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from __future__ import absolute_import
import sys
from collections import *
from .version_info import PY2
if PY2:
from UserString import *
from UserList import *
if sys.version_info < (2, 7):
from ordereddict import OrderedDict
if sys.version_info < (3, 3):
if PY2:
try:
from thread import get_ident
except ImportError:
from dummy_thread import get_ident
else:
try:
from _thread import get_ident
except ImportError:
from _dummy_thread import get_ident
def _recursive_repr(fillvalue='...'):
'Decorator to make a repr function return fillvalue for a recursive call'
def decorating_function(user_function):
repr_running = set()
def wrapper(self):
key = id(self), get_ident()
if key in repr_running:
return fillvalue
repr_running.add(key)
try:
result = user_function(self)
finally:
repr_running.discard(key)
return result
# Can't use functools.wraps() here because of bootstrap issues
wrapper.__module__ = getattr(user_function, '__module__')
wrapper.__doc__ = getattr(user_function, '__doc__')
wrapper.__name__ = getattr(user_function, '__name__')
wrapper.__annotations__ = getattr(
user_function, '__annotations__', {})
return wrapper
return decorating_function
class ChainMap(MutableMapping):
''' A ChainMap groups multiple dicts (or other mappings) together
to create a single, updateable view.
The underlying mappings are stored in a list. That list is public and can
accessed or updated using the *maps* attribute. There is no other state.
Lookups search the underlying mappings successively until a key is found.
In contrast, writes, updates, and deletions only operate on the first
mapping.
'''
def __init__(self, *maps):
'''Initialize a ChainMap by setting *maps* to the given mappings.
If no mappings are provided, a single empty dictionary is used.
'''
self.maps = list(maps) or [{}] # always at least one map
def __missing__(self, key):
raise KeyError(key)
def __getitem__(self, key):
for mapping in self.maps:
try:
# can't use 'key in mapping' with defaultdict
return mapping[key]
except KeyError:
pass
# support subclasses that define __missing__
return self.__missing__(key)
def get(self, key, default=None):
return self[key] if key in self else default
def __len__(self):
# reuses stored hash values if possible
return len(set().union(*self.maps))
def __iter__(self):
return iter(set().union(*self.maps))
def __contains__(self, key):
return any(key in m for m in self.maps)
def __bool__(self):
return any(self.maps)
@_recursive_repr()
def __repr__(self):
return '{0.__class__.__name__}({1})'.format(
self, ', '.join(map(repr, self.maps)))
@classmethod
def fromkeys(cls, iterable, *args):
'Create a ChainMap with a single dict created from the iterable.'
return cls(dict.fromkeys(iterable, *args))
def copy(self):
'New ChainMap or subclass with a new copy of maps[0] and refs to maps[1:]'
return self.__class__(self.maps[0].copy(), *self.maps[1:])
__copy__ = copy
def new_child(self, m=None): # like Django's Context.push()
'''
New ChainMap with a new map followed by all previous maps. If no
map is provided, an empty dict is used.
'''
if m is None:
m = {}
return self.__class__(m, *self.maps)
@property
def parents(self): # like Django's Context.pop()
'New ChainMap from maps[1:].'
return self.__class__(*self.maps[1:])
def __setitem__(self, key, value):
self.maps[0][key] = value
def __delitem__(self, key):
try:
del self.maps[0][key]
except KeyError:
raise KeyError(
'Key not found in the first mapping: {!r}'.format(key))
def popitem(self):
'Remove and return an item pair from maps[0]. Raise KeyError is maps[0] is empty.'
try:
return self.maps[0].popitem()
except KeyError:
raise KeyError('No keys found in the first mapping.')
def pop(self, key, *args):
'Remove *key* from maps[0] and return its value. Raise KeyError if *key* not in maps[0].'
try:
return self.maps[0].pop(key, *args)
except KeyError:
raise KeyError(
'Key not found in the first mapping: {!r}'.format(key))
def clear(self):
'Clear maps[0], leaving maps[1:] intact.'
self.maps[0].clear()
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