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Copy pathannotationlib.py
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1220 lines (1071 loc) · 44.4 KB
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"""Helpers for introspecting and wrapping annotations."""
import ast
import builtins
import enum
import keyword
import sys
import types
__all__ = [
"Format",
"ForwardRef",
"call_annotate_function",
"call_evaluate_function",
"get_annotate_from_class_namespace",
"get_annotations",
"annotations_to_string",
"type_repr",
]
class Format(enum.IntEnum):
VALUE = 1
VALUE_WITH_FAKE_GLOBALS = 2
FORWARDREF = 3
STRING = 4
_sentinel = object()
# Following `NAME_ERROR_MSG` in `ceval_macros.h`:
_NAME_ERROR_MSG = "name '{name:.200}' is not defined"
# Slots shared by ForwardRef and _Stringifier. The __forward__ names must be
# preserved for compatibility with the old typing.ForwardRef class. The remaining
# names are private.
_SLOTS = (
"__forward_is_argument__",
"__forward_is_class__",
"__forward_module__",
"__weakref__",
"__arg__",
"__globals__",
"__extra_names__",
"__code__",
"__ast_node__",
"__cell__",
"__owner__",
"__stringifier_dict__",
"__resolved_str_cache__",
)
class ForwardRef:
"""Wrapper that holds a forward reference.
Constructor arguments:
* arg: a string representing the code to be evaluated.
* module: the module where the forward reference was created.
Must be a string, not a module object.
* owner: The owning object (module, class, or function).
* is_argument: Does nothing, retained for compatibility.
* is_class: True if the forward reference was created in class scope.
"""
__slots__ = _SLOTS
def __init__(
self,
arg,
*,
module=None,
owner=None,
is_argument=True,
is_class=False,
):
if not isinstance(arg, str):
raise TypeError(f"Forward reference must be a string -- got {arg!r}")
self.__arg__ = arg
self.__forward_is_argument__ = is_argument
self.__forward_is_class__ = is_class
self.__forward_module__ = module
self.__owner__ = owner
# These are always set to None here but may be non-None if a ForwardRef
# is created through __class__ assignment on a _Stringifier object.
self.__globals__ = None
# This may be either a cell object (for a ForwardRef referring to a single name)
# or a dict mapping cell names to cell objects (for a ForwardRef containing references
# to multiple names).
self.__cell__ = None
self.__extra_names__ = None
# These are initially None but serve as a cache and may be set to a non-None
# value later.
self.__code__ = None
self.__ast_node__ = None
self.__resolved_str_cache__ = None
def __init_subclass__(cls, /, *args, **kwds):
raise TypeError("Cannot subclass ForwardRef")
def evaluate(
self,
*,
globals=None,
locals=None,
type_params=None,
owner=None,
format=Format.VALUE,
):
"""Evaluate the forward reference and return the value.
If the forward reference cannot be evaluated, raise an exception.
"""
match format:
case Format.STRING:
return self.__resolved_str__
case Format.VALUE:
is_forwardref_format = False
case Format.FORWARDREF:
is_forwardref_format = True
case _:
raise NotImplementedError(format)
if isinstance(self.__cell__, types.CellType):
try:
return self.__cell__.cell_contents
except ValueError:
pass
if owner is None:
owner = self.__owner__
if globals is None and self.__forward_module__ is not None:
globals = getattr(
sys.modules.get(self.__forward_module__, None), "__dict__", None
)
if globals is None:
globals = self.__globals__
if globals is None:
if isinstance(owner, type):
module_name = getattr(owner, "__module__", None)
if module_name:
module = sys.modules.get(module_name, None)
if module:
globals = getattr(module, "__dict__", None)
elif isinstance(owner, types.ModuleType):
globals = getattr(owner, "__dict__", None)
elif callable(owner):
globals = getattr(owner, "__globals__", None)
# If we pass None to eval() below, the globals of this module are used.
if globals is None:
globals = {}
if type_params is None and owner is not None:
type_params = getattr(owner, "__type_params__", None)
if locals is None:
locals = {}
if isinstance(owner, type):
locals.update(vars(owner))
elif (
type_params is not None
or isinstance(self.__cell__, dict)
or self.__extra_names__
):
# Create a new locals dict if necessary,
# to avoid mutating the argument.
locals = dict(locals)
# "Inject" type parameters into the local namespace
# (unless they are shadowed by assignments *in* the local namespace),
# as a way of emulating annotation scopes when calling `eval()`
if type_params is not None:
for param in type_params:
locals.setdefault(param.__name__, param)
# Similar logic can be used for nonlocals, which should not
# override locals.
if isinstance(self.__cell__, dict):
for cell_name, cell in self.__cell__.items():
try:
cell_value = cell.cell_contents
except ValueError:
pass
else:
locals.setdefault(cell_name, cell_value)
if self.__extra_names__:
locals.update(self.__extra_names__)
arg = self.__forward_arg__
if arg.isidentifier() and not keyword.iskeyword(arg):
resolved = _sentinel
if arg in locals:
resolved = locals[arg]
elif arg in globals:
resolved = globals[arg]
elif hasattr(builtins, arg):
resolved = getattr(builtins, arg)
if resolved is not _sentinel:
if isinstance(resolved, types.LazyImportType):
# We try reifying the lazy object. If this fails, we propagate
# the error in the VALUE format and leave the
# ForwardRef unresolved in the FORWARDREF format.
try:
return resolved.resolve()
except Exception:
if not is_forwardref_format:
raise
return self
else:
return resolved
elif is_forwardref_format:
return self
else:
raise NameError(_NAME_ERROR_MSG.format(name=arg), name=arg)
else:
code = self.__forward_code__
try:
return eval(code, globals=globals, locals=locals)
except Exception:
if not is_forwardref_format:
raise
# All variables, in scoping order, should be checked before
# triggering __missing__ to create a _Stringifier.
new_locals = _StringifierDict(
{**builtins.__dict__, **globals, **locals},
globals=globals,
owner=owner,
is_class=self.__forward_is_class__,
format=format,
)
try:
result = eval(code, globals=globals, locals=new_locals)
except Exception:
return self
else:
new_locals.transmogrify(self.__cell__)
return result
def _evaluate(self, globalns, localns, type_params=_sentinel, *, recursive_guard):
import typing
import warnings
if type_params is _sentinel:
typing._deprecation_warning_for_no_type_params_passed(
"typing.ForwardRef._evaluate"
)
type_params = ()
warnings._deprecated(
"ForwardRef._evaluate",
"{name} is a private API and is retained for compatibility, but will be removed"
" in Python 3.16. Use ForwardRef.evaluate() or typing.evaluate_forward_ref() instead.",
remove=(3, 16),
)
return typing.evaluate_forward_ref(
self,
globals=globalns,
locals=localns,
type_params=type_params,
_recursive_guard=recursive_guard,
)
@property
def __forward_arg__(self):
if self.__arg__ is not None:
return self.__arg__
if self.__ast_node__ is not None:
self.__arg__ = ast.unparse(self.__ast_node__)
return self.__arg__
raise AssertionError(
"Attempted to access '__forward_arg__' on an uninitialized ForwardRef"
)
@property
def __resolved_str__(self):
# __forward_arg__ with any names from __extra_names__ replaced
# with the type_repr of the value they represent
if self.__resolved_str_cache__ is None:
resolved_str = self.__forward_arg__
names = self.__extra_names__
if names:
visitor = _ExtraNameFixer(names)
ast_expr = ast.parse(resolved_str, mode="eval").body
node = visitor.visit(ast_expr)
resolved_str = ast.unparse(node)
self.__resolved_str_cache__ = resolved_str
return self.__resolved_str_cache__
@property
def __forward_code__(self):
if self.__code__ is not None:
return self.__code__
arg = self.__forward_arg__
try:
self.__code__ = compile(_rewrite_star_unpack(arg), "<string>", "eval")
except SyntaxError:
raise SyntaxError(f"Forward reference must be an expression -- got {arg!r}")
return self.__code__
def __eq__(self, other):
if not isinstance(other, ForwardRef):
return NotImplemented
return (
self.__forward_arg__ == other.__forward_arg__
and self.__forward_module__ == other.__forward_module__
# Use "is" here because we use id() for this in __hash__
# because dictionaries are not hashable.
and self.__globals__ is other.__globals__
and self.__forward_is_class__ == other.__forward_is_class__
# Two separate cells are always considered unequal in forward refs.
and (
{name: id(cell) for name, cell in self.__cell__.items()}
== {name: id(cell) for name, cell in other.__cell__.items()}
if isinstance(self.__cell__, dict) and isinstance(other.__cell__, dict)
else self.__cell__ is other.__cell__
)
and self.__owner__ == other.__owner__
and (
(tuple(sorted(self.__extra_names__.items())) if self.__extra_names__ else None) ==
(tuple(sorted(other.__extra_names__.items())) if other.__extra_names__ else None)
)
)
def __hash__(self):
return hash((
self.__forward_arg__,
self.__forward_module__,
id(self.__globals__), # dictionaries are not hashable, so hash by identity
self.__forward_is_class__,
( # cells are not hashable as well
tuple(sorted([(name, id(cell)) for name, cell in self.__cell__.items()]))
if isinstance(self.__cell__, dict) else id(self.__cell__),
),
self.__owner__,
tuple(sorted(self.__extra_names__.items())) if self.__extra_names__ else None,
))
def __or__(self, other):
return types.UnionType[self, other]
def __ror__(self, other):
return types.UnionType[other, self]
def __repr__(self):
extra = []
if self.__forward_module__ is not None:
extra.append(f", module={self.__forward_module__!r}")
if self.__forward_is_class__:
extra.append(", is_class=True")
if self.__owner__ is not None:
extra.append(f", owner={self.__owner__!r}")
return f"ForwardRef({self.__resolved_str__!r}{''.join(extra)})"
_Template = type(t"")
class _Stringifier:
# Must match the slots on ForwardRef, so we can turn an instance of one into an
# instance of the other in place.
__slots__ = _SLOTS
def __init__(
self,
node,
globals=None,
owner=None,
is_class=False,
cell=None,
*,
stringifier_dict,
extra_names=None,
):
# Either an AST node or a simple str (for the common case where a ForwardRef
# represent a single name).
assert isinstance(node, (ast.AST, str))
self.__arg__ = None
self.__forward_is_argument__ = False
self.__forward_is_class__ = is_class
self.__forward_module__ = None
self.__code__ = None
self.__ast_node__ = node
self.__globals__ = globals
self.__extra_names__ = extra_names
self.__cell__ = cell
self.__owner__ = owner
self.__stringifier_dict__ = stringifier_dict
self.__resolved_str_cache__ = None # Needed for ForwardRef
def __convert_to_ast(self, other):
if isinstance(other, _Stringifier):
if isinstance(other.__ast_node__, str):
return ast.Name(id=other.__ast_node__), other.__extra_names__
return other.__ast_node__, other.__extra_names__
elif type(other) is _Template:
return _template_to_ast(other), None
elif (
# In STRING format we don't bother with the create_unique_name() dance;
# it's better to emit the repr() of the object instead of an opaque name.
self.__stringifier_dict__.format == Format.STRING
or other is None
or type(other) in (str, int, float, bool, complex)
):
return ast.Constant(value=other), None
elif type(other) is dict:
extra_names = {}
keys = []
values = []
for key, value in other.items():
new_key, new_extra_names = self.__convert_to_ast(key)
if new_extra_names is not None:
extra_names.update(new_extra_names)
keys.append(new_key)
new_value, new_extra_names = self.__convert_to_ast(value)
if new_extra_names is not None:
extra_names.update(new_extra_names)
values.append(new_value)
return ast.Dict(keys, values), extra_names
elif type(other) in (list, tuple, set):
extra_names = {}
elts = []
for elt in other:
new_elt, new_extra_names = self.__convert_to_ast(elt)
if new_extra_names is not None:
extra_names.update(new_extra_names)
elts.append(new_elt)
ast_class = {list: ast.List, tuple: ast.Tuple, set: ast.Set}[type(other)]
return ast_class(elts), extra_names
else:
name = self.__stringifier_dict__.create_unique_name()
return ast.Name(id=name), {name: other}
def __convert_to_ast_getitem(self, other):
if isinstance(other, slice):
extra_names = {}
def conv(obj):
if obj is None:
return None
new_obj, new_extra_names = self.__convert_to_ast(obj)
if new_extra_names is not None:
extra_names.update(new_extra_names)
return new_obj
return ast.Slice(
lower=conv(other.start),
upper=conv(other.stop),
step=conv(other.step),
), extra_names
else:
return self.__convert_to_ast(other)
def __get_ast(self):
node = self.__ast_node__
if isinstance(node, str):
return ast.Name(id=node)
return node
def __make_new(self, node, extra_names=None):
new_extra_names = {}
if self.__extra_names__ is not None:
new_extra_names.update(self.__extra_names__)
if extra_names is not None:
new_extra_names.update(extra_names)
stringifier = _Stringifier(
node,
self.__globals__,
self.__owner__,
self.__forward_is_class__,
stringifier_dict=self.__stringifier_dict__,
extra_names=new_extra_names or None,
)
self.__stringifier_dict__.stringifiers.append(stringifier)
return stringifier
# Must implement this since we set __eq__. We hash by identity so that
# stringifiers in dict keys are kept separate.
def __hash__(self):
return id(self)
def __getitem__(self, other):
# Special case, to avoid stringifying references to class-scoped variables
# as '__classdict__["x"]'.
if self.__ast_node__ == "__classdict__":
raise KeyError
if isinstance(other, tuple):
extra_names = {}
elts = []
for elt in other:
new_elt, new_extra_names = self.__convert_to_ast_getitem(elt)
if new_extra_names is not None:
extra_names.update(new_extra_names)
elts.append(new_elt)
other = ast.Tuple(elts)
else:
other, extra_names = self.__convert_to_ast_getitem(other)
assert isinstance(other, ast.AST), repr(other)
return self.__make_new(ast.Subscript(self.__get_ast(), other), extra_names)
def __getattr__(self, attr):
return self.__make_new(ast.Attribute(self.__get_ast(), attr))
def __call__(self, *args, **kwargs):
extra_names = {}
ast_args = []
for arg in args:
new_arg, new_extra_names = self.__convert_to_ast(arg)
if new_extra_names is not None:
extra_names.update(new_extra_names)
ast_args.append(new_arg)
ast_kwargs = []
for key, value in kwargs.items():
new_value, new_extra_names = self.__convert_to_ast(value)
if new_extra_names is not None:
extra_names.update(new_extra_names)
ast_kwargs.append(ast.keyword(key, new_value))
return self.__make_new(ast.Call(self.__get_ast(), ast_args, ast_kwargs), extra_names)
def __iter__(self):
yield self.__make_new(ast.Starred(self.__get_ast()))
def __repr__(self):
if isinstance(self.__ast_node__, str):
return self.__ast_node__
return ast.unparse(self.__ast_node__)
def __format__(self, format_spec):
raise TypeError("Cannot stringify annotation containing string formatting")
def _make_binop(op: ast.AST):
def binop(self, other):
rhs, extra_names = self.__convert_to_ast(other)
return self.__make_new(
ast.BinOp(self.__get_ast(), op, rhs), extra_names
)
return binop
__add__ = _make_binop(ast.Add())
__sub__ = _make_binop(ast.Sub())
__mul__ = _make_binop(ast.Mult())
__matmul__ = _make_binop(ast.MatMult())
__truediv__ = _make_binop(ast.Div())
__mod__ = _make_binop(ast.Mod())
__lshift__ = _make_binop(ast.LShift())
__rshift__ = _make_binop(ast.RShift())
__or__ = _make_binop(ast.BitOr())
__xor__ = _make_binop(ast.BitXor())
__and__ = _make_binop(ast.BitAnd())
__floordiv__ = _make_binop(ast.FloorDiv())
__pow__ = _make_binop(ast.Pow())
del _make_binop
def _make_rbinop(op: ast.AST):
def rbinop(self, other):
new_other, extra_names = self.__convert_to_ast(other)
return self.__make_new(
ast.BinOp(new_other, op, self.__get_ast()), extra_names
)
return rbinop
__radd__ = _make_rbinop(ast.Add())
__rsub__ = _make_rbinop(ast.Sub())
__rmul__ = _make_rbinop(ast.Mult())
__rmatmul__ = _make_rbinop(ast.MatMult())
__rtruediv__ = _make_rbinop(ast.Div())
__rmod__ = _make_rbinop(ast.Mod())
__rlshift__ = _make_rbinop(ast.LShift())
__rrshift__ = _make_rbinop(ast.RShift())
__ror__ = _make_rbinop(ast.BitOr())
__rxor__ = _make_rbinop(ast.BitXor())
__rand__ = _make_rbinop(ast.BitAnd())
__rfloordiv__ = _make_rbinop(ast.FloorDiv())
__rpow__ = _make_rbinop(ast.Pow())
del _make_rbinop
def _make_compare(op):
def compare(self, other):
rhs, extra_names = self.__convert_to_ast(other)
return self.__make_new(
ast.Compare(
left=self.__get_ast(),
ops=[op],
comparators=[rhs],
),
extra_names,
)
return compare
__lt__ = _make_compare(ast.Lt())
__le__ = _make_compare(ast.LtE())
__eq__ = _make_compare(ast.Eq())
__ne__ = _make_compare(ast.NotEq())
__gt__ = _make_compare(ast.Gt())
__ge__ = _make_compare(ast.GtE())
del _make_compare
def _make_unary_op(op):
def unary_op(self):
return self.__make_new(ast.UnaryOp(op, self.__get_ast()))
return unary_op
__invert__ = _make_unary_op(ast.Invert())
__pos__ = _make_unary_op(ast.UAdd())
__neg__ = _make_unary_op(ast.USub())
del _make_unary_op
def _template_to_ast_constructor(template):
"""Convert a `template` instance to a non-literal AST."""
args = []
for part in template:
match part:
case str():
args.append(ast.Constant(value=part))
case _:
interp = ast.Call(
func=ast.Name(id="Interpolation"),
args=[
ast.Constant(value=part.value),
ast.Constant(value=part.expression),
ast.Constant(value=part.conversion),
ast.Constant(value=part.format_spec),
]
)
args.append(interp)
return ast.Call(func=ast.Name(id="Template"), args=args, keywords=[])
def _template_to_ast_literal(template, parsed):
"""Convert a `template` instance to a t-string literal AST."""
values = []
interp_count = 0
for part in template:
match part:
case str():
values.append(ast.Constant(value=part))
case _:
interp = ast.Interpolation(
str=part.expression,
value=parsed[interp_count],
conversion=ord(part.conversion) if part.conversion else -1,
format_spec=ast.Constant(value=part.format_spec)
if part.format_spec
else None,
)
values.append(interp)
interp_count += 1
return ast.TemplateStr(values=values)
def _template_to_ast(template):
"""Make a best-effort conversion of a `template` instance to an AST."""
# gh-138558: Not all Template instances can be represented as t-string
# literals. Return the most accurate AST we can. See issue for details.
# If any expr is empty or whitespace only, we cannot convert to a literal.
if any(part.expression.strip() == "" for part in template.interpolations):
return _template_to_ast_constructor(template)
try:
# Wrap in parens to allow whitespace inside interpolation curly braces
parsed = tuple(
ast.parse(f"({part.expression})", mode="eval").body
for part in template.interpolations
)
except SyntaxError:
return _template_to_ast_constructor(template)
return _template_to_ast_literal(template, parsed)
class _StringifierDict(dict):
def __init__(self, namespace, *, globals=None, owner=None, is_class=False, format):
super().__init__(namespace)
self.namespace = namespace
self.globals = globals
self.owner = owner
self.is_class = is_class
self.stringifiers = []
self.next_id = 1
self.format = format
def __missing__(self, key):
fwdref = _Stringifier(
key,
globals=self.globals,
owner=self.owner,
is_class=self.is_class,
stringifier_dict=self,
)
self.stringifiers.append(fwdref)
return fwdref
def transmogrify(self, cell_dict):
for obj in self.stringifiers:
obj.__class__ = ForwardRef
obj.__stringifier_dict__ = None # not needed for ForwardRef
if isinstance(obj.__ast_node__, str):
obj.__arg__ = obj.__ast_node__
obj.__ast_node__ = None
if cell_dict is not None and obj.__cell__ is None:
obj.__cell__ = cell_dict
def create_unique_name(self):
name = f"__annotationlib_name_{self.next_id}__"
self.next_id += 1
return name
def call_evaluate_function(evaluate, format, *, owner=None):
"""Call an evaluate function. Evaluate functions are normally generated for
the value of type aliases and the bounds, constraints, and defaults of
type parameter objects.
"""
return call_annotate_function(evaluate, format, owner=owner, _is_evaluate=True)
def call_annotate_function(annotate, format, *, owner=None, _is_evaluate=False):
"""Call an __annotate__ function. __annotate__ functions are normally
generated by the compiler to defer the evaluation of annotations. They
can be called with any of the format arguments in the Format enum, but
compiler-generated __annotate__ functions only support the VALUE format.
This function provides additional functionality to call __annotate__
functions with the FORWARDREF and STRING formats.
*annotate* must be an __annotate__ function, which takes a single argument
and returns a dict of annotations.
*format* must be a member of the Format enum or one of the corresponding
integer values.
*owner* can be the object that owns the annotations (i.e., the module,
class, or function that the __annotate__ function derives from). With the
FORWARDREF format, it is used to provide better evaluation capabilities
on the generated ForwardRef objects.
"""
if format == Format.VALUE_WITH_FAKE_GLOBALS:
raise ValueError("The VALUE_WITH_FAKE_GLOBALS format is for internal use only")
try:
return annotate(format)
except NotImplementedError:
pass
if format == Format.STRING:
# STRING is implemented by calling the annotate function in a special
# environment where every name lookup results in an instance of _Stringifier.
# _Stringifier supports every dunder operation and returns a new _Stringifier.
# At the end, we get a dictionary that mostly contains _Stringifier objects (or
# possibly constants if the annotate function uses them directly). We then
# convert each of those into a string to get an approximation of the
# original source.
# Attempt to call with VALUE_WITH_FAKE_GLOBALS to check if it is implemented
# See: https://github.com/python/cpython/issues/138764
# Only fail on NotImplementedError
try:
annotate(Format.VALUE_WITH_FAKE_GLOBALS)
except NotImplementedError:
# Both STRING and VALUE_WITH_FAKE_GLOBALS are not implemented: fallback to VALUE
return annotations_to_string(annotate(Format.VALUE))
except Exception:
pass
globals = _StringifierDict({}, format=format)
is_class = isinstance(owner, type)
closure, _ = _build_closure(
annotate, owner, is_class, globals, allow_evaluation=False
)
func = types.FunctionType(
annotate.__code__,
globals,
closure=closure,
argdefs=annotate.__defaults__,
kwdefaults=annotate.__kwdefaults__,
)
annos = func(Format.VALUE_WITH_FAKE_GLOBALS)
if _is_evaluate:
return _stringify_single(annos)
return {
key: _stringify_single(val)
for key, val in annos.items()
}
elif format == Format.FORWARDREF:
# FORWARDREF is implemented similarly to STRING, but there are two changes,
# at the beginning and the end of the process.
# First, while STRING uses an empty dictionary as the namespace, so that all
# name lookups result in _Stringifier objects, FORWARDREF uses the globals
# and builtins, so that defined names map to their real values.
# Second, instead of returning strings, we want to return either real values
# or ForwardRef objects. To do this, we keep track of all _Stringifier objects
# created while the annotation is being evaluated, and at the end we convert
# them all to ForwardRef objects by assigning to __class__. To make this
# technique work, we have to ensure that the _Stringifier and ForwardRef
# classes share the same attributes.
# We use this technique because while the annotations are being evaluated,
# we want to support all operations that the language allows, including even
# __getattr__ and __eq__, and return new _Stringifier objects so we can accurately
# reconstruct the source. But in the dictionary that we eventually return, we
# want to return objects with more user-friendly behavior, such as an __eq__
# that returns a bool and an defined set of attributes.
namespace = {**annotate.__builtins__, **annotate.__globals__}
is_class = isinstance(owner, type)
globals = _StringifierDict(
namespace,
globals=annotate.__globals__,
owner=owner,
is_class=is_class,
format=format,
)
closure, cell_dict = _build_closure(
annotate, owner, is_class, globals, allow_evaluation=True
)
func = types.FunctionType(
annotate.__code__,
globals,
closure=closure,
argdefs=annotate.__defaults__,
kwdefaults=annotate.__kwdefaults__,
)
try:
result = func(Format.VALUE_WITH_FAKE_GLOBALS)
except NotImplementedError:
# FORWARDREF and VALUE_WITH_FAKE_GLOBALS not supported, fall back to VALUE
return annotate(Format.VALUE)
except Exception:
pass
else:
globals.transmogrify(cell_dict)
return result
# Try again, but do not provide any globals. This allows us to return
# a value in certain cases where an exception gets raised during evaluation.
globals = _StringifierDict(
{},
globals=annotate.__globals__,
owner=owner,
is_class=is_class,
format=format,
)
closure, cell_dict = _build_closure(
annotate, owner, is_class, globals, allow_evaluation=False
)
func = types.FunctionType(
annotate.__code__,
globals,
closure=closure,
argdefs=annotate.__defaults__,
kwdefaults=annotate.__kwdefaults__,
)
result = func(Format.VALUE_WITH_FAKE_GLOBALS)
globals.transmogrify(cell_dict)
if _is_evaluate:
if isinstance(result, ForwardRef):
return result.evaluate(format=Format.FORWARDREF)
else:
return result
else:
return {
key: (
val.evaluate(format=Format.FORWARDREF)
if isinstance(val, ForwardRef)
else val
)
for key, val in result.items()
}
elif format == Format.VALUE:
# Should be impossible because __annotate__ functions must not raise
# NotImplementedError for this format.
raise RuntimeError("annotate function does not support VALUE format")
else:
raise ValueError(f"Invalid format: {format!r}")
def _build_closure(annotate, owner, is_class, stringifier_dict, *, allow_evaluation):
if not annotate.__closure__:
return None, None
new_closure = []
cell_dict = {}
for name, cell in zip(annotate.__code__.co_freevars, annotate.__closure__, strict=True):
cell_dict[name] = cell
new_cell = None
if allow_evaluation:
try:
cell.cell_contents
except ValueError:
pass
else:
new_cell = cell
if new_cell is None:
fwdref = _Stringifier(
name,
cell=cell,
owner=owner,
globals=annotate.__globals__,
is_class=is_class,
stringifier_dict=stringifier_dict,
)
stringifier_dict.stringifiers.append(fwdref)
new_cell = types.CellType(fwdref)
new_closure.append(new_cell)
return tuple(new_closure), cell_dict
def _stringify_single(anno):
if anno is ...:
return "..."
# We have to handle str specially to support PEP 563 stringified annotations.
elif isinstance(anno, str):
return anno
elif isinstance(anno, _Template):
return ast.unparse(_template_to_ast(anno))
else:
return repr(anno)
def get_annotate_from_class_namespace(obj):
"""Retrieve the annotate function from a class namespace dictionary.
Return None if the namespace does not contain an annotate function.
This is useful in metaclass ``__new__`` methods to retrieve the annotate function.
"""
try:
return obj["__annotate__"]
except KeyError:
return obj.get("__annotate_func__", None)
def get_annotations(
obj, *, globals=None, locals=None, eval_str=False, format=Format.VALUE
):
"""Compute the annotations dict for an object.
obj may be a callable, class, module, or other object with
__annotate__ or __annotations__ attributes.
Passing any other object raises TypeError.
The *format* parameter controls the format in which annotations are returned,
and must be a member of the Format enum or its integer equivalent.
For the VALUE format, the __annotations__ is tried first; if it
does not exist, the __annotate__ function is called. The
FORWARDREF format uses __annotations__ if it exists and can be
evaluated, and otherwise falls back to calling the __annotate__ function.
The STRING format tries __annotate__ first, and falls back to
using __annotations__, stringified using annotations_to_string().
This function handles several details for you:
* If eval_str is true, values of type str will
be un-stringized using eval(). This is intended
for use with stringized annotations
("from __future__ import annotations").
* If obj doesn't have an annotations dict, returns an
empty dict. (Functions and methods always have an
annotations dict; classes, modules, and other types of
callables may not.)
* Ignores inherited annotations on classes. If a class
doesn't have its own annotations dict, returns an empty dict.
* All accesses to object members and dict values are done
using getattr() and dict.get() for safety.
* Always, always, always returns a freshly-created dict.
eval_str controls whether or not values of type str are replaced
with the result of calling eval() on those values:
* If eval_str is true, eval() is called on values of type str.
* If eval_str is false (the default), values of type str are unchanged.
globals and locals are passed in to eval(); see the documentation
for eval() for more information. If either globals or locals is
None, this function may replace that value with a context-specific
default, contingent on type(obj):
* If obj is a module, globals defaults to obj.__dict__.
* If obj is a class, globals defaults to
sys.modules[obj.__module__].__dict__ and locals
defaults to the obj class namespace.
* If obj is a callable, globals defaults to obj.__globals__,
although if obj is a wrapped function (using
functools.update_wrapper()) it is first unwrapped.
"""
if eval_str and format != Format.VALUE:
raise ValueError("eval_str=True is only supported with format=Format.VALUE")
match format:
case Format.VALUE:
