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#define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj)) 532 533/* Flag bits for printing: */ 534#define Py_PRINT_RAW 1 /* No string quotes etc. */ 535 536/* 537`Type flags (tp_flags) 538 539These flags are used to extend the type structure in a backwards-compatible 540fashion. Extensions can use the flags to indicate (and test) when a given 541type structure contains a new feature. The Python core will use these when 542introducing new functionality between major revisions (to avoid mid-version 543changes in the PYTHON_API_VERSION). 544 545Arbitration of the flag bit positions will need to be coordinated among 546all extension writers who publically release their extensions (this will 547be fewer than you might expect!).. 548 549Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs. 550 551Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value. 552 553Code can use PyType_HasFeature(type_ob, flag_value) to test whether the 554given type object has a specified feature. 555 556NOTE: when building the core, Py_TPFLAGS_DEFAULT includes 557Py_TPFLAGS_HAVE_VERSION_TAG; outside the core, it doesn't. This is so 558that extensions that modify tp_dict of their own types directly don't 559break, since this was allowed in 2.5. In 3.0 they will have to 560manually remove this flag though! 561*/ 562 563/* PyBufferProcs contains bf_getcharbuffer */ 564#define Py_TPFLAGS_HAVE_GETCHARBUFFER (1L<<0) 565 566/* PySequenceMethods contains sq_contains */ 567#define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1) 568 569/* This is here for backwards compatibility. Extensions that use the old GC 570 * API will still compile but the objects will not be tracked by the GC. */ 571#define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */ 572 573/* PySequenceMethods and PyNumberMethods contain in-place operators */ 574#define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3) 575 576/* PyNumberMethods do their own coercion */ 577#define Py_TPFLAGS_CHECKTYPES (1L<<4) 578 579/* tp_richcompare is defined */ 580#define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5) 581 582/* Objects which are weakly referencable if their tp_weaklistoffset is >0 */ 583#define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6) 584 585/* tp_iter is defined */ 586#define Py_TPFLAGS_HAVE_ITER (1L<<7) 587 588/* New members introduced by Python 2.2 exist */ 589#define Py_TPFLAGS_HAVE_CLASS (1L<<8) 590 591/* Set if the type object is dynamically allocated */ 592#define Py_TPFLAGS_HEAPTYPE (1L<<9) 593 594/* Set if the type allows subclassing */ 595#define Py_TPFLAGS_BASETYPE (1L<<10) 596 597/* Set if the type is 'ready' -- fully initialized */ 598#define Py_TPFLAGS_READY (1L<<12) 599 600/* Set while the type is being 'readied', to prevent recursive ready calls */ 601#define Py_TPFLAGS_READYING (1L<<13) 602 603/* Objects support garbage collection (see objimp.h) */ 604#define Py_TPFLAGS_HAVE_GC (1L<<14) 605 606/* These two bits are preserved for Stackless Python, next after this is 17 */ 607#ifdef STACKLESS 608#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15) 609#else 610#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0 611#endif 612 613/* Objects support nb_index in PyNumberMethods */ 614#define Py_TPFLAGS_HAVE_INDEX (1L<<17) 615 616/* Objects support type attribute cache */ 617#define Py_TPFLAGS_HAVE_VERSION_TAG (1L<<18) 618#define Py_TPFLAGS_VALID_VERSION_TAG (1L<<19) 619 620/* Type is abstract and cannot be instantiated */ 621#define Py_TPFLAGS_IS_ABSTRACT (1L<<20) 622 623/* Has the new buffer protocol */ 624#define Py_TPFLAGS_HAVE_NEWBUFFER (1L<<21) 625 626/* These flags are used to determine if a type is a subclass. */ 627#define Py_TPFLAGS_INT_SUBCLASS (1L<<23) 628#define Py_TPFLAGS_LONG_SUBCLASS (1L<<24) 629#define Py_TPFLAGS_LIST_SUBCLASS (1L<<25) 630#define Py_TPFLAGS_TUPLE_SUBCLASS (1L<<26) 631#define Py_TPFLAGS_STRING_SUBCLASS (1L<<27) 632#define Py_TPFLAGS_UNICODE_SUBCLASS (1L<<28) 633#define Py_TPFLAGS_DICT_SUBCLASS (1L<<29) 634#define Py_TPFLAGS_BASE_EXC_SUBCLASS (1L<<30) 635#define Py_TPFLAGS_TYPE_SUBCLASS (1L<<31) 636 637#define Py_TPFLAGS_DEFAULT_EXTERNAL ( \ 638 Py_TPFLAGS_HAVE_GETCHARBUFFER | \ 639 Py_TPFLAGS_HAVE_SEQUENCE_IN | \ 640 Py_TPFLAGS_HAVE_INPLACEOPS | \ 641 Py_TPFLAGS_HAVE_RICHCOMPARE | \ 642 Py_TPFLAGS_HAVE_WEAKREFS | \ 643 Py_TPFLAGS_HAVE_ITER | \ 644 Py_TPFLAGS_HAVE_CLASS | \ 645 Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \ 646 Py_TPFLAGS_HAVE_INDEX | \ 647 0) 648#define Py_TPFLAGS_DEFAULT_CORE (Py_TPFLAGS_DEFAULT_EXTERNAL | \ 649 Py_TPFLAGS_HAVE_VERSION_TAG) 650 651#ifdef Py_BUILD_CORE 652#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_CORE 653#else 654#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_EXTERNAL 655#endif 656 657#define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0) 658#define PyType_FastSubclass(t,f) PyType_HasFeature(t,f) 659 660 661/* 662The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement 663reference counts. Py_DECREF calls the object's deallocator function when 664the refcount falls to 0; for 665objects that don't contain references to other objects or heap memory 666this can be the standard function free(). Both macros can be used 667wherever a void expression is allowed. The argument must not be a 668NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead. 669The macro _Py_NewReference(op) initialize reference counts to 1, and 670in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional 671bookkeeping appropriate to the special build. 672 673We assume that the reference count field can never overflow; this can 674be proven when the size of the field is the same as the pointer size, so 675we ignore the possibility. Provided a C int is at least 32 bits (which 676is implicitly assumed in many parts of this code), that's enough for 677about 2**31 references to an object. 678 679XXX The following became out of date in Python 2.2, but I'm not sure 680XXX what the full truth is now. Certainly, heap-allocated type objects 681XXX can and should be deallocated. 682Type objects should never be deallocated; the type pointer in an object 683is not considered to be a reference to the type object, to save 684complications in the deallocation function. (This is actually a 685decision that's up to the implementer of each new type so if you want, 686you can count such references to the type object.) 687 688*** WARNING*** The Py_DECREF macro must have a side-effect-free argument 689since it may evaluate its argument multiple times. (The alternative 690would be to mace it a proper function or assign it to a global temporary 691variable first, both of which are slower; and in a multi-threaded 692environment the global variable trick is not safe.) 693*/ 694 695/* First define a pile of simple helper macros, one set per special 696 * build symbol. These either expand to the obvious things, or to 697 * nothing at all when the special mode isn't in effect. The main 698 * macros can later be defined just once then, yet expand to different 699 * things depending on which special build options are and aren't in effect. 700 * Trust me <wink>: while painful, this is 20x easier to understand than, 701 * e.g, defining _Py_NewReference five different times in a maze of nested 702 * #ifdefs (we used to do that -- it was impenetrable). 703 */ 704#ifdef Py_REF_DEBUG 705PyAPI_DATA(Py_ssize_t) _Py_RefTotal; 706PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname, 707 int lineno, PyObject *op); 708PyAPI_FUNC(PyObject *) _PyDict_Dummy(void); 709PyAPI_FUNC(PyObject *) _PySet_Dummy(void); 710PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void); 711#define _Py_INC_REFTOTAL _Py_RefTotal++ 712#define _Py_DEC_REFTOTAL _Py_RefTotal-- 713#define _Py_REF_DEBUG_COMMA , 714#define _Py_CHECK_REFCNT(OP) \ 715{ if (((PyObject*)OP)->ob_refcnt < 0) \ 716 _Py_NegativeRefcount(__FILE__, __LINE__, \ 717 (PyObject *)(OP)); \ 718} 719#else 720#define _Py_INC_REFTOTAL 721#define _Py_DEC_REFTOTAL 722#define _Py_REF_DEBUG_COMMA 723#define _Py_CHECK_REFCNT(OP) /* a semicolon */; 724#endif /* Py_REF_DEBUG */ 725 726#ifdef COUNT_ALLOCS 727PyAPI_FUNC(void) inc_count(PyTypeObject *); 728PyAPI_FUNC(void) dec_count(PyTypeObject *); 729#define _Py_INC_TPALLOCS(OP) inc_count(Py_TYPE(OP)) 730#define _Py_INC_TPFREES(OP) dec_count(Py_TYPE(OP)) 731#define _Py_DEC_TPFREES(OP) Py_TYPE(OP)->tp_frees-- 732#define _Py_COUNT_ALLOCS_COMMA , 733#else 734#define _Py_INC_TPALLOCS(OP) 735#define _Py_INC_TPFREES(OP) 736#define _Py_DEC_TPFREES(OP) 737#define _Py_COUNT_ALLOCS_COMMA 738#endif /* COUNT_ALLOCS */ 739 740#ifdef Py_TRACE_REFS 741/* Py_TRACE_REFS is such major surgery that we call external routines. */ 742PyAPI_FUNC(void) _Py_NewReference(PyObject *); 743PyAPI_FUNC(void) _Py_ForgetReference(PyObject *); 744PyAPI_FUNC(void) _Py_Dealloc(PyObject *); 745PyAPI_FUNC(void) _Py_PrintReferences(FILE *); 746PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *); 747PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force); 748 749#else 750/* Without Py_TRACE_REFS, there's little enough to do that we expand code 751 * inline. 752 */ 753#define _Py_NewReference(op) ( \ 754 _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \ 755 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ 756 Py_REFCNT(op) = 1) 757 758#define _Py_ForgetReference(op) _Py_INC_TPFREES(op) 759 760#define _Py_Dealloc(op) ( \ 761 _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \ 762 (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op))) 763#endif /* !Py_TRACE_REFS */ 764 765#define Py_INCREF(op) ( \ 766 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ 767 ((PyObject*)(op))->ob_refcnt++) 768 769#define Py_DECREF(op) \ 770 do { \ 771 if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \ 772 --((PyObject*)(op))->ob_refcnt != 0) \ 773 _Py_CHECK_REFCNT(op) \ 774 else \ 775 _Py_Dealloc((PyObject *)(op)); \ 776 } while (0) 777 778/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear 779 * and tp_dealloc implementatons. 780 * 781 * Note that "the obvious" code can be deadly: 782 * 783 * Py_XDECREF(op); 784 * op = NULL; 785 * 786 * Typically, `op` is something like self->containee, and `self` is done 787 * using its `containee` member. In the code sequence above, suppose 788 * `containee` is non-NULL with a refcount of 1. Its refcount falls to 789 * 0 on the first line, which can trigger an arbitrary amount of code, 790 * possibly including finalizers (like __del__ methods or weakref callbacks) 791 * coded in Python, which in turn can release the GIL and allow other threads 792 * to run, etc. Such code may even invoke methods of `self` again, or cause 793 * cyclic gc to trigger, but-- oops! --self->containee still points to the 794 * object being torn down, and it may be in an insane state while being torn 795 * down. This has in fact been a rich historic source of miserable (rare & 796 * hard-to-diagnose) segfaulting (and other) bugs. 797 * 798 * The safe way is: 799 * 800 * Py_CLEAR(op); 801 * 802 * That arranges to set `op` to NULL _before_ decref'ing, so that any code 803 * triggered as a side-effect of `op` getting torn down no longer believes 804 * `op` points to a valid object. 805 * 806 * There are cases where it's safe to use the naive code, but they're brittle. 807 * For example, if `op` points to a Python integer, you know that destroying 808 * one of those can't cause problems -- but in part that relies on that 809 * Python integers aren't currently weakly referencable. Best practice is 810 * to use Py_CLEAR() even if you can't think of a reason for why you need to. 811 */ 812#define Py_CLEAR(op) \ 813 do { \ 814 if (op) { \ 815 PyObject *_py_tmp = (PyObject *)(op); \ 816 (op) = NULL; \ 817 Py_DECREF(_py_tmp); \ 818 } \ 819 } while (0) 820 821/* Macros to use in case the object pointer may be NULL: */ 822#define Py_XINCREF(op) do { if ((op) == NULL) ; else Py_INCREF(op); } while (0) 823#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0) 824 825/* 826These are provided as conveniences to Python runtime embedders, so that 827they can have object code that is not dependent on Python compilation flags. 828*/ 829PyAPI_FUNC(void) Py_IncRef(PyObject *); 830PyAPI_FUNC(void) Py_DecRef(PyObject *); 831 832/* 833_Py_NoneStruct is an object of undefined type which can be used in contexts 834where NULL (nil) is not suitable (since NULL often means 'error'). 835 836Don't forget to apply Py_INCREF() when returning this value!!! 837*/ 838PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */ 839#define Py_None (&_Py_NoneStruct) 840 841/* Macro for returning Py_None from a function */ 842#define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None 843 844/* 845Py_NotImplemented is a singleton used to signal that an operation is 846not implemented for a given type combination. 847*/ 848PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */ 849#define Py_NotImplemented (&_Py_NotImplementedStruct) 850 851/* Rich comparison opcodes */ 852#define Py_LT 0 853#define Py_LE 1 854#define Py_EQ 2 855#define Py_NE 3 856#define Py_GT 4 857#define Py_GE 5 858 859/* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE. 860 * Defined in object.c. 861 */ 862PyAPI_DATA(int) _Py_SwappedOp[]; 863 864/* 865Define staticforward and statichere for source compatibility with old 866C extensions. 867 868The staticforward define was needed to support certain broken C 869compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the 870static keyword when it was used with a forward declaration of a static 871initialized structure. Standard C allows the forward declaration with 872static, and we've decided to stop catering to broken C compilers. 873(In fact, we expect that the compilers are all fixed eight years later.) 874*/ 875 876#define staticforward static 877#define statichere static 878 879 880/* 881More conventions 882================ 883 884Argument Checking 885----------------- 886 887Functions that take objects as arguments normally don't check for nil 888arguments, but they do check the type of the argument, and return an 889error if the function doesn't apply to the type. 890 891Failure Modes 892------------- 893 894Functions may fail for a variety of reasons, including running out of 895memory. This is communicated to the caller in two ways: an error string 896is set (see errors.h), and the function result differs: functions that 897normally return a pointer return NULL for failure, functions returning 898an integer return -1 (which could be a legal return value too!), and 899other functions return 0 for success and -1 for failure. 900Callers should always check for errors before using the result. If 901an error was set, the caller must either explicitly clear it, or pass 902the error on to its caller. 903 904Reference Counts 905---------------- 906 907It takes a while to get used to the proper usage of reference counts. 908 909Functions that create an object set the reference count to 1; such new 910objects must be stored somewhere or destroyed again with Py_DECREF(). 911Some functions that 'store' objects, such as PyTuple_SetItem() and 912PyList_SetItem(), 913don't increment the reference count of the object, since the most 914frequent use is to store a fresh object. Functions that 'retrieve' 915objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also 916don't increment 917the reference count, since most frequently the object is only looked at 918quickly. Thus, to retrieve an object and store it again, the caller 919must call Py_INCREF() explicitly. 920 921NOTE: functions that 'consume' a reference count, like 922PyList_SetItem(), consume the reference even if the object wasn't 923successfully stored, to simplify error handling. 924 925It seems attractive to make other functions that take an object as 926argument consume a reference count; however, this may quickly get 927confusing (even the current practice is already confusing). Consider 928it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at 929times. 930*/ 931 932 933/* Trashcan mechanism, thanks to Christian Tismer. 934 935When deallocating a container object, it's possible to trigger an unbounded 936chain of deallocations, as each Py_DECREF in turn drops the refcount on "the 937next" object in the chain to 0. This can easily lead to stack faults, and 938especially in threads (which typically have less stack space to work with). 939 940A container object that participates in cyclic gc can avoid this by 941bracketing the body of its tp_dealloc function with a pair of macros: 942 943static void 944mytype_dealloc(mytype *p) 945{ 946 ... declarations go here ... 947 948 PyObject_GC_UnTrack(p); // must untrack first 949 Py_TRASHCAN_SAFE_BEGIN(p) 950 ... The body of the deallocator goes here, including all calls ... 951 ... to Py_DECREF on contained objects. ... 952 Py_TRASHCAN_SAFE_END(p) 953} 954 955CAUTION: Never return from the middle of the body! If the body needs to 956"get out early", put a label immediately before the Py_TRASHCAN_SAFE_END 957call, and goto it. Else the call-depth counter (see below) will stay 958above 0 forever, and the trashcan will never get emptied. 959 960How it works: The BEGIN macro increments a call-depth counter. So long 961as this counter is small, the body of the deallocator is run directly without 962further ado. But if the counter gets large, it instead adds p to a list of 963objects to be deallocated later, skips the body of the deallocator, and 964resumes execution after the END macro. The tp_dealloc routine then returns 965without deallocating anything (and so unbounded call-stack depth is avoided). 966 967When the call stack finishes unwinding again, code generated by the END macro 968notices this, and calls another routine to deallocate all the objects that 969may have been added to the list of deferred deallocations. In effect, a 970chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces, 971with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. 972*/ 973 974/* This is the old private API, invoked by the macros before 2.7.4. 975 Kept for binary compatibility of extensions. */ 976PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); 977PyAPI_FUNC(void) _PyTrash_destroy_chain(void); 978PyAPI_DATA(int) _PyTrash_delete_nesting; 979PyAPI_DATA(PyObject *) _PyTrash_delete_later; 980 981/* The new thread-safe private API, invoked by the macros below. */ 982PyAPI_FUNC(void) _PyTrash_thread_deposit_object(PyObject*); 983PyAPI_FUNC(void) _PyTrash_thread_destroy_chain(void); 984 985#define PyTrash_UNWIND_LEVEL 50 986 987/* Note the workaround for when the thread state is NULL (issue #17703) */ 988#define Py_TRASHCAN_SAFE_BEGIN(op) \ 989 do { \ 990 PyThreadState *_tstate = PyThreadState_GET(); \ 991 if (!_tstate || \ 992 _tstate->trash_delete_nesting < PyTrash_UNWIND_LEVEL) { \ 993 if (_tstate) \ 994 ++_tstate->trash_delete_nesting; 995 /* The body of the deallocator is here. */ 996#define Py_TRASHCAN_SAFE_END(op) \ 997 if (_tstate) { \ 998 --_tstate->trash_delete_nesting; \ 999 if (_tstate->trash_delete_later \ 1000 && _tstate->trash_delete_nesting <= 0) \ 1001 _PyTrash_thread_destroy_chain(); \ 1002 } \ 1003 } \ 1004 else \ 1005 _PyTrash_thread_deposit_object((PyObject*)op); \ 1006 } while (0); 1007 1008#ifdef __cplusplus 1009} 1010#endif 1011#endif /* !Py_OBJECT_H */ 1012