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cpython/Tools/clinic/libclinic/converter.py

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from __future__ import annotations
import builtins as bltns
import functools
from typing import Any, TypeVar, Literal, TYPE_CHECKING, cast
from collections.abc import Callable
import libclinic
from libclinic import fail
from libclinic import Sentinels, unspecified, unknown
from libclinic.codegen import CRenderData, Include, TemplateDict
from libclinic.function import Function, Parameter
CConverterClassT = TypeVar("CConverterClassT", bound=type["CConverter"])
type_checks = {
'&PyLong_Type': ('PyLong_Check', 'int'),
'&PyTuple_Type': ('PyTuple_Check', 'tuple'),
'&PyList_Type': ('PyList_Check', 'list'),
'&PySet_Type': ('PySet_Check', 'set'),
'&PyFrozenSet_Type': ('PyFrozenSet_Check', 'frozenset'),
'&PyDict_Type': ('PyDict_Check', 'dict'),
'&PyUnicode_Type': ('PyUnicode_Check', 'str'),
'&PyBytes_Type': ('PyBytes_Check', 'bytes'),
'&PyByteArray_Type': ('PyByteArray_Check', 'bytearray'),
}
def add_c_converter(
f: CConverterClassT,
name: str | None = None
) -> CConverterClassT:
if not name:
name = f.__name__
if not name.endswith('_converter'):
return f
name = name.removesuffix('_converter')
converters[name] = f
return f
def add_default_legacy_c_converter(cls: CConverterClassT) -> CConverterClassT:
# automatically add converter for default format unit
# (but without stomping on the existing one if it's already
# set, in case you subclass)
if ((cls.format_unit not in ('O&', '')) and
(cls.format_unit not in legacy_converters)):
legacy_converters[cls.format_unit] = cls
return cls
class CConverterAutoRegister(type):
def __init__(
cls, name: str, bases: tuple[type[object], ...], classdict: dict[str, Any]
) -> None:
converter_cls = cast(type["CConverter"], cls)
add_c_converter(converter_cls)
add_default_legacy_c_converter(converter_cls)
class CConverter(metaclass=CConverterAutoRegister):
"""
For the init function, self, name, function, and default
must be keyword-or-positional parameters. All other
parameters must be keyword-only.
"""
# The C name to use for this variable.
name: str
# The Python name to use for this variable.
py_name: str
# The C type to use for this variable.
# 'type' should be a Python string specifying the type, e.g. "int".
# If this is a pointer type, the type string should end with ' *'.
type: str | None = None
# The Python default value for this parameter, as a Python value.
# Or the magic value "unspecified" if there is no default.
# Or the magic value "unknown" if this value is a cannot be evaluated
# at Argument-Clinic-preprocessing time (but is presumed to be valid
# at runtime).
default: object = unspecified
# If not None, default must be isinstance() of this type.
# (You can also specify a tuple of types.)
default_type: bltns.type[object] | tuple[bltns.type[object], ...] | None = None
# "default" converted into a C value, as a string.
# Or None if there is no default.
c_default: str | None = None
# "default" converted into a Python value, as a string.
# Or None if there is no default.
py_default: str | None = None
# The default value used to initialize the C variable when
# there is no default, but not specifying a default may
# result in an "uninitialized variable" warning. This can
# easily happen when using option groups--although
# properly-written code won't actually use the variable,
# the variable does get passed in to the _impl. (Ah, if
# only dataflow analysis could inline the static function!)
#
# This value is specified as a string.
# Every non-abstract subclass should supply a valid value.
c_ignored_default: str = 'NULL'
# If true, wrap with Py_UNUSED.
unused = False
# The C converter *function* to be used, if any.
# (If this is not None, format_unit must be 'O&'.)
converter: str | None = None
# Should Argument Clinic add a '&' before the name of
# the variable when passing it into the _impl function?
impl_by_reference = False
# Should Argument Clinic add a '&' before the name of
# the variable when passing it into PyArg_ParseTuple (AndKeywords)?
parse_by_reference = True
#############################################################
#############################################################
## You shouldn't need to read anything below this point to ##
## write your own converter functions. ##
#############################################################
#############################################################
# The "format unit" to specify for this variable when
# parsing arguments using PyArg_ParseTuple (AndKeywords).
# Custom converters should always use the default value of 'O&'.
format_unit = 'O&'
# What encoding do we want for this variable? Only used
# by format units starting with 'e'.
encoding: str | None = None
# Should this object be required to be a subclass of a specific type?
# If not None, should be a string representing a pointer to a
# PyTypeObject (e.g. "&PyUnicode_Type").
# Only used by the 'O!' format unit (and the "object" converter).
subclass_of: str | None = None
# See also the 'length_name' property.
# Only used by format units ending with '#'.
length = False
# Should we show this parameter in the generated
# __text_signature__? This is *almost* always True.
# (It's only False for __new__, __init__, and METH_STATIC functions.)
show_in_signature = True
# Overrides the name used in a text signature.
# The name used for a "self" parameter must be one of
# self, type, or module; however users can set their own.
# This lets the self_converter overrule the user-settable
# name, *just* for the text signature.
# Only set by self_converter.
signature_name: str | None = None
broken_limited_capi: bool = False
# keep in sync with self_converter.__init__!
def __init__(self,
# Positional args:
name: str,
py_name: str,
function: Function,
default: object = unspecified,
*, # Keyword only args:
c_default: str | None = None,
py_default: str | None = None,
annotation: str | Literal[Sentinels.unspecified] = unspecified,
unused: bool = False,
**kwargs: Any
) -> None:
self.name = libclinic.ensure_legal_c_identifier(name)
self.py_name = py_name
self.unused = unused
self._includes: list[Include] = []
if default is not unspecified:
if (self.default_type
and default is not unknown
and not isinstance(default, self.default_type)
):
if isinstance(self.default_type, type):
types_str = self.default_type.__name__
else:
names = [cls.__name__ for cls in self.default_type]
types_str = ', '.join(names)
cls_name = self.__class__.__name__
fail(f"{cls_name}: default value {default!r} for field "
f"{name!r} is not of type {types_str!r}")
self.default = default
if c_default:
self.c_default = c_default
if py_default:
self.py_default = py_default
if annotation is not unspecified:
fail("The 'annotation' parameter is not currently permitted.")
# Make sure not to set self.function until after converter_init() has been called.
# This prevents you from caching information
# about the function in converter_init().
# (That breaks if we get cloned.)
self.converter_init(**kwargs)
self.function = function
# Add a custom __getattr__ method to improve the error message
# if somebody tries to access self.function in converter_init().
#
# mypy will assume arbitrary access is okay for a class with a __getattr__ method,
# and that's not what we want,
# so put it inside an `if not TYPE_CHECKING` block
if not TYPE_CHECKING:
def __getattr__(self, attr):
if attr == "function":
fail(
f"{self.__class__.__name__!r} object has no attribute 'function'.\n"
f"Note: accessing self.function inside converter_init is disallowed!"
)
return super().__getattr__(attr)
# this branch is just here for coverage reporting
else: # pragma: no cover
pass
def converter_init(self) -> None:
pass
def is_optional(self) -> bool:
return (self.default is not unspecified)
def _render_self(self, parameter: Parameter, data: CRenderData) -> None:
self.parameter = parameter
name = self.parser_name
# impl_arguments
s = ("&" if self.impl_by_reference else "") + name
data.impl_arguments.append(s)
if self.length:
data.impl_arguments.append(self.length_name)
# impl_parameters
data.impl_parameters.append(self.simple_declaration(by_reference=self.impl_by_reference))
if self.length:
data.impl_parameters.append(f"Py_ssize_t {self.length_name}")
def _render_non_self(
self,
parameter: Parameter,
data: CRenderData
) -> None:
self.parameter = parameter
name = self.name
# declarations
d = self.declaration(in_parser=True)
data.declarations.append(d)
# initializers
initializers = self.initialize()
if initializers:
data.initializers.append('/* initializers for ' + name + ' */\n' + initializers.rstrip())
# modifications
modifications = self.modify()
if modifications:
data.modifications.append('/* modifications for ' + name + ' */\n' + modifications.rstrip())
# keywords
if parameter.is_vararg():
pass
elif parameter.is_positional_only():
data.keywords.append('')
else:
data.keywords.append(parameter.name)
# format_units
if self.is_optional() and '|' not in data.format_units:
data.format_units.append('|')
if parameter.is_keyword_only() and '$' not in data.format_units:
data.format_units.append('$')
data.format_units.append(self.format_unit)
# parse_arguments
self.parse_argument(data.parse_arguments)
# post_parsing
if post_parsing := self.post_parsing():
data.post_parsing.append('/* Post parse cleanup for ' + name + ' */\n' + post_parsing.rstrip() + '\n')
# cleanup
cleanup = self.cleanup()
if cleanup:
data.cleanup.append('/* Cleanup for ' + name + ' */\n' + cleanup.rstrip() + "\n")
def render(self, parameter: Parameter, data: CRenderData) -> None:
"""
parameter is a clinic.Parameter instance.
data is a CRenderData instance.
"""
self._render_self(parameter, data)
self._render_non_self(parameter, data)
@functools.cached_property
def length_name(self) -> str:
"""Computes the name of the associated "length" variable."""
assert self.length is not None
return self.parser_name + "_length"
# Why is this one broken out separately?
# For "positional-only" function parsing,
# which generates a bunch of PyArg_ParseTuple calls.
def parse_argument(self, args: list[str]) -> None:
assert not (self.converter and self.encoding)
if self.format_unit == 'O&':
assert self.converter
args.append(self.converter)
if self.encoding:
args.append(libclinic.c_repr(self.encoding))
elif self.subclass_of:
args.append(self.subclass_of)
s = ("&" if self.parse_by_reference else "") + self.parser_name
args.append(s)
if self.length:
args.append(f"&{self.length_name}")
#
# All the functions after here are intended as extension points.
#
def simple_declaration(
self,
by_reference: bool = False,
*,
in_parser: bool = False
) -> str:
"""
Computes the basic declaration of the variable.
Used in computing the prototype declaration and the
variable declaration.
"""
assert isinstance(self.type, str)
prototype = [self.type]
if by_reference or not self.type.endswith('*'):
prototype.append(" ")
if by_reference:
prototype.append('*')
if in_parser:
name = self.parser_name
else:
name = self.name
if self.unused:
name = f"Py_UNUSED({name})"
prototype.append(name)
return "".join(prototype)
def declaration(self, *, in_parser: bool = False) -> str:
"""
The C statement to declare this variable.
"""
declaration = [self.simple_declaration(in_parser=True)]
default = self.c_default
if not default and self.parameter.group:
default = self.c_ignored_default
if default:
declaration.append(" = ")
declaration.append(default)
declaration.append(";")
if self.length:
declaration.append('\n')
declaration.append(f"Py_ssize_t {self.length_name};")
return "".join(declaration)
def initialize(self) -> str:
"""
The C statements required to set up this variable before parsing.
Returns a string containing this code indented at column 0.
If no initialization is necessary, returns an empty string.
"""
return ""
def modify(self) -> str:
"""
The C statements required to modify this variable after parsing.
Returns a string containing this code indented at column 0.
If no modification is necessary, returns an empty string.
"""
return ""
def post_parsing(self) -> str:
"""
The C statements required to do some operations after the end of parsing but before cleaning up.
Return a string containing this code indented at column 0.
If no operation is necessary, return an empty string.
"""
return ""
def cleanup(self) -> str:
"""
The C statements required to clean up after this variable.
Returns a string containing this code indented at column 0.
If no cleanup is necessary, returns an empty string.
"""
return ""
def pre_render(self) -> None:
"""
A second initialization function, like converter_init,
called just before rendering.
You are permitted to examine self.function here.
"""
pass
def bad_argument(self, displayname: str, expected: str, *, limited_capi: bool, expected_literal: bool = True) -> str:
assert '"' not in expected
if limited_capi:
if expected_literal:
return (f'PyErr_Format(PyExc_TypeError, '
f'"{{{{name}}}}() {displayname} must be {expected}, not %T", '
f'{{argname}});')
else:
return (f'PyErr_Format(PyExc_TypeError, '
f'"{{{{name}}}}() {displayname} must be %s, not %T", '
f'"{expected}", {{argname}});')
else:
if expected_literal:
expected = f'"{expected}"'
self.add_include('pycore_modsupport.h', '_PyArg_BadArgument()')
return f'_PyArg_BadArgument("{{{{name}}}}", "{displayname}", {expected}, {{argname}});'
def format_code(self, fmt: str, *,
argname: str,
bad_argument: str | None = None,
bad_argument2: str | None = None,
**kwargs: Any) -> str:
if '{bad_argument}' in fmt:
if not bad_argument:
raise TypeError("required 'bad_argument' argument")
fmt = fmt.replace('{bad_argument}', bad_argument)
if '{bad_argument2}' in fmt:
if not bad_argument2:
raise TypeError("required 'bad_argument2' argument")
fmt = fmt.replace('{bad_argument2}', bad_argument2)
return fmt.format(argname=argname, paramname=self.parser_name, **kwargs)
def use_converter(self) -> None:
"""Method called when self.converter is used to parse an argument."""
pass
def parse_arg(self, argname: str, displayname: str, *, limited_capi: bool) -> str | None:
if self.format_unit == 'O&':
self.use_converter()
return self.format_code("""
if (!{converter}({argname}, &{paramname})) {{{{
goto exit;
}}}}
""",
argname=argname,
converter=self.converter)
if self.format_unit == 'O!':
cast = '(%s)' % self.type if self.type != 'PyObject *' else ''
if self.subclass_of in type_checks:
typecheck, typename = type_checks[self.subclass_of]
return self.format_code("""
if (!{typecheck}({argname})) {{{{
{bad_argument}
goto exit;
}}}}
{paramname} = {cast}{argname};
""",
argname=argname,
bad_argument=self.bad_argument(displayname, typename, limited_capi=limited_capi),
typecheck=typecheck, typename=typename, cast=cast)
return self.format_code("""
if (!PyObject_TypeCheck({argname}, {subclass_of})) {{{{
{bad_argument}
goto exit;
}}}}
{paramname} = {cast}{argname};
""",
argname=argname,
bad_argument=self.bad_argument(displayname, '({subclass_of})->tp_name',
expected_literal=False, limited_capi=limited_capi),
subclass_of=self.subclass_of, cast=cast)
if self.format_unit == 'O':
cast = '(%s)' % self.type if self.type != 'PyObject *' else ''
return self.format_code("""
{paramname} = {cast}{argname};
""",
argname=argname, cast=cast)
return None
def set_template_dict(self, template_dict: TemplateDict) -> None:
pass
@property
def parser_name(self) -> str:
if self.name in libclinic.CLINIC_PREFIXED_ARGS: # bpo-39741
return libclinic.CLINIC_PREFIX + self.name
else:
return self.name
def add_include(self, name: str, reason: str,
*, condition: str | None = None) -> None:
include = Include(name, reason, condition)
self._includes.append(include)
def get_includes(self) -> list[Include]:
return self._includes
ConverterType = Callable[..., CConverter]
ConverterDict = dict[str, ConverterType]
# maps strings to callables.
# these callables must be of the form:
# def foo(name, default, *, ...)
# The callable may have any number of keyword-only parameters.
# The callable must return a CConverter object.
# The callable should not call builtins.print.
converters: ConverterDict = {}
# maps strings to callables.
# these callables follow the same rules as those for "converters" above.
# note however that they will never be called with keyword-only parameters.
legacy_converters: ConverterDict = {}
def add_legacy_c_converter(
format_unit: str,
**kwargs: Any
) -> Callable[[CConverterClassT], CConverterClassT]:
def closure(f: CConverterClassT) -> CConverterClassT:
added_f: Callable[..., CConverter]
if not kwargs:
added_f = f
else:
# type ignore due to a mypy regression :(
# https://github.com/python/mypy/issues/17646
added_f = functools.partial(f, **kwargs) # type: ignore[misc]
if format_unit:
legacy_converters[format_unit] = added_f
return f
return closure
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