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/* Py_DEBUG implies Py_TRACE_REFS. */
55#if defined(Py_DEBUG) && !defined(Py_TRACE_REFS)
56#define Py_TRACE_REFS
57#endif
58
59/* Py_TRACE_REFS implies Py_REF_DEBUG. */
60#if defined(Py_TRACE_REFS) && !defined(Py_REF_DEBUG)
61#define Py_REF_DEBUG
62#endif
63
64#ifdef Py_TRACE_REFS
65/* Define pointers to support a doubly-linked list of all live heap objects. */
66#define _PyObject_HEAD_EXTRA \
67 struct _object *_ob_next; \
68 struct _object *_ob_prev;
69
70#define _PyObject_EXTRA_INIT 0, 0,
71
72#else
73#define _PyObject_HEAD_EXTRA
74#define _PyObject_EXTRA_INIT
75#endif
76
77/* PyObject_HEAD defines the initial segment of every PyObject. */
78#define PyObject_HEAD \
79 _PyObject_HEAD_EXTRA \
80 Py_ssize_t ob_refcnt; \
81 struct _typeobject *ob_type;
82
83#define PyObject_HEAD_INIT(type) \
84 _PyObject_EXTRA_INIT \
85 1, type,
86
87#define PyVarObject_HEAD_INIT(type, size) \
88 PyObject_HEAD_INIT(type) size,
89
90/* PyObject_VAR_HEAD defines the initial segment of all variable-size
91 * container objects. These end with a declaration of an array with 1
92 * element, but enough space is malloc'ed so that the array actually
93 * has room for ob_size elements. Note that ob_size is an element count,
94 * not necessarily a byte count.
95 */
96#define PyObject_VAR_HEAD \
97 PyObject_HEAD \
98 Py_ssize_t ob_size; /* Number of items in variable part */
99#define Py_INVALID_SIZE (Py_ssize_t)-1
100
101/* Nothing is actually declared to be a PyObject, but every pointer to
102 * a Python object can be cast to a PyObject*. This is inheritance built
103 * by hand. Similarly every pointer to a variable-size Python object can,
104 * in addition, be cast to PyVarObject*.
105 */
106typedef struct _object {
107 PyObject_HEAD
108} PyObject;
109
110typedef struct {
111 PyObject_VAR_HEAD
112} PyVarObject;
113
114#define Py_REFCNT(ob) (((PyObject*)(ob))->ob_refcnt)
115#define Py_TYPE(ob) (((PyObject*)(ob))->ob_type)
116#define Py_SIZE(ob) (((PyVarObject*)(ob))->ob_size)
117
118/*
119Type objects contain a string containing the type name (to help somewhat
120in debugging), the allocation parameters (see PyObject_New() and
121PyObject_NewVar()),
122and methods for accessing objects of the type. Methods are optional, a
123nil pointer meaning that particular kind of access is not available for
124this type. The Py_DECREF() macro uses the tp_dealloc method without
125checking for a nil pointer; it should always be implemented except if
126the implementation can guarantee that the reference count will never
127reach zero (e.g., for statically allocated type objects).
128
129NB: the methods for certain type groups are now contained in separate
130method blocks.
131*/
132
133typedef PyObject * (*unaryfunc)(PyObject *);
134typedef PyObject * (*binaryfunc)(PyObject *, PyObject *);
135typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *);
136typedef int (*inquiry)(PyObject *);
137typedef Py_ssize_t (*lenfunc)(PyObject *);
138typedef int (*coercion)(PyObject **, PyObject **);
139typedef PyObject *(*intargfunc)(PyObject *, int) Py_DEPRECATED(2.5);
140typedef PyObject *(*intintargfunc)(PyObject *, int, int) Py_DEPRECATED(2.5);
141typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
142typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t);
143typedef int(*intobjargproc)(PyObject *, int, PyObject *);
144typedef int(*intintobjargproc)(PyObject *, int, int, PyObject *);
145typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *);
146typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *);
147typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *);
148
149
150
151/* int-based buffer interface */
152typedef int (*getreadbufferproc)(PyObject *, int, void **);
153typedef int (*getwritebufferproc)(PyObject *, int, void **);
154typedef int (*getsegcountproc)(PyObject *, int *);
155typedef int (*getcharbufferproc)(PyObject *, int, char **);
156/* ssize_t-based buffer interface */
157typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **);
158typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **);
159typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *);
160typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **);
161
162
163/* Py3k buffer interface */
164typedef struct bufferinfo {
165 void *buf;
166 PyObject *obj; /* owned reference */
167 Py_ssize_t len;
168 Py_ssize_t itemsize; /* This is Py_ssize_t so it can be
169 pointed to by strides in simple case.*/
170 int readonly;
171 int ndim;
172 char *format;
173 Py_ssize_t *shape;
174 Py_ssize_t *strides;
175 Py_ssize_t *suboffsets;
176 Py_ssize_t smalltable[2]; /* static store for shape and strides of
177 mono-dimensional buffers. */
178 void *internal;
179} Py_buffer;
180
181typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
182typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
183
184 /* Flags for getting buffers */
185#define PyBUF_SIMPLE 0
186#define PyBUF_WRITABLE 0x0001
187/* we used to include an E, backwards compatible alias */
188#define PyBUF_WRITEABLE PyBUF_WRITABLE
189#define PyBUF_FORMAT 0x0004
190#define PyBUF_ND 0x0008
191#define PyBUF_STRIDES (0x0010 | PyBUF_ND)
192#define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES)
193#define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES)
194#define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES)
195#define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES)
196
197#define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE)
198#define PyBUF_CONTIG_RO (PyBUF_ND)
199
200#define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE)
201#define PyBUF_STRIDED_RO (PyBUF_STRIDES)
202
203#define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT)
204#define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT)
205
206#define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT)
207#define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT)
208
209
210#define PyBUF_READ 0x100
211#define PyBUF_WRITE 0x200
212#define PyBUF_SHADOW 0x400
213/* end Py3k buffer interface */
214
215typedef int (*objobjproc)(PyObject *, PyObject *);
216typedef int (*visitproc)(PyObject *, void *);
217typedef int (*traverseproc)(PyObject *, visitproc, void *);
218
219typedef struct {
220 /* For numbers without flag bit Py_TPFLAGS_CHECKTYPES set, all
221 arguments are guaranteed to be of the object's type (modulo
222 coercion hacks -- i.e. if the type's coercion function
223 returns other types, then these are allowed as well). Numbers that
224 have the Py_TPFLAGS_CHECKTYPES flag bit set should check *both*
225 arguments for proper type and implement the necessary conversions
226 in the slot functions themselves. */
227
228 binaryfunc nb_add;
229 binaryfunc nb_subtract;
230 binaryfunc nb_multiply;
231 binaryfunc nb_divide;
232 binaryfunc nb_remainder;
233 binaryfunc nb_divmod;
234 ternaryfunc nb_power;
235 unaryfunc nb_negative;
236 unaryfunc nb_positive;
237 unaryfunc nb_absolute;
238 inquiry nb_nonzero;
239 unaryfunc nb_invert;
240 binaryfunc nb_lshift;
241 binaryfunc nb_rshift;
242 binaryfunc nb_and;
243 binaryfunc nb_xor;
244 binaryfunc nb_or;
245 coercion nb_coerce;
246 unaryfunc nb_int;
247 unaryfunc nb_long;
248 unaryfunc nb_float;
249 unaryfunc nb_oct;
250 unaryfunc nb_hex;
251 /* Added in release 2.0 */
252 binaryfunc nb_inplace_add;
253 binaryfunc nb_inplace_subtract;
254 binaryfunc nb_inplace_multiply;
255 binaryfunc nb_inplace_divide;
256 binaryfunc nb_inplace_remainder;
257 ternaryfunc nb_inplace_power;
258 binaryfunc nb_inplace_lshift;
259 binaryfunc nb_inplace_rshift;
260 binaryfunc nb_inplace_and;
261 binaryfunc nb_inplace_xor;
262 binaryfunc nb_inplace_or;
263
264 /* Added in release 2.2 */
265 /* The following require the Py_TPFLAGS_HAVE_CLASS flag */
266 binaryfunc nb_floor_divide;
267 binaryfunc nb_true_divide;
268 binaryfunc nb_inplace_floor_divide;
269 binaryfunc nb_inplace_true_divide;
270
271 /* Added in release 2.5 */
272 unaryfunc nb_index;
273} PyNumberMethods;
274
275typedef struct {
276 lenfunc sq_length;
277 binaryfunc sq_concat;
278 ssizeargfunc sq_repeat;
279 ssizeargfunc sq_item;
280 ssizessizeargfunc sq_slice;
281 ssizeobjargproc sq_ass_item;
282 ssizessizeobjargproc sq_ass_slice;
283 objobjproc sq_contains;
284 /* Added in release 2.0 */
285 binaryfunc sq_inplace_concat;
286 ssizeargfunc sq_inplace_repeat;
287} PySequenceMethods;
288
289typedef struct {
290 lenfunc mp_length;
291 binaryfunc mp_subscript;
292 objobjargproc mp_ass_subscript;
293} PyMappingMethods;
294
295typedef struct {
296 readbufferproc bf_getreadbuffer;
297 writebufferproc bf_getwritebuffer;
298 segcountproc bf_getsegcount;
299 charbufferproc bf_getcharbuffer;
300 getbufferproc bf_getbuffer;
301 releasebufferproc bf_releasebuffer;
302} PyBufferProcs;
303
304
305typedef void (*freefunc)(void *);
306typedef void (*destructor)(PyObject *);
307typedef int (*printfunc)(PyObject *, FILE *, int);
308typedef PyObject *(*getattrfunc)(PyObject *, char *);
309typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
310typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
311typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
312typedef int (*cmpfunc)(PyObject *, PyObject *);
313typedef PyObject *(*reprfunc)(PyObject *);
314typedef long (*hashfunc)(PyObject *);
315typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
316typedef PyObject *(*getiterfunc) (PyObject *);
317typedef PyObject *(*iternextfunc) (PyObject *);
318typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
319typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
320typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
321typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *);
322typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t);
323
324typedef struct _typeobject {
325 PyObject_VAR_HEAD
326 const char *tp_name; /* For printing, in format "<module>.<name>" */
327 Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
328
329 /* Methods to implement standard operations */
330
331 destructor tp_dealloc;
332 printfunc tp_print;
333 getattrfunc tp_getattr;
334 setattrfunc tp_setattr;
335 cmpfunc tp_compare;
336 reprfunc tp_repr;
337
338 /* Method suites for standard classes */
339
340 PyNumberMethods *tp_as_number;
341 PySequenceMethods *tp_as_sequence;
342 PyMappingMethods *tp_as_mapping;
343
344 /* More standard operations (here for binary compatibility) */
345
346 hashfunc tp_hash;
347 ternaryfunc tp_call;
348 reprfunc tp_str;
349 getattrofunc tp_getattro;
350 setattrofunc tp_setattro;
351
352 /* Functions to access object as input/output buffer */
353 PyBufferProcs *tp_as_buffer;
354
355 /* Flags to define presence of optional/expanded features */
356 long tp_flags;
357
358 const char *tp_doc; /* Documentation string */
359
360 /* Assigned meaning in release 2.0 */
361 /* call function for all accessible objects */
362 traverseproc tp_traverse;
363
364 /* delete references to contained objects */
365 inquiry tp_clear;
366
367 /* Assigned meaning in release 2.1 */
368 /* rich comparisons */
369 richcmpfunc tp_richcompare;
370
371 /* weak reference enabler */
372 Py_ssize_t tp_weaklistoffset;
373
374 /* Added in release 2.2 */
375 /* Iterators */
376 getiterfunc tp_iter;
377 iternextfunc tp_iternext;
378
379 /* Attribute descriptor and subclassing stuff */
380 struct PyMethodDef *tp_methods;
381 struct PyMemberDef *tp_members;
382 struct PyGetSetDef *tp_getset;
383 struct _typeobject *tp_base;
384 PyObject *tp_dict;
385 descrgetfunc tp_descr_get;
386 descrsetfunc tp_descr_set;
387 Py_ssize_t tp_dictoffset;
388 initproc tp_init;
389 allocfunc tp_alloc;
390 newfunc tp_new;
391 freefunc tp_free; /* Low-level free-memory routine */
392 inquiry tp_is_gc; /* For PyObject_IS_GC */
393 PyObject *tp_bases;
394 PyObject *tp_mro; /* method resolution order */
395 PyObject *tp_cache;
396 PyObject *tp_subclasses;
397 PyObject *tp_weaklist;
398 destructor tp_del;
399
400 /* Type attribute cache version tag. Added in version 2.6 */
401 unsigned int tp_version_tag;
402
403#ifdef COUNT_ALLOCS
404 /* these must be last and never explicitly initialized */
405 Py_ssize_t tp_allocs;
406 Py_ssize_t tp_frees;
407 Py_ssize_t tp_maxalloc;
408 struct _typeobject *tp_prev;
409 struct _typeobject *tp_next;
410#endif
411} PyTypeObject;
412
413
414/* The *real* layout of a type object when allocated on the heap */
415typedef struct _heaptypeobject {
416 /* Note: there's a dependency on the order of these members
417 in slotptr() in typeobject.c . */
418 PyTypeObject ht_type;
419 PyNumberMethods as_number;
420 PyMappingMethods as_mapping;
421 PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
422 so that the mapping wins when both
423 the mapping and the sequence define
424 a given operator (e.g. __getitem__).
425 see add_operators() in typeobject.c . */
426 PyBufferProcs as_buffer;
427 PyObject *ht_name, *ht_slots;
428 /* here are optional user slots, followed by the members. */
429} PyHeapTypeObject;
430
431/* access macro to the members which are floating "behind" the object */
432#define PyHeapType_GET_MEMBERS(etype) \
433 ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize))
434
435
436/* Generic type check */
437PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
438#define PyObject_TypeCheck(ob, tp) \
439 (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp)))
440
441PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
442PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
443PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */
444
445#define PyType_Check(op) \
446 PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS)
447#define PyType_CheckExact(op) (Py_TYPE(op) == &PyType_Type)
448
449PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
450PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
451PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
452 PyObject *, PyObject *);
453PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
454PyAPI_FUNC(PyObject *) _PyObject_LookupSpecial(PyObject *, char *, PyObject **);
455PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
456PyAPI_FUNC(void) PyType_Modified(PyTypeObject *);
457
458/* Generic operations on objects */
459PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
460PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
461PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
462PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *);
463PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
464#define PyObject_Bytes PyObject_Str
465#ifdef Py_USING_UNICODE
466PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *);
467#endif
468PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *);
469PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
470PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
471PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
472PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
473PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
474PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
475PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
476PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
477PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *);
478PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
479PyAPI_FUNC(PyObject *) _PyObject_NextNotImplemented(PyObject *);
480PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
481PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
482 PyObject *, PyObject *);
483PyAPI_FUNC(long) PyObject_Hash(PyObject *);
484PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *);
485PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
486PyAPI_FUNC(int) PyObject_Not(PyObject *);
487PyAPI_FUNC(int) PyCallable_Check(PyObject *);
488PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **);
489PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **);
490
491PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
492
493/* A slot function whose address we need to compare */
494extern int _PyObject_SlotCompare(PyObject *, PyObject *);
495/* Same as PyObject_Generic{Get,Set}Attr, but passing the attributes
496 dict as the last parameter. */
497PyAPI_FUNC(PyObject *)
498_PyObject_GenericGetAttrWithDict(PyObject *, PyObject *, PyObject *);
499PyAPI_FUNC(int)
500_PyObject_GenericSetAttrWithDict(PyObject *, PyObject *,
501 PyObject *, PyObject *);
502
503
504/* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a
505 list of strings. PyObject_Dir(NULL) is like __builtin__.dir(),
506 returning the names of the current locals. In this case, if there are
507 no current locals, NULL is returned, and PyErr_Occurred() is false.
508*/
509PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
510
511
512/* Helpers for printing recursive container types */
513PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
514PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
515
516/* Helpers for hash functions */
517PyAPI_FUNC(long) _Py_HashDouble(double);
518PyAPI_FUNC(long) _Py_HashPointer(void*);
519
520typedef struct {
521 long prefix;
522 long suffix;
523} _Py_HashSecret_t;
524PyAPI_DATA(_Py_HashSecret_t) _Py_HashSecret;
525
526#ifdef Py_DEBUG
527PyAPI_DATA(int) _Py_HashSecret_Initialized;
528#endif
529
530/* Helper for passing objects to printf and the like.
531 Leaks refcounts. Don't use it!
532*/
533#define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj))
534
535/* Flag bits for printing: */
536#define Py_PRINT_RAW 1 /* No string quotes etc. */
537
538/*
539`Type flags (tp_flags)
540
541These flags are used to extend the type structure in a backwards-compatible
542fashion. Extensions can use the flags to indicate (and test) when a given
543type structure contains a new feature. The Python core will use these when
544introducing new functionality between major revisions (to avoid mid-version
545changes in the PYTHON_API_VERSION).
546
547Arbitration of the flag bit positions will need to be coordinated among
548all extension writers who publically release their extensions (this will
549be fewer than you might expect!)..
550
551Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs.
552
553Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
554
555Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
556given type object has a specified feature.
557
558NOTE: when building the core, Py_TPFLAGS_DEFAULT includes
559Py_TPFLAGS_HAVE_VERSION_TAG; outside the core, it doesn't. This is so
560that extensions that modify tp_dict of their own types directly don't
561break, since this was allowed in 2.5. In 3.0 they will have to
562manually remove this flag though!
563*/
564
565/* PyBufferProcs contains bf_getcharbuffer */
566#define Py_TPFLAGS_HAVE_GETCHARBUFFER (1L<<0)
567
568/* PySequenceMethods contains sq_contains */
569#define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1)
570
571/* This is here for backwards compatibility. Extensions that use the old GC
572 * API will still compile but the objects will not be tracked by the GC. */
573#define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */
574
575/* PySequenceMethods and PyNumberMethods contain in-place operators */
576#define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3)
577
578/* PyNumberMethods do their own coercion */
579#define Py_TPFLAGS_CHECKTYPES (1L<<4)
580
581/* tp_richcompare is defined */
582#define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5)
583
584/* Objects which are weakly referencable if their tp_weaklistoffset is >0 */
585#define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6)
586
587/* tp_iter is defined */
588#define Py_TPFLAGS_HAVE_ITER (1L<<7)
589
590/* New members introduced by Python 2.2 exist */
591#define Py_TPFLAGS_HAVE_CLASS (1L<<8)
592
593/* Set if the type object is dynamically allocated */
594#define Py_TPFLAGS_HEAPTYPE (1L<<9)
595
596/* Set if the type allows subclassing */
597#define Py_TPFLAGS_BASETYPE (1L<<10)
598
599/* Set if the type is 'ready' -- fully initialized */
600#define Py_TPFLAGS_READY (1L<<12)
601
602/* Set while the type is being 'readied', to prevent recursive ready calls */
603#define Py_TPFLAGS_READYING (1L<<13)
604
605/* Objects support garbage collection (see objimp.h) */
606#define Py_TPFLAGS_HAVE_GC (1L<<14)
607
608/* These two bits are preserved for Stackless Python, next after this is 17 */
609#ifdef STACKLESS
610#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15)
611#else
612#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0
613#endif
614
615/* Objects support nb_index in PyNumberMethods */
616#define Py_TPFLAGS_HAVE_INDEX (1L<<17)
617
618/* Objects support type attribute cache */
619#define Py_TPFLAGS_HAVE_VERSION_TAG (1L<<18)
620#define Py_TPFLAGS_VALID_VERSION_TAG (1L<<19)
621
622/* Type is abstract and cannot be instantiated */
623#define Py_TPFLAGS_IS_ABSTRACT (1L<<20)
624
625/* Has the new buffer protocol */
626#define Py_TPFLAGS_HAVE_NEWBUFFER (1L<<21)
627
628/* These flags are used to determine if a type is a subclass. */
629#define Py_TPFLAGS_INT_SUBCLASS (1L<<23)
630#define Py_TPFLAGS_LONG_SUBCLASS (1L<<24)
631#define Py_TPFLAGS_LIST_SUBCLASS (1L<<25)
632#define Py_TPFLAGS_TUPLE_SUBCLASS (1L<<26)
633#define Py_TPFLAGS_STRING_SUBCLASS (1L<<27)
634#define Py_TPFLAGS_UNICODE_SUBCLASS (1L<<28)
635#define Py_TPFLAGS_DICT_SUBCLASS (1L<<29)
636#define Py_TPFLAGS_BASE_EXC_SUBCLASS (1L<<30)
637#define Py_TPFLAGS_TYPE_SUBCLASS (1L<<31)
638
639#define Py_TPFLAGS_DEFAULT_EXTERNAL ( \
640 Py_TPFLAGS_HAVE_GETCHARBUFFER | \
641 Py_TPFLAGS_HAVE_SEQUENCE_IN | \
642 Py_TPFLAGS_HAVE_INPLACEOPS | \
643 Py_TPFLAGS_HAVE_RICHCOMPARE | \
644 Py_TPFLAGS_HAVE_WEAKREFS | \
645 Py_TPFLAGS_HAVE_ITER | \
646 Py_TPFLAGS_HAVE_CLASS | \
647 Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \
648 Py_TPFLAGS_HAVE_INDEX | \
649 0)
650#define Py_TPFLAGS_DEFAULT_CORE (Py_TPFLAGS_DEFAULT_EXTERNAL | \
651 Py_TPFLAGS_HAVE_VERSION_TAG)
652
653#ifdef Py_BUILD_CORE
654#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_CORE
655#else
656#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_EXTERNAL
657#endif
658
659#define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0)
660#define PyType_FastSubclass(t,f) PyType_HasFeature(t,f)
661
662
663/*
664The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
665reference counts. Py_DECREF calls the object's deallocator function when
666the refcount falls to 0; for
667objects that don't contain references to other objects or heap memory
668this can be the standard function free(). Both macros can be used
669wherever a void expression is allowed. The argument must not be a
670NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
671The macro _Py_NewReference(op) initialize reference counts to 1, and
672in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
673bookkeeping appropriate to the special build.
674
675We assume that the reference count field can never overflow; this can
676be proven when the size of the field is the same as the pointer size, so
677we ignore the possibility. Provided a C int is at least 32 bits (which
678is implicitly assumed in many parts of this code), that's enough for
679about 2**31 references to an object.
680
681XXX The following became out of date in Python 2.2, but I'm not sure
682XXX what the full truth is now. Certainly, heap-allocated type objects
683XXX can and should be deallocated.
684Type objects should never be deallocated; the type pointer in an object
685is not considered to be a reference to the type object, to save
686complications in the deallocation function. (This is actually a
687decision that's up to the implementer of each new type so if you want,
688you can count such references to the type object.)
689
690*** WARNING*** The Py_DECREF macro must have a side-effect-free argument
691since it may evaluate its argument multiple times. (The alternative
692would be to mace it a proper function or assign it to a global temporary
693variable first, both of which are slower; and in a multi-threaded
694environment the global variable trick is not safe.)
695*/
696
697/* First define a pile of simple helper macros, one set per special
698 * build symbol. These either expand to the obvious things, or to
699 * nothing at all when the special mode isn't in effect. The main
700 * macros can later be defined just once then, yet expand to different
701 * things depending on which special build options are and aren't in effect.
702 * Trust me <wink>: while painful, this is 20x easier to understand than,
703 * e.g, defining _Py_NewReference five different times in a maze of nested
704 * #ifdefs (we used to do that -- it was impenetrable).
705 */
706#ifdef Py_REF_DEBUG
707PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
708PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname,
709 int lineno, PyObject *op);
710PyAPI_FUNC(PyObject *) _PyDict_Dummy(void);
711PyAPI_FUNC(PyObject *) _PySet_Dummy(void);
712PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void);
713#define _Py_INC_REFTOTAL _Py_RefTotal++
714#define _Py_DEC_REFTOTAL _Py_RefTotal--
715#define _Py_REF_DEBUG_COMMA ,
716#define _Py_CHECK_REFCNT(OP) \
717{ if (((PyObject*)OP)->ob_refcnt < 0) \
718 _Py_NegativeRefcount(__FILE__, __LINE__, \
719 (PyObject *)(OP)); \
720}
721#else
722#define _Py_INC_REFTOTAL
723#define _Py_DEC_REFTOTAL
724#define _Py_REF_DEBUG_COMMA
725#define _Py_CHECK_REFCNT(OP) /* a semicolon */;
726#endif /* Py_REF_DEBUG */
727
728#ifdef COUNT_ALLOCS
729PyAPI_FUNC(void) inc_count(PyTypeObject *);
730PyAPI_FUNC(void) dec_count(PyTypeObject *);
731#define _Py_INC_TPALLOCS(OP) inc_count(Py_TYPE(OP))
732#define _Py_INC_TPFREES(OP) dec_count(Py_TYPE(OP))
733#define _Py_DEC_TPFREES(OP) Py_TYPE(OP)->tp_frees--
734#define _Py_COUNT_ALLOCS_COMMA ,
735#else
736#define _Py_INC_TPALLOCS(OP)
737#define _Py_INC_TPFREES(OP)
738#define _Py_DEC_TPFREES(OP)
739#define _Py_COUNT_ALLOCS_COMMA
740#endif /* COUNT_ALLOCS */
741
742#ifdef Py_TRACE_REFS
743/* Py_TRACE_REFS is such major surgery that we call external routines. */
744PyAPI_FUNC(void) _Py_NewReference(PyObject *);
745PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
746PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
747PyAPI_FUNC(void) _Py_PrintReferences(FILE *);
748PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *);
749PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force);
750
751#else
752/* Without Py_TRACE_REFS, there's little enough to do that we expand code
753 * inline.
754 */
755#define _Py_NewReference(op) ( \
756 _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \
757 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
758 Py_REFCNT(op) = 1)
759
760#define _Py_ForgetReference(op) _Py_INC_TPFREES(op)
761
762#define _Py_Dealloc(op) ( \
763 _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \
764 (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op)))
765#endif /* !Py_TRACE_REFS */
766
767#define Py_INCREF(op) ( \
768 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
769 ((PyObject*)(op))->ob_refcnt++)
770
771#define Py_DECREF(op) \
772 do { \
773 if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \
774 --((PyObject*)(op))->ob_refcnt != 0) \
775 _Py_CHECK_REFCNT(op) \
776 else \
777 _Py_Dealloc((PyObject *)(op)); \
778 } while (0)
779
780/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
781 * and tp_dealloc implementations.
782 *
783 * Note that "the obvious" code can be deadly:
784 *
785 * Py_XDECREF(op);
786 * op = NULL;
787 *
788 * Typically, `op` is something like self->containee, and `self` is done
789 * using its `containee` member. In the code sequence above, suppose
790 * `containee` is non-NULL with a refcount of 1. Its refcount falls to
791 * 0 on the first line, which can trigger an arbitrary amount of code,
792 * possibly including finalizers (like __del__ methods or weakref callbacks)
793 * coded in Python, which in turn can release the GIL and allow other threads
794 * to run, etc. Such code may even invoke methods of `self` again, or cause
795 * cyclic gc to trigger, but-- oops! --self->containee still points to the
796 * object being torn down, and it may be in an insane state while being torn
797 * down. This has in fact been a rich historic source of miserable (rare &
798 * hard-to-diagnose) segfaulting (and other) bugs.
799 *
800 * The safe way is:
801 *
802 * Py_CLEAR(op);
803 *
804 * That arranges to set `op` to NULL _before_ decref'ing, so that any code
805 * triggered as a side-effect of `op` getting torn down no longer believes
806 * `op` points to a valid object.
807 *
808 * There are cases where it's safe to use the naive code, but they're brittle.
809 * For example, if `op` points to a Python integer, you know that destroying
810 * one of those can't cause problems -- but in part that relies on that
811 * Python integers aren't currently weakly referencable. Best practice is
812 * to use Py_CLEAR() even if you can't think of a reason for why you need to.
813 */
814#define Py_CLEAR(op) \
815 do { \
816 if (op) { \
817 PyObject *_py_tmp = (PyObject *)(op); \
818 (op) = NULL; \
819 Py_DECREF(_py_tmp); \
820 } \
821 } while (0)
822
823/* Macros to use in case the object pointer may be NULL: */
824#define Py_XINCREF(op) do { if ((op) == NULL) ; else Py_INCREF(op); } while (0)
825#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
826
827/* Safely decref `op` and set `op` to `op2`.
828 *
829 * As in case of Py_CLEAR "the obvious" code can be deadly:
830 *
831 * Py_DECREF(op);
832 * op = op2;
833 *
834 * The safe way is:
835 *
836 * Py_SETREF(op, op2);
837 *
838 * That arranges to set `op` to `op2` _before_ decref'ing, so that any code
839 * triggered as a side-effect of `op` getting torn down no longer believes
840 * `op` points to a valid object.
841 *
842 * Py_XSETREF is a variant of Py_SETREF that uses Py_XDECREF instead of
843 * Py_DECREF.
844 */
845
846#define Py_SETREF(op, op2) \
847 do { \
848 PyObject *_py_tmp = (PyObject *)(op); \
849 (op) = (op2); \
850 Py_DECREF(_py_tmp); \
851 } while (0)
852
853#define Py_XSETREF(op, op2) \
854 do { \
855 PyObject *_py_tmp = (PyObject *)(op); \
856 (op) = (op2); \
857 Py_XDECREF(_py_tmp); \
858 } while (0)
859
860/*
861These are provided as conveniences to Python runtime embedders, so that
862they can have object code that is not dependent on Python compilation flags.
863*/
864PyAPI_FUNC(void) Py_IncRef(PyObject *);
865PyAPI_FUNC(void) Py_DecRef(PyObject *);
866
867/*
868_Py_NoneStruct is an object of undefined type which can be used in contexts
869where NULL (nil) is not suitable (since NULL often means 'error').
870
871Don't forget to apply Py_INCREF() when returning this value!!!
872*/
873PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
874#define Py_None (&_Py_NoneStruct)
875
876/* Macro for returning Py_None from a function */
877#define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None
878
879/*
880Py_NotImplemented is a singleton used to signal that an operation is
881not implemented for a given type combination.
882*/
883PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
884#define Py_NotImplemented (&_Py_NotImplementedStruct)
885
886/* Rich comparison opcodes */
887#define Py_LT 0
888#define Py_LE 1
889#define Py_EQ 2
890#define Py_NE 3
891#define Py_GT 4
892#define Py_GE 5
893
894/* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE.
895 * Defined in object.c.
896 */
897PyAPI_DATA(int) _Py_SwappedOp[];
898
899/*
900Define staticforward and statichere for source compatibility with old
901C extensions.
902
903The staticforward define was needed to support certain broken C
904compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the
905static keyword when it was used with a forward declaration of a static
906initialized structure. Standard C allows the forward declaration with
907static, and we've decided to stop catering to broken C compilers.
908(In fact, we expect that the compilers are all fixed eight years later.)
909*/
910
911#define staticforward static
912#define statichere static
913
914
915/*
916More conventions
917================
918
919Argument Checking
920-----------------
921
922Functions that take objects as arguments normally don't check for nil
923arguments, but they do check the type of the argument, and return an
924error if the function doesn't apply to the type.
925
926Failure Modes
927-------------
928
929Functions may fail for a variety of reasons, including running out of
930memory. This is communicated to the caller in two ways: an error string
931is set (see errors.h), and the function result differs: functions that
932normally return a pointer return NULL for failure, functions returning
933an integer return -1 (which could be a legal return value too!), and
934other functions return 0 for success and -1 for failure.
935Callers should always check for errors before using the result. If
936an error was set, the caller must either explicitly clear it, or pass
937the error on to its caller.
938
939Reference Counts
940----------------
941
942It takes a while to get used to the proper usage of reference counts.
943
944Functions that create an object set the reference count to 1; such new
945objects must be stored somewhere or destroyed again with Py_DECREF().
946Some functions that 'store' objects, such as PyTuple_SetItem() and
947PyList_SetItem(),
948don't increment the reference count of the object, since the most
949frequent use is to store a fresh object. Functions that 'retrieve'
950objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
951don't increment
952the reference count, since most frequently the object is only looked at
953quickly. Thus, to retrieve an object and store it again, the caller
954must call Py_INCREF() explicitly.
955
956NOTE: functions that 'consume' a reference count, like
957PyList_SetItem(), consume the reference even if the object wasn't
958successfully stored, to simplify error handling.
959
960It seems attractive to make other functions that take an object as
961argument consume a reference count; however, this may quickly get
962confusing (even the current practice is already confusing). Consider
963it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
964times.
965*/
966
967
968/* Trashcan mechanism, thanks to Christian Tismer.
969
970When deallocating a container object, it's possible to trigger an unbounded
971chain of deallocations, as each Py_DECREF in turn drops the refcount on "the
972next" object in the chain to 0. This can easily lead to stack faults, and
973especially in threads (which typically have less stack space to work with).
974
975A container object that participates in cyclic gc can avoid this by
976bracketing the body of its tp_dealloc function with a pair of macros:
977
978static void
979mytype_dealloc(mytype *p)
980{
981 ... declarations go here ...
982
983 PyObject_GC_UnTrack(p); // must untrack first
984 Py_TRASHCAN_SAFE_BEGIN(p)
985 ... The body of the deallocator goes here, including all calls ...
986 ... to Py_DECREF on contained objects. ...
987 Py_TRASHCAN_SAFE_END(p)
988}
989
990CAUTION: Never return from the middle of the body! If the body needs to
991"get out early", put a label immediately before the Py_TRASHCAN_SAFE_END
992call, and goto it. Else the call-depth counter (see below) will stay
993above 0 forever, and the trashcan will never get emptied.
994
995How it works: The BEGIN macro increments a call-depth counter. So long
996as this counter is small, the body of the deallocator is run directly without
997further ado. But if the counter gets large, it instead adds p to a list of
998objects to be deallocated later, skips the body of the deallocator, and
999resumes execution after the END macro. The tp_dealloc routine then returns
1000without deallocating anything (and so unbounded call-stack depth is avoided).
1001
1002When the call stack finishes unwinding again, code generated by the END macro
1003notices this, and calls another routine to deallocate all the objects that
1004may have been added to the list of deferred deallocations. In effect, a
1005chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces,
1006with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL.
1007*/
1008
1009/* This is the old private API, invoked by the macros before 2.7.4.
1010 Kept for binary compatibility of extensions. */
1011PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*);
1012PyAPI_FUNC(void) _PyTrash_destroy_chain(void);
1013PyAPI_DATA(int) _PyTrash_delete_nesting;
1014PyAPI_DATA(PyObject *) _PyTrash_delete_later;
1015
1016/* The new thread-safe private API, invoked by the macros below. */
1017PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*);
1018PyAPI_FUNC(void) _PyTrash_thread_destroy_chain(void);
1019
1020#define PyTrash_UNWIND_LEVEL 50
1021
1022/* Note the workaround for when the thread state is NULL (issue #17703) */
1023#define Py_TRASHCAN_SAFE_BEGIN(op) \
1024 do { \
1025 PyThreadState *_tstate = PyThreadState_GET(); \
1026 if (!_tstate || \
1027 _tstate->trash_delete_nesting < PyTrash_UNWIND_LEVEL) { \
1028 if (_tstate) \
1029 ++_tstate->trash_delete_nesting;
1030 /* The body of the deallocator is here. */
1031#define Py_TRASHCAN_SAFE_END(op) \
1032 if (_tstate) { \
1033 --_tstate->trash_delete_nesting; \
1034 if (_tstate->trash_delete_later \
1035 && _tstate->trash_delete_nesting <= 0) \
1036 _PyTrash_thread_destroy_chain(); \
1037 } \
1038 } \
1039 else \
1040 _PyTrash_thread_deposit_object((PyObject*)op); \
1041 } while (0);
1042
1043#ifdef __cplusplus
1044}
1045#endif
1046#endif /* !Py_OBJECT_H */
1047