from __future__ import annotations

from typing import Callable

from mypy.plugin import AnalyzeTypeContext, Plugin

# The official name changed to NoneType but we have an alias for plugin compat reasons

# so we'll keep testing that here.

from mypy.types import AnyType, CallableType, NoneTyp, Type, TypeList, TypeOfAny

class TypeAnalyzePlugin(Plugin):

def get_type_analyze_hook(self, fullname: str) -> Callable[[AnalyzeTypeContext], Type] | None:

if fullname == "m.Signal":

return signal_type_analyze_callback

return None

def signal_type_analyze_callback(ctx: AnalyzeTypeContext) -> Type:

if len(ctx.type.args) != 1 or not isinstance(ctx.type.args[0], TypeList):

ctx.api.fail('Invalid "Signal" type (expected "Signal[[t, ...]]")', ctx.context)

return AnyType(TypeOfAny.from_error)

args = ctx.type.args[0]

assert isinstance(args, TypeList)

analyzed = ctx.api.analyze_callable_args(args)

if analyzed is None:

return AnyType(TypeOfAny.from_error) # Error generated elsewhere

arg_types, arg_kinds, arg_names = analyzed

arg_types = [ctx.api.analyze_type(arg) for arg in arg_types]

type_arg = CallableType(

arg_types, arg_kinds, arg_names, NoneTyp(), ctx.api.named_type("builtins.function", [])

)

return ctx.api.named_type("m.Signal", [type_arg])

def plugin(version: str) -> type[TypeAnalyzePlugin]:

return TypeAnalyzePlugin