view mercurial/thirdparty/attr/_compat.py @ 51291:0bb5299800ca

pytype: only output the "pytype crashed" message on error

If pytype did not crash while generating stub, that message is kind of
confusing. It seems simple enough to avoid it in this case.

# SPDX-License-Identifier: MIT


import inspect
import platform
import sys
import threading
import types
import warnings

from collections.abc import Mapping, Sequence  # noqa


PYPY = platform.python_implementation() == "PyPy"
PY36 = sys.version_info[:2] >= (3, 6)
HAS_F_STRINGS = PY36
PY310 = sys.version_info[:2] >= (3, 10)


if PYPY or PY36:
    ordered_dict = dict
else:
    from collections import OrderedDict

    ordered_dict = OrderedDict


def just_warn(*args, **kw):
    warnings.warn(
        "Running interpreter doesn't sufficiently support code object "
        "introspection.  Some features like bare super() or accessing "
        "__class__ will not work with slotted classes.",
        RuntimeWarning,
        stacklevel=2,
    )


class _AnnotationExtractor:
    """
    Extract type annotations from a callable, returning None whenever there
    is none.
    """

    __slots__ = ["sig"]

    def __init__(self, callable):
        try:
            self.sig = inspect.signature(callable)
        except (ValueError, TypeError):  # inspect failed
            self.sig = None

    def get_first_param_type(self):
        """
        Return the type annotation of the first argument if it's not empty.
        """
        if not self.sig:
            return None

        params = list(self.sig.parameters.values())
        if params and params[0].annotation is not inspect.Parameter.empty:
            return params[0].annotation

        return None

    def get_return_type(self):
        """
        Return the return type if it's not empty.
        """
        if (
            self.sig
            and self.sig.return_annotation is not inspect.Signature.empty
        ):
            return self.sig.return_annotation

        return None


def make_set_closure_cell():
    """Return a function of two arguments (cell, value) which sets
    the value stored in the closure cell `cell` to `value`.
    """
    # pypy makes this easy. (It also supports the logic below, but
    # why not do the easy/fast thing?)
    if PYPY:

        def set_closure_cell(cell, value):
            cell.__setstate__((value,))

        return set_closure_cell

    # Otherwise gotta do it the hard way.

    # Create a function that will set its first cellvar to `value`.
    def set_first_cellvar_to(value):
        x = value
        return

        # This function will be eliminated as dead code, but
        # not before its reference to `x` forces `x` to be
        # represented as a closure cell rather than a local.
        def force_x_to_be_a_cell():  # pragma: no cover
            return x

    try:
        # Extract the code object and make sure our assumptions about
        # the closure behavior are correct.
        co = set_first_cellvar_to.__code__
        if co.co_cellvars != ("x",) or co.co_freevars != ():
            raise AssertionError  # pragma: no cover

        # Convert this code object to a code object that sets the
        # function's first _freevar_ (not cellvar) to the argument.
        if sys.version_info >= (3, 8):

            def set_closure_cell(cell, value):
                cell.cell_contents = value

        else:
            args = [co.co_argcount]
            args.append(co.co_kwonlyargcount)
            args.extend(
                [
                    co.co_nlocals,
                    co.co_stacksize,
                    co.co_flags,
                    co.co_code,
                    co.co_consts,
                    co.co_names,
                    co.co_varnames,
                    co.co_filename,
                    co.co_name,
                    co.co_firstlineno,
                    co.co_lnotab,
                    # These two arguments are reversed:
                    co.co_cellvars,
                    co.co_freevars,
                ]
            )
            set_first_freevar_code = types.CodeType(*args)

            def set_closure_cell(cell, value):
                # Create a function using the set_first_freevar_code,
                # whose first closure cell is `cell`. Calling it will
                # change the value of that cell.
                setter = types.FunctionType(
                    set_first_freevar_code, {}, "setter", (), (cell,)
                )
                # And call it to set the cell.
                setter(value)

        # Make sure it works on this interpreter:
        def make_func_with_cell():
            x = None

            def func():
                return x  # pragma: no cover

            return func

        cell = make_func_with_cell().__closure__[0]
        set_closure_cell(cell, 100)
        if cell.cell_contents != 100:
            raise AssertionError  # pragma: no cover

    except Exception:
        return just_warn
    else:
        return set_closure_cell


set_closure_cell = make_set_closure_cell()

# Thread-local global to track attrs instances which are already being repr'd.
# This is needed because there is no other (thread-safe) way to pass info
# about the instances that are already being repr'd through the call stack
# in order to ensure we don't perform infinite recursion.
#
# For instance, if an instance contains a dict which contains that instance,
# we need to know that we're already repr'ing the outside instance from within
# the dict's repr() call.
#
# This lives here rather than in _make.py so that the functions in _make.py
# don't have a direct reference to the thread-local in their globals dict.
# If they have such a reference, it breaks cloudpickle.
repr_context = threading.local()