pointers.py/src/pointers/structure.py at master · ZeroIntensity/pointers.py · GitHub

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import ctypes

from contextlib import suppress

from typing import Any, Dict, List, Optional, Type, TypeVar, Union

from _pointers import add_ref

from ._utils import attempt_decode, get_mapped, get_py

from .base_pointers import BaseCPointer

from .c_pointer import TypedCPointer, VoidPointer

from .object_pointer import Pointer

from .util import RawType, handle

T = TypeVar("T", bound="Struct")

__all__ = (

"Struct",

"StructPointer",

)

class Struct:

"""Abstract class representing a struct."""

_hints: Dict[str, Any]

_void_p: List[str]

_internal_struct: Type[ctypes.Structure]

@classmethod

def _convert_tc_ptr(cls, typ: Any, name: str):

if typ is TypedCPointer:

raise TypeError(

"cannot instantiate: TypedCPointer has no type argument",

)

if getattr(typ, "__origin__", None) is TypedCPointer:

setattr(

cls,

name,

RawType(

ctypes.POINTER(get_mapped(typ.__args__[0])),

)

return typ

@classmethod

def _get_type(

cls,

ct: Type["ctypes._CData"],

name: str,

) -> Type["ctypes._CData"]:

attr = getattr(cls, name, None)

if isinstance(attr, RawType):

return attr.tp

if ct is ctypes.c_void_p:

cls._void_p.append(name)

return ct

def __init__(self, *args: Any, do_sync: bool = True):

class_typ: Type[Struct] = type(self)

if class_typ is Struct:

raise Exception(

"cannot instantiate Struct directly",

)

self._existing_address: Optional[int] = None

self._struct = self._internal_struct(

i if not isinstance(i, BaseCPointer) else i._as_parameter_

for i in args # fmt: off

]

)

if do_sync:

self._sync()

def __init_subclass__(cls):

hints = cls.__annotations__

cls._void_p = []

cls._hints = {

k: cls._convert_tc_ptr(v, k)

for k, v in hints.items()

if k not in {"_hints", "_void_p", "_internal_struct"}

}

class _InternalStruct(ctypes.Structure):

_fields_ = [

(

name,

cls._get_type(get_mapped(typ), name),

)

for name, typ in cls._hints.items() # fmt: off

]

cls._internal_struct = _InternalStruct

@property

def _as_parameter_(self) -> ctypes.Structure:

return self._struct

@classmethod

def from_existing(cls, struct: ctypes.Structure) -> "Struct":

"""Build a new struct from an existing ctypes structure.

Args:

struct: Existing `ctypes.Structure` object

Returns:

Created struct object.

"""

instance = cls(do_sync=False)

instance._struct = struct # type: ignore

# mypy is getting angry here for whatever reason

instance._sync()

instance._existing_address = ctypes.addressof(struct)

return instance

@handle

def __getattribute__(self, name: str):

attr = super().__getattribute__(name)

with suppress(AttributeError):

hints = super().__getattribute__("_hints")

if (name in hints) and (type(attr)) is bytes:

attr = attempt_decode(attr)

if isinstance(attr, ctypes._Pointer): # type: ignore

value = attr.contents

ct = type(value)

if ct is ctypes.c_void_p:

add_ref(ct)

return VoidPointer(

ctypes.addressof(value),

ctypes.sizeof(value),

)

py_type = get_py(ct)

return TypedCPointer(

ctypes.addressof(value),

py_type,

ctypes.sizeof(value),

False,

)

if name in super().__getattribute__("_void_p"):

ct = ctypes.c_void_p(attr) # type: ignore

return VoidPointer(attr, ctypes.sizeof(ct)) # type: ignore

return attr

def __setattr__(self, name: str, value: Any):

if hasattr(self, "_struct"):

self._struct.__setattr__(name, value)

super().__setattr__(name, value)

def _sync(self) -> None:

for name in self._hints:

setattr(self, name, getattr(self._struct, name))

def __repr__(self) -> str:

return f"<struct {type(self).__name__} at {hex(ctypes.addressof(self._struct))}>" # noqa

@property

def struct(self) -> ctypes.Structure:

"""Raw internal Structure object."""

return self._struct

def get_existing_address(self) -> int:

if not self._existing_address:

raise ValueError("instance has not been created from a C struct")

return self._existing_address

class StructPointer(Pointer[T]):

"""Class representing a pointer to a struct."""

def __init__(

self,

address: int,

existing: Optional["Struct"] = None,

self._existing = existing

super().__init__(address, True)

@property # type: ignore

@handle

def _as_parameter_(

self,

) -> Union[int, "ctypes._PointerLike"]:

existing = self._existing

if existing:

return ctypes.pointer(existing.struct)

return self.ensure()

def __repr__(self) -> str:

return f"StructPointer(address={self.address}, existing={self._existing!r})" # noqa

def __rich__(self) -> str:

return f"<[bold blue]pointer[/] to struct at {str(self)}>"

def get_existing_address(self) -> int:

return (~self).get_existing_address()

pointers.py/src/pointers/structure.py at master · ZeroIntensity/pointers.py · GitHub

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