#!/usr/bin/env python
# coding=utf-8
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from abc import ABCMeta
from collections import MutableMapping
from future.backports.misc import get_ident
from future.moves.collections import UserDict
# noinspection PyIncorrectDocstring
from future.utils import PYPY
# noinspection PyIncorrectDocstring
[docs]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
[docs]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.
"""
[docs] 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
# noinspection PyMethodMayBeStatic
[docs] def __missing__(self, key):
raise KeyError(key)
[docs] def __getitem__(self, key):
for mapping in self.maps:
try:
return mapping[key] # can't use 'key in mapping' with defaultdict
except KeyError:
pass
return self.__missing__(key) # support subclasses that define __missing__
[docs] def get(self, key, default=None):
return self[key] if key in self else default
[docs] def __len__(self):
return len(set().union(*self.maps)) # reuses stored hash values if possible
[docs] def __iter__(self):
return iter(set().union(*self.maps))
[docs] def __contains__(self, key):
return any(key in m for m in self.maps)
@recursive_repr()
[docs] def __repr__(self):
return '{0.__class__.__name__}({1})'.format(self, ', '.join(map(repr, self.maps)))
# noinspection PyIncorrectDocstring
@classmethod
[docs] def fromkeys(cls, iterable, *args):
"""Create a ChainMap with a single dict created from the iterable."""
return cls(dict.fromkeys(iterable, *args))
[docs] 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
[docs] def new_child(self): # like Django's Context.push()
"""New ChainMap with a new dict followed by all previous maps."""
return self.__class__({}, *self.maps)
@property
def parents(self): # like Django's Context.pop()
"""New ChainMap from maps[1:]."""
return self.__class__(*self.maps[1:])
[docs] def __setitem__(self, key, value):
self.maps[0][key] = value
[docs] def __delitem__(self, key):
try:
del self.maps[0][key]
except KeyError:
raise KeyError('Key not found in the first mapping: {!r}'.format(key))
[docs] 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.')
# noinspection PyIncorrectDocstring
[docs] 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))
[docs] def clear(self):
"""Clear maps[0], leaving maps[1:] intact."""
self.maps[0].clear()
[docs]class MappingProxyType(UserDict):
[docs] def __init__(self, data):
UserDict.__init__(self)
self.data = data
# noinspection PyProtectedMember
return ABCMeta._abc_invalidation_counter
[docs]class Support(object):
[docs] def cpython_only(self, func):
return self.dummy if PYPY else func