154 lines
4.8 KiB
Python
154 lines
4.8 KiB
Python
# -*- coding: utf-8 -*-
|
|
"""
|
|
pint.compat.chainmap
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Taken from the Python 3.3 source code.
|
|
|
|
:copyright: 2013, PSF
|
|
:license: PSF License
|
|
"""
|
|
|
|
from __future__ import division, unicode_literals, print_function, absolute_import
|
|
|
|
import sys
|
|
|
|
from collections import MutableMapping
|
|
if sys.version_info < (3, 0):
|
|
from thread import get_ident
|
|
elif sys.version_info < (3, 3):
|
|
from _thread import get_ident
|
|
else:
|
|
from threading 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:
|
|
return mapping[key] # can't use 'key in mapping' with defaultdict
|
|
except KeyError:
|
|
pass
|
|
return self.__missing__(key) # support subclasses that define __missing__
|
|
|
|
def get(self, key, default=None):
|
|
return self[key] if key in self else default
|
|
|
|
def __len__(self):
|
|
return len(set().union(*self.maps)) # reuses stored hash values if possible
|
|
|
|
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()
|