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
|
"""Helper to provide extensibility for pickle/cPickle.
This is only useful to add pickle support for extension types defined in
C, not for instances of user-defined classes.
"""
from types import ClassType as _ClassType
__all__ = ["pickle", "constructor",
"add_extension", "remove_extension", "clear_extension_cache"]
dispatch_table = {}
def pickle(ob_type, pickle_function, constructor_ob=None):
if type(ob_type) is _ClassType:
raise TypeError("copy_reg is not intended for use with classes")
if not callable(pickle_function):
raise TypeError("reduction functions must be callable")
dispatch_table[ob_type] = pickle_function
if constructor_ob is not None:
constructor(constructor_ob)
def constructor(object):
if not callable(object):
raise TypeError("constructors must be callable")
# Example: provide pickling support for complex numbers.
def pickle_complex(c):
return complex, (c.real, c.imag)
pickle(type(1j), pickle_complex, complex)
# Support for pickling new-style objects
def _reconstructor(cls, base, state):
if base is object:
obj = object.__new__(cls)
else:
obj = base.__new__(cls, state)
base.__init__(obj, state)
return obj
_HEAPTYPE = 1<<9
def _reduce(self):
for base in self.__class__.__mro__:
if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE:
break
else:
base = object # not really reachable
if base is object:
state = None
else:
if base is self.__class__:
raise TypeError, "can't pickle %s objects" % base.__name__
state = base(self)
args = (self.__class__, base, state)
try:
getstate = self.__getstate__
except AttributeError:
if getattr(self, "__slots__", None):
raise TypeError("a class that defines __slots__ without "
"defining __getstate__ cannot be pickled")
try:
dict = self.__dict__
except AttributeError:
dict = None
else:
dict = getstate()
if dict:
return _reconstructor, args, dict
else:
return _reconstructor, args
# A better version of _reduce, used by copy and pickle protocol 2
def __newobj__(cls, *args):
return cls.__new__(cls, *args)
def _better_reduce(obj):
cls = obj.__class__
getnewargs = getattr(obj, "__getnewargs__", None)
if getnewargs:
args = getnewargs()
else:
args = ()
getstate = getattr(obj, "__getstate__", None)
if getstate:
state = getstate()
else:
state = getattr(obj, "__dict__", None)
names = _slotnames(cls)
if names:
slots = {}
nil = []
for name in names:
value = getattr(obj, name, nil)
if value is not nil:
slots[name] = value
if slots:
state = (state, slots)
listitems = dictitems = None
if isinstance(obj, list):
listitems = iter(obj)
elif isinstance(obj, dict):
dictitems = obj.iteritems()
return __newobj__, (cls,) + args, state, listitems, dictitems
def _slotnames(cls):
"""Return a list of slot names for a given class.
This needs to find slots defined by the class and its bases, so we
can't simply return the __slots__ attribute. We must walk down
the Method Resolution Order and concatenate the __slots__ of each
class found there. (This assumes classes don't modify their
__slots__ attribute to misrepresent their slots after the class is
defined.)
"""
# Get the value from a cache in the class if possible
names = cls.__dict__.get("__slotnames__")
if names is not None:
return names
# Not cached -- calculate the value
names = []
if not hasattr(cls, "__slots__"):
# This class has no slots
pass
else:
# Slots found -- gather slot names from all base classes
for c in cls.__mro__:
if "__slots__" in c.__dict__:
names += [name for name in c.__dict__["__slots__"]
if name not in ("__dict__", "__weakref__")]
# Cache the outcome in the class if at all possible
try:
cls.__slotnames__ = names
except:
pass # But don't die if we can't
return names
# A registry of extension codes. This is an ad-hoc compression
# mechanism. Whenever a global reference to <module>, <name> is about
# to be pickled, the (<module>, <name>) tuple is looked up here to see
# if it is a registered extension code for it. Extension codes are
# universal, so that the meaning of a pickle does not depend on
# context. (There are also some codes reserved for local use that
# don't have this restriction.) Codes are positive ints; 0 is
# reserved.
_extension_registry = {} # key -> code
_inverted_registry = {} # code -> key
_extension_cache = {} # code -> object
# Don't ever rebind those names: cPickle grabs a reference to them when
# it's initialized, and won't see a rebinding.
def add_extension(module, name, code):
"""Register an extension code."""
code = int(code)
if not 1 <= code <= 0x7fffffff:
raise ValueError, "code out of range"
key = (module, name)
if (_extension_registry.get(key) == code and
_inverted_registry.get(code) == key):
return # Redundant registrations are benign
if key in _extension_registry:
raise ValueError("key %s is already registered with code %s" %
(key, _extension_registry[key]))
if code in _inverted_registry:
raise ValueError("code %s is already in use for key %s" %
(code, _inverted_registry[code]))
_extension_registry[key] = code
_inverted_registry[code] = key
def remove_extension(module, name, code):
"""Unregister an extension code. For testing only."""
key = (module, name)
if (_extension_registry.get(key) != code or
_inverted_registry.get(code) != key):
raise ValueError("key %s is not registered with code %s" %
(key, code))
del _extension_registry[key]
del _inverted_registry[code]
if code in _extension_cache:
del _extension_cache[code]
def clear_extension_cache():
_extension_cache.clear()
# Standard extension code assignments
# Reserved ranges
# First Last Count Purpose
# 1 127 127 Reserved for Python standard library
# 128 191 64 Reserved for Zope
# 192 239 48 Reserved for 3rd parties
# 240 255 16 Reserved for private use (will never be assigned)
# 256 Inf Inf Reserved for future assignment
# Extension codes are assigned by the Python Software Foundation.
|
