1#ifndef Py_OBJECT_H
2#define Py_OBJECT_H
3#ifdef __cplusplus
4extern "C" {
5#endif
6
7
8/* Object and type object interface */
9
10/*
11Objects are structures allocated on the heap. Special rules apply to
12the use of objects to ensure they are properly garbage-collected.
13Objects are never allocated statically or on the stack; they must be
14accessed through special macros and functions only. (Type objects are
15exceptions to the first rule; the standard types are represented by
16statically initialized type objects, although work on type/class unification
17for Python 2.2 made it possible to have heap-allocated type objects too).
18
19An object has a 'reference count' that is increased or decreased when a
20pointer to the object is copied or deleted; when the reference count
21reaches zero there are no references to the object left and it can be
22removed from the heap.
23
24An object has a 'type' that determines what it represents and what kind
25of data it contains. An object's type is fixed when it is created.
26Types themselves are represented as objects; an object contains a
27pointer to the corresponding type object. The type itself has a type
28pointer pointing to the object representing the type 'type', which
29contains a pointer to itself!.
30
31Objects do not float around in memory; once allocated an object keeps
32the same size and address. Objects that must hold variable-size data
33can contain pointers to variable-size parts of the object. Not all
34objects of the same type have the same size; but the size cannot change
35after allocation. (These restrictions are made so a reference to an
36object can be simply a pointer -- moving an object would require
37updating all the pointers, and changing an object's size would require
38moving it if there was another object right next to it.)
39
40Objects are always accessed through pointers of the type 'PyObject *'.
41The type 'PyObject' is a structure that only contains the reference count
42and the type pointer. The actual memory allocated for an object
43contains other data that can only be accessed after casting the pointer
44to a pointer to a longer structure type. This longer type must start
45with the reference count and type fields; the macro PyObject_HEAD should be
46used for this (to accommodate for future changes). The implementation
47of a particular object type can cast the object pointer to the proper
48type and back.
49
50A standard interface exists for objects that contain an array of items
51whose size is determined when the object is allocated.
52*/
53
54#include "pystats.h"
55
56/* Py_DEBUG implies Py_REF_DEBUG. */
57#if defined(Py_DEBUG) && !defined(Py_REF_DEBUG)
58# define Py_REF_DEBUG
59#endif
60
61#if defined(Py_LIMITED_API) && defined(Py_TRACE_REFS)
62# error Py_LIMITED_API is incompatible with Py_TRACE_REFS
63#endif
64
65#ifdef Py_TRACE_REFS
66/* Define pointers to support a doubly-linked list of all live heap objects. */
67#define _PyObject_HEAD_EXTRA \
68 PyObject *_ob_next; \
69 PyObject *_ob_prev;
70
71#define _PyObject_EXTRA_INIT _Py_NULL, _Py_NULL,
72
73#else
74# define _PyObject_HEAD_EXTRA
75# define _PyObject_EXTRA_INIT
76#endif
77
78/* PyObject_HEAD defines the initial segment of every PyObject. */
79#define PyObject_HEAD PyObject ob_base;
80
81/*
82Immortalization:
83
84The following indicates the immortalization strategy depending on the amount
85of available bits in the reference count field. All strategies are backwards
86compatible but the specific reference count value or immortalization check
87might change depending on the specializations for the underlying system.
88
89Proper deallocation of immortal instances requires distinguishing between
90statically allocated immortal instances vs those promoted by the runtime to be
91immortal. The latter should be the only instances that require
92cleanup during runtime finalization.
93*/
94
95#if SIZEOF_VOID_P > 4
96/*
97In 64+ bit systems, an object will be marked as immortal by setting all of the
98lower 32 bits of the reference count field, which is equal to: 0xFFFFFFFF
99
100Using the lower 32 bits makes the value backwards compatible by allowing
101C-Extensions without the updated checks in Py_INCREF and Py_DECREF to safely
102increase and decrease the objects reference count. The object would lose its
103immortality, but the execution would still be correct.
104
105Reference count increases will use saturated arithmetic, taking advantage of
106having all the lower 32 bits set, which will avoid the reference count to go
107beyond the refcount limit. Immortality checks for reference count decreases will
108be done by checking the bit sign flag in the lower 32 bits.
109*/
110#define _Py_IMMORTAL_REFCNT UINT_MAX
111
112#else
113/*
114In 32 bit systems, an object will be marked as immortal by setting all of the
115lower 30 bits of the reference count field, which is equal to: 0x3FFFFFFF
116
117Using the lower 30 bits makes the value backwards compatible by allowing
118C-Extensions without the updated checks in Py_INCREF and Py_DECREF to safely
119increase and decrease the objects reference count. The object would lose its
120immortality, but the execution would still be correct.
121
122Reference count increases and decreases will first go through an immortality
123check by comparing the reference count field to the immortality reference count.
124*/
125#define _Py_IMMORTAL_REFCNT (UINT_MAX >> 2)
126#endif
127
128// Make all internal uses of PyObject_HEAD_INIT immortal while preserving the
129// C-API expectation that the refcnt will be set to 1.
130#ifdef Py_BUILD_CORE
131#define PyObject_HEAD_INIT(type) \
132 { \
133 _PyObject_EXTRA_INIT \
134 { _Py_IMMORTAL_REFCNT }, \
135 (type) \
136 },
137#else
138#define PyObject_HEAD_INIT(type) \
139 { \
140 _PyObject_EXTRA_INIT \
141 { 1 }, \
142 (type) \
143 },
144#endif /* Py_BUILD_CORE */
145
146#define PyVarObject_HEAD_INIT(type, size) \
147 { \
148 PyObject_HEAD_INIT(type) \
149 (size) \
150 },
151
152/* PyObject_VAR_HEAD defines the initial segment of all variable-size
153 * container objects. These end with a declaration of an array with 1
154 * element, but enough space is malloc'ed so that the array actually
155 * has room for ob_size elements. Note that ob_size is an element count,
156 * not necessarily a byte count.
157 */
158#define PyObject_VAR_HEAD PyVarObject ob_base;
159#define Py_INVALID_SIZE (Py_ssize_t)-1
160
161/* Nothing is actually declared to be a PyObject, but every pointer to
162 * a Python object can be cast to a PyObject*. This is inheritance built
163 * by hand. Similarly every pointer to a variable-size Python object can,
164 * in addition, be cast to PyVarObject*.
165 */
166struct _object {
167 _PyObject_HEAD_EXTRA
168
169#if (defined(__GNUC__) || defined(__clang__)) \
170 && !(defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L)
171 // On C99 and older, anonymous union is a GCC and clang extension
172 __extension__
173#endif
174#ifdef _MSC_VER
175 // Ignore MSC warning C4201: "nonstandard extension used:
176 // nameless struct/union"
177 __pragma(warning(push))
178 __pragma(warning(disable: 4201))
179#endif
180 union {
181 Py_ssize_t ob_refcnt;
182#if SIZEOF_VOID_P > 4
183 PY_UINT32_T ob_refcnt_split[2];
184#endif
185 };
186#ifdef _MSC_VER
187 __pragma(warning(pop))
188#endif
189
190 PyTypeObject *ob_type;
191};
192
193/* Cast argument to PyObject* type. */
194#define _PyObject_CAST(op) _Py_CAST(PyObject*, (op))
195
196typedef struct {
197 PyObject ob_base;
198 Py_ssize_t ob_size; /* Number of items in variable part */
199} PyVarObject;
200
201/* Cast argument to PyVarObject* type. */
202#define _PyVarObject_CAST(op) _Py_CAST(PyVarObject*, (op))
203
204
205// Test if the 'x' object is the 'y' object, the same as "x is y" in Python.
206PyAPI_FUNC(int) Py_Is(PyObject *x, PyObject *y);
207#define Py_Is(x, y) ((x) == (y))
208
209
210static inline Py_ssize_t Py_REFCNT(PyObject *ob) {
211 return ob->ob_refcnt;
212}
213#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
214# define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))
215#endif
216
217
218// bpo-39573: The Py_SET_TYPE() function must be used to set an object type.
219static inline PyTypeObject* Py_TYPE(PyObject *ob) {
220 return ob->ob_type;
221}
222#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
223# define Py_TYPE(ob) Py_TYPE(_PyObject_CAST(ob))
224#endif
225
226PyAPI_DATA(PyTypeObject) PyLong_Type;
227PyAPI_DATA(PyTypeObject) PyBool_Type;
228
229// bpo-39573: The Py_SET_SIZE() function must be used to set an object size.
230static inline Py_ssize_t Py_SIZE(PyObject *ob) {
231 assert(ob->ob_type != &PyLong_Type);
232 assert(ob->ob_type != &PyBool_Type);
233 return _PyVarObject_CAST(ob)->ob_size;
234}
235#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
236# define Py_SIZE(ob) Py_SIZE(_PyObject_CAST(ob))
237#endif
238
239static inline Py_ALWAYS_INLINE int _Py_IsImmortal(PyObject *op)
240{
241#if SIZEOF_VOID_P > 4
242 return _Py_CAST(PY_INT32_T, op->ob_refcnt) < 0;
243#else
244 return op->ob_refcnt == _Py_IMMORTAL_REFCNT;
245#endif
246}
247#define _Py_IsImmortal(op) _Py_IsImmortal(_PyObject_CAST(op))
248
249static inline int Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
250 return Py_TYPE(ob) == type;
251}
252#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
253# define Py_IS_TYPE(ob, type) Py_IS_TYPE(_PyObject_CAST(ob), (type))
254#endif
255
256
257static inline void Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
258 // This immortal check is for code that is unaware of immortal objects.
259 // The runtime tracks these objects and we should avoid as much
260 // as possible having extensions inadvertently change the refcnt
261 // of an immortalized object.
262 if (_Py_IsImmortal(ob)) {
263 return;
264 }
265 ob->ob_refcnt = refcnt;
266}
267#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
268# define Py_SET_REFCNT(ob, refcnt) Py_SET_REFCNT(_PyObject_CAST(ob), (refcnt))
269#endif
270
271
272static inline void Py_SET_TYPE(PyObject *ob, PyTypeObject *type) {
273 ob->ob_type = type;
274}
275#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
276# define Py_SET_TYPE(ob, type) Py_SET_TYPE(_PyObject_CAST(ob), type)
277#endif
278
279static inline void Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size) {
280 assert(ob->ob_base.ob_type != &PyLong_Type);
281 assert(ob->ob_base.ob_type != &PyBool_Type);
282 ob->ob_size = size;
283}
284#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
285# define Py_SET_SIZE(ob, size) Py_SET_SIZE(_PyVarObject_CAST(ob), (size))
286#endif
287
288
289/*
290Type objects contain a string containing the type name (to help somewhat
291in debugging), the allocation parameters (see PyObject_New() and
292PyObject_NewVar()),
293and methods for accessing objects of the type. Methods are optional, a
294nil pointer meaning that particular kind of access is not available for
295this type. The Py_DECREF() macro uses the tp_dealloc method without
296checking for a nil pointer; it should always be implemented except if
297the implementation can guarantee that the reference count will never
298reach zero (e.g., for statically allocated type objects).
299
300NB: the methods for certain type groups are now contained in separate
301method blocks.
302*/
303
304typedef PyObject * (*unaryfunc)(PyObject *);
305typedef PyObject * (*binaryfunc)(PyObject *, PyObject *);
306typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *);
307typedef int (*inquiry)(PyObject *);
308typedef Py_ssize_t (*lenfunc)(PyObject *);
309typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
310typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t);
311typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *);
312typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *);
313typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *);
314
315typedef int (*objobjproc)(PyObject *, PyObject *);
316typedef int (*visitproc)(PyObject *, void *);
317typedef int (*traverseproc)(PyObject *, visitproc, void *);
318
319
320typedef void (*freefunc)(void *);
321typedef void (*destructor)(PyObject *);
322typedef PyObject *(*getattrfunc)(PyObject *, char *);
323typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
324typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
325typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
326typedef PyObject *(*reprfunc)(PyObject *);
327typedef Py_hash_t (*hashfunc)(PyObject *);
328typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
329typedef PyObject *(*getiterfunc) (PyObject *);
330typedef PyObject *(*iternextfunc) (PyObject *);
331typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
332typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
333typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
334typedef PyObject *(*newfunc)(PyTypeObject *, PyObject *, PyObject *);
335typedef PyObject *(*allocfunc)(PyTypeObject *, Py_ssize_t);
336
337#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030c0000 // 3.12
338typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
339 size_t nargsf, PyObject *kwnames);
340#endif
341
342typedef struct{
343 int slot; /* slot id, see below */
344 void *pfunc; /* function pointer */
345} PyType_Slot;
346
347typedef struct{
348 const char* name;
349 int basicsize;
350 int itemsize;
351 unsigned int flags;
352 PyType_Slot *slots; /* terminated by slot==0. */
353} PyType_Spec;
354
355PyAPI_FUNC(PyObject*) PyType_FromSpec(PyType_Spec*);
356#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
357PyAPI_FUNC(PyObject*) PyType_FromSpecWithBases(PyType_Spec*, PyObject*);
358#endif
359#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03040000
360PyAPI_FUNC(void*) PyType_GetSlot(PyTypeObject*, int);
361#endif
362#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
363PyAPI_FUNC(PyObject*) PyType_FromModuleAndSpec(PyObject *, PyType_Spec *, PyObject *);
364PyAPI_FUNC(PyObject *) PyType_GetModule(PyTypeObject *);
365PyAPI_FUNC(void *) PyType_GetModuleState(PyTypeObject *);
366#endif
367#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030B0000
368PyAPI_FUNC(PyObject *) PyType_GetName(PyTypeObject *);
369PyAPI_FUNC(PyObject *) PyType_GetQualName(PyTypeObject *);
370#endif
371#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030C0000
372PyAPI_FUNC(PyObject *) PyType_FromMetaclass(PyTypeObject*, PyObject*, PyType_Spec*, PyObject*);
373PyAPI_FUNC(void *) PyObject_GetTypeData(PyObject *obj, PyTypeObject *cls);
374PyAPI_FUNC(Py_ssize_t) PyType_GetTypeDataSize(PyTypeObject *cls);
375#endif
376
377/* Generic type check */
378PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
379
380static inline int PyObject_TypeCheck(PyObject *ob, PyTypeObject *type) {
381 return Py_IS_TYPE(ob, type) || PyType_IsSubtype(Py_TYPE(ob), type);
382}
383#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
384# define PyObject_TypeCheck(ob, type) PyObject_TypeCheck(_PyObject_CAST(ob), (type))
385#endif
386
387PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
388PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
389PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */
390
391PyAPI_FUNC(unsigned long) PyType_GetFlags(PyTypeObject*);
392
393PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
394PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
395PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
396 PyObject *, PyObject *);
397PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
398PyAPI_FUNC(void) PyType_Modified(PyTypeObject *);
399
400/* Generic operations on objects */
401PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
402PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
403PyAPI_FUNC(PyObject *) PyObject_ASCII(PyObject *);
404PyAPI_FUNC(PyObject *) PyObject_Bytes(PyObject *);
405PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
406PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
407PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
408PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
409PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
410PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
411PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
412PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
413PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
414PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
415PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, PyObject *, PyObject *);
416#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
417PyAPI_FUNC(int) PyObject_GenericSetDict(PyObject *, PyObject *, void *);
418#endif
419PyAPI_FUNC(Py_hash_t) PyObject_Hash(PyObject *);
420PyAPI_FUNC(Py_hash_t) PyObject_HashNotImplemented(PyObject *);
421PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
422PyAPI_FUNC(int) PyObject_Not(PyObject *);
423PyAPI_FUNC(int) PyCallable_Check(PyObject *);
424PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
425
426/* PyObject_Dir(obj) acts like Python builtins.dir(obj), returning a
427 list of strings. PyObject_Dir(NULL) is like builtins.dir(),
428 returning the names of the current locals. In this case, if there are
429 no current locals, NULL is returned, and PyErr_Occurred() is false.
430*/
431PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
432
433/* Pickle support. */
434#ifndef Py_LIMITED_API
435PyAPI_FUNC(PyObject *) _PyObject_GetState(PyObject *);
436#endif
437
438
439/* Helpers for printing recursive container types */
440PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
441PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
442
443/* Flag bits for printing: */
444#define Py_PRINT_RAW 1 /* No string quotes etc. */
445
446/*
447Type flags (tp_flags)
448
449These flags are used to change expected features and behavior for a
450particular type.
451
452Arbitration of the flag bit positions will need to be coordinated among
453all extension writers who publicly release their extensions (this will
454be fewer than you might expect!).
455
456Most flags were removed as of Python 3.0 to make room for new flags. (Some
457flags are not for backwards compatibility but to indicate the presence of an
458optional feature; these flags remain of course.)
459
460Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
461
462Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
463given type object has a specified feature.
464*/
465
466#ifndef Py_LIMITED_API
467
468/* Track types initialized using _PyStaticType_InitBuiltin(). */
469#define _Py_TPFLAGS_STATIC_BUILTIN (1 << 1)
470
471/* Placement of weakref pointers are managed by the VM, not by the type.
472 * The VM will automatically set tp_weaklistoffset.
473 */
474#define Py_TPFLAGS_MANAGED_WEAKREF (1 << 3)
475
476/* Placement of dict (and values) pointers are managed by the VM, not by the type.
477 * The VM will automatically set tp_dictoffset.
478 */
479#define Py_TPFLAGS_MANAGED_DICT (1 << 4)
480
481#define Py_TPFLAGS_PREHEADER (Py_TPFLAGS_MANAGED_WEAKREF | Py_TPFLAGS_MANAGED_DICT)
482
483/* Set if instances of the type object are treated as sequences for pattern matching */
484#define Py_TPFLAGS_SEQUENCE (1 << 5)
485/* Set if instances of the type object are treated as mappings for pattern matching */
486#define Py_TPFLAGS_MAPPING (1 << 6)
487#endif
488
489/* Disallow creating instances of the type: set tp_new to NULL and don't create
490 * the "__new__" key in the type dictionary. */
491#define Py_TPFLAGS_DISALLOW_INSTANTIATION (1UL << 7)
492
493/* Set if the type object is immutable: type attributes cannot be set nor deleted */
494#define Py_TPFLAGS_IMMUTABLETYPE (1UL << 8)
495
496/* Set if the type object is dynamically allocated */
497#define Py_TPFLAGS_HEAPTYPE (1UL << 9)
498
499/* Set if the type allows subclassing */
500#define Py_TPFLAGS_BASETYPE (1UL << 10)
501
502/* Set if the type implements the vectorcall protocol (PEP 590) */
503#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030C0000
504#define Py_TPFLAGS_HAVE_VECTORCALL (1UL << 11)
505#ifndef Py_LIMITED_API
506// Backwards compatibility alias for API that was provisional in Python 3.8
507#define _Py_TPFLAGS_HAVE_VECTORCALL Py_TPFLAGS_HAVE_VECTORCALL
508#endif
509#endif
510
511/* Set if the type is 'ready' -- fully initialized */
512#define Py_TPFLAGS_READY (1UL << 12)
513
514/* Set while the type is being 'readied', to prevent recursive ready calls */
515#define Py_TPFLAGS_READYING (1UL << 13)
516
517/* Objects support garbage collection (see objimpl.h) */
518#define Py_TPFLAGS_HAVE_GC (1UL << 14)
519
520/* These two bits are preserved for Stackless Python, next after this is 17 */
521#ifdef STACKLESS
522#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3UL << 15)
523#else
524#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0
525#endif
526
527/* Objects behave like an unbound method */
528#define Py_TPFLAGS_METHOD_DESCRIPTOR (1UL << 17)
529
530/* Object has up-to-date type attribute cache */
531#define Py_TPFLAGS_VALID_VERSION_TAG (1UL << 19)
532
533/* Type is abstract and cannot be instantiated */
534#define Py_TPFLAGS_IS_ABSTRACT (1UL << 20)
535
536// This undocumented flag gives certain built-ins their unique pattern-matching
537// behavior, which allows a single positional subpattern to match against the
538// subject itself (rather than a mapped attribute on it):
539#define _Py_TPFLAGS_MATCH_SELF (1UL << 22)
540
541/* Items (ob_size*tp_itemsize) are found at the end of an instance's memory */
542#define Py_TPFLAGS_ITEMS_AT_END (1UL << 23)
543
544/* These flags are used to determine if a type is a subclass. */
545#define Py_TPFLAGS_LONG_SUBCLASS (1UL << 24)
546#define Py_TPFLAGS_LIST_SUBCLASS (1UL << 25)
547#define Py_TPFLAGS_TUPLE_SUBCLASS (1UL << 26)
548#define Py_TPFLAGS_BYTES_SUBCLASS (1UL << 27)
549#define Py_TPFLAGS_UNICODE_SUBCLASS (1UL << 28)
550#define Py_TPFLAGS_DICT_SUBCLASS (1UL << 29)
551#define Py_TPFLAGS_BASE_EXC_SUBCLASS (1UL << 30)
552#define Py_TPFLAGS_TYPE_SUBCLASS (1UL << 31)
553
554#define Py_TPFLAGS_DEFAULT ( \
555 Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \
556 0)
557
558/* NOTE: Some of the following flags reuse lower bits (removed as part of the
559 * Python 3.0 transition). */
560
561/* The following flags are kept for compatibility; in previous
562 * versions they indicated presence of newer tp_* fields on the
563 * type struct.
564 * Starting with 3.8, binary compatibility of C extensions across
565 * feature releases of Python is not supported anymore (except when
566 * using the stable ABI, in which all classes are created dynamically,
567 * using the interpreter's memory layout.)
568 * Note that older extensions using the stable ABI set these flags,
569 * so the bits must not be repurposed.
570 */
571#define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0)
572#define Py_TPFLAGS_HAVE_VERSION_TAG (1UL << 18)
573
574
575/*
576The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
577reference counts. Py_DECREF calls the object's deallocator function when
578the refcount falls to 0; for
579objects that don't contain references to other objects or heap memory
580this can be the standard function free(). Both macros can be used
581wherever a void expression is allowed. The argument must not be a
582NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
583The macro _Py_NewReference(op) initialize reference counts to 1, and
584in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
585bookkeeping appropriate to the special build.
586
587We assume that the reference count field can never overflow; this can
588be proven when the size of the field is the same as the pointer size, so
589we ignore the possibility. Provided a C int is at least 32 bits (which
590is implicitly assumed in many parts of this code), that's enough for
591about 2**31 references to an object.
592
593XXX The following became out of date in Python 2.2, but I'm not sure
594XXX what the full truth is now. Certainly, heap-allocated type objects
595XXX can and should be deallocated.
596Type objects should never be deallocated; the type pointer in an object
597is not considered to be a reference to the type object, to save
598complications in the deallocation function. (This is actually a
599decision that's up to the implementer of each new type so if you want,
600you can count such references to the type object.)
601*/
602
603#if defined(Py_REF_DEBUG) && !defined(Py_LIMITED_API)
604PyAPI_FUNC(void) _Py_NegativeRefcount(const char *filename, int lineno,
605 PyObject *op);
606PyAPI_FUNC(void) _Py_INCREF_IncRefTotal(void);
607PyAPI_FUNC(void) _Py_DECREF_DecRefTotal(void);
608#endif // Py_REF_DEBUG && !Py_LIMITED_API
609
610PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
611
612/*
613These are provided as conveniences to Python runtime embedders, so that
614they can have object code that is not dependent on Python compilation flags.
615*/
616PyAPI_FUNC(void) Py_IncRef(PyObject *);
617PyAPI_FUNC(void) Py_DecRef(PyObject *);
618
619// Similar to Py_IncRef() and Py_DecRef() but the argument must be non-NULL.
620// Private functions used by Py_INCREF() and Py_DECREF().
621PyAPI_FUNC(void) _Py_IncRef(PyObject *);
622PyAPI_FUNC(void) _Py_DecRef(PyObject *);
623
624static inline Py_ALWAYS_INLINE void Py_INCREF(PyObject *op)
625{
626#if defined(Py_LIMITED_API) && (Py_LIMITED_API+0 >= 0x030c0000 || defined(Py_REF_DEBUG))
627 // Stable ABI implements Py_INCREF() as a function call on limited C API
628 // version 3.12 and newer, and on Python built in debug mode. _Py_IncRef()
629 // was added to Python 3.10.0a7, use Py_IncRef() on older Python versions.
630 // Py_IncRef() accepts NULL whereas _Py_IncRef() doesn't.
631# if Py_LIMITED_API+0 >= 0x030a00A7
632 _Py_IncRef(op);
633# else
634 Py_IncRef(op);
635# endif
636#else
637 // Non-limited C API and limited C API for Python 3.9 and older access
638 // directly PyObject.ob_refcnt.
639#if SIZEOF_VOID_P > 4
640 // Portable saturated add, branching on the carry flag and set low bits
641 PY_UINT32_T cur_refcnt = op->ob_refcnt_split[PY_BIG_ENDIAN];
642 PY_UINT32_T new_refcnt = cur_refcnt + 1;
643 if (new_refcnt == 0) {
644 return;
645 }
646 op->ob_refcnt_split[PY_BIG_ENDIAN] = new_refcnt;
647#else
648 // Explicitly check immortality against the immortal value
649 if (_Py_IsImmortal(op)) {
650 return;
651 }
652 op->ob_refcnt++;
653#endif
654 _Py_INCREF_STAT_INC();
655#ifdef Py_REF_DEBUG
656 _Py_INCREF_IncRefTotal();
657#endif
658#endif
659}
660#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
661# define Py_INCREF(op) Py_INCREF(_PyObject_CAST(op))
662#endif
663
664#if defined(Py_LIMITED_API) && (Py_LIMITED_API+0 >= 0x030c0000 || defined(Py_REF_DEBUG))
665// Stable ABI implements Py_DECREF() as a function call on limited C API
666// version 3.12 and newer, and on Python built in debug mode. _Py_DecRef() was
667// added to Python 3.10.0a7, use Py_DecRef() on older Python versions.
668// Py_DecRef() accepts NULL whereas _Py_IncRef() doesn't.
669static inline void Py_DECREF(PyObject *op) {
670# if Py_LIMITED_API+0 >= 0x030a00A7
671 _Py_DecRef(op);
672# else
673 Py_DecRef(op);
674# endif
675}
676#define Py_DECREF(op) Py_DECREF(_PyObject_CAST(op))
677
678#elif defined(Py_REF_DEBUG)
679static inline void Py_DECREF(const char *filename, int lineno, PyObject *op)
680{
681 if (op->ob_refcnt <= 0) {
682 _Py_NegativeRefcount(filename, lineno, op);
683 }
684 if (_Py_IsImmortal(op)) {
685 return;
686 }
687 _Py_DECREF_STAT_INC();
688 _Py_DECREF_DecRefTotal();
689 if (--op->ob_refcnt == 0) {
690 _Py_Dealloc(op);
691 }
692}
693#define Py_DECREF(op) Py_DECREF(__FILE__, __LINE__, _PyObject_CAST(op))
694
695#else
696static inline Py_ALWAYS_INLINE void Py_DECREF(PyObject *op)
697{
698 // Non-limited C API and limited C API for Python 3.9 and older access
699 // directly PyObject.ob_refcnt.
700 if (_Py_IsImmortal(op)) {
701 return;
702 }
703 _Py_DECREF_STAT_INC();
704 if (--op->ob_refcnt == 0) {
705 _Py_Dealloc(op);
706 }
707}
708#define Py_DECREF(op) Py_DECREF(_PyObject_CAST(op))
709#endif
710
711
712/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
713 * and tp_dealloc implementations.
714 *
715 * Note that "the obvious" code can be deadly:
716 *
717 * Py_XDECREF(op);
718 * op = NULL;
719 *
720 * Typically, `op` is something like self->containee, and `self` is done
721 * using its `containee` member. In the code sequence above, suppose
722 * `containee` is non-NULL with a refcount of 1. Its refcount falls to
723 * 0 on the first line, which can trigger an arbitrary amount of code,
724 * possibly including finalizers (like __del__ methods or weakref callbacks)
725 * coded in Python, which in turn can release the GIL and allow other threads
726 * to run, etc. Such code may even invoke methods of `self` again, or cause
727 * cyclic gc to trigger, but-- oops! --self->containee still points to the
728 * object being torn down, and it may be in an insane state while being torn
729 * down. This has in fact been a rich historic source of miserable (rare &
730 * hard-to-diagnose) segfaulting (and other) bugs.
731 *
732 * The safe way is:
733 *
734 * Py_CLEAR(op);
735 *
736 * That arranges to set `op` to NULL _before_ decref'ing, so that any code
737 * triggered as a side-effect of `op` getting torn down no longer believes
738 * `op` points to a valid object.
739 *
740 * There are cases where it's safe to use the naive code, but they're brittle.
741 * For example, if `op` points to a Python integer, you know that destroying
742 * one of those can't cause problems -- but in part that relies on that
743 * Python integers aren't currently weakly referencable. Best practice is
744 * to use Py_CLEAR() even if you can't think of a reason for why you need to.
745 *
746 * gh-98724: Use a temporary variable to only evaluate the macro argument once,
747 * to avoid the duplication of side effects if the argument has side effects.
748 *
749 * gh-99701: If the PyObject* type is used with casting arguments to PyObject*,
750 * the code can be miscompiled with strict aliasing because of type punning.
751 * With strict aliasing, a compiler considers that two pointers of different
752 * types cannot read or write the same memory which enables optimization
753 * opportunities.
754 *
755 * If available, use _Py_TYPEOF() to use the 'op' type for temporary variables,
756 * and so avoid type punning. Otherwise, use memcpy() which causes type erasure
757 * and so prevents the compiler to reuse an old cached 'op' value after
758 * Py_CLEAR().
759 */
760#ifdef _Py_TYPEOF
761#define Py_CLEAR(op) \
762 do { \
763 _Py_TYPEOF(op)* _tmp_op_ptr = &(op); \
764 _Py_TYPEOF(op) _tmp_old_op = (*_tmp_op_ptr); \
765 if (_tmp_old_op != NULL) { \
766 *_tmp_op_ptr = _Py_NULL; \
767 Py_DECREF(_tmp_old_op); \
768 } \
769 } while (0)
770#else
771#define Py_CLEAR(op) \
772 do { \
773 PyObject **_tmp_op_ptr = _Py_CAST(PyObject**, &(op)); \
774 PyObject *_tmp_old_op = (*_tmp_op_ptr); \
775 if (_tmp_old_op != NULL) { \
776 PyObject *_null_ptr = _Py_NULL; \
777 memcpy(_tmp_op_ptr, &_null_ptr, sizeof(PyObject*)); \
778 Py_DECREF(_tmp_old_op); \
779 } \
780 } while (0)
781#endif
782
783
784/* Function to use in case the object pointer can be NULL: */
785static inline void Py_XINCREF(PyObject *op)
786{
787 if (op != _Py_NULL) {
788 Py_INCREF(op);
789 }
790}
791#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
792# define Py_XINCREF(op) Py_XINCREF(_PyObject_CAST(op))
793#endif
794
795static inline void Py_XDECREF(PyObject *op)
796{
797 if (op != _Py_NULL) {
798 Py_DECREF(op);
799 }
800}
801#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
802# define Py_XDECREF(op) Py_XDECREF(_PyObject_CAST(op))
803#endif
804
805// Create a new strong reference to an object:
806// increment the reference count of the object and return the object.
807PyAPI_FUNC(PyObject*) Py_NewRef(PyObject *obj);
808
809// Similar to Py_NewRef(), but the object can be NULL.
810PyAPI_FUNC(PyObject*) Py_XNewRef(PyObject *obj);
811
812static inline PyObject* _Py_NewRef(PyObject *obj)
813{
814 Py_INCREF(obj);
815 return obj;
816}
817
818static inline PyObject* _Py_XNewRef(PyObject *obj)
819{
820 Py_XINCREF(obj);
821 return obj;
822}
823
824// Py_NewRef() and Py_XNewRef() are exported as functions for the stable ABI.
825// Names overridden with macros by static inline functions for best
826// performances.
827#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
828# define Py_NewRef(obj) _Py_NewRef(_PyObject_CAST(obj))
829# define Py_XNewRef(obj) _Py_XNewRef(_PyObject_CAST(obj))
830#else
831# define Py_NewRef(obj) _Py_NewRef(obj)
832# define Py_XNewRef(obj) _Py_XNewRef(obj)
833#endif
834
835
836/*
837_Py_NoneStruct is an object of undefined type which can be used in contexts
838where NULL (nil) is not suitable (since NULL often means 'error').
839
840Don't forget to apply Py_INCREF() when returning this value!!!
841*/
842PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
843#define Py_None (&_Py_NoneStruct)
844
845// Test if an object is the None singleton, the same as "x is None" in Python.
846PyAPI_FUNC(int) Py_IsNone(PyObject *x);
847#define Py_IsNone(x) Py_Is((x), Py_None)
848
849/* Macro for returning Py_None from a function */
850#define Py_RETURN_NONE return Py_None
851
852/*
853Py_NotImplemented is a singleton used to signal that an operation is
854not implemented for a given type combination.
855*/
856PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
857#define Py_NotImplemented (&_Py_NotImplementedStruct)
858
859/* Macro for returning Py_NotImplemented from a function */
860#define Py_RETURN_NOTIMPLEMENTED return Py_NotImplemented
861
862/* Rich comparison opcodes */
863#define Py_LT 0
864#define Py_LE 1
865#define Py_EQ 2
866#define Py_NE 3
867#define Py_GT 4
868#define Py_GE 5
869
870#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030A0000
871/* Result of calling PyIter_Send */
872typedef enum {
873 PYGEN_RETURN = 0,
874 PYGEN_ERROR = -1,
875 PYGEN_NEXT = 1,
876} PySendResult;
877#endif
878
879/*
880 * Macro for implementing rich comparisons
881 *
882 * Needs to be a macro because any C-comparable type can be used.
883 */
884#define Py_RETURN_RICHCOMPARE(val1, val2, op) \
885 do { \
886 switch (op) { \
887 case Py_EQ: if ((val1) == (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
888 case Py_NE: if ((val1) != (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
889 case Py_LT: if ((val1) < (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
890 case Py_GT: if ((val1) > (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
891 case Py_LE: if ((val1) <= (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
892 case Py_GE: if ((val1) >= (val2)) Py_RETURN_TRUE; Py_RETURN_FALSE; \
893 default: \
894 Py_UNREACHABLE(); \
895 } \
896 } while (0)
897
898
899/*
900More conventions
901================
902
903Argument Checking
904-----------------
905
906Functions that take objects as arguments normally don't check for nil
907arguments, but they do check the type of the argument, and return an
908error if the function doesn't apply to the type.
909
910Failure Modes
911-------------
912
913Functions may fail for a variety of reasons, including running out of
914memory. This is communicated to the caller in two ways: an error string
915is set (see errors.h), and the function result differs: functions that
916normally return a pointer return NULL for failure, functions returning
917an integer return -1 (which could be a legal return value too!), and
918other functions return 0 for success and -1 for failure.
919Callers should always check for errors before using the result. If
920an error was set, the caller must either explicitly clear it, or pass
921the error on to its caller.
922
923Reference Counts
924----------------
925
926It takes a while to get used to the proper usage of reference counts.
927
928Functions that create an object set the reference count to 1; such new
929objects must be stored somewhere or destroyed again with Py_DECREF().
930Some functions that 'store' objects, such as PyTuple_SetItem() and
931PyList_SetItem(),
932don't increment the reference count of the object, since the most
933frequent use is to store a fresh object. Functions that 'retrieve'
934objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
935don't increment
936the reference count, since most frequently the object is only looked at
937quickly. Thus, to retrieve an object and store it again, the caller
938must call Py_INCREF() explicitly.
939
940NOTE: functions that 'consume' a reference count, like
941PyList_SetItem(), consume the reference even if the object wasn't
942successfully stored, to simplify error handling.
943
944It seems attractive to make other functions that take an object as
945argument consume a reference count; however, this may quickly get
946confusing (even the current practice is already confusing). Consider
947it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
948times.
949*/
950
951#ifndef Py_LIMITED_API
952# define Py_CPYTHON_OBJECT_H
953# include "cpython/object.h"
954# undef Py_CPYTHON_OBJECT_H
955#endif
956
957
958static inline int
959PyType_HasFeature(PyTypeObject *type, unsigned long feature)
960{
961 unsigned long flags;
962#ifdef Py_LIMITED_API
963 // PyTypeObject is opaque in the limited C API
964 flags = PyType_GetFlags(type);
965#else
966 flags = type->tp_flags;
967#endif
968 return ((flags & feature) != 0);
969}
970
971#define PyType_FastSubclass(type, flag) PyType_HasFeature((type), (flag))
972
973static inline int PyType_Check(PyObject *op) {
974 return PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS);
975}
976#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
977# define PyType_Check(op) PyType_Check(_PyObject_CAST(op))
978#endif
979
980#define _PyType_CAST(op) \
981 (assert(PyType_Check(op)), _Py_CAST(PyTypeObject*, (op)))
982
983static inline int PyType_CheckExact(PyObject *op) {
984 return Py_IS_TYPE(op, &PyType_Type);
985}
986#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
987# define PyType_CheckExact(op) PyType_CheckExact(_PyObject_CAST(op))
988#endif
989
990#ifdef __cplusplus
991}
992#endif
993#endif // !Py_OBJECT_H
994

source code of include/python3.12/object.h