90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
#ifndef Py_CPYTHON_OBJIMPL_H
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# error "this header file must not be included directly"
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#endif
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#define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize )
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/* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a
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vrbl-size object with nitems items, exclusive of gc overhead (if any). The
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value is rounded up to the closest multiple of sizeof(void *), in order to
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ensure that pointer fields at the end of the object are correctly aligned
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for the platform (this is of special importance for subclasses of, e.g.,
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str or int, so that pointers can be stored after the embedded data).
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Note that there's no memory wastage in doing this, as malloc has to
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return (at worst) pointer-aligned memory anyway.
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*/
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#if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0
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# error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2"
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#endif
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#define _PyObject_VAR_SIZE(typeobj, nitems) \
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_Py_SIZE_ROUND_UP((typeobj)->tp_basicsize + \
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(nitems)*(typeobj)->tp_itemsize, \
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SIZEOF_VOID_P)
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/* This example code implements an object constructor with a custom
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allocator, where PyObject_New is inlined, and shows the important
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distinction between two steps (at least):
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1) the actual allocation of the object storage;
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2) the initialization of the Python specific fields
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in this storage with PyObject_{Init, InitVar}.
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PyObject *
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YourObject_New(...)
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{
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PyObject *op;
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op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct));
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if (op == NULL) {
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return PyErr_NoMemory();
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}
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PyObject_Init(op, &YourTypeStruct);
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op->ob_field = value;
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...
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return op;
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}
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Note that in C++, the use of the new operator usually implies that
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the 1st step is performed automatically for you, so in a C++ class
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constructor you would start directly with PyObject_Init/InitVar. */
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typedef struct {
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/* user context passed as the first argument to the 2 functions */
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void *ctx;
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/* allocate an arena of size bytes */
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void* (*alloc) (void *ctx, size_t size);
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/* free an arena */
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void (*free) (void *ctx, void *ptr, size_t size);
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} PyObjectArenaAllocator;
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/* Get the arena allocator. */
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PyAPI_FUNC(void) PyObject_GetArenaAllocator(PyObjectArenaAllocator *allocator);
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/* Set the arena allocator. */
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PyAPI_FUNC(void) PyObject_SetArenaAllocator(PyObjectArenaAllocator *allocator);
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/* Test if an object implements the garbage collector protocol */
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PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
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/* Code built with Py_BUILD_CORE must include pycore_gc.h instead which
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defines a different _PyGC_FINALIZED() macro. */
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#ifndef Py_BUILD_CORE
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// Kept for backward compatibility with Python 3.8
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# define _PyGC_FINALIZED(o) PyObject_GC_IsFinalized(o)
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#endif
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// Test if a type supports weak references
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PyAPI_FUNC(int) PyType_SUPPORTS_WEAKREFS(PyTypeObject *type);
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PyAPI_FUNC(PyObject **) PyObject_GET_WEAKREFS_LISTPTR(PyObject *op);
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