320 lines
7.9 KiB
Python
320 lines
7.9 KiB
Python
# ex:ts=4:sw=4:sts=4:et
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# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#
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# This is a copy on write dictionary and set which abuses classes to try and be nice and fast.
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#
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# Copyright (C) 2006 Tim Ansell
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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#
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#Please Note:
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# Be careful when using mutable types (ie Dict and Lists) - operations involving these are SLOW.
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# Assign a file to __warn__ to get warnings about slow operations.
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#
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import copy
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import types
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ImmutableTypes = (
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bool,
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complex,
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float,
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int,
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tuple,
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frozenset,
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str
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)
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MUTABLE = "__mutable__"
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class COWMeta(type):
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pass
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class COWDictMeta(COWMeta):
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__warn__ = False
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__hasmutable__ = False
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__marker__ = tuple()
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def __str__(cls):
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# FIXME: I have magic numbers!
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return "<COWDict Level: %i Current Keys: %i>" % (cls.__count__, len(cls.__dict__) - 3)
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__repr__ = __str__
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def cow(cls):
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class C(cls):
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__count__ = cls.__count__ + 1
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return C
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copy = cow
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__call__ = cow
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def __setitem__(cls, key, value):
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if value is not None and not isinstance(value, ImmutableTypes):
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if not isinstance(value, COWMeta):
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cls.__hasmutable__ = True
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key += MUTABLE
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setattr(cls, key, value)
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def __getmutable__(cls, key, readonly=False):
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nkey = key + MUTABLE
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try:
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return cls.__dict__[nkey]
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except KeyError:
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pass
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value = getattr(cls, nkey)
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if readonly:
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return value
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if not cls.__warn__ is False and not isinstance(value, COWMeta):
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print("Warning: Doing a copy because %s is a mutable type." % key, file=cls.__warn__)
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try:
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value = value.copy()
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except AttributeError as e:
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value = copy.copy(value)
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setattr(cls, nkey, value)
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return value
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__getmarker__ = []
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def __getreadonly__(cls, key, default=__getmarker__):
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"""\
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Get a value (even if mutable) which you promise not to change.
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"""
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return cls.__getitem__(key, default, True)
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def __getitem__(cls, key, default=__getmarker__, readonly=False):
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try:
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try:
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value = getattr(cls, key)
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except AttributeError:
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value = cls.__getmutable__(key, readonly)
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# This is for values which have been deleted
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if value is cls.__marker__:
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raise AttributeError("key %s does not exist." % key)
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return value
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except AttributeError as e:
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if not default is cls.__getmarker__:
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return default
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raise KeyError(str(e))
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def __delitem__(cls, key):
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cls.__setitem__(key, cls.__marker__)
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def __revertitem__(cls, key):
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if key not in cls.__dict__:
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key += MUTABLE
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delattr(cls, key)
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def __contains__(cls, key):
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return cls.has_key(key)
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def has_key(cls, key):
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value = cls.__getreadonly__(key, cls.__marker__)
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if value is cls.__marker__:
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return False
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return True
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def iter(cls, type, readonly=False):
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for key in dir(cls):
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if key.startswith("__"):
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continue
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if key.endswith(MUTABLE):
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key = key[:-len(MUTABLE)]
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if type == "keys":
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yield key
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try:
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if readonly:
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value = cls.__getreadonly__(key)
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else:
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value = cls[key]
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except KeyError:
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continue
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if type == "values":
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yield value
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if type == "items":
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yield (key, value)
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raise StopIteration()
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def iterkeys(cls):
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return cls.iter("keys")
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def itervalues(cls, readonly=False):
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if not cls.__warn__ is False and cls.__hasmutable__ and readonly is False:
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print("Warning: If you arn't going to change any of the values call with True.", file=cls.__warn__)
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return cls.iter("values", readonly)
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def iteritems(cls, readonly=False):
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if not cls.__warn__ is False and cls.__hasmutable__ and readonly is False:
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print("Warning: If you arn't going to change any of the values call with True.", file=cls.__warn__)
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return cls.iter("items", readonly)
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class COWSetMeta(COWDictMeta):
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def __str__(cls):
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# FIXME: I have magic numbers!
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return "<COWSet Level: %i Current Keys: %i>" % (cls.__count__, len(cls.__dict__) -3)
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__repr__ = __str__
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def cow(cls):
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class C(cls):
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__count__ = cls.__count__ + 1
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return C
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def add(cls, value):
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COWDictMeta.__setitem__(cls, repr(hash(value)), value)
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def remove(cls, value):
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COWDictMeta.__delitem__(cls, repr(hash(value)))
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def __in__(cls, value):
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return repr(hash(value)) in COWDictMeta
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def iterkeys(cls):
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raise TypeError("sets don't have keys")
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def iteritems(cls):
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raise TypeError("sets don't have 'items'")
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# These are the actual classes you use!
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class COWDictBase(object, metaclass = COWDictMeta):
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__count__ = 0
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class COWSetBase(object, metaclass = COWSetMeta):
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__count__ = 0
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if __name__ == "__main__":
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import sys
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COWDictBase.__warn__ = sys.stderr
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a = COWDictBase()
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print("a", a)
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a['a'] = 'a'
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a['b'] = 'b'
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a['dict'] = {}
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b = a.copy()
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print("b", b)
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b['c'] = 'b'
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print()
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems():
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print(x)
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print()
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b['dict']['a'] = 'b'
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b['a'] = 'c'
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems():
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print(x)
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print()
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try:
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b['dict2']
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except KeyError as e:
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print("Okay!")
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a['set'] = COWSetBase()
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a['set'].add("o1")
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a['set'].add("o1")
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a['set'].add("o2")
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print("a", a)
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for x in a['set'].itervalues():
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print(x)
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print("--")
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print("b", b)
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for x in b['set'].itervalues():
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print(x)
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print()
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b['set'].add('o3')
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print("a", a)
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for x in a['set'].itervalues():
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print(x)
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print("--")
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print("b", b)
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for x in b['set'].itervalues():
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print(x)
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print()
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a['set2'] = set()
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a['set2'].add("o1")
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a['set2'].add("o1")
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a['set2'].add("o2")
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems(readonly=True):
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print(x)
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print()
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del b['b']
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try:
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print(b['b'])
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except KeyError:
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print("Yay! deleted key raises error")
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if 'b' in b:
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print("Boo!")
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else:
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print("Yay - has_key with delete works!")
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems(readonly=True):
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print(x)
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print()
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b.__revertitem__('b')
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems(readonly=True):
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print(x)
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print()
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b.__revertitem__('dict')
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print("a", a)
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for x in a.iteritems():
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print(x)
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print("--")
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print("b", b)
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for x in b.iteritems(readonly=True):
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print(x)
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print()
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