113 lines
4.0 KiB
Python
113 lines
4.0 KiB
Python
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################### Dataclasses_fallback ###############################
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# This is the fallback dataclass code if the stdlib module isn't available.
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# It defines enough of the support types to be used with cdef classes
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# and to fail if used on regular types.
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# (Intended to be included as py code - not compiled)
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from collections import namedtuple
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try:
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from types import MappingProxyType
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except ImportError:
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# mutable fallback if unavailable
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MappingProxyType = lambda x: x
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class _MISSING_TYPE(object):
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pass
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MISSING = _MISSING_TYPE()
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_DataclassParams = namedtuple('_DataclassParams',
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["init", "repr", "eq", "order", "unsafe_hash", "frozen",
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"match_args", "kw_only", "slots", "weakref_slot"])
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class Field(object):
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__slots__ = ('name',
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'type',
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'default',
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'default_factory',
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'repr',
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'hash',
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'init',
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'compare',
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'metadata',
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'kw_only',
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'_field_type', # Private: not to be used by user code.
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)
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def __init__(self, default, default_factory, init, repr, hash, compare,
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metadata, kw_only):
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self.name = None
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self.type = None
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self.default = default
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self.default_factory = default_factory
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self.init = init
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self.repr = repr
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self.hash = hash
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self.compare = compare
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# Be aware that if MappingProxyType is unavailable (i.e. py2?) then we
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# don't enforce non-mutability that the real module does
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self.metadata = (MappingProxyType({})
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if metadata is None else
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MappingProxyType(metadata))
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self.kw_only = kw_only
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self._field_type = None
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def __repr__(self):
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return ('Field('
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'name={0!r},'
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'type={1!r},'
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'default={2!r},'
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'default_factory={3!r},'
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'init={4!r},'
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'repr={5!r},'
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'hash={6!r},'
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'compare={7!r},'
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'metadata={8!r},'
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'kwonly={9!r},'
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')'.format(self.name, self.type, self.default,
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self.default_factory, self.init,
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self.repr, self.hash, self.compare,
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self.metadata, self.kw_only))
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# A sentinel object for default values to signal that a default
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# factory will be used. This is given a nice repr() which will appear
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# in the function signature of dataclasses' constructors.
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class _HAS_DEFAULT_FACTORY_CLASS:
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def __repr__(self):
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return '<factory>'
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_HAS_DEFAULT_FACTORY = _HAS_DEFAULT_FACTORY_CLASS()
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def dataclass(*args, **kwds):
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raise NotImplementedError("Standard library 'dataclasses' module"
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"is unavailable, likely due to the version of Python you're using.")
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# Markers for the various kinds of fields and pseudo-fields.
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class _FIELD_BASE:
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def __init__(self, name):
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self.name = name
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def __repr__(self):
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return self.name
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_FIELD = _FIELD_BASE('_FIELD')
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_FIELD_CLASSVAR = _FIELD_BASE('_FIELD_CLASSVAR')
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_FIELD_INITVAR = _FIELD_BASE('_FIELD_INITVAR')
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def field(*ignore, **kwds):
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default = kwds.pop("default", MISSING)
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default_factory = kwds.pop("default_factory", MISSING)
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init = kwds.pop("init", True)
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repr = kwds.pop("repr", True)
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hash = kwds.pop("hash", None)
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compare = kwds.pop("compare", True)
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metadata = kwds.pop("metadata", None)
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kw_only = kwds.pop("kw_only", None)
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if kwds:
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raise ValueError("field received unexpected keyword arguments: %s"
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% list(kwds.keys()))
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if default is not MISSING and default_factory is not MISSING:
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raise ValueError('cannot specify both default and default_factory')
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if ignore:
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raise ValueError("'field' does not take any positional arguments")
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return Field(default, default_factory, init,
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repr, hash, compare, metadata, kw_only)
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