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class _UniffiPointerManagerCPython:
"""
Manage giving out pointers to Python objects on CPython
This class is used to generate opaque pointers that reference Python objects to pass to Rust.
It assumes a CPython platform. See _UniffiPointerManagerGeneral for the alternative.
"""
def new_pointer(self, obj):
"""
Get a pointer for an object as a ctypes.c_size_t instance
Each call to new_pointer() must be balanced with exactly one call to release_pointer()
This returns a ctypes.c_size_t. This is always the same size as a pointer and can be
interchanged with pointers for FFI function arguments and return values.
"""
# IncRef the object since we're going to pass a pointer to Rust
ctypes.pythonapi.Py_IncRef(ctypes.py_object(obj))
# id() is the object address on CPython
# (https://docs.python.org/3/library/functions.html#id)
return id(obj)
def release_pointer(self, address):
py_obj = ctypes.cast(address, ctypes.py_object)
obj = py_obj.value
ctypes.pythonapi.Py_DecRef(py_obj)
return obj
def lookup(self, address):
return ctypes.cast(address, ctypes.py_object).value
class _UniffiPointerManagerGeneral:
"""
Manage giving out pointers to Python objects on non-CPython platforms
This has the same API as _UniffiPointerManagerCPython, but doesn't assume we're running on
CPython and is slightly slower.
Instead of using real pointers, it maps integer values to objects and returns the keys as
c_size_t values.
"""
def __init__(self):
self._map = {}
self._lock = threading.Lock()
self._current_handle = 0
def new_pointer(self, obj):
with self._lock:
handle = self._current_handle
self._current_handle += 1
self._map[handle] = obj
return handle
def release_pointer(self, handle):
with self._lock:
return self._map.pop(handle)
def lookup(self, handle):
with self._lock:
return self._map[handle]
# Pick an pointer manager implementation based on the platform
if platform.python_implementation() == 'CPython':
_UniffiPointerManager = _UniffiPointerManagerCPython # type: ignore
else:
_UniffiPointerManager = _UniffiPointerManagerGeneral # type: ignore
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