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

 1  """NDG XACML ElementTree reader module containing reader base class  
 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: reader.py 8010 2012-01-30 16:24:06Z rwilkinson $" 
12  import logging 
13  log = logging.getLogger(__name__) 
14   
15  from ndg.xacml import Config, importElementTree 
16  ElementTree = importElementTree() 
17   
18  from ndg.xacml.core import XacmlPolicyBase 
19  from ndg.xacml.parsers import AbstractReader 
20   
21   
22 -class ETreeAbstractReader(AbstractReader): 
23      """Base class for ElementTree implementation of XACML reader 
24       
25      @cvar TYPE: XACML type to instantiate from parsed object 
26      @type TYPE: NoneType""" 
27      TYPE = None 
28       
29 -    def __init__(self): 
30          """Initialise ElementTree namespace map for XACML 2.0 namespaces 
31           
32          @raise NotImplementedError: TYPE class variable must be set in a  
33          derived class 
34          """ 
35          if self.__class__.TYPE is None: 
36              raise NotImplementedError('No "TYPE" class variable set to specify ' 
37                                        'the XACML type to instantiate') 
38               
39          if not Config.use_lxml: 
40              self.__namespace_map_backup = ElementTree._namespace_map.copy() 
41              ElementTree._namespace_map[''] = XacmlPolicyBase.XACML_2_0_POLICY_NS 
42           
43 -    def __del__(self): 
44          """Restore original global namespace map""" 
45          if not Config.use_lxml: 
46              ElementTree._namespace_map = self.__namespace_map_backup 
47       
48      @staticmethod 
49 -    def _parse(obj): 
50          """Parse helper method 
51          @param obj: input object to parse 
52          @type obj: ElementTree Element, or stream object 
53          @return: ElementTree element 
54          @rtype: xml.etree.Element 
55          """ 
56          if ElementTree.iselement(obj): 
57              elem = obj 
58          else: 
59              # Treat as stream object 
60              elem = ElementTree.parse(obj).getroot() 
61               
62          return elem 
63            
64  # Set up new class as an abstract base itself              
65  AbstractReader.register(ETreeAbstractReader) 
66