1
|
# Dictionaries
|
2
|
|
3
|
import itertools
|
4
|
import UserDict
|
5
|
|
6
|
def is_dict(value): return hasattr(value, 'keys')
|
7
|
|
8
|
class DictProxy(UserDict.DictMixin):
|
9
|
'''A proxy that forwards all accesses to an inner dict.'''
|
10
|
|
11
|
def __init__(self, inner=None):
|
12
|
if inner == None: inner = {}
|
13
|
self.inner = inner
|
14
|
|
15
|
def keys(self): return self.inner.keys()
|
16
|
|
17
|
def __getitem__(self, key): return self.inner[key]
|
18
|
|
19
|
def __setitem__(self, key, value): self.inner[key] = value
|
20
|
|
21
|
class KeyExistsError(KeyError):
|
22
|
def __init__(self, key):
|
23
|
KeyError.__init__(self, key)
|
24
|
|
25
|
self.key = key
|
26
|
|
27
|
class OnceOnlyDict(DictProxy):
|
28
|
'''A dict that only allows each key to be assigned once (no overwriting).'''
|
29
|
|
30
|
def __setitem__(self, key, value):
|
31
|
if key in self.inner: raise KeyExistsError(key)
|
32
|
DictProxy.__setitem__(self, key, value)
|
33
|
|
34
|
class IdCompared:
|
35
|
'''A value that's compared using `is` instead of ==.
|
36
|
Do not use this for strings as they are interned, causing `is` to have the
|
37
|
same meaning as ==.
|
38
|
'''
|
39
|
|
40
|
def __init__(self, value): self.value = value
|
41
|
|
42
|
def __eq__(self, other):
|
43
|
return (other != None and other.__class__ == self.__class__
|
44
|
and other.value is self.value)
|
45
|
|
46
|
def __hash__(self): return id(self.value)
|
47
|
|
48
|
class IdDict(dict):
|
49
|
'''A dict that stores objects by id()'''
|
50
|
|
51
|
def add(self, *values):
|
52
|
for value in values: self[id(value)] = value
|
53
|
return self
|
54
|
|
55
|
def add_vars(self, vars_): return self.add(*vars_.values())
|
56
|
|
57
|
class MergeDict:
|
58
|
'''A dict that checks each of several dicts'''
|
59
|
|
60
|
def __init__(self, *dicts): self.dicts = dicts
|
61
|
|
62
|
def __getitem__(self, key):
|
63
|
for dict_ in self.dicts:
|
64
|
try: return dict_[key]
|
65
|
except KeyError: pass
|
66
|
raise # reraise last KeyError
|
67
|
|
68
|
class AttrsDictView:
|
69
|
'''A dict view of an object's attributes
|
70
|
@pre If you want __iter__() to work, value must have a __dict__
|
71
|
'''
|
72
|
|
73
|
def __init__(self, value): self.value = value
|
74
|
|
75
|
def __iter__(self): return iter(self.value.__dict__)
|
76
|
|
77
|
def __getitem__(self, key): return getattr(self.value, key)
|
78
|
|
79
|
import util
|
80
|
|
81
|
def make_hashable(value):
|
82
|
if isinstance(value, list): value = tuple(value)
|
83
|
elif isinstance(value, dict): value = util.NamedTuple(**value)
|
84
|
return value
|
85
|
|
86
|
def join(dict0, dict1):
|
87
|
'''Joins dict0 (A->B mapping) to dict1 (B->C mapping) SQL-style.
|
88
|
If a value in dict0 has no key in dict1, uses the value itself.
|
89
|
'''
|
90
|
new_dict = {}
|
91
|
for out, in_ in dict0.iteritems():
|
92
|
new_dict[out] = dict1.get(in_, in_) # use in_ if no match found
|
93
|
return new_dict
|