Source

cpython-withatomic / Lib / copy.py

The branch '2.3' does not exist.
  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
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
"""Generic (shallow and deep) copying operations.

Interface summary:

        import copy

        x = copy.copy(y)        # make a shallow copy of y
        x = copy.deepcopy(y)    # make a deep copy of y

For module specific errors, copy.Error is raised.

The difference between shallow and deep copying is only relevant for
compound objects (objects that contain other objects, like lists or
class instances).

- A shallow copy constructs a new compound object and then (to the
  extent possible) inserts *the same objects* into in that the
  original contains.

- A deep copy constructs a new compound object and then, recursively,
  inserts *copies* into it of the objects found in the original.

Two problems often exist with deep copy operations that don't exist
with shallow copy operations:

 a) recursive objects (compound objects that, directly or indirectly,
    contain a reference to themselves) may cause a recursive loop

 b) because deep copy copies *everything* it may copy too much, e.g.
    administrative data structures that should be shared even between
    copies

Python's deep copy operation avoids these problems by:

 a) keeping a table of objects already copied during the current
    copying pass

 b) letting user-defined classes override the copying operation or the
    set of components copied

This version does not copy types like module, class, function, method,
nor stack trace, stack frame, nor file, socket, window, nor array, nor
any similar types.

Classes can use the same interfaces to control copying that they use
to control pickling: they can define methods called __getinitargs__(),
__getstate__() and __setstate__().  See the documentation for module
"pickle" for information on these methods.
"""

import types
from copy_reg import dispatch_table

class Error(Exception):
    pass
error = Error   # backward compatibility

try:
    from org.python.core import PyStringMap
except ImportError:
    PyStringMap = None

__all__ = ["Error", "copy", "deepcopy"]

def copy(x):
    """Shallow copy operation on arbitrary Python objects.

    See the module's __doc__ string for more info.
    """

    cls = type(x)

    copier = _copy_dispatch.get(cls)
    if copier:
        return copier(x)

    copier = getattr(cls, "__copy__", None)
    if copier:
        return copier(x)

    reductor = dispatch_table.get(cls)
    if reductor:
        rv = reductor(x)
    else:
        reductor = getattr(x, "__reduce_ex__", None)
        if reductor:
            rv = reductor(2)
        else:
            reductor = getattr(x, "__reduce__", None)
            if reductor:
                rv = reductor()
            else:
                raise Error("un(shallow)copyable object of type %s" % cls)

    return _reconstruct(x, rv, 0)


_copy_dispatch = d = {}

def _copy_atomic(x):
    return x
d[types.NoneType] = _copy_atomic
d[types.IntType] = _copy_atomic
d[types.LongType] = _copy_atomic
d[types.FloatType] = _copy_atomic
d[types.BooleanType] = _copy_atomic
try:
    d[types.ComplexType] = _copy_atomic
except AttributeError:
    pass
d[types.StringType] = _copy_atomic
try:
    d[types.UnicodeType] = _copy_atomic
except AttributeError:
    pass
try:
    d[types.CodeType] = _copy_atomic
except AttributeError:
    pass
d[types.TypeType] = _copy_atomic
d[types.XRangeType] = _copy_atomic
d[types.ClassType] = _copy_atomic
d[types.BuiltinFunctionType] = _copy_atomic

def _copy_list(x):
    return x[:]
d[types.ListType] = _copy_list

def _copy_tuple(x):
    return x[:]
d[types.TupleType] = _copy_tuple

def _copy_dict(x):
    return x.copy()
d[types.DictionaryType] = _copy_dict
if PyStringMap is not None:
    d[PyStringMap] = _copy_dict

def _copy_inst(x):
    if hasattr(x, '__copy__'):
        return x.__copy__()
    if hasattr(x, '__getinitargs__'):
        args = x.__getinitargs__()
        y = x.__class__(*args)
    else:
        y = _EmptyClass()
        y.__class__ = x.__class__
    if hasattr(x, '__getstate__'):
        state = x.__getstate__()
    else:
        state = x.__dict__
    if hasattr(y, '__setstate__'):
        y.__setstate__(state)
    else:
        y.__dict__.update(state)
    return y
d[types.InstanceType] = _copy_inst

del d

def deepcopy(x, memo=None, _nil=[]):
    """Deep copy operation on arbitrary Python objects.

    See the module's __doc__ string for more info.
    """

    if memo is None:
        memo = {}

    d = id(x)
    y = memo.get(d, _nil)
    if y is not _nil:
        return y

    cls = type(x)

    copier = _deepcopy_dispatch.get(cls)
    if copier:
        y = copier(x, memo)
    else:
        try:
            issc = issubclass(cls, type)
        except TypeError: # cls is not a class (old Boost; see SF #502085)
            issc = 0
        if issc:
            y = _deepcopy_atomic(x, memo)
        else:
            copier = getattr(x, "__deepcopy__", None)
            if copier:
                y = copier(memo)
            else:
                reductor = dispatch_table.get(cls)
                if reductor:
                    rv = reductor(x)
                else:
                    reductor = getattr(x, "__reduce_ex__", None)
                    if reductor:
                        rv = reductor(2)
                    else:
                        reductor = getattr(x, "__reduce__", None)
                        if reductor:
                            rv = reductor()
                        else:
                            raise Error(
                                "un(deep)copyable object of type %s" % cls)
                y = _reconstruct(x, rv, 1, memo)

    memo[d] = y
    _keep_alive(x, memo) # Make sure x lives at least as long as d
    return y

_deepcopy_dispatch = d = {}

def _deepcopy_atomic(x, memo):
    return x
d[types.NoneType] = _deepcopy_atomic
d[types.IntType] = _deepcopy_atomic
d[types.LongType] = _deepcopy_atomic
d[types.FloatType] = _deepcopy_atomic
d[types.BooleanType] = _deepcopy_atomic
try:
    d[types.ComplexType] = _deepcopy_atomic
except AttributeError:
    pass
d[types.StringType] = _deepcopy_atomic
try:
    d[types.UnicodeType] = _deepcopy_atomic
except AttributeError:
    pass
try:
    d[types.CodeType] = _deepcopy_atomic
except AttributeError:
    pass
d[types.TypeType] = _deepcopy_atomic
d[types.XRangeType] = _deepcopy_atomic
d[types.ClassType] = _deepcopy_atomic
d[types.BuiltinFunctionType] = _deepcopy_atomic

def _deepcopy_list(x, memo):
    y = []
    memo[id(x)] = y
    for a in x:
        y.append(deepcopy(a, memo))
    return y
d[types.ListType] = _deepcopy_list

def _deepcopy_tuple(x, memo):
    y = []
    for a in x:
        y.append(deepcopy(a, memo))
    d = id(x)
    try:
        return memo[d]
    except KeyError:
        pass
    for i in range(len(x)):
        if x[i] is not y[i]:
            y = tuple(y)
            break
    else:
        y = x
    memo[d] = y
    return y
d[types.TupleType] = _deepcopy_tuple

def _deepcopy_dict(x, memo):
    y = {}
    memo[id(x)] = y
    for key, value in x.iteritems():
        y[deepcopy(key, memo)] = deepcopy(value, memo)
    return y
d[types.DictionaryType] = _deepcopy_dict
if PyStringMap is not None:
    d[PyStringMap] = _deepcopy_dict

def _keep_alive(x, memo):
    """Keeps a reference to the object x in the memo.

    Because we remember objects by their id, we have
    to assure that possibly temporary objects are kept
    alive by referencing them.
    We store a reference at the id of the memo, which should
    normally not be used unless someone tries to deepcopy
    the memo itself...
    """
    try:
        memo[id(memo)].append(x)
    except KeyError:
        # aha, this is the first one :-)
        memo[id(memo)]=[x]

def _deepcopy_inst(x, memo):
    if hasattr(x, '__deepcopy__'):
        return x.__deepcopy__(memo)
    if hasattr(x, '__getinitargs__'):
        args = x.__getinitargs__()
        args = deepcopy(args, memo)
        y = x.__class__(*args)
    else:
        y = _EmptyClass()
        y.__class__ = x.__class__
    memo[id(x)] = y
    if hasattr(x, '__getstate__'):
        state = x.__getstate__()
    else:
        state = x.__dict__
    state = deepcopy(state, memo)
    if hasattr(y, '__setstate__'):
        y.__setstate__(state)
    else:
        y.__dict__.update(state)
    return y
d[types.InstanceType] = _deepcopy_inst

def _reconstruct(x, info, deep, memo=None):
    if isinstance(info, str):
        return x
    assert isinstance(info, tuple)
    if memo is None:
        memo = {}
    n = len(info)
    assert n in (2, 3, 4, 5)
    callable, args = info[:2]
    if n > 2:
        state = info[2]
    else:
        state = {}
    if n > 3:
        listiter = info[3]
    else:
        listiter = None
    if n > 4:
        dictiter = info[4]
    else:
        dictiter = None
    if deep:
        args = deepcopy(args, memo)
    y = callable(*args)
    memo[id(x)] = y
    if listiter is not None:
        for item in listiter:
            if deep:
                item = deepcopy(item, memo)
            y.append(item)
    if dictiter is not None:
        for key, value in dictiter:
            if deep:
                key = deepcopy(key, memo)
                value = deepcopy(value, memo)
            y[key] = value
    if state:
        if deep:
            state = deepcopy(state, memo)
        if hasattr(y, '__setstate__'):
            y.__setstate__(state)
        else:
            if isinstance(state, tuple) and len(state) == 2:
                state, slotstate = state
            else:
                slotstate = None
            if state is not None:
                y.__dict__.update(state)
            if slotstate is not None:
                for key, value in slotstate.iteritems():
                    setattr(y, key, value)
    return y

del d

del types

# Helper for instance creation without calling __init__
class _EmptyClass:
    pass

def _test():
    l = [None, 1, 2L, 3.14, 'xyzzy', (1, 2L), [3.14, 'abc'],
         {'abc': 'ABC'}, (), [], {}]
    l1 = copy(l)
    print l1==l
    l1 = map(copy, l)
    print l1==l
    l1 = deepcopy(l)
    print l1==l
    class C:
        def __init__(self, arg=None):
            self.a = 1
            self.arg = arg
            if __name__ == '__main__':
                import sys
                file = sys.argv[0]
            else:
                file = __file__
            self.fp = open(file)
            self.fp.close()
        def __getstate__(self):
            return {'a': self.a, 'arg': self.arg}
        def __setstate__(self, state):
            for key, value in state.iteritems():
                setattr(self, key, value)
        def __deepcopy__(self, memo=None):
            new = self.__class__(deepcopy(self.arg, memo))
            new.a = self.a
            return new
    c = C('argument sketch')
    l.append(c)
    l2 = copy(l)
    print l == l2
    print l
    print l2
    l2 = deepcopy(l)
    print l == l2
    print l
    print l2
    l.append({l[1]: l, 'xyz': l[2]})
    l3 = copy(l)
    import repr
    print map(repr.repr, l)
    print map(repr.repr, l1)
    print map(repr.repr, l2)
    print map(repr.repr, l3)
    l3 = deepcopy(l)
    import repr
    print map(repr.repr, l)
    print map(repr.repr, l1)
    print map(repr.repr, l2)
    print map(repr.repr, l3)

if __name__ == '__main__':
    _test()
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.