Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/IPython/utils/ipstruct.py: 26%

1# encoding: utf-8

2"""A dict subclass that supports attribute style access.

4Authors:

6* Fernando Perez (original)

7* Brian Granger (refactoring to a dict subclass)

8"""

10#-----------------------------------------------------------------------------

12#

13# Distributed under the terms of the BSD License. The full license is in

14# the file COPYING, distributed as part of this software.

15#-----------------------------------------------------------------------------

17#-----------------------------------------------------------------------------

18# Imports

19#-----------------------------------------------------------------------------

21__all__ = ['Struct']

23#-----------------------------------------------------------------------------

24# Code

25#-----------------------------------------------------------------------------

28class Struct(dict):

29 """A dict subclass with attribute style access.

31 This dict subclass has a a few extra features:

33 * Attribute style access.

34 * Protection of class members (like keys, items) when using attribute

35 style access.

36 * The ability to restrict assignment to only existing keys.

37 * Intelligent merging.

38 * Overloaded operators.

39 """

40 _allownew = True

41 def __init__(self, *args, **kw):

42 """Initialize with a dictionary, another Struct, or data.

44 Parameters

45 ----------

46 *args : dict, Struct

47 Initialize with one dict or Struct

48 **kw : dict

49 Initialize with key, value pairs.

51 Examples

52 --------

53 >>> s = Struct(a=10,b=30)

54 >>> s.a

55 10

56 >>> s.b

57 30

58 >>> s2 = Struct(s,c=30)

59 >>> sorted(s2.keys())

60 ['a', 'b', 'c']

61 """

62 object.__setattr__(self, '_allownew', True)

63 dict.__init__(self, *args, **kw)

65 def __setitem__(self, key, value):

66 """Set an item with check for allownew.

68 Examples

69 --------

70 >>> s = Struct()

71 >>> s['a'] = 10

72 >>> s.allow_new_attr(False)

73 >>> s['a'] = 10

74 >>> s['a']

75 10

76 >>> try:

77 ... s['b'] = 20

78 ... except KeyError:

79 ... print('this is not allowed')

80 ...

81 this is not allowed

82 """

83 if not self._allownew and key not in self:

84 raise KeyError(

85 "can't create new attribute %s when allow_new_attr(False)" % key)

86 dict.__setitem__(self, key, value)

88 def __setattr__(self, key, value):

89 """Set an attr with protection of class members.

91 This calls :meth:`self.__setitem__` but convert :exc:`KeyError` to

92 :exc:`AttributeError`.

94 Examples

95 --------

96 >>> s = Struct()

97 >>> s.a = 10

98 >>> s.a

99 10

100 >>> try:

101 ... s.get = 10

102 ... except AttributeError:

103 ... print("you can't set a class member")

104 ...

105 you can't set a class member

106 """

107 # If key is an str it might be a class member or instance var

108 if isinstance(key, str):

109 # I can't simply call hasattr here because it calls getattr, which

110 # calls self.__getattr__, which returns True for keys in

111 # self._data. But I only want keys in the class and in

112 # self.__dict__

113 if key in self.__dict__ or hasattr(Struct, key):

114 raise AttributeError(

115 'attr %s is a protected member of class Struct.' % key

116 )

117 try:

118 self.__setitem__(key, value)

119 except KeyError as e:

120 raise AttributeError(e) from e

121

122 def __getattr__(self, key):

123 """Get an attr by calling :meth:`dict.__getitem__`.

124

125 Like :meth:`__setattr__`, this method converts :exc:`KeyError` to

126 :exc:`AttributeError`.

127

128 Examples

129 --------

130 >>> s = Struct(a=10)

131 >>> s.a

132 10

133 >>> type(s.get)

134 <...method'>

135 >>> try:

136 ... s.b

137 ... except AttributeError:

138 ... print("I don't have that key")

139 ...

140 I don't have that key

141 """

142 try:

143 result = self[key]

144 except KeyError as e:

145 raise AttributeError(key) from e

146 else:

147 return result

148

149 def __iadd__(self, other):

150 """s += s2 is a shorthand for s.merge(s2).

151

152 Examples

153 --------

154 >>> s = Struct(a=10,b=30)

155 >>> s2 = Struct(a=20,c=40)

156 >>> s += s2

157 >>> sorted(s.keys())

158 ['a', 'b', 'c']

159 """

160 self.merge(other)

161 return self

162

163 def __add__(self,other):

164 """s + s2 -> New Struct made from s.merge(s2).

165

166 Examples

167 --------

168 >>> s1 = Struct(a=10,b=30)

169 >>> s2 = Struct(a=20,c=40)

170 >>> s = s1 + s2

171 >>> sorted(s.keys())

172 ['a', 'b', 'c']

173 """

174 sout = self.copy()

175 sout.merge(other)

176 return sout

177

178 def __sub__(self,other):

179 """s1 - s2 -> remove keys in s2 from s1.

180

181 Examples

182 --------

183 >>> s1 = Struct(a=10,b=30)

184 >>> s2 = Struct(a=40)

185 >>> s = s1 - s2

186 >>> s

187 {'b': 30}

188 """

189 sout = self.copy()

190 sout -= other

191 return sout

192

193 def __isub__(self,other):

194 """Inplace remove keys from self that are in other.

195

196 Examples

197 --------

198 >>> s1 = Struct(a=10,b=30)

199 >>> s2 = Struct(a=40)

200 >>> s1 -= s2

201 >>> s1

202 {'b': 30}

203 """

204 for k in other.keys():

205 if k in self:

206 del self[k]

207 return self

208

209 def __dict_invert(self, data):

210 """Helper function for merge.

211

212 Takes a dictionary whose values are lists and returns a dict with

213 the elements of each list as keys and the original keys as values.

214 """

215 outdict = {}

216 for k,lst in data.items():

217 if isinstance(lst, str):

218 lst = lst.split()

219 for entry in lst:

220 outdict[entry] = k

221 return outdict

222

223 def dict(self):

224 return self

225

226 def copy(self):

227 """Return a copy as a Struct.

228

229 Examples

230 --------

231 >>> s = Struct(a=10,b=30)

232 >>> s2 = s.copy()

233 >>> type(s2) is Struct

234 True

235 """

236 return Struct(dict.copy(self))

237

238 def hasattr(self, key):

239 """hasattr function available as a method.

240

241 Implemented like has_key.

242

243 Examples

244 --------

245 >>> s = Struct(a=10)

246 >>> s.hasattr('a')

247 True

248 >>> s.hasattr('b')

249 False

250 >>> s.hasattr('get')

251 False

252 """

253 return key in self

254

255 def allow_new_attr(self, allow = True):

256 """Set whether new attributes can be created in this Struct.

257

258 This can be used to catch typos by verifying that the attribute user

259 tries to change already exists in this Struct.

260 """

261 object.__setattr__(self, '_allownew', allow)

262

263 def merge(self, __loc_data__=None, __conflict_solve=None, **kw):

264 """Merge two Structs with customizable conflict resolution.

265

266 This is similar to :meth:`update`, but much more flexible. First, a

267 dict is made from data+key=value pairs. When merging this dict with

268 the Struct S, the optional dictionary 'conflict' is used to decide

269 what to do.

270

271 If conflict is not given, the default behavior is to preserve any keys

272 with their current value (the opposite of the :meth:`update` method's

273 behavior).

274

275 Parameters

276 ----------

277 __loc_data__ : dict, Struct

278 The data to merge into self

279 __conflict_solve : dict

280 The conflict policy dict. The keys are binary functions used to

281 resolve the conflict and the values are lists of strings naming

282 the keys the conflict resolution function applies to. Instead of

283 a list of strings a space separated string can be used, like

284 'a b c'.

285 **kw : dict

286 Additional key, value pairs to merge in

287

288 Notes

289 -----

290 The `__conflict_solve` dict is a dictionary of binary functions which will be used to

291 solve key conflicts. Here is an example::

292

293 __conflict_solve = dict(

294 func1=['a','b','c'],

295 func2=['d','e']

296 )

297

298 In this case, the function :func:`func1` will be used to resolve

299 keys 'a', 'b' and 'c' and the function :func:`func2` will be used for

300 keys 'd' and 'e'. This could also be written as::

301

302 __conflict_solve = dict(func1='a b c',func2='d e')

303

304 These functions will be called for each key they apply to with the

305 form::

306

307 func1(self['a'], other['a'])

308

309 The return value is used as the final merged value.

310

311 As a convenience, merge() provides five (the most commonly needed)

312 pre-defined policies: preserve, update, add, add_flip and add_s. The

313 easiest explanation is their implementation::

314

315 preserve = lambda old,new: old

316 update = lambda old,new: new

317 add = lambda old,new: old + new

318 add_flip = lambda old,new: new + old # note change of order!

319 add_s = lambda old,new: old + ' ' + new # only for str!

320

321 You can use those four words (as strings) as keys instead

322 of defining them as functions, and the merge method will substitute

323 the appropriate functions for you.

324

325 For more complicated conflict resolution policies, you still need to

326 construct your own functions.

327

328 Examples

329 --------

330 This show the default policy:

331

332 >>> s = Struct(a=10,b=30)

333 >>> s2 = Struct(a=20,c=40)

334 >>> s.merge(s2)

335 >>> sorted(s.items())

336 [('a', 10), ('b', 30), ('c', 40)]

337

338 Now, show how to specify a conflict dict:

339

340 >>> s = Struct(a=10,b=30)

341 >>> s2 = Struct(a=20,b=40)

342 >>> conflict = {'update':'a','add':'b'}

343 >>> s.merge(s2,conflict)

344 >>> sorted(s.items())

345 [('a', 20), ('b', 70)]

346 """

347

348 data_dict = dict(__loc_data__,**kw)

349

350 # policies for conflict resolution: two argument functions which return

351 # the value that will go in the new struct

352 preserve = lambda old,new: old

353 update = lambda old,new: new

354 add = lambda old,new: old + new

355 add_flip = lambda old,new: new + old # note change of order!

356 add_s = lambda old,new: old + ' ' + new

357

358 # default policy is to keep current keys when there's a conflict

359 conflict_solve = dict.fromkeys(self, preserve)

360

361 # the conflict_solve dictionary is given by the user 'inverted': we

362 # need a name-function mapping, it comes as a function -> names

363 # dict. Make a local copy (b/c we'll make changes), replace user

364 # strings for the three builtin policies and invert it.

365 if __conflict_solve:

366 inv_conflict_solve_user = __conflict_solve.copy()

367 for name, func in [('preserve',preserve), ('update',update),

368 ('add',add), ('add_flip',add_flip),

369 ('add_s',add_s)]:

370 if name in inv_conflict_solve_user.keys():

371 inv_conflict_solve_user[func] = inv_conflict_solve_user[name]

372 del inv_conflict_solve_user[name]

373 conflict_solve.update(self.__dict_invert(inv_conflict_solve_user))

374 for key in data_dict:

375 if key not in self:

376 self[key] = data_dict[key]

377 else:

378 self[key] = conflict_solve[key](self[key],data_dict[key])

379