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153 lines
4.4 KiB
153 lines
4.4 KiB
# -*- coding: utf-8 -*-
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from collections import MutableMapping
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from thread import get_ident
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# from reprlib 3.2.1
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def recursive_repr(fillvalue=u'...'):
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"""
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Decorator to make a repr function return fillvalue for a recursive call
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"""
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def decorating_function(user_function):
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repr_running = set()
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def wrapper(self):
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key = id(self), get_ident()
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if key in repr_running:
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return fillvalue
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repr_running.add(key)
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try:
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result = user_function(self)
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finally:
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repr_running.discard(key)
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return result
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# Can't use functools.wraps() here because of bootstrap issues
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wrapper.__module__ = getattr(user_function, u'__module__')
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wrapper.__doc__ = getattr(user_function, u'__doc__')
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wrapper.__name__ = getattr(user_function, u'__name__')
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wrapper.__annotations__ = getattr(user_function, u'__annotations__', {})
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return wrapper
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return decorating_function
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# from collections 3.2.1
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class _ChainMap(MutableMapping):
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"""A ChainMap groups multiple dicts (or other mappings) together
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to create a single, updateable view.
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The underlying mappings are stored in a list. That list is public and can
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accessed or updated using the *maps* attribute. There is no other state.
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Lookups search the underlying mappings successively until a key is found.
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In contrast, writes, updates, and deletions only operate on the first
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mapping.
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"""
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def __init__(self, *maps):
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"""Initialize a ChainMap by setting *maps* to the given mappings.
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If no mappings are provided, a single empty dictionary is used.
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"""
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self.maps = list(maps) or [{}] # always at least one map
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def __missing__(self, key):
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raise KeyError(key)
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def __getitem__(self, key):
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for mapping in self.maps:
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try:
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return mapping[
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key] # can't use 'key in mapping' with defaultdict
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except KeyError:
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pass
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return self.__missing__(
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key) # support subclasses that define __missing__
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def get(self, key, default=None):
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return self[key] if key in self else default
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def __len__(self):
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return len(
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set().union(*self.maps)) # reuses stored hash values if possible
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def __iter__(self):
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return iter(set().union(*self.maps))
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def __contains__(self, key):
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return any(key in m for m in self.maps)
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@recursive_repr()
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def __repr__(self):
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return u'{0.__class__.__name__}({1})'.format(
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self, u', '.join(map(repr, self.maps)))
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@classmethod
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def fromkeys(cls, iterable, *args):
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"""
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Create a ChainMap with a single dict created from the iterable.
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"""
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return cls(dict.fromkeys(iterable, *args))
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def copy(self):
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"""
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New ChainMap or subclass with a new copy of maps[0] and refs to maps[1:]
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"""
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return self.__class__(self.maps[0].copy(), *self.maps[1:])
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__copy__ = copy
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def new_child(self): # like Django's Context.push()
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"""
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New ChainMap with a new dict followed by all previous maps.
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"""
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return self.__class__({}, *self.maps)
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@property
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def parents(self): # like Django's Context.pop()
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"""
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New ChainMap from maps[1:].
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"""
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return self.__class__(*self.maps[1:])
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def __setitem__(self, key, value):
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self.maps[0][key] = value
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def __delitem__(self, key):
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try:
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del self.maps[0][key]
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except KeyError:
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raise KeyError(
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u'Key not found in the first mapping: {!r}'.format(key))
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def popitem(self):
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"""
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Remove and return an item pair from maps[0].
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Raise KeyError is maps[0] is empty.
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"""
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try:
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return self.maps[0].popitem()
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except KeyError:
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raise KeyError(u'No keys found in the first mapping.')
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def pop(self, key, *args):
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"""
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Remove *key* from maps[0] and return its value.
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Raise KeyError if *key* not in maps[0].
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"""
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try:
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return self.maps[0].pop(key, *args)
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except KeyError:
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raise KeyError(
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u'Key not found in the first mapping: {!r}'.format(key))
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def clear(self):
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"""
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Clear maps[0], leaving maps[1:] intact.
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"""
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self.maps[0].clear()
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