patch null pointers

Author: ZeroIntensity

pyproject.toml

@@ -23,4 +23,4 @@ classifiers = [
 dependencies = [
     "typing_extensions",
 ]
-version = "2.1.0"
+version = "2.1.1"

src/pointers/__init__.py

@@ -27,4 +27,4 @@
 from .std_structs import DivT, Lconv, LDivT, Tm
 from .structure import Struct
 
-__version__ = "2.1.0"
+__version__ = "2.1.1"

src/pointers/_utils.py

@@ -15,6 +15,36 @@
     "make_py",
 )
 
+_C_TYPES: Dict[type, Type["ctypes._CData"]] = {
+    bytes: ctypes.c_char_p,
+    str: ctypes.c_wchar_p,
+    int: ctypes.c_int,
+    float: ctypes.c_float,
+    bool: ctypes.c_bool,
+}
+
+_PY_TYPES: Dict[Type["ctypes._CData"], type] = {
+    ctypes.c_bool: bool,
+    ctypes.c_char: bytes,
+    ctypes.c_wchar: str,
+    ctypes.c_ubyte: int,
+    ctypes.c_short: int,
+    ctypes.c_int: int,
+    ctypes.c_uint: int,
+    ctypes.c_long: int,
+    ctypes.c_ulong: int,
+    ctypes.c_longlong: int,
+    ctypes.c_ulonglong: int,
+    ctypes.c_size_t: int,
+    ctypes.c_ssize_t: int,
+    ctypes.c_float: float,
+    ctypes.c_double: float,
+    ctypes.c_longdouble: float,
+    ctypes.c_char_p: bytes,
+    ctypes.c_wchar_p: str,
+    ctypes.c_void_p: int,
+}
+
 
 def move_to_mem(
     ptr: "ctypes._PointerLike",
@@ -52,15 +82,7 @@ def map_type(data: Any) -> "ctypes._CData":
 
 def get_mapped(typ: Any):
     """Get the C mapped value of the given type."""
-    types: Dict[type, Type["ctypes._CData"]] = {
-        bytes: ctypes.c_char_p,
-        str: ctypes.c_wchar_p,
-        int: ctypes.c_int,
-        float: ctypes.c_float,
-        bool: ctypes.c_bool,
-    }
-
-    res = types.get(typ)
+    res = _C_TYPES.get(typ)
 
     if not res:
         raise ValueError(f'"{typ.__name__}" is not mappable to a c type')
@@ -86,30 +108,8 @@ def get_py(
     if data.__name__.startswith("LP_"):
         return BaseCPointer
 
-    types: Dict[Type["ctypes._CData"], type] = {
-        ctypes.c_bool: bool,
-        ctypes.c_char: bytes,
-        ctypes.c_wchar: str,
-        ctypes.c_ubyte: int,
-        ctypes.c_short: int,
-        ctypes.c_int: int,
-        ctypes.c_uint: int,
-        ctypes.c_long: int,
-        ctypes.c_ulong: int,
-        ctypes.c_longlong: int,
-        ctypes.c_ulonglong: int,
-        ctypes.c_size_t: int,
-        ctypes.c_ssize_t: int,
-        ctypes.c_float: float,
-        ctypes.c_double: float,
-        ctypes.c_longdouble: float,
-        ctypes.c_char_p: bytes,
-        ctypes.c_wchar_p: str,
-        ctypes.c_void_p: int,
-    }
-
     try:
-        return types[data]
+        return _PY_TYPES[data]
     except KeyError as e:
         raise ValueError(
             f"{data} is not a valid ctypes type",

src/pointers/base_pointers.py

@@ -246,12 +246,11 @@ def __init__(
         """  # noqa
         self._address: Optional[int] = address
         self._type: Type[T] = typ
-        obj = ~self
 
         if increment_ref and address:
-            add_ref(obj)
+            add_ref(~self)
 
-        self._origin_size = sys.getsizeof(obj)
+        self._origin_size = sys.getsizeof(~self if address else None)
 
     @property
     def type(self):
@@ -285,12 +284,17 @@ def assign(
                 "can only point to object pointer",
             )
 
-        if new.type is not self.type:
+        if (new.type is not self.type) and self.address:
             raise TypeError(
                 f"object at new address must be the same type (pointer looks at {self.type.__name__}, target is {new.type.__name__})",  # noqa
             )
 
-        remove_ref(~self)
+        if not self.address:
+            self._type = new.type
+
+        with suppress(NullPointerError):
+            remove_ref(~self)
+
         self._address = new.address
         add_ref(~self)
 

src/pointers/object_pointer.py

@@ -63,10 +63,11 @@ def move(
 
     @classmethod
     def make_from(cls, obj: Nullable[T]) -> "Pointer[T]":
+        is_null = obj is NULL
         return Pointer(
-            id(obj) if obj is not NULL else None,
+            id(obj) if not is_null else None,
             type(obj),  # type: ignore
-            True,
+            not is_null,
         )
 
 

tests/test_pointer.py

@@ -81,6 +81,14 @@ def _():
     with raises(NullPointerError):
         print(~to_ptr(NULL))
 
+    ptr2 = to_ptr(NULL)
+    ptr2 >>= 1
+
+    with raises(TypeError):
+        ptr2 >>= ""
+
+    ptr2 >>= NULL
+
 
 @test("operator magic")
 def _():