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

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Push — master ( 934b7f...dcd100 )

by Max

created 2019-09-02 13:36 UTC

structured_data.adt.Product.__init_subclass__() B

↳ Parent: structured_data.adt

Complexity

Conditions

Size

Total Lines	40
Code Lines	31

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	6
eloc	31
nop	6
dl	0
loc	40
rs	8.2026
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


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
        # Similar to https://github.com/PyCQA/pylint/issues/1802
        values = cls.__defaults.copy()  # pylint: disable=protected-access
        fields_iter = iter(cls.__fields)  # pylint: disable=protected-access
        for arg, field in zip(args, fields_iter):
            values[field] = arg
        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)
        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			class Sum:
221			"""Base class of classes with disjoint constructors.
222
223			Examines PEP 526 __annotations__ to determine subclasses.
224
225			If repr is true, a __repr__() method is added to the class.
226			If order is true, rich comparison dunder methods are added.
227
228			The Sum class examines the class to find Ctor annotations.
229			A Ctor annotation is the adt.Ctor class itself, or the result of indexing
230			the class, either with a single type hint, or a tuple of type hints.
231			All other annotations are ignored.
232
233			The subclass is not subclassable, but has subclasses at each of the
234			names that had Ctor annotations. Each subclass takes a fixed number of
235			arguments, corresponding to the type hints given to its annotation, if any.
236			"""
237
238			__slots__ = ()
239
240			def __new__(args, *kwargs): # pylint: disable=no-method-argument
241			cls, *args = args
242			if not issubclass(cls, _adt_constructor.ADTConstructor):
243			raise TypeError
244			return super(Sum, cls).__new__(cls, args, *kwargs)
245
246			# Both of these are for consistency with modules defined in the stdlib.
247			# BOOM!
248			def __init_subclass__(
249			cls,
250			*,
251			repr=True, # pylint: disable=redefined-builtin
252			eq=True, # pylint: disable=invalid-name
253			order=False,
254			**kwargs
255			):
256			super().__init_subclass__(**kwargs)
257			if issubclass(cls, _adt_constructor.ADTConstructor):
258			return
259			_ordering_options_are_valid(eq=eq, order=order)
260
261			subclass_order: typing.List[typing.Type[_T]] = []
262
263			for name, args in _sum_args_from_annotations(cls).items():
264			_adt_constructor.make_constructor(cls, name, args, subclass_order)
265
266			_prewritten_methods.SUBCLASS_ORDER[cls] = tuple(subclass_order)
267
268			cls.__init_subclass__ = (
269			_prewritten_methods.PrewrittenSumMethods.__init_subclass__
270			) # type: ignore
271
272			_sum_new(cls, frozenset(subclass_order))
273
274			_set_new_functions(
275			cls,
276			_prewritten_methods.PrewrittenSumMethods.__setattr__,
277			_prewritten_methods.PrewrittenSumMethods.__delattr__,
278			)
279			_set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__bool__)
280
281			if repr:
282			_set_new_functions(cls, _prewritten_methods.PrewrittenSumMethods.__repr__)
283
284			equality_methods_were_set = False
285			if eq:
286			equality_methods_were_set = not _set_new_functions(
287			cls,
288			_prewritten_methods.PrewrittenSumMethods.__eq__,
289			_prewritten_methods.PrewrittenSumMethods.__ne__,
290			)
291
292			if equality_methods_were_set:
293			cls.__hash__ = _prewritten_methods.PrewrittenSumMethods.__hash__
294
295			if order:
296			_set_ordering(
297			can_set=equality_methods_were_set,
298			setter=_set_new_functions,
299			cls=cls,
300			source=_prewritten_methods.PrewrittenSumMethods,
301			)
302
303
304			class Product(_adt_constructor.ADTConstructor, tuple):
305			"""Base class of classes with typed fields.
306
307			Examines PEP 526 __annotations__ to determine fields.
308
309			If repr is true, a __repr__() method is added to the class.
310			If order is true, rich comparison dunder methods are added.
311
312			The Product class examines the class to find annotations.
313			Annotations with a value of "None" are discarded.
314			Fields may have default values, and can be set to inspect.empty to
315			indicate "no default".
316
317			The subclass is subclassable. The implementation was designed with a focus
318			on flexibility over ideals of purity, and therefore provides various
319			optional facilities that conflict with, for example, Liskov
320			substitutability. For the purposes of matching, each class is considered
321			distinct.
322			"""
323
324			__slots__ = ()
325
326			def __new__(args, *kwargs): # pylint: disable=no-method-argument
327			cls, *args = args
328			if cls is Product:
329			raise TypeError
330			# Similar to https://github.com/PyCQA/pylint/issues/1802
331			values = cls.__defaults.copy() # pylint: disable=protected-access
332			fields_iter = iter(cls.__fields) # pylint: disable=protected-access
333			for arg, field in zip(args, fields_iter):
334			values[field] = arg
335			for field in fields_iter:
336			if field in values and field not in kwargs:
337			continue
338			values[field] = kwargs.pop(field)
339			if kwargs:
340			raise TypeError(kwargs)
341			return super(Product, cls).__new__(
342			cls,
343			[
344			values[field]
345			for field in cls.__fields # pylint: disable=protected-access
346			],
347			)
348
349			__repr = True
350			__eq = True
351			__order = False
352			__eq_succeeded = None
353
354			# Both of these are for consistency with modules defined in the stdlib.
355			# BOOM!
356			def __init_subclass__(
357			cls,
358			*,
359			repr=None, # pylint: disable=redefined-builtin
360			eq=None, # pylint: disable=invalid-name
361			order=None,
362			**kwargs
363			):
364			super().__init_subclass__(**kwargs)
365
366			if repr is not None:
367			cls.__repr = repr
368			if eq is not None:
369			cls.__eq = eq
370			if order is not None:
371			cls.__order = order
372
373			_ordering_options_are_valid(eq=cls.__eq, order=cls.__order)
374
375			cls.__annotations = _product_args_from_annotations(cls)
376			cls.__fields = {field: index for (index, field) in enumerate(cls.__annotations)}
377
378			cls.__defaults = _extract_defaults(cls=cls, annotations=cls.__annotations)
379
380			_product_new(cls, cls.__annotations, cls.__defaults)
381
382			cls.__eq_succeeded = False
383			if cls.__eq:
384			cls.__eq_succeeded = not _cant_set_new_functions(
385			cls,
386			_prewritten_methods.PrewrittenProductMethods.__eq__,
387			_prewritten_methods.PrewrittenProductMethods.__ne__,
388			)
389
390			if cls.__order:
391			_set_ordering(
392			can_set=cls.__eq_succeeded,
393			setter=_cant_set_new_functions,
394			cls=cls,
395			source=_prewritten_methods.PrewrittenProductMethods,
396			)
397
398			def __dir__(self):
399			return super().__dir__() + list(self.__fields)
400
401			def __getattribute__(self, name):
402			try:
403			return super().__getattribute__(name)
404			except AttributeError:
405			index = self.__fields.get(name)
406			if index is None:
407			raise
408			return tuple.__getitem__(self, index)
409
410			__setattr__ = _prewritten_methods.PrewrittenProductMethods.__setattr__
411			__delattr__ = _prewritten_methods.PrewrittenProductMethods.__delattr__
412			__bool__ = _prewritten_methods.PrewrittenProductMethods.__bool__
413
414			@property
415			def __repr__(self):
416			if self.__repr:
417			return _prewritten_methods.PrewrittenProductMethods.__repr__.__get__(
418			self, type(self)
419			)
420			return super().__repr__
421
422			@property
423			def __hash__(self):
424			if self.__eq_succeeded:
425			return _prewritten_methods.PrewrittenProductMethods.__hash__.__get__(
426			self, type(self)
427			)
428			return super().__hash__
429
430			@property
431			def __eq__(self): # pylint: disable=unexpected-special-method-signature
432			if self.__eq_succeeded:
433			# I think this is a Pylint bug, but I'm not sure how to reduce it.
434			# pylint: disable=no-value-for-parameter
435			return _prewritten_methods.PrewrittenProductMethods.__eq__.__get__(
436			self, type(self)
437			)
438			return super().__eq__
439
440			@property
441			def __ne__(self): # pylint: disable=unexpected-special-method-signature
442			if self.__eq_succeeded:
443			# I think this is a Pylint bug, but I'm not sure how to reduce it.
444			# pylint: disable=no-value-for-parameter
445			return _prewritten_methods.PrewrittenProductMethods.__ne__.__get__(
446			self, type(self)
447			)
448			return super().__ne__
449
450			@property
451			def __lt__(self): # pylint: disable=unexpected-special-method-signature
452			if self.__order:
453			# I think this is a Pylint bug, but I'm not sure how to reduce it.
454			# pylint: disable=no-value-for-parameter
455			return _prewritten_methods.PrewrittenProductMethods.__lt__.__get__(
456			self, type(self)
457			)
458			return super().__lt__
459
460			@property
461			def __le__(self): # pylint: disable=unexpected-special-method-signature
462			if self.__order:
463			# I think this is a Pylint bug, but I'm not sure how to reduce it.
464			# pylint: disable=no-value-for-parameter
465			return _prewritten_methods.PrewrittenProductMethods.__le__.__get__(
466			self, type(self)
467			)
468			return super().__le__
469
470			@property
471			def __gt__(self): # pylint: disable=unexpected-special-method-signature
472			if self.__order:
473			# I think this is a Pylint bug, but I'm not sure how to reduce it.
474			# pylint: disable=no-value-for-parameter
475			return _prewritten_methods.PrewrittenProductMethods.__gt__.__get__(
476			self, type(self)
477			)
478			return super().__gt__
479
480			@property
481			def __ge__(self): # pylint: disable=unexpected-special-method-signature
482			if self.__order:
483			# I think this is a Pylint bug, but I'm not sure how to reduce it.
484			# pylint: disable=no-value-for-parameter
485			return _prewritten_methods.PrewrittenProductMethods.__ge__.__get__(
486			self, type(self)
487			)
488			return super().__ge__
489
490
491			__all__ = ["Ctor", "Product", "Sum"]
492

mwchase / python-structured-data

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structured_data.adt.Product.__init_subclass__() B

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