"""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.

"""

# XXX need to support copy_reg here too...

import types

class Error(Exception):

pass

error = Error # backward compatibility

try:

from org.python.core import PyStringMap

except ImportError:

PyStringMap = None

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

def copy(x):

"""Shallow copy operation on arbitrary Python objects.

See the module's __doc__ string for more info.

"""

try:

copierfunction = _copy_dispatch[type(x)]

except KeyError:

try:

copier = x.__copy__

except AttributeError:

try:

reductor = x.__reduce__

except AttributeError:

raise error, \

"un(shallow)copyable object of type %s" % type(x)

else:

y = _reconstruct(x, reductor(), 0)

else:

y = copier()

else:

y = copierfunction(x)

return y

_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

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

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 = apply(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):

"""Deep copy operation on arbitrary Python objects.

See the module's __doc__ string for more info.

"""

if memo is None:

memo = {}

d = id(x)

if d in memo:

return memo[d]

try:

copierfunction = _deepcopy_dispatch[type(x)]

except KeyError:

try:

issc = issubclass(type(x), type)

except TypeError:

issc = 0

if issc:

y = _deepcopy_dispatch[type](x, memo)

else:

try:

copier = x.__deepcopy__

except AttributeError:

try:

reductor = x.__reduce__

except AttributeError:

raise error, \

"un-deep-copyable object of type %s" % type(x)

else:

y = _reconstruct(x, reductor(), 1, memo)

else:

y = copier(memo)

else:

y = copierfunction(x, 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

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

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 = apply(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)

callable, args = info[:2]

if n > 2:

state = info[2]

else:

state = {}

if deep:

args = deepcopy(args, memo)

y = callable(*args)

if state:

if deep:

state = deepcopy(state, memo)

if hasattr(y, '__setstate__'):

y.__setstate__(state)

else:

y.__dict__.update(state)

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()