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163 lines
4.4 KiB
163 lines
4.4 KiB
from weakref import ref
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from blinker._saferef import BoundMethodWeakref
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try:
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callable
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except NameError:
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def callable(object):
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return hasattr(object, '__call__')
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try:
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from collections import defaultdict
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except:
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class defaultdict(dict):
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def __init__(self, default_factory=None, *a, **kw):
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if (default_factory is not None and
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not hasattr(default_factory, '__call__')):
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raise TypeError('first argument must be callable')
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dict.__init__(self, *a, **kw)
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self.default_factory = default_factory
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def __getitem__(self, key):
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try:
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return dict.__getitem__(self, key)
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except KeyError:
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return self.__missing__(key)
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def __missing__(self, key):
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if self.default_factory is None:
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raise KeyError(key)
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self[key] = value = self.default_factory()
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return value
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def __reduce__(self):
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if self.default_factory is None:
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args = tuple()
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else:
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args = self.default_factory,
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return type(self), args, None, None, self.items()
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def copy(self):
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return self.__copy__()
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def __copy__(self):
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return type(self)(self.default_factory, self)
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def __deepcopy__(self, memo):
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import copy
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return type(self)(self.default_factory,
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copy.deepcopy(self.items()))
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def __repr__(self):
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return 'defaultdict(%s, %s)' % (self.default_factory,
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dict.__repr__(self))
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try:
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from contextlib import contextmanager
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except ImportError:
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def contextmanager(fn):
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def oops(*args, **kw):
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raise RuntimeError("Python 2.5 or above is required to use "
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"context managers.")
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oops.__name__ = fn.__name__
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return oops
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class _symbol(object):
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def __init__(self, name):
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"""Construct a new named symbol."""
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self.__name__ = self.name = name
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def __reduce__(self):
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return symbol, (self.name,)
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def __repr__(self):
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return self.name
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_symbol.__name__ = 'symbol'
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class symbol(object):
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"""A constant symbol.
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>>> symbol('foo') is symbol('foo')
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True
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>>> symbol('foo')
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foo
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A slight refinement of the MAGICCOOKIE=object() pattern. The primary
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advantage of symbol() is its repr(). They are also singletons.
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Repeated calls of symbol('name') will all return the same instance.
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"""
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symbols = {}
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def __new__(cls, name):
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try:
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return cls.symbols[name]
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except KeyError:
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return cls.symbols.setdefault(name, _symbol(name))
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try:
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text = (str, unicode)
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except NameError:
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text = str
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def hashable_identity(obj):
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if hasattr(obj, '__func__'):
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return (id(obj.__func__), id(obj.__self__))
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elif hasattr(obj, 'im_func'):
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return (id(obj.im_func), id(obj.im_self))
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elif isinstance(obj, text):
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return obj
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else:
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return id(obj)
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WeakTypes = (ref, BoundMethodWeakref)
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class annotatable_weakref(ref):
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"""A weakref.ref that supports custom instance attributes."""
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def reference(object, callback=None, **annotations):
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"""Return an annotated weak ref."""
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if callable(object):
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weak = callable_reference(object, callback)
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else:
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weak = annotatable_weakref(object, callback)
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for key, value in annotations.items():
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setattr(weak, key, value)
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return weak
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def callable_reference(object, callback=None):
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"""Return an annotated weak ref, supporting bound instance methods."""
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if hasattr(object, 'im_self') and object.im_self is not None:
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return BoundMethodWeakref(target=object, on_delete=callback)
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elif hasattr(object, '__self__') and object.__self__ is not None:
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return BoundMethodWeakref(target=object, on_delete=callback)
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return annotatable_weakref(object, callback)
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class lazy_property(object):
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"""A @property that is only evaluated once."""
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def __init__(self, deferred):
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self._deferred = deferred
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self.__doc__ = deferred.__doc__
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def __get__(self, obj, cls):
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if obj is None:
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return self
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value = self._deferred(obj)
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setattr(obj, self._deferred.__name__, value)
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return value
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