ndg.xacml.utils

1 """Utilities package for NDG XACML 2 3 NERC DataGrid 4 """ 5 __author__ = "P J Kershaw" 6 __date__ = "02/04/09" 7 __copyright__ = "" 8 __license__ = "BSD - see LICENSE file in top-level directory" 9 __contact__ = "Philip.Kershaw@stfc.ac.uk" 10 __revision__ = '$Id: __init__.py 7324 2010-08-13 14:20:05Z pjkersha $' 11 import UserDict 12 13 # Interpret a string as a boolean 14 str2Bool = lambda str: str.lower() in ("yes", "true", "t", "1") 15

16 -class UniqList(list):

17 """Extended version of list type to enable a list with unique items. 18 If an item is added that is already present then it is silently omitted 19 from the list 20 """ 21

22 - def extend(self, iter):

23 """Extend a list with input iterable 24 @param iter: iterable object 25 @type iter: iterable type 26 """ 27 return super(UniqList, self).extend([i for i in iter if i not in self])

28

29 - def __iadd__(self, iter):

30 """Extend a list with input iterable 31 @param iter: iterable object 32 @type iter: iterable type 33 """ 34 return super(UniqList, self).__iadd__([i for i in iter 35 if i not in self])

36

37 - def append(self, item):

38 """Add an item to the list 39 @param item: item to append to list 40 @type item: any 41 """ 42 for i in self: 43 if i == item: 44 return None 45 46 return super(UniqList, self).append(item)

47 48

49 -class TypedList(list):

50 """Extend list type to enabled only items of a given type. Supports 51 any type where the array type in the Standard Library is restricted to 52 only limited set of primitive types 53 """ 54

55 - def __init__(self, elementType, *arg, **kw):

56 """ 57 @type elementType: type/tuple 58 @param elementType: object type or types which the list is allowed to 59 contain. If more than one type, pass as a tuple 60 """ 61 self.__elementType = elementType 62 super(TypedList, self).__init__(*arg, **kw)

63

64 - def __repr__(self):

65 """@return: represent instance giving type information about the 66 elements 67 @rtype: string 68 """ 69 return "%r type: %s" % (self.__elementType, 70 super(TypedList, self).__repr__())

71

72 - def _getElementType(self):

73 """@return: the element type for this list 74 @rtype: type 75 """ 76 return self.__elementType

77 78 elementType = property(fget=_getElementType, 79 doc="The allowed type or types for list elements") 80

81 - def extend(self, iter):

82 """Extend a list with input iterable 83 @param iter: iterable object 84 @type iter: iterable type 85 @raise TypeError: input item doesn't match list type 86 """ 87 for i in iter: 88 if not isinstance(i, self.__elementType): 89 raise TypeError("List items must be of type %s" % 90 (self.__elementType,)) 91 92 return super(TypedList, self).extend(iter)

93

94 - def __iadd__(self, iter):

95 """Extend a list with input iterable 96 @param iter: iterable object 97 @type iter: iterable type 98 @raise TypeError: input item doesn't match list type 99 """ 100 for i in iter: 101 if not isinstance(i, self.__elementType): 102 raise TypeError("List items must be of type %s" % 103 (self.__elementType,)) 104 105 return super(TypedList, self).__iadd__(iter)

106

107 - def append(self, item):

108 """Add an item to the list 109 @param iter: iterable object 110 @type iter: iterable type 111 @raise TypeError: input item doesn't match list type 112 """ 113 if not isinstance(item, self.__elementType): 114 raise TypeError("List items must be of type %s" % 115 (self.__elementType,)) 116 117 return super(TypedList, self).append(item)

118 119

120 -class RestrictedKeyNamesDict(dict):

121 """Utility class for holding a constrained list of key names 122 """ 123

124 - def __init__(self, *arg, **kw):

125 """Alter standard dict() initialisation to fix key names set at 126 initialisation 127 """ 128 super(RestrictedKeyNamesDict, self).__init__(*arg, **kw) 129 self.__keyNames = self.keys()

130

131 - def __setitem__(self, key, val):

132 """@param key: key for item to set 133 @type key: any 134 @param val: value to set for this key 135 @type val: any 136 """ 137 if key not in self.__keyNames: 138 raise KeyError('Key name %r not recognised. Valid key names ' 139 'are: %r' % (key, self.__keyNames)) 140 141 dict.__setitem__(self, key, val)

142

143 - def update(self, d, **kw):

144 """@param d: dictionary to update from 145 @type d: dict 146 @param kw: keywords to update dictionary with 147 @type kw: dict 148 """ 149 for dictArg in (d, kw): 150 for k in dictArg: 151 if k not in self.__keyNames: 152 raise KeyError('Key name "%s" not recognised. Valid ' 153 'key names are: %s' % 154 self.__keyNames) 155 156 dict.update(self, d, **kw)

157 158 159 _isIterable = lambda obj: getattr(obj, '__iter__', False) 160 161

162 -class VettedDict(UserDict.DictMixin):

163 """Enforce custom checking on keys and items before addition to a 164 dictionary 165 """ 166

167 - def __init__(self, *args):

168 """Initialise setting the allowed type or types for keys and items 169 170 @param args: two arguments: the first is a callable which filters for 171 permissable keys in this dict, the second sets the type or list of 172 types permissable for items in this dict 173 @type args: tuple 174 """ 175 if len(args) != 2: 176 raise TypeError('__init__() takes 2 arguments, KeyFilter and ' 177 'valueFilter (%d given)' % len(args)) 178 179 # Validation of inputs 180 for arg, argName in zip(args, ('KeyFilter', 'valueFilter')): 181 if not callable(arg): 182 raise TypeError('Expecting callable for %r input; got %r' % 183 (argName, type(arg))) 184 185 self.__KeyFilter, self.__valueFilter = args 186 187 self.__map = {}

188

189 - def _verifyKeyValPair(self, key, val):

190 """Check given key value pair and return False if they should be 191 filtered out. Filter functions may also raise an exception if they 192 wish to abort completely 193 194 @param key: dict key to check 195 @type key: basestring 196 @param val: value to check 197 @type val: any 198 """ 199 if not self.__KeyFilter(key): 200 return False 201 202 elif not self.__valueFilter(val): 203 return False 204 205 else: 206 return True

207

208 - def __setitem__(self, key, val):

209 """Enforce type checking when setting new items 210 211 @param key: key for item to set 212 @type key: any 213 @param val: value to set for this key 214 @type val: any 215 """ 216 if self._verifyKeyValPair(key, val): 217 self.__map[key] = val

218

219 - def __getitem__(self, key):

220 """Provide implementation for getting items 221 @param key: key for item to retrieve 222 @type key: any 223 @return: value for input key 224 @rtype: any 225 """ 226 if key not in self.__map: 227 raise KeyError('%r key not found in dict' % key) 228 229 return self.__map[key]

230

231 - def get(self, key, *arg):

232 """Provide implementation of get item with default 233 234 @param key: key for item to retrieve 235 @type key: any 236 @param arg: use to set a default argument 237 @type arg: tuple 238 """ 239 if key in self.__map: 240 return self.__map[key] 241 242 elif len(arg) > 1: 243 # Default value set 244 return arg[1] 245 else: 246 return None

247

248 - def __repr__(self):

249 return repr(self.__map)

250

251 - def keys(self):

252 return self.__map.keys()

253

254 - def items(self):

255 return self.__map.items()

256

257 - def values(self):

258 return self.__map.values()

259

260 - def __contains__(self, val):

261 return self.__map.__contains__(val)

262

Source Code for Package ndg.xacml.utils