Skip to content
Navigation Menu
{{ message }}
forked from ipython/ipython
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathipstruct.py
More file actions
391 lines (317 loc) · 11.6 KB
/
Copy pathipstruct.py
File metadata and controls
391 lines (317 loc) · 11.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
# encoding: utf-8
"""A dict subclass that supports attribute style access.
Authors:
* Fernando Perez (original)
* Brian Granger (refactoring to a dict subclass)
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2011 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
__all__ = ['Struct']
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
class Struct(dict):
"""A dict subclass with attribute style access.
This dict subclass has a a few extra features:
* Attribute style access.
* Protection of class members (like keys, items) when using attribute
style access.
* The ability to restrict assignment to only existing keys.
* Intelligent merging.
* Overloaded operators.
"""
_allownew = True
def __init__(self, *args, **kw):
"""Initialize with a dictionary, another Struct, or data.
Parameters
----------
args : dict, Struct
Initialize with one dict or Struct
kw : dict
Initialize with key, value pairs.
Examples
--------
>>> s = Struct(a=10,b=30)
>>> s.a
10
>>> s.b
30
>>> s2 = Struct(s,c=30)
>>> sorted(s2.keys())
['a', 'b', 'c']
"""
object.__setattr__(self, '_allownew', True)
dict.__init__(self, *args, **kw)
def __setitem__(self, key, value):
"""Set an item with check for allownew.
Examples
--------
>>> s = Struct()
>>> s['a'] = 10
>>> s.allow_new_attr(False)
>>> s['a'] = 10
>>> s['a']
10
>>> try:
... s['b'] = 20
... except KeyError:
... print('this is not allowed')
...
this is not allowed
"""
if not self._allownew and key not in self:
raise KeyError(
"can't create new attribute %s when allow_new_attr(False)" % key)
dict.__setitem__(self, key, value)
def __setattr__(self, key, value):
"""Set an attr with protection of class members.
This calls :meth:`self.__setitem__` but convert :exc:`KeyError` to
:exc:`AttributeError`.
Examples
--------
>>> s = Struct()
>>> s.a = 10
>>> s.a
10
>>> try:
... s.get = 10
... except AttributeError:
... print("you can't set a class member")
...
you can't set a class member
"""
# If key is an str it might be a class member or instance var
if isinstance(key, str):
# I can't simply call hasattr here because it calls getattr, which
# calls self.__getattr__, which returns True for keys in
# self._data. But I only want keys in the class and in
# self.__dict__
if key in self.__dict__ or hasattr(Struct, key):
raise AttributeError(
'attr %s is a protected member of class Struct.' % key
)
try:
self.__setitem__(key, value)
except KeyError as e:
raise AttributeError(e)
def __getattr__(self, key):
"""Get an attr by calling :meth:`dict.__getitem__`.
Like :meth:`__setattr__`, this method converts :exc:`KeyError` to
:exc:`AttributeError`.
Examples
--------
>>> s = Struct(a=10)
>>> s.a
10
>>> type(s.get)
<... 'builtin_function_or_method'>
>>> try:
... s.b
... except AttributeError:
... print("I don't have that key")
...
I don't have that key
"""
try:
result = self[key]
except KeyError:
raise AttributeError(key)
else:
return result
def __iadd__(self, other):
"""s += s2 is a shorthand for s.merge(s2).
Examples
--------
>>> s = Struct(a=10,b=30)
>>> s2 = Struct(a=20,c=40)
>>> s += s2
>>> sorted(s.keys())
['a', 'b', 'c']
"""
self.merge(other)
return self
def __add__(self,other):
"""s + s2 -> New Struct made from s.merge(s2).
Examples
--------
>>> s1 = Struct(a=10,b=30)
>>> s2 = Struct(a=20,c=40)
>>> s = s1 + s2
>>> sorted(s.keys())
['a', 'b', 'c']
"""
sout = self.copy()
sout.merge(other)
return sout
def __sub__(self,other):
"""s1 - s2 -> remove keys in s2 from s1.
Examples
--------
>>> s1 = Struct(a=10,b=30)
>>> s2 = Struct(a=40)
>>> s = s1 - s2
>>> s
{'b': 30}
"""
sout = self.copy()
sout -= other
return sout
def __isub__(self,other):
"""Inplace remove keys from self that are in other.
Examples
--------
>>> s1 = Struct(a=10,b=30)
>>> s2 = Struct(a=40)
>>> s1 -= s2
>>> s1
{'b': 30}
"""
for k in other.keys():
if k in self:
del self[k]
return self
def __dict_invert(self, data):
"""Helper function for merge.
Takes a dictionary whose values are lists and returns a dict with
the elements of each list as keys and the original keys as values.
"""
outdict = {}
for k,lst in data.items():
if isinstance(lst, str):
lst = lst.split()
for entry in lst:
outdict[entry] = k
return outdict
def dict(self):
return self
def copy(self):
"""Return a copy as a Struct.
Examples
--------
>>> s = Struct(a=10,b=30)
>>> s2 = s.copy()
>>> type(s2) is Struct
True
"""
return Struct(dict.copy(self))
def hasattr(self, key):
"""hasattr function available as a method.
Implemented like has_key.
Examples
--------
>>> s = Struct(a=10)
>>> s.hasattr('a')
True
>>> s.hasattr('b')
False
>>> s.hasattr('get')
False
"""
return key in self
def allow_new_attr(self, allow = True):
"""Set whether new attributes can be created in this Struct.
This can be used to catch typos by verifying that the attribute user
tries to change already exists in this Struct.
"""
object.__setattr__(self, '_allownew', allow)
def merge(self, __loc_data__=None, __conflict_solve=None, **kw):
"""Merge two Structs with customizable conflict resolution.
This is similar to :meth:`update`, but much more flexible. First, a
dict is made from data+key=value pairs. When merging this dict with
the Struct S, the optional dictionary 'conflict' is used to decide
what to do.
If conflict is not given, the default behavior is to preserve any keys
with their current value (the opposite of the :meth:`update` method's
behavior).
Parameters
----------
__loc_data : dict, Struct
The data to merge into self
__conflict_solve : dict
The conflict policy dict. The keys are binary functions used to
resolve the conflict and the values are lists of strings naming
the keys the conflict resolution function applies to. Instead of
a list of strings a space separated string can be used, like
'a b c'.
kw : dict
Additional key, value pairs to merge in
Notes
-----
The `__conflict_solve` dict is a dictionary of binary functions which will be used to
solve key conflicts. Here is an example::
__conflict_solve = dict(
func1=['a','b','c'],
func2=['d','e']
)
In this case, the function :func:`func1` will be used to resolve
keys 'a', 'b' and 'c' and the function :func:`func2` will be used for
keys 'd' and 'e'. This could also be written as::
__conflict_solve = dict(func1='a b c',func2='d e')
These functions will be called for each key they apply to with the
form::
func1(self['a'], other['a'])
The return value is used as the final merged value.
As a convenience, merge() provides five (the most commonly needed)
pre-defined policies: preserve, update, add, add_flip and add_s. The
easiest explanation is their implementation::
preserve = lambda old,new: old
update = lambda old,new: new
add = lambda old,new: old + new
add_flip = lambda old,new: new + old # note change of order!
add_s = lambda old,new: old + ' ' + new # only for str!
You can use those four words (as strings) as keys instead
of defining them as functions, and the merge method will substitute
the appropriate functions for you.
For more complicated conflict resolution policies, you still need to
construct your own functions.
Examples
--------
This show the default policy:
>>> s = Struct(a=10,b=30)
>>> s2 = Struct(a=20,c=40)
>>> s.merge(s2)
>>> sorted(s.items())
[('a', 10), ('b', 30), ('c', 40)]
Now, show how to specify a conflict dict:
>>> s = Struct(a=10,b=30)
>>> s2 = Struct(a=20,b=40)
>>> conflict = {'update':'a','add':'b'}
>>> s.merge(s2,conflict)
>>> sorted(s.items())
[('a', 20), ('b', 70)]
"""
data_dict = dict(__loc_data__,**kw)
# policies for conflict resolution: two argument functions which return
# the value that will go in the new struct
preserve = lambda old,new: old
update = lambda old,new: new
add = lambda old,new: old + new
add_flip = lambda old,new: new + old # note change of order!
add_s = lambda old,new: old + ' ' + new
# default policy is to keep current keys when there's a conflict
conflict_solve = dict.fromkeys(self, preserve)
# the conflict_solve dictionary is given by the user 'inverted': we
# need a name-function mapping, it comes as a function -> names
# dict. Make a local copy (b/c we'll make changes), replace user
# strings for the three builtin policies and invert it.
if __conflict_solve:
inv_conflict_solve_user = __conflict_solve.copy()
for name, func in [('preserve',preserve), ('update',update),
('add',add), ('add_flip',add_flip),
('add_s',add_s)]:
if name in inv_conflict_solve_user.keys():
inv_conflict_solve_user[func] = inv_conflict_solve_user[name]
del inv_conflict_solve_user[name]
conflict_solve.update(self.__dict_invert(inv_conflict_solve_user))
for key in data_dict:
if key not in self:
self[key] = data_dict[key]
else:
self[key] = conflict_solve[key](self[key],data_dict[key])
You can’t perform that action at this time.