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"""Extra information about the reflection API |
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""" |
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import inspect |
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from functools import lru_cache |
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from typing import ( |
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Dict, |
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Type, |
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Callable, |
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get_type_hints, |
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Optional, |
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Awaitable, |
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Any, |
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Mapping, |
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Sequence, |
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) |
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import typing |
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RETURN_ANNOTATION = "return" |
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_TYPE_AWAITABLE = type(typing.Awaitable) |
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class FunctionSpec: |
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""" |
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Describes the arguments of a function |
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""" |
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args: Sequence[str] |
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annotations: Mapping[str, Type] |
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defaults: Mapping[str, Any] |
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return_type: Optional[Type] |
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arity: int |
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def __init__(self, args, annotations, defaults, return_type): |
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self.args = args |
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self.annotations = annotations |
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self.defaults = defaults |
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self.return_type = return_type |
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self.arity = len(args) |
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def __repr__(self): |
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def _arg_type_string(arg): |
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return self.annotations[arg].__name__ if arg in self.annotations else "?" |
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signature = ", ".join(_arg_type_string(arg) for arg in self.args) |
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if self.return_type: |
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return f"({signature}) -> {self.return_type.__name__}" |
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else: |
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return f"({signature})" |
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def without_argument(self, arg_to_remove: str): |
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""" |
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Returns the function spec with the specified argument removed |
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:param arg_to_remove: |
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:return: |
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""" |
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new_args = [arg for arg in self.args if arg != arg_to_remove] |
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return FunctionSpec(new_args, self.annotations, self.defaults, self.return_type) |
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class CachingReflector: |
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""" |
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Takes a function and returns an object representing |
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the function's type signature. Results are cached |
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so subsequent calls do not need to call the reflection |
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API. |
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""" |
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@property |
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def overview_of_cache(self) -> Dict[str, str]: |
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""" |
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Gives a humanish readable representation of what has been reflected on. |
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Removed since lru cache is now used |
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:return: |
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""" |
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return {"hidden": ""} |
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@lru_cache(maxsize=1024) |
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def get_function_spec(self, func) -> FunctionSpec: |
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""" |
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Returns details about the function's signature |
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:param func: |
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:return: |
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""" |
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return reflect(func) |
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def reflect(func: Callable) -> FunctionSpec: |
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""" |
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Extension to inspect.getfullargspec with a little more. |
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:param func: |
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:return: |
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""" |
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spec = inspect.getfullargspec(func) |
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annotations = get_type_hints(func) |
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defaults = _get_default_args(func) |
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ret = annotations.pop(RETURN_ANNOTATION, None) |
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if ret and inspect.iscoroutinefunction(func): |
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ret = Awaitable[ret] # type: ignore # todo: figure this out |
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return FunctionSpec(spec.args, annotations, defaults, ret) |
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def _get_default_args(func): |
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arguments = inspect.signature(func).parameters.items() |
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return { |
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name: argument.default |
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for name, argument in arguments |
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if argument.default is not inspect.Parameter.empty |
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} |
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def remove_optional_type(dep_type) -> Optional[Type]: |
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"""if the Type is Optional[T] returns T else None |
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:param dep_type: |
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:return: |
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""" |
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try: |
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# Hacky: an optional type has [T, None] in __args__ |
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if len(dep_type.__args__) == 2 and dep_type.__args__[1] == None.__class__: |
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return dep_type.__args__[0] |
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except: |
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pass |
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return None |
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def remove_awaitable_type(dep_type) -> Optional[Type]: |
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"""if the Type is Awaitable[T] returns T else None |
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:param dep_type: |
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:return: |
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""" |
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if isinstance(dep_type, _TYPE_AWAITABLE) or ( |
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hasattr(dep_type, "_name") and dep_type._name == "Awaitable" |
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): |
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return dep_type.__args__[0] # type: ignore |
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return None |
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meadsteve /
lagom
