/Include/object.h
C++ Header | 981 lines | 470 code | 129 blank | 382 comment | 21 complexity | b6abdc3f0dd97130f96f41b732822b4c MD5 | raw file
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. Keep 78 this in sync with Util/PyTypeBuilder.h. */ 79#define PyObject_HEAD \ 80 _PyObject_HEAD_EXTRA \ 81 Py_ssize_t ob_refcnt; \ 82 struct _typeobject *ob_type; 83 84#define PyObject_HEAD_INIT(type) \ 85 _PyObject_EXTRA_INIT \ 86 1, type, 87 88#define PyVarObject_HEAD_INIT(type, size) \ 89 PyObject_HEAD_INIT(type) size, 90 91/* PyObject_VAR_HEAD defines the initial segment of all variable-size 92 * container objects. These end with a declaration of an array with 1 93 * element, but enough space is malloc'ed so that the array actually 94 * has room for ob_size elements. Note that ob_size is an element count, 95 * not necessarily a byte count. 96 */ 97#define PyObject_VAR_HEAD \ 98 PyObject_HEAD \ 99 Py_ssize_t ob_size; /* Number of items in variable part */ 100#define Py_INVALID_SIZE (Py_ssize_t)-1 101 102/* Nothing is actually declared to be a PyObject, but every pointer to 103 * a Python object can be cast to a PyObject*. This is inheritance built 104 * by hand. Similarly every pointer to a variable-size Python object can, 105 * in addition, be cast to PyVarObject*. 106 */ 107typedef struct _object { 108 PyObject_HEAD 109} PyObject; 110 111typedef struct PyVarObject { 112 PyObject_VAR_HEAD 113} PyVarObject; 114 115#define Py_REFCNT(ob) (((PyObject*)(ob))->ob_refcnt) 116#define Py_TYPE(ob) (((PyObject*)(ob))->ob_type) 117#define Py_SIZE(ob) (((PyVarObject*)(ob))->ob_size) 118 119/* 120Type objects contain a string containing the type name (to help somewhat 121in debugging), the allocation parameters (see PyObject_New() and 122PyObject_NewVar()), 123and methods for accessing objects of the type. Methods are optional, a 124nil pointer meaning that particular kind of access is not available for 125this type. The Py_DECREF() macro uses the tp_dealloc method without 126checking for a nil pointer; it should always be implemented except if 127the implementation can guarantee that the reference count will never 128reach zero (e.g., for statically allocated type objects). 129 130NB: the methods for certain type groups are now contained in separate 131method blocks. 132*/ 133 134typedef PyObject * (*unaryfunc)(PyObject *); 135typedef PyObject * (*binaryfunc)(PyObject *, PyObject *); 136typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *); 137typedef int (*inquiry)(PyObject *); 138typedef Py_ssize_t (*lenfunc)(PyObject *); 139typedef int (*coercion)(PyObject **, PyObject **); 140typedef PyObject *(*intargfunc)(PyObject *, int) Py_DEPRECATED(2.5); 141typedef PyObject *(*intintargfunc)(PyObject *, int, int) Py_DEPRECATED(2.5); 142typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t); 143typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t); 144typedef int(*intobjargproc)(PyObject *, int, PyObject *); 145typedef int(*intintobjargproc)(PyObject *, int, int, PyObject *); 146typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *); 147typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *); 148typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *); 149 150 151 152/* int-based buffer interface */ 153typedef int (*getreadbufferproc)(PyObject *, int, void **); 154typedef int (*getwritebufferproc)(PyObject *, int, void **); 155typedef int (*getsegcountproc)(PyObject *, int *); 156typedef int (*getcharbufferproc)(PyObject *, int, char **); 157/* ssize_t-based buffer interface */ 158typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **); 159typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **); 160typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *); 161typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **); 162 163/* Py3k buffer interface */ 164 165typedef struct bufferinfo { 166 void *buf; 167 PyObject *obj; /* borrowed reference */ 168 Py_ssize_t len; 169 Py_ssize_t itemsize; /* This is Py_ssize_t so it can be 170 pointed to by strides in simple case.*/ 171 int readonly; 172 int ndim; 173 char *format; 174 Py_ssize_t *shape; 175 Py_ssize_t *strides; 176 Py_ssize_t *suboffsets; 177 void *internal; 178} Py_buffer; 179 180typedef int (*getbufferproc)(PyObject *, Py_buffer *, int); 181typedef void (*releasebufferproc)(PyObject *, Py_buffer *); 182 183 /* Flags for getting buffers */ 184#define PyBUF_SIMPLE 0 185#define PyBUF_WRITABLE 0x0001 186/* we used to include an E, backwards compatible alias */ 187#define PyBUF_WRITEABLE PyBUF_WRITABLE 188#define PyBUF_FORMAT 0x0004 189#define PyBUF_ND 0x0008 190#define PyBUF_STRIDES (0x0010 | PyBUF_ND) 191#define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES) 192#define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES) 193#define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES) 194#define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES) 195 196#define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE) 197#define PyBUF_CONTIG_RO (PyBUF_ND) 198 199#define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE) 200#define PyBUF_STRIDED_RO (PyBUF_STRIDES) 201 202#define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT) 203#define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT) 204 205#define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT) 206#define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT) 207 208 209#define PyBUF_READ 0x100 210#define PyBUF_WRITE 0x200 211#define PyBUF_SHADOW 0x400 212/* end Py3k buffer interface */ 213 214typedef int (*objobjproc)(PyObject *, PyObject *); 215typedef int (*visitproc)(PyObject *, void *); 216typedef int (*traverseproc)(PyObject *, visitproc, void *); 217 218typedef struct PyNumberMethods { 219 /* For numbers without flag bit Py_TPFLAGS_CHECKTYPES set, all 220 arguments are guaranteed to be of the object's type (modulo 221 coercion hacks -- i.e. if the type's coercion function 222 returns other types, then these are allowed as well). Numbers that 223 have the Py_TPFLAGS_CHECKTYPES flag bit set should check *both* 224 arguments for proper type and implement the necessary conversions 225 in the slot functions themselves. */ 226 227 binaryfunc nb_add; 228 binaryfunc nb_subtract; 229 binaryfunc nb_multiply; 230 binaryfunc nb_divide; 231 binaryfunc nb_remainder; 232 binaryfunc nb_divmod; 233 ternaryfunc nb_power; 234 unaryfunc nb_negative; 235 unaryfunc nb_positive; 236 unaryfunc nb_absolute; 237 inquiry nb_nonzero; 238 unaryfunc nb_invert; 239 binaryfunc nb_lshift; 240 binaryfunc nb_rshift; 241 binaryfunc nb_and; 242 binaryfunc nb_xor; 243 binaryfunc nb_or; 244 coercion nb_coerce; 245 unaryfunc nb_int; 246 unaryfunc nb_long; 247 unaryfunc nb_float; 248 unaryfunc nb_oct; 249 unaryfunc nb_hex; 250 /* Added in release 2.0 */ 251 binaryfunc nb_inplace_add; 252 binaryfunc nb_inplace_subtract; 253 binaryfunc nb_inplace_multiply; 254 binaryfunc nb_inplace_divide; 255 binaryfunc nb_inplace_remainder; 256 ternaryfunc nb_inplace_power; 257 binaryfunc nb_inplace_lshift; 258 binaryfunc nb_inplace_rshift; 259 binaryfunc nb_inplace_and; 260 binaryfunc nb_inplace_xor; 261 binaryfunc nb_inplace_or; 262 263 /* Added in release 2.2 */ 264 /* The following require the Py_TPFLAGS_HAVE_CLASS flag */ 265 binaryfunc nb_floor_divide; 266 binaryfunc nb_true_divide; 267 binaryfunc nb_inplace_floor_divide; 268 binaryfunc nb_inplace_true_divide; 269 270 /* Added in release 2.5 */ 271 unaryfunc nb_index; 272} PyNumberMethods; 273 274typedef struct PySequenceMethods { 275 lenfunc sq_length; 276 binaryfunc sq_concat; 277 ssizeargfunc sq_repeat; 278 ssizeargfunc sq_item; 279 ssizessizeargfunc sq_slice; 280 ssizeobjargproc sq_ass_item; 281 ssizessizeobjargproc sq_ass_slice; 282 objobjproc sq_contains; 283 /* Added in release 2.0 */ 284 binaryfunc sq_inplace_concat; 285 ssizeargfunc sq_inplace_repeat; 286} PySequenceMethods; 287 288typedef struct PyMappingMethods { 289 lenfunc mp_length; 290 binaryfunc mp_subscript; 291 objobjargproc mp_ass_subscript; 292} PyMappingMethods; 293 294typedef struct PyBufferProcs { 295 readbufferproc bf_getreadbuffer; 296 writebufferproc bf_getwritebuffer; 297 segcountproc bf_getsegcount; 298 charbufferproc bf_getcharbuffer; 299 getbufferproc bf_getbuffer; 300 releasebufferproc bf_releasebuffer; 301} PyBufferProcs; 302 303 304typedef void (*freefunc)(void *); 305typedef void (*destructor)(PyObject *); 306typedef int (*printfunc)(PyObject *, FILE *, int); 307typedef PyObject *(*getattrfunc)(PyObject *, char *); 308typedef PyObject *(*getattrofunc)(PyObject *, PyObject *); 309typedef int (*setattrfunc)(PyObject *, char *, PyObject *); 310typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *); 311typedef int (*cmpfunc)(PyObject *, PyObject *); 312typedef PyObject *(*reprfunc)(PyObject *); 313typedef long (*hashfunc)(PyObject *); 314typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int); 315typedef PyObject *(*getiterfunc) (PyObject *); 316typedef PyObject *(*iternextfunc) (PyObject *); 317typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *); 318typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *); 319typedef int (*initproc)(PyObject *, PyObject *, PyObject *); 320typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *); 321typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t); 322 323typedef struct _typeobject { 324 PyObject_VAR_HEAD 325 const char *tp_name; /* For printing, in format "<module>.<name>" */ 326 Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */ 327 328 /* Methods to implement standard operations */ 329 330 destructor tp_dealloc; 331 printfunc tp_print; 332 getattrfunc tp_getattr; 333 setattrfunc tp_setattr; 334 cmpfunc tp_compare; 335 reprfunc tp_repr; 336 337 /* Method suites for standard classes */ 338 339 PyNumberMethods *tp_as_number; 340 PySequenceMethods *tp_as_sequence; 341 PyMappingMethods *tp_as_mapping; 342 343 /* More standard operations (here for binary compatibility) */ 344 345 hashfunc tp_hash; 346 ternaryfunc tp_call; 347 reprfunc tp_str; 348 getattrofunc tp_getattro; 349 setattrofunc tp_setattro; 350 351 /* Functions to access object as input/output buffer */ 352 PyBufferProcs *tp_as_buffer; 353 354 /* Flags to define presence of optional/expanded features */ 355 long tp_flags; 356 357 const char *tp_doc; /* Documentation string */ 358 359 /* Assigned meaning in release 2.0 */ 360 /* call function for all accessible objects */ 361 traverseproc tp_traverse; 362 363 /* delete references to contained objects */ 364 inquiry tp_clear; 365 366 /* Assigned meaning in release 2.1 */ 367 /* rich comparisons */ 368 richcmpfunc tp_richcompare; 369 370 /* weak reference enabler */ 371 Py_ssize_t tp_weaklistoffset; 372 373 /* Added in release 2.2 */ 374 /* Iterators */ 375 getiterfunc tp_iter; 376 iternextfunc tp_iternext; 377 378 /* Attribute descriptor and subclassing stuff */ 379 struct PyMethodDef *tp_methods; 380 struct PyMemberDef *tp_members; 381 struct PyGetSetDef *tp_getset; 382 struct _typeobject *tp_base; 383 PyObject *tp_dict; 384 descrgetfunc tp_descr_get; 385 descrsetfunc tp_descr_set; 386 Py_ssize_t tp_dictoffset; 387 initproc tp_init; 388 allocfunc tp_alloc; 389 newfunc tp_new; 390 freefunc tp_free; /* Low-level free-memory routine */ 391 inquiry tp_is_gc; /* For PyObject_IS_GC */ 392 PyObject *tp_bases; 393 PyObject *tp_mro; /* method resolution order */ 394 PyObject *tp_cache; 395 PyObject *tp_subclasses; 396 PyObject *tp_weaklist; 397 destructor tp_del; 398 399 /* Type attribute cache version tag. Added in version 2.6 */ 400 unsigned int tp_version_tag; 401 402 /* A list of weakrefs to code objects listening for modifications. 403 Added in Unladen. */ 404 PyObject *tp_code_listeners; 405 406#ifdef COUNT_ALLOCS 407 /* these must be last and never explicitly initialized */ 408 Py_ssize_t tp_allocs; 409 Py_ssize_t tp_frees; 410 Py_ssize_t tp_maxalloc; 411 struct _typeobject *tp_prev; 412 struct _typeobject *tp_next; 413#endif 414} PyTypeObject; 415 416 417/* The *real* layout of a type object when allocated on the heap */ 418typedef struct _heaptypeobject { 419 /* Note: there's a dependency on the order of these members 420 in slotptr() in typeobject.c . */ 421 PyTypeObject ht_type; 422 PyNumberMethods as_number; 423 PyMappingMethods as_mapping; 424 PySequenceMethods as_sequence; /* as_sequence comes after as_mapping, 425 so that the mapping wins when both 426 the mapping and the sequence define 427 a given operator (e.g. __getitem__). 428 see add_operators() in typeobject.c . */ 429 PyBufferProcs as_buffer; 430 PyObject *ht_name, *ht_slots; 431 /* here are optional user slots, followed by the members. */ 432} PyHeapTypeObject; 433 434/* access macro to the members which are floating "behind" the object */ 435#define PyHeapType_GET_MEMBERS(etype) \ 436 ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize)) 437 438 439/* Generic type check */ 440PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *); 441#define PyObject_TypeCheck(ob, tp) \ 442 (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp))) 443 444PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */ 445PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */ 446PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */ 447 448#define PyType_Check(op) \ 449 PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS) 450#define PyType_CheckExact(op) (Py_TYPE(op) == &PyType_Type) 451 452PyAPI_FUNC(int) PyType_Ready(PyTypeObject *); 453PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t); 454PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *, 455 PyObject *, PyObject *); 456PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *); 457PyAPI_FUNC(unsigned int) PyType_ClearCache(void); 458PyAPI_FUNC(void) PyType_Modified(PyTypeObject *); 459PyAPI_FUNC(int) _PyType_AddCodeListener(PyTypeObject *type, PyObject *code); 460 461/* Generic operations on objects */ 462PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int); 463PyAPI_FUNC(void) _PyObject_Dump(PyObject *); 464PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *); 465PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *); 466PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *); 467#define PyObject_Bytes PyObject_Str 468#ifdef Py_USING_UNICODE 469PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *); 470#endif 471PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *); 472PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int); 473PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int); 474PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *); 475PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *); 476PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *); 477PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *); 478PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *); 479PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *); 480PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *); 481PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *); 482PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *); 483PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, 484 PyObject *, PyObject *); 485PyAPI_FUNC(long) PyObject_Hash(PyObject *); 486PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *); 487PyAPI_FUNC(int) PyObject_IsTrue(PyObject *); 488PyAPI_FUNC(int) PyObject_Not(PyObject *); 489PyAPI_FUNC(int) PyCallable_Check(PyObject *); 490PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **); 491PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **); 492PyAPI_FUNC(int) _PyObject_ShouldBindMethod(PyObject *, PyObject *); 493PyAPI_FUNC(PyObject *) PyObject_GetMethod(PyObject *, PyObject *); 494 495PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *); 496 497/* A slot function whose address we need to compare */ 498extern int _PyObject_SlotCompare(PyObject *, PyObject *); 499 500 501/* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a 502 list of strings. PyObject_Dir(NULL) is like __builtin__.dir(), 503 returning the names of the current locals. In this case, if there are 504 no current locals, NULL is returned, and PyErr_Occurred() is false. 505*/ 506PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *); 507 508 509/* Helpers for printing recursive container types */ 510PyAPI_FUNC(int) Py_ReprEnter(PyObject *); 511PyAPI_FUNC(void) Py_ReprLeave(PyObject *); 512 513/* Helpers for hash functions */ 514PyAPI_FUNC(long) _Py_HashDouble(double); 515PyAPI_FUNC(long) _Py_HashPointer(void*); 516 517/* Helper for passing objects to printf and the like */ 518#define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj)) 519 520/* Flag bits for printing: */ 521#define Py_PRINT_RAW 1 /* No string quotes etc. */ 522 523/* 524`Type flags (tp_flags) 525 526These flags are used to extend the type structure in a backwards-compatible 527fashion. Extensions can use the flags to indicate (and test) when a given 528type structure contains a new feature. The Python core will use these when 529introducing new functionality between major revisions (to avoid mid-version 530changes in the PYTHON_API_VERSION). 531 532Arbitration of the flag bit positions will need to be coordinated among 533all extension writers who publically release their extensions (this will 534be fewer than you might expect!).. 535 536Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs. 537 538Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value. 539 540Code can use PyType_HasFeature(type_ob, flag_value) to test whether the 541given type object has a specified feature. 542 543NOTE: when building the core, Py_TPFLAGS_DEFAULT includes 544Py_TPFLAGS_HAVE_VERSION_TAG; outside the core, it doesn't. This is so 545that extensions that modify tp_dict of their own types directly don't 546break, since this was allowed in 2.5. In 3.0 they will have to 547manually remove this flag though! 548*/ 549 550/* PyBufferProcs contains bf_getcharbuffer */ 551#define Py_TPFLAGS_HAVE_GETCHARBUFFER (1L<<0) 552 553/* PySequenceMethods contains sq_contains */ 554#define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1) 555 556/* This is here for backwards compatibility. Extensions that use the old GC 557 * API will still compile but the objects will not be tracked by the GC. */ 558#define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */ 559 560/* PySequenceMethods and PyNumberMethods contain in-place operators */ 561#define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3) 562 563/* PyNumberMethods do their own coercion */ 564#define Py_TPFLAGS_CHECKTYPES (1L<<4) 565 566/* tp_richcompare is defined */ 567#define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5) 568 569/* Objects which are weakly referencable if their tp_weaklistoffset is >0 */ 570#define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6) 571 572/* tp_iter is defined */ 573#define Py_TPFLAGS_HAVE_ITER (1L<<7) 574 575/* New members introduced by Python 2.2 exist */ 576#define Py_TPFLAGS_HAVE_CLASS (1L<<8) 577 578/* Set if the type object is dynamically allocated */ 579#define Py_TPFLAGS_HEAPTYPE (1L<<9) 580 581/* Set if the type allows subclassing */ 582#define Py_TPFLAGS_BASETYPE (1L<<10) 583 584/* Set if the type is 'ready' -- fully initialized */ 585#define Py_TPFLAGS_READY (1L<<12) 586 587/* Set while the type is being 'readied', to prevent recursive ready calls */ 588#define Py_TPFLAGS_READYING (1L<<13) 589 590/* Objects support garbage collection (see objimp.h) */ 591#define Py_TPFLAGS_HAVE_GC (1L<<14) 592 593/* These two bits are preserved for Stackless Python, next after this is 17 */ 594#ifdef STACKLESS 595#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15) 596#else 597#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0 598#endif 599 600/* Objects support nb_index in PyNumberMethods */ 601#define Py_TPFLAGS_HAVE_INDEX (1L<<17) 602 603/* Objects support type attribute cache */ 604#define Py_TPFLAGS_HAVE_VERSION_TAG (1L<<18) 605#define Py_TPFLAGS_VALID_VERSION_TAG (1L<<19) 606 607/* Type is abstract and cannot be instantiated */ 608#define Py_TPFLAGS_IS_ABSTRACT (1L<<20) 609 610/* Has the new buffer protocol */ 611#define Py_TPFLAGS_HAVE_NEWBUFFER (1L<<21) 612 613/* These flags are used to determine if a type is a subclass. */ 614#define Py_TPFLAGS_INT_SUBCLASS (1L<<23) 615#define Py_TPFLAGS_LONG_SUBCLASS (1L<<24) 616#define Py_TPFLAGS_LIST_SUBCLASS (1L<<25) 617#define Py_TPFLAGS_TUPLE_SUBCLASS (1L<<26) 618#define Py_TPFLAGS_STRING_SUBCLASS (1L<<27) 619#define Py_TPFLAGS_UNICODE_SUBCLASS (1L<<28) 620#define Py_TPFLAGS_DICT_SUBCLASS (1L<<29) 621#define Py_TPFLAGS_BASE_EXC_SUBCLASS (1L<<30) 622#define Py_TPFLAGS_TYPE_SUBCLASS (1L<<31) 623 624#define Py_TPFLAGS_DEFAULT_EXTERNAL ( \ 625 Py_TPFLAGS_HAVE_GETCHARBUFFER | \ 626 Py_TPFLAGS_HAVE_SEQUENCE_IN | \ 627 Py_TPFLAGS_HAVE_INPLACEOPS | \ 628 Py_TPFLAGS_HAVE_RICHCOMPARE | \ 629 Py_TPFLAGS_HAVE_WEAKREFS | \ 630 Py_TPFLAGS_HAVE_ITER | \ 631 Py_TPFLAGS_HAVE_CLASS | \ 632 Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \ 633 Py_TPFLAGS_HAVE_INDEX | \ 634 0) 635#define Py_TPFLAGS_DEFAULT_CORE (Py_TPFLAGS_DEFAULT_EXTERNAL | \ 636 Py_TPFLAGS_HAVE_VERSION_TAG) 637 638#ifdef Py_BUILD_CORE 639#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_CORE 640#else 641#define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_EXTERNAL 642#endif 643 644#define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0) 645#define PyType_FastSubclass(t,f) PyType_HasFeature(t,f) 646 647 648/* 649The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement 650reference counts. Py_DECREF calls the object's deallocator function when 651the refcount falls to 0; for 652objects that don't contain references to other objects or heap memory 653this can be the standard function free(). Both macros can be used 654wherever a void expression is allowed. The argument must not be a 655NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead. 656The macro _Py_NewReference(op) initialize reference counts to 1, and 657in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional 658bookkeeping appropriate to the special build. 659 660We assume that the reference count field can never overflow; this can 661be proven when the size of the field is the same as the pointer size, so 662we ignore the possibility. Provided a C int is at least 32 bits (which 663is implicitly assumed in many parts of this code), that's enough for 664about 2**31 references to an object. 665 666XXX The following became out of date in Python 2.2, but I'm not sure 667XXX what the full truth is now. Certainly, heap-allocated type objects 668XXX can and should be deallocated. 669Type objects should never be deallocated; the type pointer in an object 670is not considered to be a reference to the type object, to save 671complications in the deallocation function. (This is actually a 672decision that's up to the implementer of each new type so if you want, 673you can count such references to the type object.) 674 675*** WARNING*** The Py_DECREF macro must have a side-effect-free argument 676since it may evaluate its argument multiple times. (The alternative 677would be to mace it a proper function or assign it to a global temporary 678variable first, both of which are slower; and in a multi-threaded 679environment the global variable trick is not safe.) 680*/ 681 682/* First define a pile of simple helper macros, one set per special 683 * build symbol. These either expand to the obvious things, or to 684 * nothing at all when the special mode isn't in effect. The main 685 * macros can later be defined just once then, yet expand to different 686 * things depending on which special build options are and aren't in effect. 687 * Trust me <wink>: while painful, this is 20x easier to understand than, 688 * e.g, defining _Py_NewReference five different times in a maze of nested 689 * #ifdefs (we used to do that -- it was impenetrable). 690 */ 691#ifdef Py_REF_DEBUG 692PyAPI_DATA(Py_ssize_t) _Py_RefTotal; 693PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname, 694 int lineno, PyObject *op); 695PyAPI_FUNC(PyObject *) _PyDict_Dummy(void); 696PyAPI_FUNC(PyObject *) _PySet_Dummy(void); 697PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void); 698#define _Py_INC_REFTOTAL _Py_RefTotal++ 699#define _Py_DEC_REFTOTAL _Py_RefTotal-- 700#define _Py_REF_DEBUG_COMMA , 701#define _Py_CHECK_REFCNT(OP) \ 702{ if (((PyObject*)OP)->ob_refcnt < 0) \ 703 _Py_NegativeRefcount(__FILE__, __LINE__, \ 704 (PyObject *)(OP)); \ 705} 706#else 707#define _Py_INC_REFTOTAL 708#define _Py_DEC_REFTOTAL 709#define _Py_REF_DEBUG_COMMA 710#define _Py_CHECK_REFCNT(OP) /* a semicolon */; 711#endif /* Py_REF_DEBUG */ 712 713#ifdef COUNT_ALLOCS 714PyAPI_FUNC(void) inc_count(PyTypeObject *); 715PyAPI_FUNC(void) dec_count(PyTypeObject *); 716#define _Py_INC_TPALLOCS(OP) inc_count(Py_TYPE(OP)) 717#define _Py_INC_TPFREES(OP) dec_count(Py_TYPE(OP)) 718#define _Py_DEC_TPFREES(OP) Py_TYPE(OP)->tp_frees-- 719#define _Py_COUNT_ALLOCS_COMMA , 720#else 721#define _Py_INC_TPALLOCS(OP) 722#define _Py_INC_TPFREES(OP) 723#define _Py_DEC_TPFREES(OP) 724#define _Py_COUNT_ALLOCS_COMMA 725#endif /* COUNT_ALLOCS */ 726 727#ifdef Py_TRACE_REFS 728/* Py_TRACE_REFS is such major surgery that we call external routines. */ 729PyAPI_FUNC(void) _Py_NewReference(PyObject *); 730PyAPI_FUNC(void) _Py_ForgetReference(PyObject *); 731PyAPI_FUNC(void) _Py_Dealloc(PyObject *); 732PyAPI_FUNC(void) _Py_PrintReferences(FILE *); 733PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *); 734PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force); 735 736#else 737/* Without Py_TRACE_REFS, there's little enough to do that we expand code 738 * inline. 739 */ 740#define _Py_NewReference(op) ( \ 741 _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \ 742 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ 743 Py_REFCNT(op) = 1) 744 745#define _Py_ForgetReference(op) _Py_INC_TPFREES(op) 746 747#define _Py_Dealloc(op) ( \ 748 _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \ 749 (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op))) 750#endif /* !Py_TRACE_REFS */ 751 752#define Py_INCREF(op) ( \ 753 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ 754 ((PyObject*)(op))->ob_refcnt++) 755 756#define Py_DECREF(op) \ 757 if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \ 758 --((PyObject*)(op))->ob_refcnt != 0) \ 759 _Py_CHECK_REFCNT(op) \ 760 else \ 761 _Py_Dealloc((PyObject *)(op)) 762 763/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear 764 * and tp_dealloc implementatons. 765 * 766 * Note that "the obvious" code can be deadly: 767 * 768 * Py_XDECREF(op); 769 * op = NULL; 770 * 771 * Typically, `op` is something like self->containee, and `self` is done 772 * using its `containee` member. In the code sequence above, suppose 773 * `containee` is non-NULL with a refcount of 1. Its refcount falls to 774 * 0 on the first line, which can trigger an arbitrary amount of code, 775 * possibly including finalizers (like __del__ methods or weakref callbacks) 776 * coded in Python, which in turn can release the GIL and allow other threads 777 * to run, etc. Such code may even invoke methods of `self` again, or cause 778 * cyclic gc to trigger, but-- oops! --self->containee still points to the 779 * object being torn down, and it may be in an insane state while being torn 780 * down. This has in fact been a rich historic source of miserable (rare & 781 * hard-to-diagnose) segfaulting (and other) bugs. 782 * 783 * The safe way is: 784 * 785 * Py_CLEAR(op); 786 * 787 * That arranges to set `op` to NULL _before_ decref'ing, so that any code 788 * triggered as a side-effect of `op` getting torn down no longer believes 789 * `op` points to a valid object. 790 * 791 * There are cases where it's safe to use the naive code, but they're brittle. 792 * For example, if `op` points to a Python integer, you know that destroying 793 * one of those can't cause problems -- but in part that relies on that 794 * Python integers aren't currently weakly referencable. Best practice is 795 * to use Py_CLEAR() even if you can't think of a reason for why you need to. 796 */ 797#define Py_CLEAR(op) \ 798 do { \ 799 if (op) { \ 800 PyObject *_py_tmp = (PyObject *)(op); \ 801 (op) = NULL; \ 802 Py_DECREF(_py_tmp); \ 803 } \ 804 } while (0) 805 806/* Macros to use in case the object pointer may be NULL: */ 807#define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op) 808#define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op) 809 810/* 811These are provided as conveniences to Python runtime embedders, so that 812they can have object code that is not dependent on Python compilation flags. 813*/ 814PyAPI_FUNC(void) Py_IncRef(PyObject *); 815PyAPI_FUNC(void) Py_DecRef(PyObject *); 816 817/* 818_Py_NoneStruct is an object of undefined type which can be used in contexts 819where NULL (nil) is not suitable (since NULL often means 'error'). 820 821Don't forget to apply Py_INCREF() when returning this value!!! 822*/ 823PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */ 824#define Py_None (&_Py_NoneStruct) 825 826/* Macro for returning Py_None from a function */ 827#define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None 828 829/* 830Py_NotImplemented is a singleton used to signal that an operation is 831not implemented for a given type combination. 832*/ 833PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */ 834#define Py_NotImplemented (&_Py_NotImplementedStruct) 835 836/* Rich comparison opcodes */ 837#define Py_LT 0 838#define Py_LE 1 839#define Py_EQ 2 840#define Py_NE 3 841#define Py_GT 4 842#define Py_GE 5 843 844/* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE. 845 * Defined in object.c. 846 */ 847PyAPI_DATA(int) _Py_SwappedOp[]; 848 849/* 850Define staticforward and statichere for source compatibility with old 851C extensions. 852 853The staticforward define was needed to support certain broken C 854compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the 855static keyword when it was used with a forward declaration of a static 856initialized structure. Standard C allows the forward declaration with 857static, and we've decided to stop catering to broken C compilers. 858(In fact, we expect that the compilers are all fixed eight years later.) 859*/ 860 861#define staticforward static 862#define statichere static 863 864 865/* 866More conventions 867================ 868 869Argument Checking 870----------------- 871 872Functions that take objects as arguments normally don't check for nil 873arguments, but they do check the type of the argument, and return an 874error if the function doesn't apply to the type. 875 876Failure Modes 877------------- 878 879Functions may fail for a variety of reasons, including running out of 880memory. This is communicated to the caller in two ways: an error string 881is set (see errors.h), and the function result differs: functions that 882normally return a pointer return NULL for failure, functions returning 883an integer return -1 (which could be a legal return value too!), and 884other functions return 0 for success and -1 for failure. 885Callers should always check for errors before using the result. If 886an error was set, the caller must either explicitly clear it, or pass 887the error on to its caller. 888 889Reference Counts 890---------------- 891 892It takes a while to get used to the proper usage of reference counts. 893 894Functions that create an object set the reference count to 1; such new 895objects must be stored somewhere or destroyed again with Py_DECREF(). 896Some functions that 'store' objects, such as PyTuple_SetItem() and 897PyList_SetItem(), 898don't increment the reference count of the object, since the most 899frequent use is to store a fresh object. Functions that 'retrieve' 900objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also 901don't increment 902the reference count, since most frequently the object is only looked at 903quickly. Thus, to retrieve an object and store it again, the caller 904must call Py_INCREF() explicitly. 905 906NOTE: functions that 'consume' a reference count, like 907PyList_SetItem(), consume the reference even if the object wasn't 908successfully stored, to simplify error handling. 909 910It seems attractive to make other functions that take an object as 911argument consume a reference count; however, this may quickly get 912confusing (even the current practice is already confusing). Consider 913it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at 914times. 915*/ 916 917 918/* Trashcan mechanism, thanks to Christian Tismer. 919 920When deallocating a container object, it's possible to trigger an unbounded 921chain of deallocations, as each Py_DECREF in turn drops the refcount on "the 922next" object in the chain to 0. This can easily lead to stack faults, and 923especially in threads (which typically have less stack space to work with). 924 925A container object that participates in cyclic gc can avoid this by 926bracketing the body of its tp_dealloc function with a pair of macros: 927 928static void 929mytype_dealloc(mytype *p) 930{ 931 ... declarations go here ... 932 933 PyObject_GC_UnTrack(p); // must untrack first 934 Py_TRASHCAN_SAFE_BEGIN(p) 935 ... The body of the deallocator goes here, including all calls ... 936 ... to Py_DECREF on contained objects. ... 937 Py_TRASHCAN_SAFE_END(p) 938} 939 940CAUTION: Never return from the middle of the body! If the body needs to 941"get out early", put a label immediately before the Py_TRASHCAN_SAFE_END 942call, and goto it. Else the call-depth counter (see below) will stay 943above 0 forever, and the trashcan will never get emptied. 944 945How it works: The BEGIN macro increments a call-depth counter. So long 946as this counter is small, the body of the deallocator is run directly without 947further ado. But if the counter gets large, it instead adds p to a list of 948objects to be deallocated later, skips the body of the deallocator, and 949resumes execution after the END macro. The tp_dealloc routine then returns 950without deallocating anything (and so unbounded call-stack depth is avoided). 951 952When the call stack finishes unwinding again, code generated by the END macro 953notices this, and calls another routine to deallocate all the objects that 954may have been added to the list of deferred deallocations. In effect, a 955chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces, 956with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. 957*/ 958 959PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); 960PyAPI_FUNC(void) _PyTrash_destroy_chain(void); 961PyAPI_DATA(int) _PyTrash_delete_nesting; 962PyAPI_DATA(PyObject *) _PyTrash_delete_later; 963 964#define PyTrash_UNWIND_LEVEL 50 965 966#define Py_TRASHCAN_SAFE_BEGIN(op) \ 967 if (_PyTrash_delete_nesting < PyTrash_UNWIND_LEVEL) { \ 968 ++_PyTrash_delete_nesting; 969 /* The body of the deallocator is here. */ 970#define Py_TRASHCAN_SAFE_END(op) \ 971 --_PyTrash_delete_nesting; \ 972 if (_PyTrash_delete_later && _PyTrash_delete_nesting <= 0) \ 973 _PyTrash_destroy_chain(); \ 974 } \ 975 else \ 976 _PyTrash_deposit_object((PyObject*)op); 977 978#ifdef __cplusplus 979} 980#endif 981#endif /* !Py_OBJECT_H */