1 | #ifndef Py_OBJECT_H |
2 | #define Py_OBJECT_H |
3 | #ifdef __cplusplus |
4 | extern "C" { |
5 | #endif |
6 | |
7 | |
8 | /* Object and type object interface */ |
9 | |
10 | /* |
11 | Objects are structures allocated on the heap. Special rules apply to |
12 | the use of objects to ensure they are properly garbage-collected. |
13 | Objects are never allocated statically or on the stack; they must be |
14 | accessed through special macros and functions only. (Type objects are |
15 | exceptions to the first rule; the standard types are represented by |
16 | statically initialized type objects, although work on type/class unification |
17 | for Python 2.2 made it possible to have heap-allocated type objects too). |
18 | |
19 | An object has a 'reference count' that is increased or decreased when a |
20 | pointer to the object is copied or deleted; when the reference count |
21 | reaches zero there are no references to the object left and it can be |
22 | removed from the heap. |
23 | |
24 | An object has a 'type' that determines what it represents and what kind |
25 | of data it contains. An object's type is fixed when it is created. |
26 | Types themselves are represented as objects; an object contains a |
27 | pointer to the corresponding type object. The type itself has a type |
28 | pointer pointing to the object representing the type 'type', which |
29 | contains a pointer to itself!). |
30 | |
31 | Objects do not float around in memory; once allocated an object keeps |
32 | the same size and address. Objects that must hold variable-size data |
33 | can contain pointers to variable-size parts of the object. Not all |
34 | objects of the same type have the same size; but the size cannot change |
35 | after allocation. (These restrictions are made so a reference to an |
36 | object can be simply a pointer -- moving an object would require |
37 | updating all the pointers, and changing an object's size would require |
38 | moving it if there was another object right next to it.) |
39 | |
40 | Objects are always accessed through pointers of the type 'PyObject *'. |
41 | The type 'PyObject' is a structure that only contains the reference count |
42 | and the type pointer. The actual memory allocated for an object |
43 | contains other data that can only be accessed after casting the pointer |
44 | to a pointer to a longer structure type. This longer type must start |
45 | with the reference count and type fields; the macro PyObject_HEAD should be |
46 | used for this (to accommodate for future changes). The implementation |
47 | of a particular object type can cast the object pointer to the proper |
48 | type and back. |
49 | |
50 | A standard interface exists for objects that contain an array of items |
51 | whose 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 | #if defined(Py_LIMITED_API) && defined(Py_REF_DEBUG) |
65 | #error Py_LIMITED_API is incompatible with Py_DEBUG, Py_TRACE_REFS, and Py_REF_DEBUG |
66 | #endif |
67 | |
68 | |
69 | #ifdef Py_TRACE_REFS |
70 | /* Define pointers to support a doubly-linked list of all live heap objects. */ |
71 | #define _PyObject_HEAD_EXTRA \ |
72 | struct _object *_ob_next; \ |
73 | struct _object *_ob_prev; |
74 | |
75 | #define _PyObject_EXTRA_INIT 0, 0, |
76 | |
77 | #else |
78 | #define |
79 | #define |
80 | #endif |
81 | |
82 | /* PyObject_HEAD defines the initial segment of every PyObject. */ |
83 | #define PyObject_HEAD PyObject ob_base; |
84 | |
85 | #define PyObject_HEAD_INIT(type) \ |
86 | { _PyObject_EXTRA_INIT \ |
87 | 1, type }, |
88 | |
89 | #define PyVarObject_HEAD_INIT(type, size) \ |
90 | { PyObject_HEAD_INIT(type) size }, |
91 | |
92 | /* PyObject_VAR_HEAD defines the initial segment of all variable-size |
93 | * container objects. These end with a declaration of an array with 1 |
94 | * element, but enough space is malloc'ed so that the array actually |
95 | * has room for ob_size elements. Note that ob_size is an element count, |
96 | * not necessarily a byte count. |
97 | */ |
98 | #define PyObject_VAR_HEAD PyVarObject ob_base; |
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 | */ |
106 | typedef struct _object { |
107 | _PyObject_HEAD_EXTRA |
108 | Py_ssize_t ob_refcnt; |
109 | struct _typeobject *ob_type; |
110 | } PyObject; |
111 | |
112 | typedef struct { |
113 | PyObject ob_base; |
114 | Py_ssize_t ob_size; /* Number of items in variable part */ |
115 | } PyVarObject; |
116 | |
117 | #define Py_REFCNT(ob) (((PyObject*)(ob))->ob_refcnt) |
118 | #define Py_TYPE(ob) (((PyObject*)(ob))->ob_type) |
119 | #define Py_SIZE(ob) (((PyVarObject*)(ob))->ob_size) |
120 | |
121 | /********************* String Literals ****************************************/ |
122 | /* This structure helps managing static strings. The basic usage goes like this: |
123 | Instead of doing |
124 | |
125 | r = PyObject_CallMethod(o, "foo", "args", ...); |
126 | |
127 | do |
128 | |
129 | _Py_IDENTIFIER(foo); |
130 | ... |
131 | r = _PyObject_CallMethodId(o, &PyId_foo, "args", ...); |
132 | |
133 | PyId_foo is a static variable, either on block level or file level. On first |
134 | usage, the string "foo" is interned, and the structures are linked. On interpreter |
135 | shutdown, all strings are released (through _PyUnicode_ClearStaticStrings). |
136 | |
137 | Alternatively, _Py_static_string allows choosing the variable name. |
138 | _PyUnicode_FromId returns a borrowed reference to the interned string. |
139 | _PyObject_{Get,Set,Has}AttrId are __getattr__ versions using _Py_Identifier*. |
140 | */ |
141 | typedef struct _Py_Identifier { |
142 | struct _Py_Identifier *next; |
143 | const char* string; |
144 | PyObject *object; |
145 | } _Py_Identifier; |
146 | |
147 | #define _Py_static_string_init(value) { 0, value, 0 } |
148 | #define _Py_static_string(varname, value) static _Py_Identifier varname = _Py_static_string_init(value) |
149 | #define _Py_IDENTIFIER(varname) _Py_static_string(PyId_##varname, #varname) |
150 | |
151 | /* |
152 | Type objects contain a string containing the type name (to help somewhat |
153 | in debugging), the allocation parameters (see PyObject_New() and |
154 | PyObject_NewVar()), |
155 | and methods for accessing objects of the type. Methods are optional, a |
156 | nil pointer meaning that particular kind of access is not available for |
157 | this type. The Py_DECREF() macro uses the tp_dealloc method without |
158 | checking for a nil pointer; it should always be implemented except if |
159 | the implementation can guarantee that the reference count will never |
160 | reach zero (e.g., for statically allocated type objects). |
161 | |
162 | NB: the methods for certain type groups are now contained in separate |
163 | method blocks. |
164 | */ |
165 | |
166 | typedef PyObject * (*unaryfunc)(PyObject *); |
167 | typedef PyObject * (*binaryfunc)(PyObject *, PyObject *); |
168 | typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *); |
169 | typedef int (*inquiry)(PyObject *); |
170 | typedef Py_ssize_t (*lenfunc)(PyObject *); |
171 | typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t); |
172 | typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t); |
173 | typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *); |
174 | typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *); |
175 | typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *); |
176 | |
177 | #ifndef Py_LIMITED_API |
178 | /* buffer interface */ |
179 | typedef struct bufferinfo { |
180 | void *buf; |
181 | PyObject *obj; /* owned reference */ |
182 | Py_ssize_t len; |
183 | Py_ssize_t itemsize; /* This is Py_ssize_t so it can be |
184 | pointed to by strides in simple case.*/ |
185 | int readonly; |
186 | int ndim; |
187 | char *format; |
188 | Py_ssize_t *shape; |
189 | Py_ssize_t *strides; |
190 | Py_ssize_t *suboffsets; |
191 | void *internal; |
192 | } Py_buffer; |
193 | |
194 | typedef int (*getbufferproc)(PyObject *, Py_buffer *, int); |
195 | typedef void (*releasebufferproc)(PyObject *, Py_buffer *); |
196 | |
197 | /* Maximum number of dimensions */ |
198 | #define PyBUF_MAX_NDIM 64 |
199 | |
200 | /* Flags for getting buffers */ |
201 | #define PyBUF_SIMPLE 0 |
202 | #define PyBUF_WRITABLE 0x0001 |
203 | /* we used to include an E, backwards compatible alias */ |
204 | #define PyBUF_WRITEABLE PyBUF_WRITABLE |
205 | #define PyBUF_FORMAT 0x0004 |
206 | #define PyBUF_ND 0x0008 |
207 | #define PyBUF_STRIDES (0x0010 | PyBUF_ND) |
208 | #define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES) |
209 | #define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES) |
210 | #define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES) |
211 | #define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES) |
212 | |
213 | #define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE) |
214 | #define PyBUF_CONTIG_RO (PyBUF_ND) |
215 | |
216 | #define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE) |
217 | #define PyBUF_STRIDED_RO (PyBUF_STRIDES) |
218 | |
219 | #define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT) |
220 | #define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT) |
221 | |
222 | #define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT) |
223 | #define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT) |
224 | |
225 | |
226 | #define PyBUF_READ 0x100 |
227 | #define PyBUF_WRITE 0x200 |
228 | |
229 | /* End buffer interface */ |
230 | #endif /* Py_LIMITED_API */ |
231 | |
232 | typedef int (*objobjproc)(PyObject *, PyObject *); |
233 | typedef int (*visitproc)(PyObject *, void *); |
234 | typedef int (*traverseproc)(PyObject *, visitproc, void *); |
235 | |
236 | #ifndef Py_LIMITED_API |
237 | typedef struct { |
238 | /* Number implementations must check *both* |
239 | arguments for proper type and implement the necessary conversions |
240 | in the slot functions themselves. */ |
241 | |
242 | binaryfunc nb_add; |
243 | binaryfunc nb_subtract; |
244 | binaryfunc nb_multiply; |
245 | binaryfunc nb_remainder; |
246 | binaryfunc nb_divmod; |
247 | ternaryfunc nb_power; |
248 | unaryfunc nb_negative; |
249 | unaryfunc nb_positive; |
250 | unaryfunc nb_absolute; |
251 | inquiry nb_bool; |
252 | unaryfunc nb_invert; |
253 | binaryfunc nb_lshift; |
254 | binaryfunc nb_rshift; |
255 | binaryfunc nb_and; |
256 | binaryfunc nb_xor; |
257 | binaryfunc nb_or; |
258 | unaryfunc nb_int; |
259 | void *nb_reserved; /* the slot formerly known as nb_long */ |
260 | unaryfunc nb_float; |
261 | |
262 | binaryfunc nb_inplace_add; |
263 | binaryfunc nb_inplace_subtract; |
264 | binaryfunc nb_inplace_multiply; |
265 | binaryfunc nb_inplace_remainder; |
266 | ternaryfunc nb_inplace_power; |
267 | binaryfunc nb_inplace_lshift; |
268 | binaryfunc nb_inplace_rshift; |
269 | binaryfunc nb_inplace_and; |
270 | binaryfunc nb_inplace_xor; |
271 | binaryfunc nb_inplace_or; |
272 | |
273 | binaryfunc nb_floor_divide; |
274 | binaryfunc nb_true_divide; |
275 | binaryfunc nb_inplace_floor_divide; |
276 | binaryfunc nb_inplace_true_divide; |
277 | |
278 | unaryfunc nb_index; |
279 | |
280 | binaryfunc nb_matrix_multiply; |
281 | binaryfunc nb_inplace_matrix_multiply; |
282 | } PyNumberMethods; |
283 | |
284 | typedef struct { |
285 | lenfunc sq_length; |
286 | binaryfunc sq_concat; |
287 | ssizeargfunc sq_repeat; |
288 | ssizeargfunc sq_item; |
289 | void *was_sq_slice; |
290 | ssizeobjargproc sq_ass_item; |
291 | void *was_sq_ass_slice; |
292 | objobjproc sq_contains; |
293 | |
294 | binaryfunc sq_inplace_concat; |
295 | ssizeargfunc sq_inplace_repeat; |
296 | } PySequenceMethods; |
297 | |
298 | typedef struct { |
299 | lenfunc mp_length; |
300 | binaryfunc mp_subscript; |
301 | objobjargproc mp_ass_subscript; |
302 | } PyMappingMethods; |
303 | |
304 | typedef struct { |
305 | unaryfunc am_await; |
306 | unaryfunc am_aiter; |
307 | unaryfunc am_anext; |
308 | } PyAsyncMethods; |
309 | |
310 | typedef struct { |
311 | getbufferproc bf_getbuffer; |
312 | releasebufferproc bf_releasebuffer; |
313 | } PyBufferProcs; |
314 | #endif /* Py_LIMITED_API */ |
315 | |
316 | typedef void (*freefunc)(void *); |
317 | typedef void (*destructor)(PyObject *); |
318 | #ifndef Py_LIMITED_API |
319 | /* We can't provide a full compile-time check that limited-API |
320 | users won't implement tp_print. However, not defining printfunc |
321 | and making tp_print of a different function pointer type |
322 | should at least cause a warning in most cases. */ |
323 | typedef int (*printfunc)(PyObject *, FILE *, int); |
324 | #endif |
325 | typedef PyObject *(*getattrfunc)(PyObject *, char *); |
326 | typedef PyObject *(*getattrofunc)(PyObject *, PyObject *); |
327 | typedef int (*setattrfunc)(PyObject *, char *, PyObject *); |
328 | typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *); |
329 | typedef PyObject *(*reprfunc)(PyObject *); |
330 | typedef Py_hash_t (*hashfunc)(PyObject *); |
331 | typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int); |
332 | typedef PyObject *(*getiterfunc) (PyObject *); |
333 | typedef PyObject *(*iternextfunc) (PyObject *); |
334 | typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *); |
335 | typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *); |
336 | typedef int (*initproc)(PyObject *, PyObject *, PyObject *); |
337 | typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *); |
338 | typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t); |
339 | |
340 | #ifdef Py_LIMITED_API |
341 | typedef struct _typeobject PyTypeObject; /* opaque */ |
342 | #else |
343 | typedef struct _typeobject { |
344 | PyObject_VAR_HEAD |
345 | const char *tp_name; /* For printing, in format "<module>.<name>" */ |
346 | Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */ |
347 | |
348 | /* Methods to implement standard operations */ |
349 | |
350 | destructor tp_dealloc; |
351 | printfunc tp_print; |
352 | getattrfunc tp_getattr; |
353 | setattrfunc tp_setattr; |
354 | PyAsyncMethods *tp_as_async; /* formerly known as tp_compare (Python 2) |
355 | or tp_reserved (Python 3) */ |
356 | reprfunc tp_repr; |
357 | |
358 | /* Method suites for standard classes */ |
359 | |
360 | PyNumberMethods *tp_as_number; |
361 | PySequenceMethods *tp_as_sequence; |
362 | PyMappingMethods *tp_as_mapping; |
363 | |
364 | /* More standard operations (here for binary compatibility) */ |
365 | |
366 | hashfunc tp_hash; |
367 | ternaryfunc tp_call; |
368 | reprfunc tp_str; |
369 | getattrofunc tp_getattro; |
370 | setattrofunc tp_setattro; |
371 | |
372 | /* Functions to access object as input/output buffer */ |
373 | PyBufferProcs *tp_as_buffer; |
374 | |
375 | /* Flags to define presence of optional/expanded features */ |
376 | unsigned long tp_flags; |
377 | |
378 | const char *tp_doc; /* Documentation string */ |
379 | |
380 | /* Assigned meaning in release 2.0 */ |
381 | /* call function for all accessible objects */ |
382 | traverseproc tp_traverse; |
383 | |
384 | /* delete references to contained objects */ |
385 | inquiry tp_clear; |
386 | |
387 | /* Assigned meaning in release 2.1 */ |
388 | /* rich comparisons */ |
389 | richcmpfunc tp_richcompare; |
390 | |
391 | /* weak reference enabler */ |
392 | Py_ssize_t tp_weaklistoffset; |
393 | |
394 | /* Iterators */ |
395 | getiterfunc tp_iter; |
396 | iternextfunc tp_iternext; |
397 | |
398 | /* Attribute descriptor and subclassing stuff */ |
399 | struct PyMethodDef *tp_methods; |
400 | struct PyMemberDef *tp_members; |
401 | struct PyGetSetDef *tp_getset; |
402 | struct _typeobject *tp_base; |
403 | PyObject *tp_dict; |
404 | descrgetfunc tp_descr_get; |
405 | descrsetfunc tp_descr_set; |
406 | Py_ssize_t tp_dictoffset; |
407 | initproc tp_init; |
408 | allocfunc tp_alloc; |
409 | newfunc tp_new; |
410 | freefunc tp_free; /* Low-level free-memory routine */ |
411 | inquiry tp_is_gc; /* For PyObject_IS_GC */ |
412 | PyObject *tp_bases; |
413 | PyObject *tp_mro; /* method resolution order */ |
414 | PyObject *tp_cache; |
415 | PyObject *tp_subclasses; |
416 | PyObject *tp_weaklist; |
417 | destructor tp_del; |
418 | |
419 | /* Type attribute cache version tag. Added in version 2.6 */ |
420 | unsigned int tp_version_tag; |
421 | |
422 | destructor tp_finalize; |
423 | |
424 | #ifdef COUNT_ALLOCS |
425 | /* these must be last and never explicitly initialized */ |
426 | Py_ssize_t tp_allocs; |
427 | Py_ssize_t tp_frees; |
428 | Py_ssize_t tp_maxalloc; |
429 | struct _typeobject *tp_prev; |
430 | struct _typeobject *tp_next; |
431 | #endif |
432 | } PyTypeObject; |
433 | #endif |
434 | |
435 | typedef struct{ |
436 | int slot; /* slot id, see below */ |
437 | void *pfunc; /* function pointer */ |
438 | } PyType_Slot; |
439 | |
440 | typedef struct{ |
441 | const char* name; |
442 | int basicsize; |
443 | int itemsize; |
444 | unsigned int flags; |
445 | PyType_Slot *slots; /* terminated by slot==0. */ |
446 | } PyType_Spec; |
447 | |
448 | PyAPI_FUNC(PyObject*) PyType_FromSpec(PyType_Spec*); |
449 | #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000 |
450 | PyAPI_FUNC(PyObject*) PyType_FromSpecWithBases(PyType_Spec*, PyObject*); |
451 | #endif |
452 | #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03040000 |
453 | PyAPI_FUNC(void*) PyType_GetSlot(PyTypeObject*, int); |
454 | #endif |
455 | |
456 | #ifndef Py_LIMITED_API |
457 | /* The *real* layout of a type object when allocated on the heap */ |
458 | typedef struct _heaptypeobject { |
459 | /* Note: there's a dependency on the order of these members |
460 | in slotptr() in typeobject.c . */ |
461 | PyTypeObject ht_type; |
462 | PyAsyncMethods as_async; |
463 | PyNumberMethods as_number; |
464 | PyMappingMethods as_mapping; |
465 | PySequenceMethods as_sequence; /* as_sequence comes after as_mapping, |
466 | so that the mapping wins when both |
467 | the mapping and the sequence define |
468 | a given operator (e.g. __getitem__). |
469 | see add_operators() in typeobject.c . */ |
470 | PyBufferProcs as_buffer; |
471 | PyObject *ht_name, *ht_slots, *ht_qualname; |
472 | struct _dictkeysobject *ht_cached_keys; |
473 | /* here are optional user slots, followed by the members. */ |
474 | } PyHeapTypeObject; |
475 | |
476 | /* access macro to the members which are floating "behind" the object */ |
477 | #define PyHeapType_GET_MEMBERS(etype) \ |
478 | ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize)) |
479 | #endif |
480 | |
481 | /* Generic type check */ |
482 | PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *); |
483 | #define PyObject_TypeCheck(ob, tp) \ |
484 | (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp))) |
485 | |
486 | PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */ |
487 | PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */ |
488 | PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */ |
489 | |
490 | PyAPI_FUNC(unsigned long) PyType_GetFlags(PyTypeObject*); |
491 | |
492 | #define PyType_Check(op) \ |
493 | PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS) |
494 | #define PyType_CheckExact(op) (Py_TYPE(op) == &PyType_Type) |
495 | |
496 | PyAPI_FUNC(int) PyType_Ready(PyTypeObject *); |
497 | PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t); |
498 | PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *, |
499 | PyObject *, PyObject *); |
500 | #ifndef Py_LIMITED_API |
501 | PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *); |
502 | PyAPI_FUNC(PyObject *) _PyType_LookupId(PyTypeObject *, _Py_Identifier *); |
503 | PyAPI_FUNC(PyObject *) _PyObject_LookupSpecial(PyObject *, _Py_Identifier *); |
504 | PyAPI_FUNC(PyTypeObject *) _PyType_CalculateMetaclass(PyTypeObject *, PyObject *); |
505 | #endif |
506 | PyAPI_FUNC(unsigned int) PyType_ClearCache(void); |
507 | PyAPI_FUNC(void) PyType_Modified(PyTypeObject *); |
508 | |
509 | #ifndef Py_LIMITED_API |
510 | PyAPI_FUNC(PyObject *) _PyType_GetDocFromInternalDoc(const char *, const char *); |
511 | PyAPI_FUNC(PyObject *) _PyType_GetTextSignatureFromInternalDoc(const char *, const char *); |
512 | #endif |
513 | |
514 | /* Generic operations on objects */ |
515 | struct _Py_Identifier; |
516 | #ifndef Py_LIMITED_API |
517 | PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int); |
518 | PyAPI_FUNC(void) _Py_BreakPoint(void); |
519 | PyAPI_FUNC(void) _PyObject_Dump(PyObject *); |
520 | #endif |
521 | PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *); |
522 | PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *); |
523 | PyAPI_FUNC(PyObject *) PyObject_ASCII(PyObject *); |
524 | PyAPI_FUNC(PyObject *) PyObject_Bytes(PyObject *); |
525 | PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int); |
526 | PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int); |
527 | PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *); |
528 | PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *); |
529 | PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *); |
530 | PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *); |
531 | PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *); |
532 | PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *); |
533 | PyAPI_FUNC(int) _PyObject_IsAbstract(PyObject *); |
534 | PyAPI_FUNC(PyObject *) _PyObject_GetAttrId(PyObject *, struct _Py_Identifier *); |
535 | PyAPI_FUNC(int) _PyObject_SetAttrId(PyObject *, struct _Py_Identifier *, PyObject *); |
536 | PyAPI_FUNC(int) _PyObject_HasAttrId(PyObject *, struct _Py_Identifier *); |
537 | #ifndef Py_LIMITED_API |
538 | PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *); |
539 | #endif |
540 | PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *); |
541 | #ifndef Py_LIMITED_API |
542 | PyAPI_FUNC(PyObject *) _PyObject_NextNotImplemented(PyObject *); |
543 | #endif |
544 | PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *); |
545 | PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, |
546 | PyObject *, PyObject *); |
547 | PyAPI_FUNC(int) PyObject_GenericSetDict(PyObject *, PyObject *, void *); |
548 | PyAPI_FUNC(Py_hash_t) PyObject_Hash(PyObject *); |
549 | PyAPI_FUNC(Py_hash_t) PyObject_HashNotImplemented(PyObject *); |
550 | PyAPI_FUNC(int) PyObject_IsTrue(PyObject *); |
551 | PyAPI_FUNC(int) PyObject_Not(PyObject *); |
552 | PyAPI_FUNC(int) PyCallable_Check(PyObject *); |
553 | |
554 | PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *); |
555 | #ifndef Py_LIMITED_API |
556 | PyAPI_FUNC(void) PyObject_CallFinalizer(PyObject *); |
557 | PyAPI_FUNC(int) PyObject_CallFinalizerFromDealloc(PyObject *); |
558 | #endif |
559 | |
560 | /* Same as PyObject_Generic{Get,Set}Attr, but passing the attributes |
561 | dict as the last parameter. */ |
562 | PyAPI_FUNC(PyObject *) |
563 | _PyObject_GenericGetAttrWithDict(PyObject *, PyObject *, PyObject *); |
564 | PyAPI_FUNC(int) |
565 | _PyObject_GenericSetAttrWithDict(PyObject *, PyObject *, |
566 | PyObject *, PyObject *); |
567 | |
568 | /* Helper to look up a builtin object */ |
569 | #ifndef Py_LIMITED_API |
570 | PyAPI_FUNC(PyObject *) |
571 | _PyObject_GetBuiltin(const char *name); |
572 | #endif |
573 | |
574 | /* PyObject_Dir(obj) acts like Python builtins.dir(obj), returning a |
575 | list of strings. PyObject_Dir(NULL) is like builtins.dir(), |
576 | returning the names of the current locals. In this case, if there are |
577 | no current locals, NULL is returned, and PyErr_Occurred() is false. |
578 | */ |
579 | PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *); |
580 | |
581 | |
582 | /* Helpers for printing recursive container types */ |
583 | PyAPI_FUNC(int) Py_ReprEnter(PyObject *); |
584 | PyAPI_FUNC(void) Py_ReprLeave(PyObject *); |
585 | |
586 | /* Flag bits for printing: */ |
587 | #define Py_PRINT_RAW 1 /* No string quotes etc. */ |
588 | |
589 | /* |
590 | `Type flags (tp_flags) |
591 | |
592 | These flags are used to extend the type structure in a backwards-compatible |
593 | fashion. Extensions can use the flags to indicate (and test) when a given |
594 | type structure contains a new feature. The Python core will use these when |
595 | introducing new functionality between major revisions (to avoid mid-version |
596 | changes in the PYTHON_API_VERSION). |
597 | |
598 | Arbitration of the flag bit positions will need to be coordinated among |
599 | all extension writers who publically release their extensions (this will |
600 | be fewer than you might expect!).. |
601 | |
602 | Most flags were removed as of Python 3.0 to make room for new flags. (Some |
603 | flags are not for backwards compatibility but to indicate the presence of an |
604 | optional feature; these flags remain of course.) |
605 | |
606 | Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value. |
607 | |
608 | Code can use PyType_HasFeature(type_ob, flag_value) to test whether the |
609 | given type object has a specified feature. |
610 | */ |
611 | |
612 | /* Set if the type object is dynamically allocated */ |
613 | #define Py_TPFLAGS_HEAPTYPE (1UL << 9) |
614 | |
615 | /* Set if the type allows subclassing */ |
616 | #define Py_TPFLAGS_BASETYPE (1UL << 10) |
617 | |
618 | /* Set if the type is 'ready' -- fully initialized */ |
619 | #define Py_TPFLAGS_READY (1UL << 12) |
620 | |
621 | /* Set while the type is being 'readied', to prevent recursive ready calls */ |
622 | #define Py_TPFLAGS_READYING (1UL << 13) |
623 | |
624 | /* Objects support garbage collection (see objimp.h) */ |
625 | #define Py_TPFLAGS_HAVE_GC (1UL << 14) |
626 | |
627 | /* These two bits are preserved for Stackless Python, next after this is 17 */ |
628 | #ifdef STACKLESS |
629 | #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3UL << 15) |
630 | #else |
631 | #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0 |
632 | #endif |
633 | |
634 | /* Objects support type attribute cache */ |
635 | #define Py_TPFLAGS_HAVE_VERSION_TAG (1UL << 18) |
636 | #define Py_TPFLAGS_VALID_VERSION_TAG (1UL << 19) |
637 | |
638 | /* Type is abstract and cannot be instantiated */ |
639 | #define Py_TPFLAGS_IS_ABSTRACT (1UL << 20) |
640 | |
641 | /* These flags are used to determine if a type is a subclass. */ |
642 | #define Py_TPFLAGS_LONG_SUBCLASS (1UL << 24) |
643 | #define Py_TPFLAGS_LIST_SUBCLASS (1UL << 25) |
644 | #define Py_TPFLAGS_TUPLE_SUBCLASS (1UL << 26) |
645 | #define Py_TPFLAGS_BYTES_SUBCLASS (1UL << 27) |
646 | #define Py_TPFLAGS_UNICODE_SUBCLASS (1UL << 28) |
647 | #define Py_TPFLAGS_DICT_SUBCLASS (1UL << 29) |
648 | #define Py_TPFLAGS_BASE_EXC_SUBCLASS (1UL << 30) |
649 | #define Py_TPFLAGS_TYPE_SUBCLASS (1UL << 31) |
650 | |
651 | #define Py_TPFLAGS_DEFAULT ( \ |
652 | Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \ |
653 | Py_TPFLAGS_HAVE_VERSION_TAG | \ |
654 | 0) |
655 | |
656 | /* NOTE: The following flags reuse lower bits (removed as part of the |
657 | * Python 3.0 transition). */ |
658 | |
659 | /* Type structure has tp_finalize member (3.4) */ |
660 | #define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0) |
661 | |
662 | #ifdef Py_LIMITED_API |
663 | #define PyType_HasFeature(t,f) ((PyType_GetFlags(t) & (f)) != 0) |
664 | #else |
665 | #define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0) |
666 | #endif |
667 | #define PyType_FastSubclass(t,f) PyType_HasFeature(t,f) |
668 | |
669 | |
670 | /* |
671 | The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement |
672 | reference counts. Py_DECREF calls the object's deallocator function when |
673 | the refcount falls to 0; for |
674 | objects that don't contain references to other objects or heap memory |
675 | this can be the standard function free(). Both macros can be used |
676 | wherever a void expression is allowed. The argument must not be a |
677 | NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead. |
678 | The macro _Py_NewReference(op) initialize reference counts to 1, and |
679 | in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional |
680 | bookkeeping appropriate to the special build. |
681 | |
682 | We assume that the reference count field can never overflow; this can |
683 | be proven when the size of the field is the same as the pointer size, so |
684 | we ignore the possibility. Provided a C int is at least 32 bits (which |
685 | is implicitly assumed in many parts of this code), that's enough for |
686 | about 2**31 references to an object. |
687 | |
688 | XXX The following became out of date in Python 2.2, but I'm not sure |
689 | XXX what the full truth is now. Certainly, heap-allocated type objects |
690 | XXX can and should be deallocated. |
691 | Type objects should never be deallocated; the type pointer in an object |
692 | is not considered to be a reference to the type object, to save |
693 | complications in the deallocation function. (This is actually a |
694 | decision that's up to the implementer of each new type so if you want, |
695 | you can count such references to the type object.) |
696 | */ |
697 | |
698 | /* First define a pile of simple helper macros, one set per special |
699 | * build symbol. These either expand to the obvious things, or to |
700 | * nothing at all when the special mode isn't in effect. The main |
701 | * macros can later be defined just once then, yet expand to different |
702 | * things depending on which special build options are and aren't in effect. |
703 | * Trust me <wink>: while painful, this is 20x easier to understand than, |
704 | * e.g, defining _Py_NewReference five different times in a maze of nested |
705 | * #ifdefs (we used to do that -- it was impenetrable). |
706 | */ |
707 | #ifdef Py_REF_DEBUG |
708 | PyAPI_DATA(Py_ssize_t) _Py_RefTotal; |
709 | PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname, |
710 | int lineno, PyObject *op); |
711 | PyAPI_FUNC(PyObject *) _PyDict_Dummy(void); |
712 | PyAPI_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 | /* Py_REF_DEBUG also controls the display of refcounts and memory block |
722 | * allocations at the interactive prompt and at interpreter shutdown |
723 | */ |
724 | PyAPI_FUNC(void) _PyDebug_PrintTotalRefs(void); |
725 | #define _PY_DEBUG_PRINT_TOTAL_REFS() _PyDebug_PrintTotalRefs() |
726 | #else |
727 | #define _Py_INC_REFTOTAL |
728 | #define _Py_DEC_REFTOTAL |
729 | #define _Py_REF_DEBUG_COMMA |
730 | #define _Py_CHECK_REFCNT(OP) /* a semicolon */; |
731 | #define _PY_DEBUG_PRINT_TOTAL_REFS() |
732 | #endif /* Py_REF_DEBUG */ |
733 | |
734 | #ifdef COUNT_ALLOCS |
735 | PyAPI_FUNC(void) inc_count(PyTypeObject *); |
736 | PyAPI_FUNC(void) dec_count(PyTypeObject *); |
737 | #define _Py_INC_TPALLOCS(OP) inc_count(Py_TYPE(OP)) |
738 | #define _Py_INC_TPFREES(OP) dec_count(Py_TYPE(OP)) |
739 | #define _Py_DEC_TPFREES(OP) Py_TYPE(OP)->tp_frees-- |
740 | #define _Py_COUNT_ALLOCS_COMMA , |
741 | #else |
742 | #define _Py_INC_TPALLOCS(OP) |
743 | #define _Py_INC_TPFREES(OP) |
744 | #define _Py_DEC_TPFREES(OP) |
745 | #define _Py_COUNT_ALLOCS_COMMA |
746 | #endif /* COUNT_ALLOCS */ |
747 | |
748 | #ifdef Py_TRACE_REFS |
749 | /* Py_TRACE_REFS is such major surgery that we call external routines. */ |
750 | PyAPI_FUNC(void) _Py_NewReference(PyObject *); |
751 | PyAPI_FUNC(void) _Py_ForgetReference(PyObject *); |
752 | PyAPI_FUNC(void) _Py_Dealloc(PyObject *); |
753 | PyAPI_FUNC(void) _Py_PrintReferences(FILE *); |
754 | PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *); |
755 | PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force); |
756 | |
757 | #else |
758 | /* Without Py_TRACE_REFS, there's little enough to do that we expand code |
759 | * inline. |
760 | */ |
761 | #define _Py_NewReference(op) ( \ |
762 | _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \ |
763 | _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
764 | Py_REFCNT(op) = 1) |
765 | |
766 | #define _Py_ForgetReference(op) _Py_INC_TPFREES(op) |
767 | |
768 | #ifdef Py_LIMITED_API |
769 | PyAPI_FUNC(void) _Py_Dealloc(PyObject *); |
770 | #else |
771 | #define _Py_Dealloc(op) ( \ |
772 | _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \ |
773 | (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op))) |
774 | #endif |
775 | #endif /* !Py_TRACE_REFS */ |
776 | |
777 | #define Py_INCREF(op) ( \ |
778 | _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
779 | ((PyObject *)(op))->ob_refcnt++) |
780 | |
781 | #define Py_DECREF(op) \ |
782 | do { \ |
783 | PyObject *_py_decref_tmp = (PyObject *)(op); \ |
784 | if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
785 | --(_py_decref_tmp)->ob_refcnt != 0) \ |
786 | _Py_CHECK_REFCNT(_py_decref_tmp) \ |
787 | else \ |
788 | _Py_Dealloc(_py_decref_tmp); \ |
789 | } while (0) |
790 | |
791 | /* Safely decref `op` and set `op` to NULL, especially useful in tp_clear |
792 | * and tp_dealloc implementations. |
793 | * |
794 | * Note that "the obvious" code can be deadly: |
795 | * |
796 | * Py_XDECREF(op); |
797 | * op = NULL; |
798 | * |
799 | * Typically, `op` is something like self->containee, and `self` is done |
800 | * using its `containee` member. In the code sequence above, suppose |
801 | * `containee` is non-NULL with a refcount of 1. Its refcount falls to |
802 | * 0 on the first line, which can trigger an arbitrary amount of code, |
803 | * possibly including finalizers (like __del__ methods or weakref callbacks) |
804 | * coded in Python, which in turn can release the GIL and allow other threads |
805 | * to run, etc. Such code may even invoke methods of `self` again, or cause |
806 | * cyclic gc to trigger, but-- oops! --self->containee still points to the |
807 | * object being torn down, and it may be in an insane state while being torn |
808 | * down. This has in fact been a rich historic source of miserable (rare & |
809 | * hard-to-diagnose) segfaulting (and other) bugs. |
810 | * |
811 | * The safe way is: |
812 | * |
813 | * Py_CLEAR(op); |
814 | * |
815 | * That arranges to set `op` to NULL _before_ decref'ing, so that any code |
816 | * triggered as a side-effect of `op` getting torn down no longer believes |
817 | * `op` points to a valid object. |
818 | * |
819 | * There are cases where it's safe to use the naive code, but they're brittle. |
820 | * For example, if `op` points to a Python integer, you know that destroying |
821 | * one of those can't cause problems -- but in part that relies on that |
822 | * Python integers aren't currently weakly referencable. Best practice is |
823 | * to use Py_CLEAR() even if you can't think of a reason for why you need to. |
824 | */ |
825 | #define Py_CLEAR(op) \ |
826 | do { \ |
827 | PyObject *_py_tmp = (PyObject *)(op); \ |
828 | if (_py_tmp != NULL) { \ |
829 | (op) = NULL; \ |
830 | Py_DECREF(_py_tmp); \ |
831 | } \ |
832 | } while (0) |
833 | |
834 | /* Macros to use in case the object pointer may be NULL: */ |
835 | #define Py_XINCREF(op) \ |
836 | do { \ |
837 | PyObject *_py_xincref_tmp = (PyObject *)(op); \ |
838 | if (_py_xincref_tmp != NULL) \ |
839 | Py_INCREF(_py_xincref_tmp); \ |
840 | } while (0) |
841 | |
842 | #define Py_XDECREF(op) \ |
843 | do { \ |
844 | PyObject *_py_xdecref_tmp = (PyObject *)(op); \ |
845 | if (_py_xdecref_tmp != NULL) \ |
846 | Py_DECREF(_py_xdecref_tmp); \ |
847 | } while (0) |
848 | |
849 | #ifndef Py_LIMITED_API |
850 | /* Safely decref `op` and set `op` to `op2`. |
851 | * |
852 | * As in case of Py_CLEAR "the obvious" code can be deadly: |
853 | * |
854 | * Py_DECREF(op); |
855 | * op = op2; |
856 | * |
857 | * The safe way is: |
858 | * |
859 | * Py_SETREF(op, op2); |
860 | * |
861 | * That arranges to set `op` to `op2` _before_ decref'ing, so that any code |
862 | * triggered as a side-effect of `op` getting torn down no longer believes |
863 | * `op` points to a valid object. |
864 | * |
865 | * Py_XSETREF is a variant of Py_SETREF that uses Py_XDECREF instead of |
866 | * Py_DECREF. |
867 | */ |
868 | |
869 | #define Py_SETREF(op, op2) \ |
870 | do { \ |
871 | PyObject *_py_tmp = (PyObject *)(op); \ |
872 | (op) = (op2); \ |
873 | Py_DECREF(_py_tmp); \ |
874 | } while (0) |
875 | |
876 | #define Py_XSETREF(op, op2) \ |
877 | do { \ |
878 | PyObject *_py_tmp = (PyObject *)(op); \ |
879 | (op) = (op2); \ |
880 | Py_XDECREF(_py_tmp); \ |
881 | } while (0) |
882 | |
883 | #endif /* ifndef Py_LIMITED_API */ |
884 | |
885 | /* |
886 | These are provided as conveniences to Python runtime embedders, so that |
887 | they can have object code that is not dependent on Python compilation flags. |
888 | */ |
889 | PyAPI_FUNC(void) Py_IncRef(PyObject *); |
890 | PyAPI_FUNC(void) Py_DecRef(PyObject *); |
891 | |
892 | PyAPI_DATA(PyTypeObject) _PyNone_Type; |
893 | PyAPI_DATA(PyTypeObject) _PyNotImplemented_Type; |
894 | |
895 | /* |
896 | _Py_NoneStruct is an object of undefined type which can be used in contexts |
897 | where NULL (nil) is not suitable (since NULL often means 'error'). |
898 | |
899 | Don't forget to apply Py_INCREF() when returning this value!!! |
900 | */ |
901 | PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */ |
902 | #define Py_None (&_Py_NoneStruct) |
903 | |
904 | /* Macro for returning Py_None from a function */ |
905 | #define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None |
906 | |
907 | /* |
908 | Py_NotImplemented is a singleton used to signal that an operation is |
909 | not implemented for a given type combination. |
910 | */ |
911 | PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */ |
912 | #define Py_NotImplemented (&_Py_NotImplementedStruct) |
913 | |
914 | /* Macro for returning Py_NotImplemented from a function */ |
915 | #define Py_RETURN_NOTIMPLEMENTED \ |
916 | return Py_INCREF(Py_NotImplemented), Py_NotImplemented |
917 | |
918 | /* Rich comparison opcodes */ |
919 | #define Py_LT 0 |
920 | #define Py_LE 1 |
921 | #define Py_EQ 2 |
922 | #define Py_NE 3 |
923 | #define Py_GT 4 |
924 | #define Py_GE 5 |
925 | |
926 | /* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE. |
927 | * Defined in object.c. |
928 | */ |
929 | PyAPI_DATA(int) _Py_SwappedOp[]; |
930 | |
931 | |
932 | /* |
933 | More conventions |
934 | ================ |
935 | |
936 | Argument Checking |
937 | ----------------- |
938 | |
939 | Functions that take objects as arguments normally don't check for nil |
940 | arguments, but they do check the type of the argument, and return an |
941 | error if the function doesn't apply to the type. |
942 | |
943 | Failure Modes |
944 | ------------- |
945 | |
946 | Functions may fail for a variety of reasons, including running out of |
947 | memory. This is communicated to the caller in two ways: an error string |
948 | is set (see errors.h), and the function result differs: functions that |
949 | normally return a pointer return NULL for failure, functions returning |
950 | an integer return -1 (which could be a legal return value too!), and |
951 | other functions return 0 for success and -1 for failure. |
952 | Callers should always check for errors before using the result. If |
953 | an error was set, the caller must either explicitly clear it, or pass |
954 | the error on to its caller. |
955 | |
956 | Reference Counts |
957 | ---------------- |
958 | |
959 | It takes a while to get used to the proper usage of reference counts. |
960 | |
961 | Functions that create an object set the reference count to 1; such new |
962 | objects must be stored somewhere or destroyed again with Py_DECREF(). |
963 | Some functions that 'store' objects, such as PyTuple_SetItem() and |
964 | PyList_SetItem(), |
965 | don't increment the reference count of the object, since the most |
966 | frequent use is to store a fresh object. Functions that 'retrieve' |
967 | objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also |
968 | don't increment |
969 | the reference count, since most frequently the object is only looked at |
970 | quickly. Thus, to retrieve an object and store it again, the caller |
971 | must call Py_INCREF() explicitly. |
972 | |
973 | NOTE: functions that 'consume' a reference count, like |
974 | PyList_SetItem(), consume the reference even if the object wasn't |
975 | successfully stored, to simplify error handling. |
976 | |
977 | It seems attractive to make other functions that take an object as |
978 | argument consume a reference count; however, this may quickly get |
979 | confusing (even the current practice is already confusing). Consider |
980 | it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at |
981 | times. |
982 | */ |
983 | |
984 | |
985 | /* Trashcan mechanism, thanks to Christian Tismer. |
986 | |
987 | When deallocating a container object, it's possible to trigger an unbounded |
988 | chain of deallocations, as each Py_DECREF in turn drops the refcount on "the |
989 | next" object in the chain to 0. This can easily lead to stack faults, and |
990 | especially in threads (which typically have less stack space to work with). |
991 | |
992 | A container object that participates in cyclic gc can avoid this by |
993 | bracketing the body of its tp_dealloc function with a pair of macros: |
994 | |
995 | static void |
996 | mytype_dealloc(mytype *p) |
997 | { |
998 | ... declarations go here ... |
999 | |
1000 | PyObject_GC_UnTrack(p); // must untrack first |
1001 | Py_TRASHCAN_SAFE_BEGIN(p) |
1002 | ... The body of the deallocator goes here, including all calls ... |
1003 | ... to Py_DECREF on contained objects. ... |
1004 | Py_TRASHCAN_SAFE_END(p) |
1005 | } |
1006 | |
1007 | CAUTION: Never return from the middle of the body! If the body needs to |
1008 | "get out early", put a label immediately before the Py_TRASHCAN_SAFE_END |
1009 | call, and goto it. Else the call-depth counter (see below) will stay |
1010 | above 0 forever, and the trashcan will never get emptied. |
1011 | |
1012 | How it works: The BEGIN macro increments a call-depth counter. So long |
1013 | as this counter is small, the body of the deallocator is run directly without |
1014 | further ado. But if the counter gets large, it instead adds p to a list of |
1015 | objects to be deallocated later, skips the body of the deallocator, and |
1016 | resumes execution after the END macro. The tp_dealloc routine then returns |
1017 | without deallocating anything (and so unbounded call-stack depth is avoided). |
1018 | |
1019 | When the call stack finishes unwinding again, code generated by the END macro |
1020 | notices this, and calls another routine to deallocate all the objects that |
1021 | may have been added to the list of deferred deallocations. In effect, a |
1022 | chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces, |
1023 | with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. |
1024 | */ |
1025 | |
1026 | /* This is the old private API, invoked by the macros before 3.2.4. |
1027 | Kept for binary compatibility of extensions using the stable ABI. */ |
1028 | PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); |
1029 | PyAPI_FUNC(void) _PyTrash_destroy_chain(void); |
1030 | PyAPI_DATA(int) _PyTrash_delete_nesting; |
1031 | PyAPI_DATA(PyObject *) _PyTrash_delete_later; |
1032 | |
1033 | /* The new thread-safe private API, invoked by the macros below. */ |
1034 | PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*); |
1035 | PyAPI_FUNC(void) _PyTrash_thread_destroy_chain(void); |
1036 | |
1037 | #define PyTrash_UNWIND_LEVEL 50 |
1038 | |
1039 | #define Py_TRASHCAN_SAFE_BEGIN(op) \ |
1040 | do { \ |
1041 | PyThreadState *_tstate = PyThreadState_GET(); \ |
1042 | if (_tstate->trash_delete_nesting < PyTrash_UNWIND_LEVEL) { \ |
1043 | ++_tstate->trash_delete_nesting; |
1044 | /* The body of the deallocator is here. */ |
1045 | #define Py_TRASHCAN_SAFE_END(op) \ |
1046 | --_tstate->trash_delete_nesting; \ |
1047 | if (_tstate->trash_delete_later && _tstate->trash_delete_nesting <= 0) \ |
1048 | _PyTrash_thread_destroy_chain(); \ |
1049 | } \ |
1050 | else \ |
1051 | _PyTrash_thread_deposit_object((PyObject*)op); \ |
1052 | } while (0); |
1053 | |
1054 | #ifndef Py_LIMITED_API |
1055 | PyAPI_FUNC(void) |
1056 | _PyDebugAllocatorStats(FILE *out, const char *block_name, int num_blocks, |
1057 | size_t sizeof_block); |
1058 | PyAPI_FUNC(void) |
1059 | _PyObject_DebugTypeStats(FILE *out); |
1060 | #endif /* ifndef Py_LIMITED_API */ |
1061 | |
1062 | #ifdef __cplusplus |
1063 | } |
1064 | #endif |
1065 | #endif /* !Py_OBJECT_H */ |
1066 | |