structured_data.adt._unpack_args() - Code Metrics - Inspection of "Remove explicit loop" - mwchase/python-structured-data - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( ee2acb...c9efce )

by Max

created 2019-09-02 15:11 UTC

structured_data.adt._unpack_args() A

↳ Parent: structured_data.adt

Complexity

Conditions

Size

Total Lines	9
Code Lines	9

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	5
eloc	9
nop	5
dl	0
loc	9
rs	9.3333
c	0
b	0
f	0

"""Base classes for defining abstract data types.

This module provides three public members, which are used together.

Given a structure, possibly a choice of different structures, that you'd like
to associate with a type:

- First, create a class, that subclasses the Sum class.
- Then, for each possible structure, add an attribute annotation to the class
  with the desired name of the constructor, and a type of ``Ctor``, with the
  types within the constructor as arguments.

To look inside an ADT instance, use the functions from the
:mod:`structured_data.match` module.

Putting it together:

>>> from structured_data import match
>>> class Example(Sum):
...     FirstConstructor: Ctor[int, str]
...     SecondConstructor: Ctor[bytes]
...     ThirdConstructor: Ctor
...     def __iter__(self):
...         matchable = match.Matchable(self)
...         if matchable(Example.FirstConstructor(match.pat.count, match.pat.string)):
...             count, string = matchable[match.pat.count, match.pat.string]
...             for _ in range(count):
...                 yield string
...         elif matchable(Example.SecondConstructor(match.pat.bytes)):
...             bytes_ = matchable[match.pat.bytes]
...             for byte in bytes_:
...                 yield chr(byte)
...         elif matchable(Example.ThirdConstructor()):
...             yield "Third"
...             yield "Constructor"
>>> list(Example.FirstConstructor(5, "abc"))
['abc', 'abc', 'abc', 'abc', 'abc']
>>> list(Example.SecondConstructor(b"abc"))
['a', 'b', 'c']
>>> list(Example.ThirdConstructor())
['Third', 'Constructor']
"""

import inspect
import sys
import typing

from . import _adt_constructor
from . import _ctor
from . import _prewritten_methods

_T = typing.TypeVar("_T")


if typing.TYPE_CHECKING:  # pragma: nocover

    class Ctor:
        """Dummy class for type-checking purposes."""

    class ConcreteCtor(typing.Generic[_T]):
        """Wrapper class for type-checking purposes.

        The type parameter should be a Tuple type of fixed size.
        Classes containing this annotation (meaning they haven't been
        processed by the ``adt`` decorator) should not be instantiated.
        """


else:
    from ._ctor import Ctor


# This is fine.
def _name(cls: typing.Type[_T], function) -> str:
    """Return the name of a function accessed through a descriptor."""
    return function.__get__(None, cls).__name__


# This is mostly fine, though the list of classes is somewhat ad-hoc, to say
# the least.
def _cant_set_new_functions(cls: typing.Type[_T], *functions) -> typing.Optional[str]:
    for function in functions:
        name = _name(cls, function)
        existing = getattr(cls, name, None)
        if existing not in (
            getattr(object, name, None),
            getattr(Product, name, None),
            None,
            function,
        ):
            return name
    return None


def _set_new_functions(cls: typing.Type[_T], *functions) -> typing.Optional[str]:
    """Attempt to set the attributes corresponding to the functions on cls.

    If any attributes are already defined, fail *before* setting any, and
    return the already-defined name.
    """
    cant_set = _cant_set_new_functions(cls, *functions)
    if cant_set:
        return cant_set
    for function in functions:
        setattr(cls, _name(cls, function), function)
    return None


_K = typing.TypeVar("_K")
_V = typing.TypeVar("_V")


def _nillable_write(dct: typing.Dict[_K, _V], key: _K, value: typing.Optional[_V]):
    if value is None:
        dct.pop(key, typing.cast(_V, None))
    else:
        dct[key] = value


def _sum_new(_cls: typing.Type[_T], subclasses):
    def base(cls, args):
        return super(_cls, cls).__new__(cls, args)

    new = _cls.__dict__.get("__new__", staticmethod(base))

    def __new__(cls, args):
        if cls not in subclasses:
            raise TypeError
        return new.__get__(None, cls)(cls, args)

    _cls.__new__ = staticmethod(__new__)  # type: ignore


def _product_new(
    _cls: typing.Type[_T],
    annotations: typing.Dict[str, typing.Any],
    defaults: typing.Dict[str, typing.Any],
):
    def __new__(*args, **kwargs):
        cls, *args = args
        return super(_cls, cls).__new__(cls, *args, **kwargs)

    __new__.__signature__ = inspect.signature(__new__).replace(
        parameters=[inspect.Parameter("cls", inspect.Parameter.POSITIONAL_ONLY)]
        + [
            inspect.Parameter(
                field,
                inspect.Parameter.POSITIONAL_OR_KEYWORD,
                annotation=annotation,
                default=defaults.get(field, inspect.Parameter.empty),
            )
            for (field, annotation) in annotations.items()
        ]
    )
    _cls.__new__ = __new__


def _all_annotations(
    cls: typing.Type[_T]
) -> typing.Iterator[typing.Tuple[typing.Type[_T], str, typing.Any]]:
    for superclass in reversed(cls.__mro__):
        for key, value in vars(superclass).get("__annotations__", {}).items():
            yield (superclass, key, value)


def _sum_args_from_annotations(cls: typing.Type[_T]) -> typing.Dict[str, typing.Tuple]:
    args: typing.Dict[str, typing.Tuple] = {}
    for superclass, key, value in _all_annotations(cls):
        _nillable_write(
            args, key, _ctor.get_args(value, vars(sys.modules[superclass.__module__]))
        )
    return args


def _product_args_from_annotations(
    cls: typing.Type[_T]
) -> typing.Dict[str, typing.Any]:
    args: typing.Dict[str, typing.Any] = {}
    for _, key, value in _all_annotations(cls):
        if value == "None" or _ctor.annotation_is_classvar(
            value, vars(sys.modules[cls.__module__])
        ):
            value = None
        _nillable_write(args, key, value)
    return args


def _ordering_options_are_valid(*, eq, order):
    if order and not eq:
        raise ValueError("eq must be true if order is true")


def _set_ordering(*, can_set, setter, cls, source):
    if not can_set:
        raise ValueError("Can't add ordering methods if equality methods are provided.")
    collision = setter(cls, source.__lt__, source.__le__, source.__gt__, source.__ge__)
    if collision:
        raise TypeError(
            "Cannot overwrite attribute {collision} in class "
            "{name}. Consider using functools.total_ordering".format(
                collision=collision, name=cls.__name__
            )
        )


def _extract_defaults(*, cls, annotations):
    defaults = {}
    field_names = iter(reversed(tuple(annotations)))
    for field in field_names:
        default = getattr(cls, field, inspect.Parameter.empty)
        if default is inspect.Parameter.empty:
            break
        defaults[field] = default
    for field in field_names:
        if getattr(cls, field, inspect.Parameter.empty) is not inspect.Parameter.empty:
            raise TypeError
    return defaults


def _unpack_args(*, args, kwargs, fields, values):
    fields_iter = iter(fields)
    values.update({field: arg for (arg, field) in zip(args, fields_iter)})
    for field in fields_iter:
        if field in values and field not in kwargs:
            continue
        values[field] = kwargs.pop(field)
    if kwargs:
        raise TypeError(kwargs)


class Sum:
    """Base class of classes with disjoint constructors.

    Examines PEP 526 __annotations__ to determine subclasses.

    If repr is true, a __repr__() method is added to the class.
    If order is true, rich comparison dunder methods are added.

    The Sum class examines the class to find Ctor annotations.
    A Ctor annotation is the adt.Ctor class itself, or the result of indexing
    the class, either with a single type hint, or a tuple of type hints.
    All other annotations are ignored.

    The subclass is not subclassable, but has subclasses at each of the
    names that had Ctor annotations. Each subclass takes a fixed number of
    arguments, corresponding to the type hints given to its annotation, if any.
    """

    __slots__ = ()

    def __new__(*args, **kwargs):  # pylint: disable=no-method-argument
        cls, *args = args
        if not issubclass(cls, _adt_constructor.ADTConstructor):
            raise TypeError
        return super(Sum, cls).__new__(cls, *args, **kwargs)

    # Both of these are for consistency with modules defined in the stdlib.
    # BOOM!
    def __init_subclass__(
        cls,
        *,
        repr=True,  # pylint: disable=redefined-builtin
        eq=True,  # pylint: disable=invalid-name
        order=False,
        **kwargs
    ):
        super().__init_subclass__(**kwargs)
        if issubclass(cls, _adt_constructor.ADTConstructor):
            return
        _ordering_options_are_valid(eq=eq, order=order)

        subclass_order: typing.List[typing.Type[_T]] = []

        for name, args in _sum_args_from_annotations(cls).items():
            _adt_constructor.make_constructor(cls, name, args, subclass_order)

        _prewritten_methods.SUBCLASS_ORDER[cls] = tuple(subclass_order)

        cls.__init_subclass__ = (
            _prewritten_methods.PrewrittenSumMethods.__init_subclass__
        )  # type: ignore

        _sum_new(cls, frozenset(subclass_order))

        _set_new_functions(
            cls,
            _prewritten_methods.PrewrittenSumMethods.__setattr__,
            _prewritten_methods.PrewrittenSumMethods.__delattr__,
        )
        _set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__bool__)

        if repr:
            _set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__repr__)

        equality_methods_were_set = False
        if eq:
            equality_methods_were_set = not _set_new_functions(
                cls,
                _prewritten_methods.PrewrittenSumMethods.__eq__,
                _prewritten_methods.PrewrittenSumMethods.__ne__,
            )

        if equality_methods_were_set:
            cls.__hash__ = _prewritten_methods.PrewrittenSumMethods.__hash__

        if order:
            _set_ordering(
                can_set=equality_methods_were_set,
                setter=_set_new_functions,
                cls=cls,
                source=_prewritten_methods.PrewrittenSumMethods,
            )


class Product(_adt_constructor.ADTConstructor, tuple):
    """Base class of classes with typed fields.

    Examines PEP 526 __annotations__ to determine fields.

    If repr is true, a __repr__() method is added to the class.
    If order is true, rich comparison dunder methods are added.

    The Product class examines the class to find annotations.
    Annotations with a value of "None" are discarded.
    Fields may have default values, and can be set to inspect.empty to
    indicate "no default".

    The subclass is subclassable. The implementation was designed with a focus
    on flexibility over ideals of purity, and therefore provides various
    optional facilities that conflict with, for example, Liskov
    substitutability. For the purposes of matching, each class is considered
    distinct.
    """

    __slots__ = ()

    def __new__(*args, **kwargs):  # pylint: disable=no-method-argument
        cls, *args = args
        if cls is Product:
            raise TypeError
        # Probably a result of not having positional-only args.
        values = cls.__defaults.copy()  # pylint: disable=protected-access
        _unpack_args(
            args=args,
            kwargs=kwargs,
            fields=cls.__fields,  # pylint: disable=protected-access
            values=values,
        )
        return super(Product, cls).__new__(
            cls,
            [
                values[field]
                for field in cls.__fields  # pylint: disable=protected-access
            ],
        )

    __repr = True
    __eq = True
    __order = False
    __eq_succeeded = None

    # Both of these are for consistency with modules defined in the stdlib.
    # BOOM!
    def __init_subclass__(
        cls,
        *,
        repr=None,  # pylint: disable=redefined-builtin
        eq=None,  # pylint: disable=invalid-name
        order=None,
        **kwargs
    ):
        super().__init_subclass__(**kwargs)

        if repr is not None:
            cls.__repr = repr
        if eq is not None:
            cls.__eq = eq
        if order is not None:
            cls.__order = order

        _ordering_options_are_valid(eq=cls.__eq, order=cls.__order)

        cls.__annotations = _product_args_from_annotations(cls)
        cls.__fields = {field: index for (index, field) in enumerate(cls.__annotations)}

        cls.__defaults = _extract_defaults(cls=cls, annotations=cls.__annotations)

        _product_new(cls, cls.__annotations, cls.__defaults)

        cls.__eq_succeeded = False
        if cls.__eq:
            cls.__eq_succeeded = not _cant_set_new_functions(
                cls,
                _prewritten_methods.PrewrittenProductMethods.__eq__,
                _prewritten_methods.PrewrittenProductMethods.__ne__,
            )

        if cls.__order:
            _set_ordering(
                can_set=cls.__eq_succeeded,
                setter=_cant_set_new_functions,
                cls=cls,
                source=_prewritten_methods.PrewrittenProductMethods,
            )

    def __dir__(self):
        return super().__dir__() + list(self.__fields)

    def __getattribute__(self, name):
        try:
            return super().__getattribute__(name)
        except AttributeError:
            index = self.__fields.get(name)
            if index is None:
                raise
            return tuple.__getitem__(self, index)

    __setattr__ = _prewritten_methods.PrewrittenProductMethods.__setattr__
    __delattr__ = _prewritten_methods.PrewrittenProductMethods.__delattr__
    __bool__ = _prewritten_methods.PrewrittenProductMethods.__bool__

    @property
    def __repr__(self):
        if self.__repr:
            return _prewritten_methods.PrewrittenProductMethods.__repr__.__get__(
                self, type(self)
            )
        return super().__repr__

    @property
    def __hash__(self):
        if self.__eq_succeeded:
            return _prewritten_methods.PrewrittenProductMethods.__hash__.__get__(
                self, type(self)
            )
        return super().__hash__

    @property
    def __eq__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__eq_succeeded:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__eq__.__get__(
                self, type(self)
            )
        return super().__eq__

    @property
    def __ne__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__eq_succeeded:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__ne__.__get__(
                self, type(self)
            )
        return super().__ne__

    @property
    def __lt__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__order:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__lt__.__get__(
                self, type(self)
            )
        return super().__lt__

    @property
    def __le__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__order:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__le__.__get__(
                self, type(self)
            )
        return super().__le__

    @property
    def __gt__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__order:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__gt__.__get__(
                self, type(self)
            )
        return super().__gt__

    @property
    def __ge__(self):  # pylint: disable=unexpected-special-method-signature
        if self.__order:
            # I think this is a Pylint bug, but I'm not sure how to reduce it.
            # pylint: disable=no-value-for-parameter
            return _prewritten_methods.PrewrittenProductMethods.__ge__.__get__(
                self, type(self)
            )
        return super().__ge__


__all__ = ["Ctor", "Product", "Sum"]


1			"""Base classes for defining abstract data types.
2
3			This module provides three public members, which are used together.
4
5			Given a structure, possibly a choice of different structures, that you'd like
6			to associate with a type:
7
8			- First, create a class, that subclasses the Sum class.
9			- Then, for each possible structure, add an attribute annotation to the class
10			with the desired name of the constructor, and a type of ``Ctor``, with the
11			types within the constructor as arguments.
12
13			To look inside an ADT instance, use the functions from the
14			:mod:`structured_data.match` module.
15
16			Putting it together:
17
18			>>> from structured_data import match
19			>>> class Example(Sum):
20			... FirstConstructor: Ctor[int, str]
21			... SecondConstructor: Ctor[bytes]
22			... ThirdConstructor: Ctor
23			... def __iter__(self):
24			... matchable = match.Matchable(self)
25			... if matchable(Example.FirstConstructor(match.pat.count, match.pat.string)):
26			... count, string = matchable[match.pat.count, match.pat.string]
27			... for _ in range(count):
28			... yield string
29			... elif matchable(Example.SecondConstructor(match.pat.bytes)):
30			... bytes_ = matchable[match.pat.bytes]
31			... for byte in bytes_:
32			... yield chr(byte)
33			... elif matchable(Example.ThirdConstructor()):
34			... yield "Third"
35			... yield "Constructor"
36			>>> list(Example.FirstConstructor(5, "abc"))
37			['abc', 'abc', 'abc', 'abc', 'abc']
38			>>> list(Example.SecondConstructor(b"abc"))
39			['a', 'b', 'c']
40			>>> list(Example.ThirdConstructor())
41			['Third', 'Constructor']
42			"""
43
44			import inspect
45			import sys
46			import typing
47
48			from . import _adt_constructor
49			from . import _ctor
50			from . import _prewritten_methods
51
52			_T = typing.TypeVar("_T")
53
54
55			if typing.TYPE_CHECKING: # pragma: nocover
56
57			class Ctor:
58			"""Dummy class for type-checking purposes."""
59
60			class ConcreteCtor(typing.Generic[_T]):
61			"""Wrapper class for type-checking purposes.
62
63			The type parameter should be a Tuple type of fixed size.
64			Classes containing this annotation (meaning they haven't been
65			processed by the ``adt`` decorator) should not be instantiated.
66			"""
67
68
69			else:
70			from ._ctor import Ctor
71
72
73			# This is fine.
74			def _name(cls: typing.Type[_T], function) -> str:
75			"""Return the name of a function accessed through a descriptor."""
76			return function.__get__(None, cls).__name__
77
78
79			# This is mostly fine, though the list of classes is somewhat ad-hoc, to say
80			# the least.
81			def _cant_set_new_functions(cls: typing.Type[_T], *functions) -> typing.Optional[str]:
82			for function in functions:
83			name = _name(cls, function)
84			existing = getattr(cls, name, None)
85			if existing not in (
86			getattr(object, name, None),
87			getattr(Product, name, None),
88			None,
89			function,
90			):
91			return name
92			return None
93
94
95			def _set_new_functions(cls: typing.Type[_T], *functions) -> typing.Optional[str]:
96			"""Attempt to set the attributes corresponding to the functions on cls.
97
98			If any attributes are already defined, fail before setting any, and
99			return the already-defined name.
100			"""
101			cant_set = _cant_set_new_functions(cls, *functions)
102			if cant_set:
103			return cant_set
104			for function in functions:
105			setattr(cls, _name(cls, function), function)
106			return None
107
108
109			_K = typing.TypeVar("_K")
110			_V = typing.TypeVar("_V")
111
112
113			def _nillable_write(dct: typing.Dict[_K, _V], key: _K, value: typing.Optional[_V]):
114			if value is None:
115			dct.pop(key, typing.cast(_V, None))
116			else:
117			dct[key] = value
118
119
120			def _sum_new(_cls: typing.Type[_T], subclasses):
121			def base(cls, args):
122			return super(_cls, cls).__new__(cls, args)
123
124			new = _cls.__dict__.get("__new__", staticmethod(base))
125
126			def __new__(cls, args):
127			if cls not in subclasses:
128			raise TypeError
129			return new.__get__(None, cls)(cls, args)
130
131			_cls.__new__ = staticmethod(__new__) # type: ignore
132
133
134			def _product_new(
135			_cls: typing.Type[_T],
136			annotations: typing.Dict[str, typing.Any],
137			defaults: typing.Dict[str, typing.Any],
138			):
139			def __new__(args, *kwargs):
140			cls, *args = args
141			return super(_cls, cls).__new__(cls, args, *kwargs)
142
143			__new__.__signature__ = inspect.signature(__new__).replace(
144			parameters=[inspect.Parameter("cls", inspect.Parameter.POSITIONAL_ONLY)]
145			+ [
146			inspect.Parameter(
147			field,
148			inspect.Parameter.POSITIONAL_OR_KEYWORD,
149			annotation=annotation,
150			default=defaults.get(field, inspect.Parameter.empty),
151			)
152			for (field, annotation) in annotations.items()
153			]
154			)
155			_cls.__new__ = __new__
156
157
158			def _all_annotations(
159			cls: typing.Type[_T]
160			) -> typing.Iterator[typing.Tuple[typing.Type[_T], str, typing.Any]]:
161			for superclass in reversed(cls.__mro__):
162			for key, value in vars(superclass).get("__annotations__", {}).items():
163			yield (superclass, key, value)
164
165
166			def _sum_args_from_annotations(cls: typing.Type[_T]) -> typing.Dict[str, typing.Tuple]:
167			args: typing.Dict[str, typing.Tuple] = {}
168			for superclass, key, value in _all_annotations(cls):
169			_nillable_write(
170			args, key, _ctor.get_args(value, vars(sys.modules[superclass.__module__]))
171			)
172			return args
173
174
175			def _product_args_from_annotations(
176			cls: typing.Type[_T]
177			) -> typing.Dict[str, typing.Any]:
178			args: typing.Dict[str, typing.Any] = {}
179			for _, key, value in _all_annotations(cls):
180			if value == "None" or _ctor.annotation_is_classvar(
181			value, vars(sys.modules[cls.__module__])
182			):
183			value = None
184			_nillable_write(args, key, value)
185			return args
186
187
188			def _ordering_options_are_valid(*, eq, order):
189			if order and not eq:
190			raise ValueError("eq must be true if order is true")
191
192
193			def _set_ordering(*, can_set, setter, cls, source):
194			if not can_set:
195			raise ValueError("Can't add ordering methods if equality methods are provided.")
196			collision = setter(cls, source.__lt__, source.__le__, source.__gt__, source.__ge__)
197			if collision:
198			raise TypeError(
199			"Cannot overwrite attribute {collision} in class "
200			"{name}. Consider using functools.total_ordering".format(
201			collision=collision, name=cls.__name__
202			)
203			)
204
205
206			def _extract_defaults(*, cls, annotations):
207			defaults = {}
208			field_names = iter(reversed(tuple(annotations)))
209			for field in field_names:
210			default = getattr(cls, field, inspect.Parameter.empty)
211			if default is inspect.Parameter.empty:
212			break
213			defaults[field] = default
214			for field in field_names:
215			if getattr(cls, field, inspect.Parameter.empty) is not inspect.Parameter.empty:
216			raise TypeError
217			return defaults
218
219
220			def _unpack_args(*, args, kwargs, fields, values):
221			fields_iter = iter(fields)
222			values.update({field: arg for (arg, field) in zip(args, fields_iter)})
223			for field in fields_iter:
224			if field in values and field not in kwargs:
225			continue
226			values[field] = kwargs.pop(field)
227			if kwargs:
228			raise TypeError(kwargs)
229
230
231			class Sum:
232			"""Base class of classes with disjoint constructors.
233
234			Examines PEP 526 __annotations__ to determine subclasses.
235
236			If repr is true, a __repr__() method is added to the class.
237			If order is true, rich comparison dunder methods are added.
238
239			The Sum class examines the class to find Ctor annotations.
240			A Ctor annotation is the adt.Ctor class itself, or the result of indexing
241			the class, either with a single type hint, or a tuple of type hints.
242			All other annotations are ignored.
243
244			The subclass is not subclassable, but has subclasses at each of the
245			names that had Ctor annotations. Each subclass takes a fixed number of
246			arguments, corresponding to the type hints given to its annotation, if any.
247			"""
248
249			__slots__ = ()
250
251			def __new__(args, *kwargs): # pylint: disable=no-method-argument
252			cls, *args = args
253			if not issubclass(cls, _adt_constructor.ADTConstructor):
254			raise TypeError
255			return super(Sum, cls).__new__(cls, args, *kwargs)
256
257			# Both of these are for consistency with modules defined in the stdlib.
258			# BOOM!
259			def __init_subclass__(
260			cls,
261			*,
262			repr=True, # pylint: disable=redefined-builtin
263			eq=True, # pylint: disable=invalid-name
264			order=False,
265			**kwargs
266			):
267			super().__init_subclass__(**kwargs)
268			if issubclass(cls, _adt_constructor.ADTConstructor):
269			return
270			_ordering_options_are_valid(eq=eq, order=order)
271
272			subclass_order: typing.List[typing.Type[_T]] = []
273
274			for name, args in _sum_args_from_annotations(cls).items():
275			_adt_constructor.make_constructor(cls, name, args, subclass_order)
276
277			_prewritten_methods.SUBCLASS_ORDER[cls] = tuple(subclass_order)
278
279			cls.__init_subclass__ = (
280			_prewritten_methods.PrewrittenSumMethods.__init_subclass__
281			) # type: ignore
282
283			_sum_new(cls, frozenset(subclass_order))
284
285			_set_new_functions(
286			cls,
287			_prewritten_methods.PrewrittenSumMethods.__setattr__,
288			_prewritten_methods.PrewrittenSumMethods.__delattr__,
289			)
290			_set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__bool__)
291
292			if repr:
293			_set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__repr__)
294
295			equality_methods_were_set = False
296			if eq:
297			equality_methods_were_set = not _set_new_functions(
298			cls,
299			_prewritten_methods.PrewrittenSumMethods.__eq__,
300			_prewritten_methods.PrewrittenSumMethods.__ne__,
301			)
302
303			if equality_methods_were_set:
304			cls.__hash__ = _prewritten_methods.PrewrittenSumMethods.__hash__
305
306			if order:
307			_set_ordering(
308			can_set=equality_methods_were_set,
309			setter=_set_new_functions,
310			cls=cls,
311			source=_prewritten_methods.PrewrittenSumMethods,
312			)
313
314
315			class Product(_adt_constructor.ADTConstructor, tuple):
316			"""Base class of classes with typed fields.
317
318			Examines PEP 526 __annotations__ to determine fields.
319
320			If repr is true, a __repr__() method is added to the class.
321			If order is true, rich comparison dunder methods are added.
322
323			The Product class examines the class to find annotations.
324			Annotations with a value of "None" are discarded.
325			Fields may have default values, and can be set to inspect.empty to
326			indicate "no default".
327
328			The subclass is subclassable. The implementation was designed with a focus
329			on flexibility over ideals of purity, and therefore provides various
330			optional facilities that conflict with, for example, Liskov
331			substitutability. For the purposes of matching, each class is considered
332			distinct.
333			"""
334
335			__slots__ = ()
336
337			def __new__(args, *kwargs): # pylint: disable=no-method-argument
338			cls, *args = args
339			if cls is Product:
340			raise TypeError
341			# Probably a result of not having positional-only args.
342			values = cls.__defaults.copy() # pylint: disable=protected-access
343			_unpack_args(
344			args=args,
345			kwargs=kwargs,
346			fields=cls.__fields, # pylint: disable=protected-access
347			values=values,
348			)
349			return super(Product, cls).__new__(
350			cls,
351			[
352			values[field]
353			for field in cls.__fields # pylint: disable=protected-access
354			],
355			)
356
357			__repr = True
358			__eq = True
359			__order = False
360			__eq_succeeded = None
361
362			# Both of these are for consistency with modules defined in the stdlib.
363			# BOOM!
364			def __init_subclass__(
365			cls,
366			*,
367			repr=None, # pylint: disable=redefined-builtin
368			eq=None, # pylint: disable=invalid-name
369			order=None,
370			**kwargs
371			):
372			super().__init_subclass__(**kwargs)
373
374			if repr is not None:
375			cls.__repr = repr
376			if eq is not None:
377			cls.__eq = eq
378			if order is not None:
379			cls.__order = order
380
381			_ordering_options_are_valid(eq=cls.__eq, order=cls.__order)
382
383			cls.__annotations = _product_args_from_annotations(cls)
384			cls.__fields = {field: index for (index, field) in enumerate(cls.__annotations)}
385
386			cls.__defaults = _extract_defaults(cls=cls, annotations=cls.__annotations)
387
388			_product_new(cls, cls.__annotations, cls.__defaults)
389
390			cls.__eq_succeeded = False
391			if cls.__eq:
392			cls.__eq_succeeded = not _cant_set_new_functions(
393			cls,
394			_prewritten_methods.PrewrittenProductMethods.__eq__,
395			_prewritten_methods.PrewrittenProductMethods.__ne__,
396			)
397
398			if cls.__order:
399			_set_ordering(
400			can_set=cls.__eq_succeeded,
401			setter=_cant_set_new_functions,
402			cls=cls,
403			source=_prewritten_methods.PrewrittenProductMethods,
404			)
405
406			def __dir__(self):
407			return super().__dir__() + list(self.__fields)
408
409			def __getattribute__(self, name):
410			try:
411			return super().__getattribute__(name)
412			except AttributeError:
413			index = self.__fields.get(name)
414			if index is None:
415			raise
416			return tuple.__getitem__(self, index)
417
418			__setattr__ = _prewritten_methods.PrewrittenProductMethods.__setattr__
419			__delattr__ = _prewritten_methods.PrewrittenProductMethods.__delattr__
420			__bool__ = _prewritten_methods.PrewrittenProductMethods.__bool__
421
422			@property
423			def __repr__(self):
424			if self.__repr:
425			return _prewritten_methods.PrewrittenProductMethods.__repr__.__get__(
426			self, type(self)
427			)
428			return super().__repr__
429
430			@property
431			def __hash__(self):
432			if self.__eq_succeeded:
433			return _prewritten_methods.PrewrittenProductMethods.__hash__.__get__(
434			self, type(self)
435			)
436			return super().__hash__
437
438			@property
439			def __eq__(self): # pylint: disable=unexpected-special-method-signature
440			if self.__eq_succeeded:
441			# I think this is a Pylint bug, but I'm not sure how to reduce it.
442			# pylint: disable=no-value-for-parameter
443			return _prewritten_methods.PrewrittenProductMethods.__eq__.__get__(
444			self, type(self)
445			)
446			return super().__eq__
447
448			@property
449			def __ne__(self): # pylint: disable=unexpected-special-method-signature
450			if self.__eq_succeeded:
451			# I think this is a Pylint bug, but I'm not sure how to reduce it.
452			# pylint: disable=no-value-for-parameter
453			return _prewritten_methods.PrewrittenProductMethods.__ne__.__get__(
454			self, type(self)
455			)
456			return super().__ne__
457
458			@property
459			def __lt__(self): # pylint: disable=unexpected-special-method-signature
460			if self.__order:
461			# I think this is a Pylint bug, but I'm not sure how to reduce it.
462			# pylint: disable=no-value-for-parameter
463			return _prewritten_methods.PrewrittenProductMethods.__lt__.__get__(
464			self, type(self)
465			)
466			return super().__lt__
467
468			@property
469			def __le__(self): # pylint: disable=unexpected-special-method-signature
470			if self.__order:
471			# I think this is a Pylint bug, but I'm not sure how to reduce it.
472			# pylint: disable=no-value-for-parameter
473			return _prewritten_methods.PrewrittenProductMethods.__le__.__get__(
474			self, type(self)
475			)
476			return super().__le__
477
478			@property
479			def __gt__(self): # pylint: disable=unexpected-special-method-signature
480			if self.__order:
481			# I think this is a Pylint bug, but I'm not sure how to reduce it.
482			# pylint: disable=no-value-for-parameter
483			return _prewritten_methods.PrewrittenProductMethods.__gt__.__get__(
484			self, type(self)
485			)
486			return super().__gt__
487
488			@property
489			def __ge__(self): # pylint: disable=unexpected-special-method-signature
490			if self.__order:
491			# I think this is a Pylint bug, but I'm not sure how to reduce it.
492			# pylint: disable=no-value-for-parameter
493			return _prewritten_methods.PrewrittenProductMethods.__ge__.__get__(
494			self, type(self)
495			)
496			return super().__ge__
497
498
499			__all__ = ["Ctor", "Product", "Sum"]
500

mwchase / python-structured-data

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