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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 #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  */
106 typedef struct _object {
107     PyObject_HEAD
108 } PyObject;
109 
110 typedef 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 /*
119 Type objects contain a string containing the type name (to help somewhat
120 in debugging), the allocation parameters (see PyObject_New() and
121 PyObject_NewVar()),
122 and methods for accessing objects of the type.  Methods are optional, a
123 nil pointer meaning that particular kind of access is not available for
124 this type.  The Py_DECREF() macro uses the tp_dealloc method without
125 checking for a nil pointer; it should always be implemented except if
126 the implementation can guarantee that the reference count will never
127 reach zero (e.g., for statically allocated type objects).
128 
129 NB: the methods for certain type groups are now contained in separate
130 method blocks.
131 */
132 
133 typedef PyObject * (*unaryfunc)(PyObject *);
134 typedef PyObject * (*binaryfunc)(PyObject *, PyObject *);
135 typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *);
136 typedef int (*inquiry)(PyObject *);
137 typedef Py_ssize_t (*lenfunc)(PyObject *);
138 typedef int (*coercion)(PyObject **, PyObject **);
139 typedef PyObject *(*intargfunc)(PyObject *, int) Py_DEPRECATED(2.5);
140 typedef PyObject *(*intintargfunc)(PyObject *, int, int) Py_DEPRECATED(2.5);
141 typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
142 typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t);
143 typedef int(*intobjargproc)(PyObject *, int, PyObject *);
144 typedef int(*intintobjargproc)(PyObject *, int, int, PyObject *);
145 typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *);
146 typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *);
147 typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *);
148 
149 
150 
151 /* int-based buffer interface */
152 typedef int (*getreadbufferproc)(PyObject *, int, void **);
153 typedef int (*getwritebufferproc)(PyObject *, int, void **);
154 typedef int (*getsegcountproc)(PyObject *, int *);
155 typedef int (*getcharbufferproc)(PyObject *, int, char **);
156 /* ssize_t-based buffer interface */
157 typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **);
158 typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **);
159 typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *);
160 typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **);
161 
162 
163 /* Py3k buffer interface */
164 typedef 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 
181 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
182 typedef 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 
215 typedef int (*objobjproc)(PyObject *, PyObject *);
216 typedef int (*visitproc)(PyObject *, void *);
217 typedef int (*traverseproc)(PyObject *, visitproc, void *);
218 
219 typedef 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 
275 typedef 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 
289 typedef struct {
290     lenfunc mp_length;
291     binaryfunc mp_subscript;
292     objobjargproc mp_ass_subscript;
293 } PyMappingMethods;
294 
295 typedef 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 
305 typedef void (*freefunc)(void *);
306 typedef void (*destructor)(PyObject *);
307 typedef int (*printfunc)(PyObject *, FILE *, int);
308 typedef PyObject *(*getattrfunc)(PyObject *, char *);
309 typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
310 typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
311 typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
312 typedef int (*cmpfunc)(PyObject *, PyObject *);
313 typedef PyObject *(*reprfunc)(PyObject *);
314 typedef long (*hashfunc)(PyObject *);
315 typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
316 typedef PyObject *(*getiterfunc) (PyObject *);
317 typedef PyObject *(*iternextfunc) (PyObject *);
318 typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
319 typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
320 typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
321 typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *);
322 typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t);
323 
324 typedef 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 */
415 typedef 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 */
437 PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
438 #define PyObject_TypeCheck(ob, tp) \
439     (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp)))
440 
441 PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
442 PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
443 PyAPI_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 
449 PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
450 PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
451 PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
452                                                PyObject *, PyObject *);
453 PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
454 PyAPI_FUNC(PyObject *) _PyObject_LookupSpecial(PyObject *, char *, PyObject **);
455 PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
456 PyAPI_FUNC(void) PyType_Modified(PyTypeObject *);
457 
458 /* Generic operations on objects */
459 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
460 PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
461 PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
462 PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *);
463 PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
464 #define PyObject_Bytes PyObject_Str
465 #ifdef Py_USING_UNICODE
466 PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *);
467 #endif
468 PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *);
469 PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
470 PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
471 PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
472 PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
473 PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
474 PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
475 PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
476 PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
477 PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *);
478 PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
479 PyAPI_FUNC(PyObject *) _PyObject_NextNotImplemented(PyObject *);
480 PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
481 PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
482                                               PyObject *, PyObject *);
483 PyAPI_FUNC(long) PyObject_Hash(PyObject *);
484 PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *);
485 PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
486 PyAPI_FUNC(int) PyObject_Not(PyObject *);
487 PyAPI_FUNC(int) PyCallable_Check(PyObject *);
488 PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **);
489 PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **);
490 
491 PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
492 
493 /* A slot function whose address we need to compare */
494 extern int _PyObject_SlotCompare(PyObject *, PyObject *);
495 /* Same as PyObject_Generic{Get,Set}Attr, but passing the attributes
496    dict as the last parameter. */
497 PyAPI_FUNC(PyObject *)
498 _PyObject_GenericGetAttrWithDict(PyObject *, PyObject *, PyObject *);
499 PyAPI_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 */
509 PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
510 
511 
512 /* Helpers for printing recursive container types */
513 PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
514 PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
515 
516 /* Helpers for hash functions */
517 PyAPI_FUNC(long) _Py_HashDouble(double);
518 PyAPI_FUNC(long) _Py_HashPointer(void*);
519 
520 typedef struct {
521     long prefix;
522     long suffix;
523 } _Py_HashSecret_t;
524 PyAPI_DATA(_Py_HashSecret_t) _Py_HashSecret;
525 
526 #ifdef Py_DEBUG
527 PyAPI_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 
541 These flags are used to extend the type structure in a backwards-compatible
542 fashion. Extensions can use the flags to indicate (and test) when a given
543 type structure contains a new feature. The Python core will use these when
544 introducing new functionality between major revisions (to avoid mid-version
545 changes in the PYTHON_API_VERSION).
546 
547 Arbitration of the flag bit positions will need to be coordinated among
548 all extension writers who publically release their extensions (this will
549 be fewer than you might expect!)..
550 
551 Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs.
552 
553 Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
554 
555 Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
556 given type object has a specified feature.
557 
558 NOTE: when building the core, Py_TPFLAGS_DEFAULT includes
559 Py_TPFLAGS_HAVE_VERSION_TAG; outside the core, it doesn't.  This is so
560 that extensions that modify tp_dict of their own types directly don't
561 break, since this was allowed in 2.5.  In 3.0 they will have to
562 manually 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 /*
664 The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
665 reference counts.  Py_DECREF calls the object's deallocator function when
666 the refcount falls to 0; for
667 objects that don't contain references to other objects or heap memory
668 this can be the standard function free().  Both macros can be used
669 wherever a void expression is allowed.  The argument must not be a
670 NULL pointer.  If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
671 The macro _Py_NewReference(op) initialize reference counts to 1, and
672 in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
673 bookkeeping appropriate to the special build.
674 
675 We assume that the reference count field can never overflow; this can
676 be proven when the size of the field is the same as the pointer size, so
677 we ignore the possibility.  Provided a C int is at least 32 bits (which
678 is implicitly assumed in many parts of this code), that's enough for
679 about 2**31 references to an object.
680 
681 XXX The following became out of date in Python 2.2, but I'm not sure
682 XXX what the full truth is now.  Certainly, heap-allocated type objects
683 XXX can and should be deallocated.
684 Type objects should never be deallocated; the type pointer in an object
685 is not considered to be a reference to the type object, to save
686 complications in the deallocation function.  (This is actually a
687 decision that's up to the implementer of each new type so if you want,
688 you can count such references to the type object.)
689 
690 *** WARNING*** The Py_DECREF macro must have a side-effect-free argument
691 since it may evaluate its argument multiple times.  (The alternative
692 would be to mace it a proper function or assign it to a global temporary
693 variable first, both of which are slower; and in a multi-threaded
694 environment 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
707 PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
708 PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname,
709                                             int lineno, PyObject *op);
710 PyAPI_FUNC(PyObject *) _PyDict_Dummy(void);
711 PyAPI_FUNC(PyObject *) _PySet_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 #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
729 PyAPI_FUNC(void) inc_count(PyTypeObject *);
730 PyAPI_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. */
744 PyAPI_FUNC(void) _Py_NewReference(PyObject *);
745 PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
746 PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
747 PyAPI_FUNC(void) _Py_PrintReferences(FILE *);
748 PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *);
749 PyAPI_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 /*
861 These are provided as conveniences to Python runtime embedders, so that
862 they can have object code that is not dependent on Python compilation flags.
863 */
864 PyAPI_FUNC(void) Py_IncRef(PyObject *);
865 PyAPI_FUNC(void) Py_DecRef(PyObject *);
866 
867 /*
868 _Py_NoneStruct is an object of undefined type which can be used in contexts
869 where NULL (nil) is not suitable (since NULL often means 'error').
870 
871 Don't forget to apply Py_INCREF() when returning this value!!!
872 */
873 PyAPI_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 /*
880 Py_NotImplemented is a singleton used to signal that an operation is
881 not implemented for a given type combination.
882 */
883 PyAPI_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  */
897 PyAPI_DATA(int) _Py_SwappedOp[];
898 
899 /*
900 Define staticforward and statichere for source compatibility with old
901 C extensions.
902 
903 The staticforward define was needed to support certain broken C
904 compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the
905 static keyword when it was used with a forward declaration of a static
906 initialized structure.  Standard C allows the forward declaration with
907 static, 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 /*
916 More conventions
917 ================
918 
919 Argument Checking
920 -----------------
921 
922 Functions that take objects as arguments normally don't check for nil
923 arguments, but they do check the type of the argument, and return an
924 error if the function doesn't apply to the type.
925 
926 Failure Modes
927 -------------
928 
929 Functions may fail for a variety of reasons, including running out of
930 memory.  This is communicated to the caller in two ways: an error string
931 is set (see errors.h), and the function result differs: functions that
932 normally return a pointer return NULL for failure, functions returning
933 an integer return -1 (which could be a legal return value too!), and
934 other functions return 0 for success and -1 for failure.
935 Callers should always check for errors before using the result.  If
936 an error was set, the caller must either explicitly clear it, or pass
937 the error on to its caller.
938 
939 Reference Counts
940 ----------------
941 
942 It takes a while to get used to the proper usage of reference counts.
943 
944 Functions that create an object set the reference count to 1; such new
945 objects must be stored somewhere or destroyed again with Py_DECREF().
946 Some functions that 'store' objects, such as PyTuple_SetItem() and
947 PyList_SetItem(),
948 don't increment the reference count of the object, since the most
949 frequent use is to store a fresh object.  Functions that 'retrieve'
950 objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
951 don't increment
952 the reference count, since most frequently the object is only looked at
953 quickly.  Thus, to retrieve an object and store it again, the caller
954 must call Py_INCREF() explicitly.
955 
956 NOTE: functions that 'consume' a reference count, like
957 PyList_SetItem(), consume the reference even if the object wasn't
958 successfully stored, to simplify error handling.
959 
960 It seems attractive to make other functions that take an object as
961 argument consume a reference count; however, this may quickly get
962 confusing (even the current practice is already confusing).  Consider
963 it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
964 times.
965 */
966 
967 
968 /* Trashcan mechanism, thanks to Christian Tismer.
969 
970 When deallocating a container object, it's possible to trigger an unbounded
971 chain of deallocations, as each Py_DECREF in turn drops the refcount on "the
972 next" object in the chain to 0.  This can easily lead to stack faults, and
973 especially in threads (which typically have less stack space to work with).
974 
975 A container object that participates in cyclic gc can avoid this by
976 bracketing the body of its tp_dealloc function with a pair of macros:
977 
978 static void
979 mytype_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 
990 CAUTION:  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
992 call, and goto it.  Else the call-depth counter (see below) will stay
993 above 0 forever, and the trashcan will never get emptied.
994 
995 How it works:  The BEGIN macro increments a call-depth counter.  So long
996 as this counter is small, the body of the deallocator is run directly without
997 further ado.  But if the counter gets large, it instead adds p to a list of
998 objects to be deallocated later, skips the body of the deallocator, and
999 resumes execution after the END macro.  The tp_dealloc routine then returns
1000 without deallocating anything (and so unbounded call-stack depth is avoided).
1001 
1002 When the call stack finishes unwinding again, code generated by the END macro
1003 notices this, and calls another routine to deallocate all the objects that
1004 may have been added to the list of deferred deallocations.  In effect, a
1005 chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces,
1006 with 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. */
1011 PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*);
1012 PyAPI_FUNC(void) _PyTrash_destroy_chain(void);
1013 PyAPI_DATA(int) _PyTrash_delete_nesting;
1014 PyAPI_DATA(PyObject *) _PyTrash_delete_later;
1015 
1016 /* The new thread-safe private API, invoked by the macros below. */
1017 PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*);
1018 PyAPI_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