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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
import collections.abc
import sys
if sys.version_info >= (3, 7):
odict = dict
else:
from collections import OrderedDict as odict # pragma: no cover
class ImmutableDict(collections.abc.Mapping):
def __init__(self, dictionary, no_copy=False):
"""Make an immutable dictionary from the specified dictionary.
If *no_copy* is `True`, then *dictionary* will be wrapped instead
of copied. Only set this if you are sure there will be no external
references to the dictionary.
"""
if no_copy and isinstance(dictionary, odict):
self._odict = dictionary
else:
self._odict = odict(dictionary)
self._hash = None
def __getitem__(self, key):
return self._odict.__getitem__(key)
def __hash__(self):
if self._hash is None:
self._hash = 0
for key in sorted(self._odict.keys()):
self._hash ^= hash(key)
return self._hash
def __len__(self):
return len(self._odict)
def __iter__(self):
return iter(self._odict)
def constify(o):
"""
Convert mutable types to immutable types.
"""
if isinstance(o, bytearray):
return bytes(o)
if isinstance(o, tuple):
try:
hash(o)
return o
except Exception:
return tuple(constify(elt) for elt in o)
if isinstance(o, list):
return tuple(constify(elt) for elt in o)
if isinstance(o, dict):
cdict = odict()
for k, v in o.items():
cdict[k] = constify(v)
return ImmutableDict(cdict, True)
return o
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