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- # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
-
- # Copyright (C) 2003-2017 Nominum, Inc.
- #
- # Permission to use, copy, modify, and distribute this software and its
- # documentation for any purpose with or without fee is hereby granted,
- # provided that the above copyright notice and this permission notice
- # appear in all copies.
- #
- # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
- # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
- # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
- # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-
- class Set(object):
-
- """A simple set class.
-
- This class was originally used to deal with sets being missing in
- ancient versions of python, but dnspython will continue to use it
- as these sets are based on lists and are thus indexable, and this
- ability is widely used in dnspython applications.
- """
-
- __slots__ = ['items']
-
- def __init__(self, items=None):
- """Initialize the set.
-
- *items*, an iterable or ``None``, the initial set of items.
- """
-
- self.items = []
- if items is not None:
- for item in items:
- self.add(item)
-
- def __repr__(self):
- return "dns.simpleset.Set(%s)" % repr(self.items)
-
- def add(self, item):
- """Add an item to the set.
- """
-
- if item not in self.items:
- self.items.append(item)
-
- def remove(self, item):
- """Remove an item from the set.
- """
-
- self.items.remove(item)
-
- def discard(self, item):
- """Remove an item from the set if present.
- """
-
- try:
- self.items.remove(item)
- except ValueError:
- pass
-
- def _clone(self):
- """Make a (shallow) copy of the set.
-
- There is a 'clone protocol' that subclasses of this class
- should use. To make a copy, first call your super's _clone()
- method, and use the object returned as the new instance. Then
- make shallow copies of the attributes defined in the subclass.
-
- This protocol allows us to write the set algorithms that
- return new instances (e.g. union) once, and keep using them in
- subclasses.
- """
-
- cls = self.__class__
- obj = cls.__new__(cls)
- obj.items = list(self.items)
- return obj
-
- def __copy__(self):
- """Make a (shallow) copy of the set.
- """
-
- return self._clone()
-
- def copy(self):
- """Make a (shallow) copy of the set.
- """
-
- return self._clone()
-
- def union_update(self, other):
- """Update the set, adding any elements from other which are not
- already in the set.
- """
-
- if not isinstance(other, Set):
- raise ValueError('other must be a Set instance')
- if self is other:
- return
- for item in other.items:
- self.add(item)
-
- def intersection_update(self, other):
- """Update the set, removing any elements from other which are not
- in both sets.
- """
-
- if not isinstance(other, Set):
- raise ValueError('other must be a Set instance')
- if self is other:
- return
- # we make a copy of the list so that we can remove items from
- # the list without breaking the iterator.
- for item in list(self.items):
- if item not in other.items:
- self.items.remove(item)
-
- def difference_update(self, other):
- """Update the set, removing any elements from other which are in
- the set.
- """
-
- if not isinstance(other, Set):
- raise ValueError('other must be a Set instance')
- if self is other:
- self.items = []
- else:
- for item in other.items:
- self.discard(item)
-
- def union(self, other):
- """Return a new set which is the union of ``self`` and ``other``.
-
- Returns the same Set type as this set.
- """
-
- obj = self._clone()
- obj.union_update(other)
- return obj
-
- def intersection(self, other):
- """Return a new set which is the intersection of ``self`` and
- ``other``.
-
- Returns the same Set type as this set.
- """
-
- obj = self._clone()
- obj.intersection_update(other)
- return obj
-
- def difference(self, other):
- """Return a new set which ``self`` - ``other``, i.e. the items
- in ``self`` which are not also in ``other``.
-
- Returns the same Set type as this set.
- """
-
- obj = self._clone()
- obj.difference_update(other)
- return obj
-
- def __or__(self, other):
- return self.union(other)
-
- def __and__(self, other):
- return self.intersection(other)
-
- def __add__(self, other):
- return self.union(other)
-
- def __sub__(self, other):
- return self.difference(other)
-
- def __ior__(self, other):
- self.union_update(other)
- return self
-
- def __iand__(self, other):
- self.intersection_update(other)
- return self
-
- def __iadd__(self, other):
- self.union_update(other)
- return self
-
- def __isub__(self, other):
- self.difference_update(other)
- return self
-
- def update(self, other):
- """Update the set, adding any elements from other which are not
- already in the set.
-
- *other*, the collection of items with which to update the set, which
- may be any iterable type.
- """
-
- for item in other:
- self.add(item)
-
- def clear(self):
- """Make the set empty."""
- self.items = []
-
- def __eq__(self, other):
- # Yes, this is inefficient but the sets we're dealing with are
- # usually quite small, so it shouldn't hurt too much.
- for item in self.items:
- if item not in other.items:
- return False
- for item in other.items:
- if item not in self.items:
- return False
- return True
-
- def __ne__(self, other):
- return not self.__eq__(other)
-
- def __len__(self):
- return len(self.items)
-
- def __iter__(self):
- return iter(self.items)
-
- def __getitem__(self, i):
- return self.items[i]
-
- def __delitem__(self, i):
- del self.items[i]
-
- def issubset(self, other):
- """Is this set a subset of *other*?
-
- Returns a ``bool``.
- """
-
- if not isinstance(other, Set):
- raise ValueError('other must be a Set instance')
- for item in self.items:
- if item not in other.items:
- return False
- return True
-
- def issuperset(self, other):
- """Is this set a superset of *other*?
-
- Returns a ``bool``.
- """
-
- if not isinstance(other, Set):
- raise ValueError('other must be a Set instance')
- for item in other.items:
- if item not in self.items:
- return False
- return True
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