mirror of https://github.com/python/cpython
760 lines
28 KiB
C
760 lines
28 KiB
C
#ifndef Py_OBJECT_H
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#define Py_OBJECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Object and type object interface */
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/*
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Objects are structures allocated on the heap. Special rules apply to
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the use of objects to ensure they are properly garbage-collected.
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Objects are never allocated statically or on the stack; they must be
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accessed through special macros and functions only. (Type objects are
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exceptions to the first rule; the standard types are represented by
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statically initialized type objects, although work on type/class unification
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for Python 2.2 made it possible to have heap-allocated type objects too).
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An object has a 'reference count' that is increased or decreased when a
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pointer to the object is copied or deleted; when the reference count
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reaches zero there are no references to the object left and it can be
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removed from the heap.
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An object has a 'type' that determines what it represents and what kind
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of data it contains. An object's type is fixed when it is created.
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Types themselves are represented as objects; an object contains a
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pointer to the corresponding type object. The type itself has a type
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pointer pointing to the object representing the type 'type', which
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contains a pointer to itself!.
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Objects do not float around in memory; once allocated an object keeps
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the same size and address. Objects that must hold variable-size data
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can contain pointers to variable-size parts of the object. Not all
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objects of the same type have the same size; but the size cannot change
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after allocation. (These restrictions are made so a reference to an
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object can be simply a pointer -- moving an object would require
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updating all the pointers, and changing an object's size would require
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moving it if there was another object right next to it.)
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Objects are always accessed through pointers of the type 'PyObject *'.
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The type 'PyObject' is a structure that only contains the reference count
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and the type pointer. The actual memory allocated for an object
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contains other data that can only be accessed after casting the pointer
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to a pointer to a longer structure type. This longer type must start
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with the reference count and type fields; the macro PyObject_HEAD should be
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used for this (to accommodate for future changes). The implementation
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of a particular object type can cast the object pointer to the proper
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type and back.
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A standard interface exists for objects that contain an array of items
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whose size is determined when the object is allocated.
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*/
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/* Py_DEBUG implies Py_REF_DEBUG. */
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#if defined(Py_DEBUG) && !defined(Py_REF_DEBUG)
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# define Py_REF_DEBUG
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#endif
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#if defined(Py_LIMITED_API) && defined(Py_TRACE_REFS)
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# error Py_LIMITED_API is incompatible with Py_TRACE_REFS
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#endif
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/* PyTypeObject structure is defined in cpython/object.h.
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In Py_LIMITED_API, PyTypeObject is an opaque structure. */
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typedef struct _typeobject PyTypeObject;
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#ifdef Py_TRACE_REFS
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/* Define pointers to support a doubly-linked list of all live heap objects. */
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#define _PyObject_HEAD_EXTRA \
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struct _object *_ob_next; \
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struct _object *_ob_prev;
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#define _PyObject_EXTRA_INIT 0, 0,
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#else
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# define _PyObject_HEAD_EXTRA
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# define _PyObject_EXTRA_INIT
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#endif
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/* PyObject_HEAD defines the initial segment of every PyObject. */
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#define PyObject_HEAD PyObject ob_base;
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#define PyObject_HEAD_INIT(type) \
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{ _PyObject_EXTRA_INIT \
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1, type },
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#define PyVarObject_HEAD_INIT(type, size) \
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{ PyObject_HEAD_INIT(type) size },
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/* PyObject_VAR_HEAD defines the initial segment of all variable-size
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* container objects. These end with a declaration of an array with 1
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* element, but enough space is malloc'ed so that the array actually
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* has room for ob_size elements. Note that ob_size is an element count,
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* not necessarily a byte count.
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*/
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#define PyObject_VAR_HEAD PyVarObject ob_base;
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#define Py_INVALID_SIZE (Py_ssize_t)-1
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/* Nothing is actually declared to be a PyObject, but every pointer to
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* a Python object can be cast to a PyObject*. This is inheritance built
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* by hand. Similarly every pointer to a variable-size Python object can,
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* in addition, be cast to PyVarObject*.
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*/
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typedef struct _object {
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_PyObject_HEAD_EXTRA
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Py_ssize_t ob_refcnt;
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PyTypeObject *ob_type;
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} PyObject;
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/* Cast argument to PyObject* type. */
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#define _PyObject_CAST(op) ((PyObject*)(op))
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#define _PyObject_CAST_CONST(op) ((const PyObject*)(op))
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typedef struct {
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PyObject ob_base;
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Py_ssize_t ob_size; /* Number of items in variable part */
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} PyVarObject;
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/* Cast argument to PyVarObject* type. */
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#define _PyVarObject_CAST(op) ((PyVarObject*)(op))
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#define _PyVarObject_CAST_CONST(op) ((const PyVarObject*)(op))
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// Test if the 'x' object is the 'y' object, the same as "x is y" in Python.
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PyAPI_FUNC(int) Py_Is(PyObject *x, PyObject *y);
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#define Py_Is(x, y) ((x) == (y))
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static inline Py_ssize_t _Py_REFCNT(const PyObject *ob) {
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return ob->ob_refcnt;
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}
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#define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))
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// bpo-39573: The Py_SET_TYPE() function must be used to set an object type.
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static inline PyTypeObject* _Py_TYPE(const PyObject *ob) {
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return ob->ob_type;
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}
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#define Py_TYPE(ob) _Py_TYPE(_PyObject_CAST_CONST(ob))
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// bpo-39573: The Py_SET_SIZE() function must be used to set an object size.
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static inline Py_ssize_t _Py_SIZE(const PyVarObject *ob) {
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return ob->ob_size;
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}
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#define Py_SIZE(ob) _Py_SIZE(_PyVarObject_CAST_CONST(ob))
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static inline int _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
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// bpo-44378: Don't use Py_TYPE() since Py_TYPE() requires a non-const
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// object.
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return ob->ob_type == type;
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}
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#define Py_IS_TYPE(ob, type) _Py_IS_TYPE(_PyObject_CAST_CONST(ob), type)
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static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
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ob->ob_refcnt = refcnt;
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}
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#define Py_SET_REFCNT(ob, refcnt) _Py_SET_REFCNT(_PyObject_CAST(ob), refcnt)
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static inline void _Py_SET_TYPE(PyObject *ob, PyTypeObject *type) {
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ob->ob_type = type;
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}
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#define Py_SET_TYPE(ob, type) _Py_SET_TYPE(_PyObject_CAST(ob), type)
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static inline void _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size) {
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ob->ob_size = size;
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}
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#define Py_SET_SIZE(ob, size) _Py_SET_SIZE(_PyVarObject_CAST(ob), size)
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/*
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Type objects contain a string containing the type name (to help somewhat
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in debugging), the allocation parameters (see PyObject_New() and
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PyObject_NewVar()),
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and methods for accessing objects of the type. Methods are optional, a
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nil pointer meaning that particular kind of access is not available for
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this type. The Py_DECREF() macro uses the tp_dealloc method without
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checking for a nil pointer; it should always be implemented except if
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the implementation can guarantee that the reference count will never
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reach zero (e.g., for statically allocated type objects).
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NB: the methods for certain type groups are now contained in separate
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method blocks.
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*/
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typedef PyObject * (*unaryfunc)(PyObject *);
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typedef PyObject * (*binaryfunc)(PyObject *, PyObject *);
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typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *);
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typedef int (*inquiry)(PyObject *);
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typedef Py_ssize_t (*lenfunc)(PyObject *);
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typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
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typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t);
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typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *);
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typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *);
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typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *);
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typedef int (*objobjproc)(PyObject *, PyObject *);
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typedef int (*visitproc)(PyObject *, void *);
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typedef int (*traverseproc)(PyObject *, visitproc, void *);
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typedef void (*freefunc)(void *);
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typedef void (*destructor)(PyObject *);
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typedef PyObject *(*getattrfunc)(PyObject *, char *);
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typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
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typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
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typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
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typedef PyObject *(*reprfunc)(PyObject *);
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typedef Py_hash_t (*hashfunc)(PyObject *);
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typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
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typedef PyObject *(*getiterfunc) (PyObject *);
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typedef PyObject *(*iternextfunc) (PyObject *);
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typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
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typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
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typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
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typedef PyObject *(*newfunc)(PyTypeObject *, PyObject *, PyObject *);
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typedef PyObject *(*allocfunc)(PyTypeObject *, Py_ssize_t);
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typedef struct{
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int slot; /* slot id, see below */
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void *pfunc; /* function pointer */
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} PyType_Slot;
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typedef struct{
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const char* name;
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int basicsize;
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int itemsize;
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unsigned int flags;
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PyType_Slot *slots; /* terminated by slot==0. */
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} PyType_Spec;
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PyAPI_FUNC(PyObject*) PyType_FromSpec(PyType_Spec*);
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
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PyAPI_FUNC(PyObject*) PyType_FromSpecWithBases(PyType_Spec*, PyObject*);
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#endif
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03040000
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PyAPI_FUNC(void*) PyType_GetSlot(PyTypeObject*, int);
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#endif
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
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PyAPI_FUNC(PyObject*) PyType_FromModuleAndSpec(PyObject *, PyType_Spec *, PyObject *);
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PyAPI_FUNC(PyObject *) PyType_GetModule(struct _typeobject *);
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PyAPI_FUNC(void *) PyType_GetModuleState(struct _typeobject *);
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#endif
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030B0000
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PyAPI_FUNC(PyObject *) PyType_GetName(PyTypeObject *);
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PyAPI_FUNC(PyObject *) PyType_GetQualName(PyTypeObject *);
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#endif
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/* Generic type check */
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PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
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static inline int _PyObject_TypeCheck(PyObject *ob, PyTypeObject *type) {
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return Py_IS_TYPE(ob, type) || PyType_IsSubtype(Py_TYPE(ob), type);
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}
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#define PyObject_TypeCheck(ob, type) _PyObject_TypeCheck(_PyObject_CAST(ob), type)
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PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
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PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
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PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */
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PyAPI_FUNC(unsigned long) PyType_GetFlags(PyTypeObject*);
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PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
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PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
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PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
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PyObject *, PyObject *);
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PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
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PyAPI_FUNC(void) PyType_Modified(PyTypeObject *);
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/* Generic operations on objects */
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PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_ASCII(PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_Bytes(PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
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PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
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PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
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PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
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PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
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PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
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PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
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PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
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PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
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PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, PyObject *, PyObject *);
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
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PyAPI_FUNC(int) PyObject_GenericSetDict(PyObject *, PyObject *, void *);
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#endif
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PyAPI_FUNC(Py_hash_t) PyObject_Hash(PyObject *);
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PyAPI_FUNC(Py_hash_t) PyObject_HashNotImplemented(PyObject *);
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PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
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PyAPI_FUNC(int) PyObject_Not(PyObject *);
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PyAPI_FUNC(int) PyCallable_Check(PyObject *);
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PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
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/* PyObject_Dir(obj) acts like Python builtins.dir(obj), returning a
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list of strings. PyObject_Dir(NULL) is like builtins.dir(),
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returning the names of the current locals. In this case, if there are
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no current locals, NULL is returned, and PyErr_Occurred() is false.
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*/
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PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
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/* Helpers for printing recursive container types */
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PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
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PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
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/* Flag bits for printing: */
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#define Py_PRINT_RAW 1 /* No string quotes etc. */
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/*
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Type flags (tp_flags)
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These flags are used to change expected features and behavior for a
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particular type.
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Arbitration of the flag bit positions will need to be coordinated among
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all extension writers who publicly release their extensions (this will
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be fewer than you might expect!).
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Most flags were removed as of Python 3.0 to make room for new flags. (Some
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flags are not for backwards compatibility but to indicate the presence of an
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optional feature; these flags remain of course.)
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Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
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Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
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given type object has a specified feature.
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*/
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#ifndef Py_LIMITED_API
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/* Set if instances of the type object are treated as sequences for pattern matching */
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#define Py_TPFLAGS_SEQUENCE (1 << 5)
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/* Set if instances of the type object are treated as mappings for pattern matching */
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#define Py_TPFLAGS_MAPPING (1 << 6)
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#endif
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/* Disallow creating instances of the type: set tp_new to NULL and don't create
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* the "__new__" key in the type dictionary. */
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#define Py_TPFLAGS_DISALLOW_INSTANTIATION (1UL << 7)
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/* Set if the type object is immutable: type attributes cannot be set nor deleted */
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#define Py_TPFLAGS_IMMUTABLETYPE (1UL << 8)
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/* Set if the type object is dynamically allocated */
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#define Py_TPFLAGS_HEAPTYPE (1UL << 9)
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/* Set if the type allows subclassing */
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#define Py_TPFLAGS_BASETYPE (1UL << 10)
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/* Set if the type implements the vectorcall protocol (PEP 590) */
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#ifndef Py_LIMITED_API
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#define Py_TPFLAGS_HAVE_VECTORCALL (1UL << 11)
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// Backwards compatibility alias for API that was provisional in Python 3.8
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#define _Py_TPFLAGS_HAVE_VECTORCALL Py_TPFLAGS_HAVE_VECTORCALL
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#endif
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/* Set if the type is 'ready' -- fully initialized */
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#define Py_TPFLAGS_READY (1UL << 12)
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/* Set while the type is being 'readied', to prevent recursive ready calls */
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#define Py_TPFLAGS_READYING (1UL << 13)
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/* Objects support garbage collection (see objimpl.h) */
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#define Py_TPFLAGS_HAVE_GC (1UL << 14)
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/* These two bits are preserved for Stackless Python, next after this is 17 */
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#ifdef STACKLESS
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#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3UL << 15)
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#else
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#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0
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#endif
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/* Objects behave like an unbound method */
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#define Py_TPFLAGS_METHOD_DESCRIPTOR (1UL << 17)
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/* Object has up-to-date type attribute cache */
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#define Py_TPFLAGS_VALID_VERSION_TAG (1UL << 19)
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/* Type is abstract and cannot be instantiated */
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#define Py_TPFLAGS_IS_ABSTRACT (1UL << 20)
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// This undocumented flag gives certain built-ins their unique pattern-matching
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// behavior, which allows a single positional subpattern to match against the
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// subject itself (rather than a mapped attribute on it):
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#define _Py_TPFLAGS_MATCH_SELF (1UL << 22)
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/* These flags are used to determine if a type is a subclass. */
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#define Py_TPFLAGS_LONG_SUBCLASS (1UL << 24)
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#define Py_TPFLAGS_LIST_SUBCLASS (1UL << 25)
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#define Py_TPFLAGS_TUPLE_SUBCLASS (1UL << 26)
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#define Py_TPFLAGS_BYTES_SUBCLASS (1UL << 27)
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#define Py_TPFLAGS_UNICODE_SUBCLASS (1UL << 28)
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#define Py_TPFLAGS_DICT_SUBCLASS (1UL << 29)
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#define Py_TPFLAGS_BASE_EXC_SUBCLASS (1UL << 30)
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#define Py_TPFLAGS_TYPE_SUBCLASS (1UL << 31)
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#define Py_TPFLAGS_DEFAULT ( \
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Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \
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0)
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/* NOTE: Some of the following flags reuse lower bits (removed as part of the
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* Python 3.0 transition). */
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/* The following flags are kept for compatibility; in previous
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* versions they indicated presence of newer tp_* fields on the
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* type struct.
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* Starting with 3.8, binary compatibility of C extensions across
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* feature releases of Python is not supported anymore (except when
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* using the stable ABI, in which all classes are created dynamically,
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* using the interpreter's memory layout.)
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* Note that older extensions using the stable ABI set these flags,
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* so the bits must not be repurposed.
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*/
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#define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0)
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#define Py_TPFLAGS_HAVE_VERSION_TAG (1UL << 18)
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/*
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The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
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reference counts. Py_DECREF calls the object's deallocator function when
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the refcount falls to 0; for
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objects that don't contain references to other objects or heap memory
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this can be the standard function free(). Both macros can be used
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wherever a void expression is allowed. The argument must not be a
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NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
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The macro _Py_NewReference(op) initialize reference counts to 1, and
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in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
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bookkeeping appropriate to the special build.
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We assume that the reference count field can never overflow; this can
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be proven when the size of the field is the same as the pointer size, so
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we ignore the possibility. Provided a C int is at least 32 bits (which
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is implicitly assumed in many parts of this code), that's enough for
|
|
about 2**31 references to an object.
|
|
|
|
XXX The following became out of date in Python 2.2, but I'm not sure
|
|
XXX what the full truth is now. Certainly, heap-allocated type objects
|
|
XXX can and should be deallocated.
|
|
Type objects should never be deallocated; the type pointer in an object
|
|
is not considered to be a reference to the type object, to save
|
|
complications in the deallocation function. (This is actually a
|
|
decision that's up to the implementer of each new type so if you want,
|
|
you can count such references to the type object.)
|
|
*/
|
|
|
|
#ifdef Py_REF_DEBUG
|
|
PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
|
|
PyAPI_FUNC(void) _Py_NegativeRefcount(const char *filename, int lineno,
|
|
PyObject *op);
|
|
#endif /* Py_REF_DEBUG */
|
|
|
|
PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
|
|
|
|
/*
|
|
These are provided as conveniences to Python runtime embedders, so that
|
|
they can have object code that is not dependent on Python compilation flags.
|
|
*/
|
|
PyAPI_FUNC(void) Py_IncRef(PyObject *);
|
|
PyAPI_FUNC(void) Py_DecRef(PyObject *);
|
|
|
|
// Similar to Py_IncRef() and Py_DecRef() but the argument must be non-NULL.
|
|
// Private functions used by Py_INCREF() and Py_DECREF().
|
|
PyAPI_FUNC(void) _Py_IncRef(PyObject *);
|
|
PyAPI_FUNC(void) _Py_DecRef(PyObject *);
|
|
|
|
static inline void _Py_INCREF(PyObject *op)
|
|
{
|
|
#if defined(Py_REF_DEBUG) && defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000
|
|
// Stable ABI for Python 3.10 built in debug mode.
|
|
_Py_IncRef(op);
|
|
#else
|
|
// Non-limited C API and limited C API for Python 3.9 and older access
|
|
// directly PyObject.ob_refcnt.
|
|
#ifdef Py_REF_DEBUG
|
|
_Py_RefTotal++;
|
|
#endif
|
|
op->ob_refcnt++;
|
|
#endif
|
|
}
|
|
#define Py_INCREF(op) _Py_INCREF(_PyObject_CAST(op))
|
|
|
|
static inline void _Py_DECREF(
|
|
#if defined(Py_REF_DEBUG) && !(defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000)
|
|
const char *filename, int lineno,
|
|
#endif
|
|
PyObject *op)
|
|
{
|
|
#if defined(Py_REF_DEBUG) && defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000
|
|
// Stable ABI for Python 3.10 built in debug mode.
|
|
_Py_DecRef(op);
|
|
#else
|
|
// Non-limited C API and limited C API for Python 3.9 and older access
|
|
// directly PyObject.ob_refcnt.
|
|
#ifdef Py_REF_DEBUG
|
|
_Py_RefTotal--;
|
|
#endif
|
|
if (--op->ob_refcnt != 0) {
|
|
#ifdef Py_REF_DEBUG
|
|
if (op->ob_refcnt < 0) {
|
|
_Py_NegativeRefcount(filename, lineno, op);
|
|
}
|
|
#endif
|
|
}
|
|
else {
|
|
_Py_Dealloc(op);
|
|
}
|
|
#endif
|
|
}
|
|
#if defined(Py_REF_DEBUG) && !(defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000)
|
|
# define Py_DECREF(op) _Py_DECREF(__FILE__, __LINE__, _PyObject_CAST(op))
|
|
#else
|
|
# define Py_DECREF(op) _Py_DECREF(_PyObject_CAST(op))
|
|
#endif
|
|
|
|
|
|
/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
|
|
* and tp_dealloc implementations.
|
|
*
|
|
* Note that "the obvious" code can be deadly:
|
|
*
|
|
* Py_XDECREF(op);
|
|
* op = NULL;
|
|
*
|
|
* Typically, `op` is something like self->containee, and `self` is done
|
|
* using its `containee` member. In the code sequence above, suppose
|
|
* `containee` is non-NULL with a refcount of 1. Its refcount falls to
|
|
* 0 on the first line, which can trigger an arbitrary amount of code,
|
|
* possibly including finalizers (like __del__ methods or weakref callbacks)
|
|
* coded in Python, which in turn can release the GIL and allow other threads
|
|
* to run, etc. Such code may even invoke methods of `self` again, or cause
|
|
* cyclic gc to trigger, but-- oops! --self->containee still points to the
|
|
* object being torn down, and it may be in an insane state while being torn
|
|
* down. This has in fact been a rich historic source of miserable (rare &
|
|
* hard-to-diagnose) segfaulting (and other) bugs.
|
|
*
|
|
* The safe way is:
|
|
*
|
|
* Py_CLEAR(op);
|
|
*
|
|
* That arranges to set `op` to NULL _before_ decref'ing, so that any code
|
|
* triggered as a side-effect of `op` getting torn down no longer believes
|
|
* `op` points to a valid object.
|
|
*
|
|
* There are cases where it's safe to use the naive code, but they're brittle.
|
|
* For example, if `op` points to a Python integer, you know that destroying
|
|
* one of those can't cause problems -- but in part that relies on that
|
|
* Python integers aren't currently weakly referencable. Best practice is
|
|
* to use Py_CLEAR() even if you can't think of a reason for why you need to.
|
|
*/
|
|
#define Py_CLEAR(op) \
|
|
do { \
|
|
PyObject *_py_tmp = _PyObject_CAST(op); \
|
|
if (_py_tmp != NULL) { \
|
|
(op) = NULL; \
|
|
Py_DECREF(_py_tmp); \
|
|
} \
|
|
} while (0)
|
|
|
|
/* Function to use in case the object pointer can be NULL: */
|
|
static inline void _Py_XINCREF(PyObject *op)
|
|
{
|
|
if (op != NULL) {
|
|
Py_INCREF(op);
|
|
}
|
|
}
|
|
|
|
#define Py_XINCREF(op) _Py_XINCREF(_PyObject_CAST(op))
|
|
|
|
static inline void _Py_XDECREF(PyObject *op)
|
|
{
|
|
if (op != NULL) {
|
|
Py_DECREF(op);
|
|
}
|
|
}
|
|
|
|
#define Py_XDECREF(op) _Py_XDECREF(_PyObject_CAST(op))
|
|
|
|
// Create a new strong reference to an object:
|
|
// increment the reference count of the object and return the object.
|
|
PyAPI_FUNC(PyObject*) Py_NewRef(PyObject *obj);
|
|
|
|
// Similar to Py_NewRef(), but the object can be NULL.
|
|
PyAPI_FUNC(PyObject*) Py_XNewRef(PyObject *obj);
|
|
|
|
static inline PyObject* _Py_NewRef(PyObject *obj)
|
|
{
|
|
Py_INCREF(obj);
|
|
return obj;
|
|
}
|
|
|
|
static inline PyObject* _Py_XNewRef(PyObject *obj)
|
|
{
|
|
Py_XINCREF(obj);
|
|
return obj;
|
|
}
|
|
|
|
// Py_NewRef() and Py_XNewRef() are exported as functions for the stable ABI.
|
|
// Names overriden with macros by static inline functions for best
|
|
// performances.
|
|
#define Py_NewRef(obj) _Py_NewRef(_PyObject_CAST(obj))
|
|
#define Py_XNewRef(obj) _Py_XNewRef(_PyObject_CAST(obj))
|
|
|
|
|
|
/*
|
|
_Py_NoneStruct is an object of undefined type which can be used in contexts
|
|
where NULL (nil) is not suitable (since NULL often means 'error').
|
|
|
|
Don't forget to apply Py_INCREF() when returning this value!!!
|
|
*/
|
|
PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
|
|
#define Py_None (&_Py_NoneStruct)
|
|
|
|
// Test if an object is the None singleton, the same as "x is None" in Python.
|
|
PyAPI_FUNC(int) Py_IsNone(PyObject *x);
|
|
#define Py_IsNone(x) Py_Is((x), Py_None)
|
|
|
|
/* Macro for returning Py_None from a function */
|
|
#define Py_RETURN_NONE return Py_NewRef(Py_None)
|
|
|
|
/*
|
|
Py_NotImplemented is a singleton used to signal that an operation is
|
|
not implemented for a given type combination.
|
|
*/
|
|
PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
|
|
#define Py_NotImplemented (&_Py_NotImplementedStruct)
|
|
|
|
/* Macro for returning Py_NotImplemented from a function */
|
|
#define Py_RETURN_NOTIMPLEMENTED return Py_NewRef(Py_NotImplemented)
|
|
|
|
/* Rich comparison opcodes */
|
|
#define Py_LT 0
|
|
#define Py_LE 1
|
|
#define Py_EQ 2
|
|
#define Py_NE 3
|
|
#define Py_GT 4
|
|
#define Py_GE 5
|
|
|
|
#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030A0000
|
|
/* Result of calling PyIter_Send */
|
|
typedef enum {
|
|
PYGEN_RETURN = 0,
|
|
PYGEN_ERROR = -1,
|
|
PYGEN_NEXT = 1,
|
|
} PySendResult;
|
|
#endif
|
|
|
|
/*
|
|
* Macro for implementing rich comparisons
|
|
*
|
|
* Needs to be a macro because any C-comparable type can be used.
|
|
*/
|
|
#define Py_RETURN_RICHCOMPARE(val1, val2, op) \
|
|
do { \
|
|
switch (op) { \
|
|
case Py_EQ: if ((val1) == (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
case Py_NE: if ((val1) != (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
case Py_LT: if ((val1) < (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
case Py_GT: if ((val1) > (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
case Py_LE: if ((val1) <= (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
case Py_GE: if ((val1) >= (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
|
|
default: \
|
|
Py_UNREACHABLE(); \
|
|
} \
|
|
} while (0)
|
|
|
|
|
|
/*
|
|
More conventions
|
|
================
|
|
|
|
Argument Checking
|
|
-----------------
|
|
|
|
Functions that take objects as arguments normally don't check for nil
|
|
arguments, but they do check the type of the argument, and return an
|
|
error if the function doesn't apply to the type.
|
|
|
|
Failure Modes
|
|
-------------
|
|
|
|
Functions may fail for a variety of reasons, including running out of
|
|
memory. This is communicated to the caller in two ways: an error string
|
|
is set (see errors.h), and the function result differs: functions that
|
|
normally return a pointer return NULL for failure, functions returning
|
|
an integer return -1 (which could be a legal return value too!), and
|
|
other functions return 0 for success and -1 for failure.
|
|
Callers should always check for errors before using the result. If
|
|
an error was set, the caller must either explicitly clear it, or pass
|
|
the error on to its caller.
|
|
|
|
Reference Counts
|
|
----------------
|
|
|
|
It takes a while to get used to the proper usage of reference counts.
|
|
|
|
Functions that create an object set the reference count to 1; such new
|
|
objects must be stored somewhere or destroyed again with Py_DECREF().
|
|
Some functions that 'store' objects, such as PyTuple_SetItem() and
|
|
PyList_SetItem(),
|
|
don't increment the reference count of the object, since the most
|
|
frequent use is to store a fresh object. Functions that 'retrieve'
|
|
objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
|
|
don't increment
|
|
the reference count, since most frequently the object is only looked at
|
|
quickly. Thus, to retrieve an object and store it again, the caller
|
|
must call Py_INCREF() explicitly.
|
|
|
|
NOTE: functions that 'consume' a reference count, like
|
|
PyList_SetItem(), consume the reference even if the object wasn't
|
|
successfully stored, to simplify error handling.
|
|
|
|
It seems attractive to make other functions that take an object as
|
|
argument consume a reference count; however, this may quickly get
|
|
confusing (even the current practice is already confusing). Consider
|
|
it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
|
|
times.
|
|
*/
|
|
|
|
#ifndef Py_LIMITED_API
|
|
# define Py_CPYTHON_OBJECT_H
|
|
# include "cpython/object.h"
|
|
# undef Py_CPYTHON_OBJECT_H
|
|
#endif
|
|
|
|
|
|
static inline int
|
|
PyType_HasFeature(PyTypeObject *type, unsigned long feature)
|
|
{
|
|
unsigned long flags;
|
|
#ifdef Py_LIMITED_API
|
|
// PyTypeObject is opaque in the limited C API
|
|
flags = PyType_GetFlags(type);
|
|
#else
|
|
flags = type->tp_flags;
|
|
#endif
|
|
return ((flags & feature) != 0);
|
|
}
|
|
|
|
#define PyType_FastSubclass(type, flag) PyType_HasFeature(type, flag)
|
|
|
|
static inline int _PyType_Check(PyObject *op) {
|
|
return PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS);
|
|
}
|
|
#define PyType_Check(op) _PyType_Check(_PyObject_CAST(op))
|
|
|
|
static inline int _PyType_CheckExact(PyObject *op) {
|
|
return Py_IS_TYPE(op, &PyType_Type);
|
|
}
|
|
#define PyType_CheckExact(op) _PyType_CheckExact(_PyObject_CAST(op))
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
#endif /* !Py_OBJECT_H */
|