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805365ee39
svn+ssh://pythondev@svn.python.org/python/branches/p3yk ........ r55077 | guido.van.rossum | 2007-05-02 11:54:37 -0700 (Wed, 02 May 2007) | 2 lines Use the new print syntax, at least. ........ r55142 | fred.drake | 2007-05-04 21:27:30 -0700 (Fri, 04 May 2007) | 1 line remove old cruftiness ........ r55143 | fred.drake | 2007-05-04 21:52:16 -0700 (Fri, 04 May 2007) | 1 line make this work with the new Python ........ r55162 | neal.norwitz | 2007-05-06 22:29:18 -0700 (Sun, 06 May 2007) | 1 line Get asdl code gen working with Python 2.3. Should continue to work with 3.0 ........ r55164 | neal.norwitz | 2007-05-07 00:00:38 -0700 (Mon, 07 May 2007) | 1 line Verify checkins to p3yk (sic) branch go to 3000 list. ........ r55166 | neal.norwitz | 2007-05-07 00:12:35 -0700 (Mon, 07 May 2007) | 1 line Fix this test so it runs again by importing warnings_test properly. ........ r55167 | neal.norwitz | 2007-05-07 01:03:22 -0700 (Mon, 07 May 2007) | 8 lines So long xrange. range() now supports values that are outside -sys.maxint to sys.maxint. floats raise a TypeError. This has been sitting for a long time. It probably has some problems and needs cleanup. Objects/rangeobject.c now uses 4-space indents since it is almost completely new. ........ r55171 | guido.van.rossum | 2007-05-07 10:21:26 -0700 (Mon, 07 May 2007) | 4 lines Fix two tests that were previously depending on significant spaces at the end of a line (and before that on Python 2.x print behavior that has no exact equivalent in 3.0). ........
371 lines
9.5 KiB
Python
371 lines
9.5 KiB
Python
"""Generic (shallow and deep) copying operations.
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Interface summary:
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import copy
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x = copy.copy(y) # make a shallow copy of y
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x = copy.deepcopy(y) # make a deep copy of y
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For module specific errors, copy.Error is raised.
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The difference between shallow and deep copying is only relevant for
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compound objects (objects that contain other objects, like lists or
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class instances).
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- A shallow copy constructs a new compound object and then (to the
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extent possible) inserts *the same objects* into it that the
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original contains.
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- A deep copy constructs a new compound object and then, recursively,
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inserts *copies* into it of the objects found in the original.
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Two problems often exist with deep copy operations that don't exist
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with shallow copy operations:
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a) recursive objects (compound objects that, directly or indirectly,
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contain a reference to themselves) may cause a recursive loop
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b) because deep copy copies *everything* it may copy too much, e.g.
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administrative data structures that should be shared even between
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copies
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Python's deep copy operation avoids these problems by:
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a) keeping a table of objects already copied during the current
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copying pass
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b) letting user-defined classes override the copying operation or the
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set of components copied
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This version does not copy types like module, class, function, method,
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nor stack trace, stack frame, nor file, socket, window, nor array, nor
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any similar types.
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Classes can use the same interfaces to control copying that they use
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to control pickling: they can define methods called __getinitargs__(),
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__getstate__() and __setstate__(). See the documentation for module
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"pickle" for information on these methods.
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"""
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import types
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from copy_reg import dispatch_table
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class Error(Exception):
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pass
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error = Error # backward compatibility
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try:
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from org.python.core import PyStringMap
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except ImportError:
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PyStringMap = None
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__all__ = ["Error", "copy", "deepcopy"]
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def copy(x):
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"""Shallow copy operation on arbitrary Python objects.
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See the module's __doc__ string for more info.
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"""
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cls = type(x)
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copier = _copy_dispatch.get(cls)
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if copier:
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return copier(x)
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copier = getattr(cls, "__copy__", None)
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if copier:
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return copier(x)
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reductor = dispatch_table.get(cls)
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if reductor:
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rv = reductor(x)
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else:
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reductor = getattr(x, "__reduce_ex__", None)
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if reductor:
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rv = reductor(2)
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else:
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reductor = getattr(x, "__reduce__", None)
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if reductor:
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rv = reductor()
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else:
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raise Error("un(shallow)copyable object of type %s" % cls)
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return _reconstruct(x, rv, 0)
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_copy_dispatch = d = {}
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def _copy_immutable(x):
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return x
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for t in (type(None), int, float, bool, str, tuple,
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frozenset, type, range, types.ClassType,
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types.BuiltinFunctionType,
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types.FunctionType):
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d[t] = _copy_immutable
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for name in ("ComplexType", "UnicodeType", "CodeType"):
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t = getattr(types, name, None)
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if t is not None:
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d[t] = _copy_immutable
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def _copy_with_constructor(x):
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return type(x)(x)
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for t in (list, dict, set):
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d[t] = _copy_with_constructor
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def _copy_with_copy_method(x):
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return x.copy()
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if PyStringMap is not None:
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d[PyStringMap] = _copy_with_copy_method
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del d
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def deepcopy(x, memo=None, _nil=[]):
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"""Deep copy operation on arbitrary Python objects.
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See the module's __doc__ string for more info.
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"""
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if memo is None:
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memo = {}
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d = id(x)
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y = memo.get(d, _nil)
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if y is not _nil:
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return y
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cls = type(x)
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copier = _deepcopy_dispatch.get(cls)
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if copier:
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y = copier(x, memo)
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else:
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try:
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issc = issubclass(cls, type)
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except TypeError: # cls is not a class (old Boost; see SF #502085)
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issc = 0
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if issc:
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y = _deepcopy_atomic(x, memo)
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else:
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copier = getattr(x, "__deepcopy__", None)
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if copier:
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y = copier(memo)
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else:
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reductor = dispatch_table.get(cls)
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if reductor:
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rv = reductor(x)
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else:
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reductor = getattr(x, "__reduce_ex__", None)
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if reductor:
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rv = reductor(2)
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else:
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reductor = getattr(x, "__reduce__", None)
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if reductor:
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rv = reductor()
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else:
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raise Error(
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"un(deep)copyable object of type %s" % cls)
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y = _reconstruct(x, rv, 1, memo)
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memo[d] = y
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_keep_alive(x, memo) # Make sure x lives at least as long as d
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return y
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_deepcopy_dispatch = d = {}
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def _deepcopy_atomic(x, memo):
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return x
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d[type(None)] = _deepcopy_atomic
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d[int] = _deepcopy_atomic
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d[float] = _deepcopy_atomic
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d[bool] = _deepcopy_atomic
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try:
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d[complex] = _deepcopy_atomic
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except NameError:
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pass
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d[str] = _deepcopy_atomic
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try:
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d[str] = _deepcopy_atomic
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except NameError:
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pass
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try:
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d[types.CodeType] = _deepcopy_atomic
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except AttributeError:
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pass
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d[type] = _deepcopy_atomic
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d[range] = _deepcopy_atomic
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d[types.ClassType] = _deepcopy_atomic
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d[types.BuiltinFunctionType] = _deepcopy_atomic
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d[types.FunctionType] = _deepcopy_atomic
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def _deepcopy_list(x, memo):
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y = []
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memo[id(x)] = y
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for a in x:
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y.append(deepcopy(a, memo))
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return y
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d[list] = _deepcopy_list
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def _deepcopy_tuple(x, memo):
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y = []
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for a in x:
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y.append(deepcopy(a, memo))
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d = id(x)
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try:
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return memo[d]
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except KeyError:
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pass
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for i in range(len(x)):
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if x[i] is not y[i]:
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y = tuple(y)
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break
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else:
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y = x
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memo[d] = y
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return y
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d[tuple] = _deepcopy_tuple
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def _deepcopy_dict(x, memo):
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y = {}
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memo[id(x)] = y
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for key, value in x.items():
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y[deepcopy(key, memo)] = deepcopy(value, memo)
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return y
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d[dict] = _deepcopy_dict
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if PyStringMap is not None:
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d[PyStringMap] = _deepcopy_dict
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def _keep_alive(x, memo):
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"""Keeps a reference to the object x in the memo.
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Because we remember objects by their id, we have
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to assure that possibly temporary objects are kept
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alive by referencing them.
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We store a reference at the id of the memo, which should
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normally not be used unless someone tries to deepcopy
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the memo itself...
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"""
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try:
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memo[id(memo)].append(x)
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except KeyError:
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# aha, this is the first one :-)
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memo[id(memo)]=[x]
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def _reconstruct(x, info, deep, memo=None):
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if isinstance(info, str):
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return x
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assert isinstance(info, tuple)
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if memo is None:
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memo = {}
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n = len(info)
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assert n in (2, 3, 4, 5)
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callable, args = info[:2]
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if n > 2:
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state = info[2]
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else:
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state = {}
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if n > 3:
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listiter = info[3]
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else:
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listiter = None
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if n > 4:
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dictiter = info[4]
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else:
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dictiter = None
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if deep:
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args = deepcopy(args, memo)
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y = callable(*args)
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memo[id(x)] = y
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if listiter is not None:
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for item in listiter:
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if deep:
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item = deepcopy(item, memo)
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y.append(item)
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if dictiter is not None:
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for key, value in dictiter:
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if deep:
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key = deepcopy(key, memo)
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value = deepcopy(value, memo)
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y[key] = value
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if state:
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if deep:
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state = deepcopy(state, memo)
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if hasattr(y, '__setstate__'):
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y.__setstate__(state)
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else:
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if isinstance(state, tuple) and len(state) == 2:
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state, slotstate = state
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else:
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slotstate = None
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if state is not None:
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y.__dict__.update(state)
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if slotstate is not None:
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for key, value in slotstate.items():
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setattr(y, key, value)
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return y
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del d
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del types
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# Helper for instance creation without calling __init__
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class _EmptyClass:
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pass
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def _test():
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l = [None, 1, 2, 3.14, 'xyzzy', (1, 2), [3.14, 'abc'],
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{'abc': 'ABC'}, (), [], {}]
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l1 = copy(l)
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print(l1==l)
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l1 = map(copy, l)
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print(l1==l)
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l1 = deepcopy(l)
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print(l1==l)
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class C:
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def __init__(self, arg=None):
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self.a = 1
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self.arg = arg
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if __name__ == '__main__':
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import sys
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file = sys.argv[0]
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else:
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file = __file__
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self.fp = open(file)
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self.fp.close()
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def __getstate__(self):
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return {'a': self.a, 'arg': self.arg}
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def __setstate__(self, state):
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for key, value in state.items():
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setattr(self, key, value)
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def __deepcopy__(self, memo=None):
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new = self.__class__(deepcopy(self.arg, memo))
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new.a = self.a
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return new
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c = C('argument sketch')
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l.append(c)
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l2 = copy(l)
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print(l == l2)
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print(l)
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print(l2)
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l2 = deepcopy(l)
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print(l == l2)
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print(l)
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print(l2)
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l.append({l[1]: l, 'xyz': l[2]})
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l3 = copy(l)
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import repr
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print(map(repr.repr, l))
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print(map(repr.repr, l1))
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print(map(repr.repr, l2))
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print(map(repr.repr, l3))
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l3 = deepcopy(l)
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import repr
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print(map(repr.repr, l))
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print(map(repr.repr, l1))
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print(map(repr.repr, l2))
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print(map(repr.repr, l3))
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if __name__ == '__main__':
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_test()
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