type FUNCTION_ELEMENT_LOCAL_NAME: string 
 35       
 36      @cvar VARIABLE_REFERENCE_ELEMENT_LOCAL_NAME: XML local name for variable 
 37      reference element 
 38      @type VARIABLE_REFERENCE_ELEMENT_LOCAL_NAME: string 
 39       
 40      @cvar TYPE: XACML class type that this reader will read values into 
 41      @type TYPE: abc.ABCMeta 
 42      ''' 
 43      TYPE = Apply 
 44       
 45      # These two are not currently implemented.  When an implementation is made 
 46      # the ELEMENT_LOCAL_NAME may be referenced from the native class rather than 
 47      # a class variable here 
 48      FUNCTION_ELEMENT_LOCAL_NAME = 'Function' 
 49      VARIABLE_REFERENCE_ELEMENT_LOCAL_NAME = 'VariableReference' 
 50       
 51 -    def __call__(self, obj, common): 
 52          """Parse Apply type object 
 53   
 54          @param obj: input object to parse 
 55          @type obj: ElementTree Element, or stream object 
 56          @return: ElementTree element 
 57          @rtype: xml.etree.Element 
 58          """ 
 59          elem = super(ApplyReader, self)._parse(obj) 
 60           
 61          xacmlType = self.__class__.TYPE 
 62          applyObj = xacmlType() 
 63           
 64          if QName.getLocalPart(elem.tag) != xacmlType.ELEMENT_LOCAL_NAME: 
 65              raise XMLParseError("No \"%s\" element found" %  
 66                                  xacmlType.ELEMENT_LOCAL_NAME) 
 67               
 68          # Unpack *required* attributes from top-level element 
 69          attributeValues = [] 
 70          for attributeName in (xacmlType.FUNCTION_ID_ATTRIB_NAME, ): 
 71              attributeValue = elem.attrib.get(attributeName) 
 72              if attributeValue is None: 
 73                  raise XMLParseError('No "%s" attribute found in "%s" ' 
 74                                      'element' % (attributeName, 
 75                                                   xacmlType.ELEMENT_LOCAL_NAME)) 
 76                   
 77              attributeValues.append(attributeValue)  
 78                      
 79          applyObj.functionId, = attributeValues 
 80           
 81          # Allow for any of the defined Expression sub-types in the child  
 82          # elements 
 83          for subElem in getElementChildren(elem): 
 84              localName = QName.getLocalPart(subElem.tag) 
 85              if localName == xacmlType.ELEMENT_LOCAL_NAME: 
 86                  applyObj.expressions.append(ApplyReader.parse(subElem, common)) 
 87                
 88              elif localName == AttributeValue.ELEMENT_LOCAL_NAME: 
 89                  AttributeValueReader = ReaderFactory.getReader(AttributeValue)  
 90                  applyObj.expressions.append(AttributeValueReader.parse(subElem, 
 91                                                                         common)) 
 92                    
 93              elif localName == SubjectAttributeDesignator.ELEMENT_LOCAL_NAME: 
 94                  SubjectAttributeDesignatorReader = ReaderFactory.getReader( 
 95                                                  SubjectAttributeDesignator) 
 96                  applyObj.expressions.append( 
 97                                  SubjectAttributeDesignatorReader.parse(subElem, 
 98                                                                         common)) 
 99                   
100              elif localName == ResourceAttributeDesignator.ELEMENT_LOCAL_NAME: 
101                  ResourceAttributeDesignatorReader = ReaderFactory.getReader( 
102                                                  ResourceAttributeDesignator) 
103                  applyObj.expressions.append( 
104                                  ResourceAttributeDesignatorReader.parse(subElem, 
105                                                                          common)) 
106                   
107              elif localName == EnvironmentAttributeDesignator.ELEMENT_LOCAL_NAME: 
108                  EnvironmentAttributeDesignatorReader = ReaderFactory.getReader( 
109                                                  EnvironmentAttributeDesignator) 
110                  applyObj.expressions.append( 
111                              EnvironmentAttributeDesignatorReader.parse(subElem, 
112                                                                         common)) 
113                   
114              elif localName == ActionAttributeDesignator.ELEMENT_LOCAL_NAME: 
115                  ActionAttributeDesignatorReader = ReaderFactory.getReader( 
116                                                  ActionAttributeDesignator) 
117                  applyObj.expressions.append( 
118                                  ActionAttributeDesignatorReader.parse(subElem, 
119                                                                        common)) 
120                   
121              elif localName == EnvironmentAttributeDesignator.ELEMENT_LOCAL_NAME: 
122                  EnvironmentAttributeDesignatorReader = ReaderFactory.getReader( 
123                                                  EnvironmentAttributeDesignator) 
124                  applyObj.expressions.append( 
125                              EnvironmentAttributeDesignatorReader.parse(subElem, 
126                                                                         common)) 
127                   
128              elif localName == AttributeSelector.ELEMENT_LOCAL_NAME: 
129                  AttributeSelectorReader = ReaderFactory.getReader( 
130                                                              AttributeSelector) 
131                  applyObj.expressions.append( 
132                                          AttributeSelectorReader.parse(subElem, 
133                                                                        common)) 
134               
135              elif localName == Condition.ELEMENT_LOCAL_NAME: 
136                  ConditionReader = ReaderFactory.getReader(Condition) 
137                  applyObj.expressions.append(ConditionReader.parse(subElem, 
138                                                                    common)) 
139                   
140              elif localName == self.__class__.FUNCTION_ELEMENT_LOCAL_NAME: 
141                  raise NotImplementedError('%r Apply sub-element not ' 
142                                            'implemented', localName) 
143               
144              elif (localName == VariableReference.ELEMENT_LOCAL_NAME): 
145                  raise NotImplementedError('%r Apply sub-element not ' 
146                                            'implemented', localName) 
147              else: 
148                  raise XMLParseError('%r Apply sub-element not recognised',  
149                                      localName) 
150      
151          return applyObj 
152