Source Code for Module ndg.xacml.core.functions.v2.concatenate

 1  """NDG XACML concatenate functions module 
 2   
 3  NERC DataGrid 
 4  """ 
 5  __author__ = "R B Wilkinson" 
 6  __date__ = "06/02/12" 
 7  __copyright__ = "" 
 8  __license__ = "BSD - see LICENSE file in top-level directory" 
 9  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
10  __revision__ = '$Id$' 
11  from ndg.xacml.core.attributevalue import AttributeValueClassFactory 
12  from ndg.xacml.core.functions import (AbstractFunction, 
13                                        FunctionClassFactoryBase) 
14  from ndg.xacml.core.context.exceptions import (XacmlContextError, 
15                                                 XacmlContextTypeError) 
16   
17  attributeValueClassFactory = AttributeValueClassFactory() 
18   
19 -class ConcatenateBase(AbstractFunction): 
20      """Base class for XACML <type>-concatenate functions 
21   
22      @cvar FUNCTION_NS: namespace for this function 
23      @type FUNCTION_NS: string 
24      @cvar TYPE_REST: type for all but first argument 
25      @type TYPE_REST: type 
26      """ 
27      FUNCTION_NS = None 
28      TYPE_REST = attributeValueClassFactory( 
29                                      'http://www.w3.org/2001/XMLSchema#string') 
30   
31 -    def evaluate(self, *args): 
32          """Perform CONCATENATE function on the variable length argument list of 
33          elements 
34   
35          access_control-xacml-2.0-core-spec-os, Feb 2005 - A.3.9 String functions 
36          @param *args: variable number of arguments to be concatenated 
37          @type *args: ndg.xacml.utils.TypedList 
38   
39          @return: result of concatenating the inputs 
40          @rtype: type of first argument 
41          """ 
42          # This implementation works because both concatenate functions append 
43          # string values to a first argument, which may not be a string but is of 
44          # the same type as the return value. (The native type of the first 
45          # argument and return value must be basestring.) 
46          if len(args) < 2: 
47              # Must have at least two arguments. 
48              raise XacmlContextError( 
49                              "Argument list should have length two or greater") 
50          else: 
51              # Check types. 
52              if not isinstance(args[0], self.__class__.TYPE): 
53                  raise XacmlContextTypeError('Expecting %r derived type for ' 
54                                              'argument 1; got %r' % 
55                                              (self.__class__.TYPE, 
56                                               type(args[0]))) 
57              for n, arg in enumerate(args[1:]): 
58                  if not isinstance(arg, self.__class__.TYPE_REST): 
59                      raise XacmlContextTypeError('Expecting %r derived type for ' 
60                                                  'argument %d; got %r' % 
61                                                  (self.__class__.TYPE_REST, 
62                                                   n + 1, 
63                                                   type(arg))) 
64   
65              result = ''.join([a.value for a in args]) 
66          returnValue = self.__class__.TYPE(result) 
67          return returnValue 
68   
69   
70 -class FunctionClassFactory(FunctionClassFactoryBase): 
71      """Class Factory for *-concatenate XACML 2.0 function classes 
72   
73      @cvar FUNCTION_NAMES: concatenate function URNs 
74      @type FUNCTION_NAMES: tuple 
75   
76      @cvar FUNCTION_NS_SUFFIX: generic suffix for concatenate function URNs 
77      @type FUNCTION_NS_SUFFIX: string 
78   
79      @cvar FUNCTION_BASE_CLASS: base class for all concatenate classes 
80      @type FUNCTION_BASE_CLASS: type 
81      """ 
82      FUNCTION_NAMES = ( 
83          'urn:oasis:names:tc:xacml:2.0:function:string-concatenate', 
84          'urn:oasis:names:tc:xacml:2.0:function:url-string-concatenate' 
85      ) 
86      FUNCTION_NS_SUFFIX = '-concatenate' 
87      FUNCTION_BASE_CLASS = ConcatenateBase 
88