Include/object.h

   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 /* Py3k buffer interface */
 163
 164 typedef struct bufferinfo {
 165         void *buf;
 166         Py_ssize_t len;
 167         Py_ssize_t itemsize;  /* This is Py_ssize_t so it can be
 168                                  pointed to by strides in simple case.*/
 169         int readonly;
 170         int ndim;
 171         char *format;
 172         Py_ssize_t *shape;
 173         Py_ssize_t *strides;
 174         Py_ssize_t *suboffsets;
 175         void *internal;
 176 } Py_buffer;
 177
 178 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
 179 typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
 180
 181         /* Flags for getting buffers */
 182 #define PyBUF_SIMPLE 0
 183 #define PyBUF_WRITABLE 0x0001
 184 /*  we used to include an E, backwards compatible alias  */
 185 #define PyBUF_WRITEABLE PyBUF_WRITABLE
 186 #define PyBUF_LOCK 0x0002
 187 #define PyBUF_FORMAT 0x0004
 188 #define PyBUF_ND 0x0008
 189 #define PyBUF_STRIDES (0x0010 | PyBUF_ND)
 190 #define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES)
 191 #define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES)
 192 #define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES)
 193 #define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES)
 194
 195 #define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE)
 196 #define PyBUF_CONTIG_RO (PyBUF_ND)
 197 #define PyBUF_CONTIG_LCK (PyBUF_ND | PyBUF_LOCK)
 198 #define PyBUF_CONTIG_XLCK (PyBUF_ND | PyBUF_LOCK | PyBUF_WRITABLE)
 199
 200 #define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE)
 201 #define PyBUF_STRIDED_RO (PyBUF_STRIDES)
 202 #define PyBUF_STRIDED_LCK (PyBUF_STRIDES | PyBUF_LOCK)
 203 #define PyBUF_STRIDED_XLCK (PyBUF_STRIDES | PyBUF_LOCK | PyBUF_WRITABLE)
 204
 205 #define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT)
 206 #define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT)
 207 #define PyBUF_RECORDS_LCK (PyBUF_STRIDES | PyBUF_LOCK | PyBUF_FORMAT)
 208 #define PyBUF_RECORDS_XLCK (PyBUF_STRIDES | PyBUF_LOCK | PyBUF_WRITABLE \
 209                             | PyBUF_FORMAT)
 210
 211 #define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT)
 212 #define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT)
 213 #define PyBUF_FULL_LCK (PyBUF_INDIRECT | PyBUF_LOCK | PyBUF_FORMAT)
 214 #define PyBUF_FULL_XLCK (PyBUF_INDIRECT | PyBUF_LOCK | PyBUF_WRITABLE \
 215                          | PyBUF_FORMAT)
 216
 217
 218 #define PyBUF_READ  0x100
 219 #define PyBUF_WRITE 0x200
 220 #define PyBUF_SHADOW 0x400
 221 /* end Py3k buffer interface */
 222
 223 typedef int (*objobjproc)(PyObject *, PyObject *);
 224 typedef int (*visitproc)(PyObject *, void *);
 225 typedef int (*traverseproc)(PyObject *, visitproc, void *);
 226
 227 typedef struct {
 228         /* For numbers without flag bit Py_TPFLAGS_CHECKTYPES set, all
 229            arguments are guaranteed to be of the object's type (modulo
 230            coercion hacks -- i.e. if the type's coercion function
 231            returns other types, then these are allowed as well).  Numbers that
 232            have the Py_TPFLAGS_CHECKTYPES flag bit set should check *both*
 233            arguments for proper type and implement the necessary conversions
 234            in the slot functions themselves. */
 235
 236         binaryfunc nb_add;
 237         binaryfunc nb_subtract;
 238         binaryfunc nb_multiply;
 239         binaryfunc nb_divide;
 240         binaryfunc nb_remainder;
 241         binaryfunc nb_divmod;
 242         ternaryfunc nb_power;
 243         unaryfunc nb_negative;
 244         unaryfunc nb_positive;
 245         unaryfunc nb_absolute;
 246         inquiry nb_nonzero;
 247         unaryfunc nb_invert;
 248         binaryfunc nb_lshift;
 249         binaryfunc nb_rshift;
 250         binaryfunc nb_and;
 251         binaryfunc nb_xor;
 252         binaryfunc nb_or;
 253         coercion nb_coerce;
 254         unaryfunc nb_int;
 255         unaryfunc nb_long;
 256         unaryfunc nb_float;
 257         unaryfunc nb_oct;
 258         unaryfunc nb_hex;
 259         /* Added in release 2.0 */
 260         binaryfunc nb_inplace_add;
 261         binaryfunc nb_inplace_subtract;
 262         binaryfunc nb_inplace_multiply;
 263         binaryfunc nb_inplace_divide;
 264         binaryfunc nb_inplace_remainder;
 265         ternaryfunc nb_inplace_power;
 266         binaryfunc nb_inplace_lshift;
 267         binaryfunc nb_inplace_rshift;
 268         binaryfunc nb_inplace_and;
 269         binaryfunc nb_inplace_xor;
 270         binaryfunc nb_inplace_or;
 271
 272         /* Added in release 2.2 */
 273         /* The following require the Py_TPFLAGS_HAVE_CLASS flag */
 274         binaryfunc nb_floor_divide;
 275         binaryfunc nb_true_divide;
 276         binaryfunc nb_inplace_floor_divide;
 277         binaryfunc nb_inplace_true_divide;
 278
 279         /* Added in release 2.5 */
 280         unaryfunc nb_index;
 281 } PyNumberMethods;
 282
 283 typedef struct {
 284         lenfunc sq_length;
 285         binaryfunc sq_concat;
 286         ssizeargfunc sq_repeat;
 287         ssizeargfunc sq_item;
 288         ssizessizeargfunc sq_slice;
 289         ssizeobjargproc sq_ass_item;
 290         ssizessizeobjargproc sq_ass_slice;
 291         objobjproc sq_contains;
 292         /* Added in release 2.0 */
 293         binaryfunc sq_inplace_concat;
 294         ssizeargfunc sq_inplace_repeat;
 295 } PySequenceMethods;
 296
 297 typedef struct {
 298         lenfunc mp_length;
 299         binaryfunc mp_subscript;
 300         objobjargproc mp_ass_subscript;
 301 } PyMappingMethods;
 302
 303 typedef struct {
 304         readbufferproc bf_getreadbuffer;
 305         writebufferproc bf_getwritebuffer;
 306         segcountproc bf_getsegcount;
 307         charbufferproc bf_getcharbuffer;
 308         getbufferproc bf_getbuffer;
 309         releasebufferproc bf_releasebuffer;
 310 } PyBufferProcs;
 311
 312
 313 typedef void (*freefunc)(void *);
 314 typedef void (*destructor)(PyObject *);
 315 typedef int (*printfunc)(PyObject *, FILE *, int);
 316 typedef PyObject *(*getattrfunc)(PyObject *, char *);
 317 typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
 318 typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
 319 typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
 320 typedef int (*cmpfunc)(PyObject *, PyObject *);
 321 typedef PyObject *(*reprfunc)(PyObject *);
 322 typedef long (*hashfunc)(PyObject *);
 323 typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
 324 typedef PyObject *(*getiterfunc) (PyObject *);
 325 typedef PyObject *(*iternextfunc) (PyObject *);
 326 typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
 327 typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
 328 typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
 329 typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *);
 330 typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t);
 331
 332 typedef struct _typeobject {
 333         PyObject_VAR_HEAD
 334         const char *tp_name; /* For printing, in format "<module>.<name>" */
 335         Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
 336
 337         /* Methods to implement standard operations */
 338
 339         destructor tp_dealloc;
 340         printfunc tp_print;
 341         getattrfunc tp_getattr;
 342         setattrfunc tp_setattr;
 343         cmpfunc tp_compare;
 344         reprfunc tp_repr;
 345
 346         /* Method suites for standard classes */
 347
 348         PyNumberMethods *tp_as_number;
 349         PySequenceMethods *tp_as_sequence;
 350         PyMappingMethods *tp_as_mapping;
 351
 352         /* More standard operations (here for binary compatibility) */
 353
 354         hashfunc tp_hash;
 355         ternaryfunc tp_call;
 356         reprfunc tp_str;
 357         getattrofunc tp_getattro;
 358         setattrofunc tp_setattro;
 359
 360         /* Functions to access object as input/output buffer */
 361         PyBufferProcs *tp_as_buffer;
 362
 363         /* Flags to define presence of optional/expanded features */
 364         long tp_flags;
 365
 366         const char *tp_doc; /* Documentation string */
 367
 368         /* Assigned meaning in release 2.0 */
 369         /* call function for all accessible objects */
 370         traverseproc tp_traverse;
 371
 372         /* delete references to contained objects */
 373         inquiry tp_clear;
 374
 375         /* Assigned meaning in release 2.1 */
 376         /* rich comparisons */
 377         richcmpfunc tp_richcompare;
 378
 379         /* weak reference enabler */
 380         Py_ssize_t tp_weaklistoffset;
 381
 382         /* Added in release 2.2 */
 383         /* Iterators */
 384         getiterfunc tp_iter;
 385         iternextfunc tp_iternext;
 386
 387         /* Attribute descriptor and subclassing stuff */
 388         struct PyMethodDef *tp_methods;
 389         struct PyMemberDef *tp_members;
 390         struct PyGetSetDef *tp_getset;
 391         struct _typeobject *tp_base;
 392         PyObject *tp_dict;
 393         descrgetfunc tp_descr_get;
 394         descrsetfunc tp_descr_set;
 395         Py_ssize_t tp_dictoffset;
 396         initproc tp_init;
 397         allocfunc tp_alloc;
 398         newfunc tp_new;
 399         freefunc tp_free; /* Low-level free-memory routine */
 400         inquiry tp_is_gc; /* For PyObject_IS_GC */
 401         PyObject *tp_bases;
 402         PyObject *tp_mro; /* method resolution order */
 403         PyObject *tp_cache;
 404         PyObject *tp_subclasses;
 405         PyObject *tp_weaklist;
 406         destructor tp_del;
 407
 408         /* Type attribute cache version tag. Added in version 2.6 */
 409         unsigned int tp_version_tag;
 410
 411 #ifdef COUNT_ALLOCS
 412         /* these must be last and never explicitly initialized */
 413         Py_ssize_t tp_allocs;
 414         Py_ssize_t tp_frees;
 415         Py_ssize_t tp_maxalloc;
 416         struct _typeobject *tp_prev;
 417         struct _typeobject *tp_next;
 418 #endif
 419 } PyTypeObject;
 420
 421
 422 /* The *real* layout of a type object when allocated on the heap */
 423 typedef struct _heaptypeobject {
 424         /* Note: there's a dependency on the order of these members
 425            in slotptr() in typeobject.c . */
 426         PyTypeObject ht_type;
 427         PyNumberMethods as_number;
 428         PyMappingMethods as_mapping;
 429         PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
 430                                           so that the mapping wins when both
 431                                           the mapping and the sequence define
 432                                           a given operator (e.g. __getitem__).
 433                                           see add_operators() in typeobject.c . */
 434         PyBufferProcs as_buffer;
 435         PyObject *ht_name, *ht_slots;
 436         /* here are optional user slots, followed by the members. */
 437 } PyHeapTypeObject;
 438
 439 /* access macro to the members which are floating "behind" the object */
 440 #define PyHeapType_GET_MEMBERS(etype) \
 441     ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize))
 442
 443
 444 /* Generic type check */
 445 PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
 446 #define PyObject_TypeCheck(ob, tp) \
 447         (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp)))
 448
 449 PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
 450 PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
 451 PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */
 452
 453 #define PyType_Check(op) \
 454         PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS)
 455 #define PyType_CheckExact(op) (Py_TYPE(op) == &PyType_Type)
 456
 457 PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
 458 PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
 459 PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
 460                                                PyObject *, PyObject *);
 461 PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
 462 PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
 463
 464 /* Generic operations on objects */
 465 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
 466 PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
 467 PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
 468 PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *);
 469 PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
 470 #ifdef Py_USING_UNICODE
 471 PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *);
 472 #endif
 473 PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *);
 474 PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
 475 PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
 476 PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
 477 PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
 478 PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
 479 PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
 480 PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
 481 PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
 482 PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *);
 483 PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
 484 PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
 485 PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
 486                                               PyObject *, PyObject *);
 487 PyAPI_FUNC(long) PyObject_Hash(PyObject *);
 488 PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
 489 PyAPI_FUNC(int) PyObject_Not(PyObject *);
 490 PyAPI_FUNC(int) PyCallable_Check(PyObject *);
 491 PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **);
 492 PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **);
 493
 494 PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
 495
 496 /* A slot function whose address we need to compare */
 497 extern int _PyObject_SlotCompare(PyObject *, PyObject *);
 498
 499
 500 /* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a
 501    list of strings.  PyObject_Dir(NULL) is like __builtin__.dir(),
 502    returning the names of the current locals.  In this case, if there are
 503    no current locals, NULL is returned, and PyErr_Occurred() is false.
 504 */
 505 PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
 506
 507
 508 /* Helpers for printing recursive container types */
 509 PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
 510 PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
 511
 512 /* Helpers for hash functions */
 513 PyAPI_FUNC(long) _Py_HashDouble(double);
 514 PyAPI_FUNC(long) _Py_HashPointer(void*);
 515
 516 /* Helper for passing objects to printf and the like */
 517 #define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj))
 518
 519 /* Flag bits for printing: */
 520 #define Py_PRINT_RAW    1       /* No string quotes etc. */
 521
 522 /*
 523 `Type flags (tp_flags)
 524
 525 These flags are used to extend the type structure in a backwards-compatible
 526 fashion. Extensions can use the flags to indicate (and test) when a given
 527 type structure contains a new feature. The Python core will use these when
 528 introducing new functionality between major revisions (to avoid mid-version
 529 changes in the PYTHON_API_VERSION).
 530
 531 Arbitration of the flag bit positions will need to be coordinated among
 532 all extension writers who publically release their extensions (this will
 533 be fewer than you might expect!)..
 534
 535 Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs.
 536
 537 Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
 538
 539 Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
 540 given type object has a specified feature.
 541 */
 542
 543 /* PyBufferProcs contains bf_getcharbuffer */
 544 #define Py_TPFLAGS_HAVE_GETCHARBUFFER  (1L<<0)
 545
 546 /* PySequenceMethods contains sq_contains */
 547 #define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1)
 548
 549 /* This is here for backwards compatibility.  Extensions that use the old GC
 550  * API will still compile but the objects will not be tracked by the GC. */
 551 #define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */
 552
 553 /* PySequenceMethods and PyNumberMethods contain in-place operators */
 554 #define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3)
 555
 556 /* PyNumberMethods do their own coercion */
 557 #define Py_TPFLAGS_CHECKTYPES (1L<<4)
 558
 559 /* tp_richcompare is defined */
 560 #define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5)
 561
 562 /* Objects which are weakly referencable if their tp_weaklistoffset is >0 */
 563 #define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6)
 564
 565 /* tp_iter is defined */
 566 #define Py_TPFLAGS_HAVE_ITER (1L<<7)
 567
 568 /* New members introduced by Python 2.2 exist */
 569 #define Py_TPFLAGS_HAVE_CLASS (1L<<8)
 570
 571 /* Set if the type object is dynamically allocated */
 572 #define Py_TPFLAGS_HEAPTYPE (1L<<9)
 573
 574 /* Set if the type allows subclassing */
 575 #define Py_TPFLAGS_BASETYPE (1L<<10)
 576
 577 /* Set if the type is 'ready' -- fully initialized */
 578 #define Py_TPFLAGS_READY (1L<<12)
 579
 580 /* Set while the type is being 'readied', to prevent recursive ready calls */
 581 #define Py_TPFLAGS_READYING (1L<<13)
 582
 583 /* Objects support garbage collection (see objimp.h) */
 584 #define Py_TPFLAGS_HAVE_GC (1L<<14)
 585
 586 /* These two bits are preserved for Stackless Python, next after this is 17 */
 587 #ifdef STACKLESS
 588 #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15)
 589 #else
 590 #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0
 591 #endif
 592
 593 /* Objects support nb_index in PyNumberMethods */
 594 #define Py_TPFLAGS_HAVE_INDEX (1L<<17)
 595
 596 /* Objects support type attribute cache */
 597 #define Py_TPFLAGS_HAVE_VERSION_TAG   (1L<<18)
 598 #define Py_TPFLAGS_VALID_VERSION_TAG  (1L<<19)
 599
 600 /* Type is abstract and cannot be instantiated */
 601 #define Py_TPFLAGS_IS_ABSTRACT (1L<<20)
 602
 603 /* Has the new buffer protocol */
 604 #define Py_TPFLAGS_HAVE_NEWBUFFER (1L<<21)
 605
 606 /* These flags are used to determine if a type is a subclass. */
 607 #define Py_TPFLAGS_INT_SUBCLASS         (1L<<23)
 608 #define Py_TPFLAGS_LONG_SUBCLASS        (1L<<24)
 609 #define Py_TPFLAGS_LIST_SUBCLASS        (1L<<25)
 610 #define Py_TPFLAGS_TUPLE_SUBCLASS       (1L<<26)
 611 #define Py_TPFLAGS_STRING_SUBCLASS      (1L<<27)
 612 #define Py_TPFLAGS_UNICODE_SUBCLASS     (1L<<28)
 613 #define Py_TPFLAGS_DICT_SUBCLASS        (1L<<29)
 614 #define Py_TPFLAGS_BASE_EXC_SUBCLASS    (1L<<30)
 615 #define Py_TPFLAGS_TYPE_SUBCLASS        (1L<<31)
 616
 617 #define Py_TPFLAGS_DEFAULT  ( \
 618                              Py_TPFLAGS_HAVE_GETCHARBUFFER | \
 619                              Py_TPFLAGS_HAVE_SEQUENCE_IN | \
 620                              Py_TPFLAGS_HAVE_INPLACEOPS | \
 621                              Py_TPFLAGS_HAVE_RICHCOMPARE | \
 622                              Py_TPFLAGS_HAVE_WEAKREFS | \
 623                              Py_TPFLAGS_HAVE_ITER | \
 624                              Py_TPFLAGS_HAVE_CLASS | \
 625                              Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \
 626                              Py_TPFLAGS_HAVE_INDEX | \
 627                              Py_TPFLAGS_HAVE_VERSION_TAG | \
 628                             0)
 629
 630 #define PyType_HasFeature(t,f)  (((t)->tp_flags & (f)) != 0)
 631 #define PyType_FastSubclass(t,f)  PyType_HasFeature(t,f)
 632
 633
 634 /*
 635 The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
 636 reference counts.  Py_DECREF calls the object's deallocator function when
 637 the refcount falls to 0; for
 638 objects that don't contain references to other objects or heap memory
 639 this can be the standard function free().  Both macros can be used
 640 wherever a void expression is allowed.  The argument must not be a
 641 NULL pointer.  If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
 642 The macro _Py_NewReference(op) initialize reference counts to 1, and
 643 in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
 644 bookkeeping appropriate to the special build.
 645
 646 We assume that the reference count field can never overflow; this can
 647 be proven when the size of the field is the same as the pointer size, so
 648 we ignore the possibility.  Provided a C int is at least 32 bits (which
 649 is implicitly assumed in many parts of this code), that's enough for
 650 about 2**31 references to an object.
 651
 652 XXX The following became out of date in Python 2.2, but I'm not sure
 653 XXX what the full truth is now.  Certainly, heap-allocated type objects
 654 XXX can and should be deallocated.
 655 Type objects should never be deallocated; the type pointer in an object
 656 is not considered to be a reference to the type object, to save
 657 complications in the deallocation function.  (This is actually a
 658 decision that's up to the implementer of each new type so if you want,
 659 you can count such references to the type object.)
 660
 661 *** WARNING*** The Py_DECREF macro must have a side-effect-free argument
 662 since it may evaluate its argument multiple times.  (The alternative
 663 would be to mace it a proper function or assign it to a global temporary
 664 variable first, both of which are slower; and in a multi-threaded
 665 environment the global variable trick is not safe.)
 666 */
 667
 668 /* First define a pile of simple helper macros, one set per special
 669  * build symbol.  These either expand to the obvious things, or to
 670  * nothing at all when the special mode isn't in effect.  The main
 671  * macros can later be defined just once then, yet expand to different
 672  * things depending on which special build options are and aren't in effect.
 673  * Trust me <wink>:  while painful, this is 20x easier to understand than,
 674  * e.g, defining _Py_NewReference five different times in a maze of nested
 675  * #ifdefs (we used to do that -- it was impenetrable).
 676  */
 677 #ifdef Py_REF_DEBUG
 678 PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
 679 PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname,
 680                                             int lineno, PyObject *op);
 681 PyAPI_FUNC(PyObject *) _PyDict_Dummy(void);
 682 PyAPI_FUNC(PyObject *) _PySet_Dummy(void);
 683 PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void);
 684 #define _Py_INC_REFTOTAL        _Py_RefTotal++
 685 #define _Py_DEC_REFTOTAL        _Py_RefTotal--
 686 #define _Py_REF_DEBUG_COMMA     ,
 687 #define _Py_CHECK_REFCNT(OP)                                    \
 688 {       if (((PyObject*)OP)->ob_refcnt < 0)                             \
 689                 _Py_NegativeRefcount(__FILE__, __LINE__,        \
 690                                      (PyObject *)(OP));         \
 691 }
 692 #else
 693 #define _Py_INC_REFTOTAL
 694 #define _Py_DEC_REFTOTAL
 695 #define _Py_REF_DEBUG_COMMA
 696 #define _Py_CHECK_REFCNT(OP)    /* a semicolon */;
 697 #endif /* Py_REF_DEBUG */
 698
 699 #ifdef COUNT_ALLOCS
 700 PyAPI_FUNC(void) inc_count(PyTypeObject *);
 701 PyAPI_FUNC(void) dec_count(PyTypeObject *);
 702 #define _Py_INC_TPALLOCS(OP)    inc_count(Py_TYPE(OP))
 703 #define _Py_INC_TPFREES(OP)     dec_count(Py_TYPE(OP))
 704 #define _Py_DEC_TPFREES(OP)     Py_TYPE(OP)->tp_frees--
 705 #define _Py_COUNT_ALLOCS_COMMA  ,
 706 #else
 707 #define _Py_INC_TPALLOCS(OP)
 708 #define _Py_INC_TPFREES(OP)
 709 #define _Py_DEC_TPFREES(OP)
 710 #define _Py_COUNT_ALLOCS_COMMA
 711 #endif /* COUNT_ALLOCS */
 712
 713 #ifdef Py_TRACE_REFS
 714 /* Py_TRACE_REFS is such major surgery that we call external routines. */
 715 PyAPI_FUNC(void) _Py_NewReference(PyObject *);
 716 PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
 717 PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
 718 PyAPI_FUNC(void) _Py_PrintReferences(FILE *);
 719 PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *);
 720 PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force);
 721
 722 #else
 723 /* Without Py_TRACE_REFS, there's little enough to do that we expand code
 724  * inline.
 725  */
 726 #define _Py_NewReference(op) (                          \
 727         _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA     \
 728         _Py_INC_REFTOTAL  _Py_REF_DEBUG_COMMA           \
 729         Py_REFCNT(op) = 1)
 730
 731 #define _Py_ForgetReference(op) _Py_INC_TPFREES(op)
 732
 733 #define _Py_Dealloc(op) (                               \
 734         _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA      \
 735         (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op)))
 736 #endif /* !Py_TRACE_REFS */
 737
 738 #define Py_INCREF(op) (                         \
 739         _Py_INC_REFTOTAL  _Py_REF_DEBUG_COMMA   \
 740         ((PyObject*)(op))->ob_refcnt++)
 741
 742 #define Py_DECREF(op)                                   \
 743         if (_Py_DEC_REFTOTAL  _Py_REF_DEBUG_COMMA       \
 744             --((PyObject*)(op))->ob_refcnt != 0)                \
 745                 _Py_CHECK_REFCNT(op)                    \
 746         else                                            \
 747                 _Py_Dealloc((PyObject *)(op))
 748
 749 /* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
 750  * and tp_dealloc implementatons.
 751  *
 752  * Note that "the obvious" code can be deadly:
 753  *
 754  *     Py_XDECREF(op);
 755  *     op = NULL;
 756  *
 757  * Typically, `op` is something like self->containee, and `self` is done
 758  * using its `containee` member.  In the code sequence above, suppose
 759  * `containee` is non-NULL with a refcount of 1.  Its refcount falls to
 760  * 0 on the first line, which can trigger an arbitrary amount of code,
 761  * possibly including finalizers (like __del__ methods or weakref callbacks)
 762  * coded in Python, which in turn can release the GIL and allow other threads
 763  * to run, etc.  Such code may even invoke methods of `self` again, or cause
 764  * cyclic gc to trigger, but-- oops! --self->containee still points to the
 765  * object being torn down, and it may be in an insane state while being torn
 766  * down.  This has in fact been a rich historic source of miserable (rare &
 767  * hard-to-diagnose) segfaulting (and other) bugs.
 768  *
 769  * The safe way is:
 770  *
 771  *      Py_CLEAR(op);
 772  *
 773  * That arranges to set `op` to NULL _before_ decref'ing, so that any code
 774  * triggered as a side-effect of `op` getting torn down no longer believes
 775  * `op` points to a valid object.
 776  *
 777  * There are cases where it's safe to use the naive code, but they're brittle.
 778  * For example, if `op` points to a Python integer, you know that destroying
 779  * one of those can't cause problems -- but in part that relies on that
 780  * Python integers aren't currently weakly referencable.  Best practice is
 781  * to use Py_CLEAR() even if you can't think of a reason for why you need to.
 782  */
 783 #define Py_CLEAR(op)                            \
 784         do {                                    \
 785                 if (op) {                       \
 786                         PyObject *tmp = (PyObject *)(op);       \
 787                         (op) = NULL;            \
 788                         Py_DECREF(tmp);         \
 789                 }                               \
 790         } while (0)
 791
 792 /* Macros to use in case the object pointer may be NULL: */
 793 #define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op)
 794 #define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op)
 795
 796 /*
 797 These are provided as conveniences to Python runtime embedders, so that
 798 they can have object code that is not dependent on Python compilation flags.
 799 */
 800 PyAPI_FUNC(void) Py_IncRef(PyObject *);
 801 PyAPI_FUNC(void) Py_DecRef(PyObject *);
 802
 803 /*
 804 _Py_NoneStruct is an object of undefined type which can be used in contexts
 805 where NULL (nil) is not suitable (since NULL often means 'error').
 806
 807 Don't forget to apply Py_INCREF() when returning this value!!!
 808 */
 809 PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
 810 #define Py_None (&_Py_NoneStruct)
 811
 812 /* Macro for returning Py_None from a function */
 813 #define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None
 814
 815 /*
 816 Py_NotImplemented is a singleton used to signal that an operation is
 817 not implemented for a given type combination.
 818 */
 819 PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
 820 #define Py_NotImplemented (&_Py_NotImplementedStruct)
 821
 822 /* Rich comparison opcodes */
 823 #define Py_LT 0
 824 #define Py_LE 1
 825 #define Py_EQ 2
 826 #define Py_NE 3
 827 #define Py_GT 4
 828 #define Py_GE 5
 829
 830 /* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE.
 831  * Defined in object.c.
 832  */
 833 PyAPI_DATA(int) _Py_SwappedOp[];
 834
 835 /*
 836 Define staticforward and statichere for source compatibility with old
 837 C extensions.
 838
 839 The staticforward define was needed to support certain broken C
 840 compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the
 841 static keyword when it was used with a forward declaration of a static
 842 initialized structure.  Standard C allows the forward declaration with
 843 static, and we've decided to stop catering to broken C compilers.
 844 (In fact, we expect that the compilers are all fixed eight years later.)
 845 */
 846
 847 #define staticforward static
 848 #define statichere static
 849
 850
 851 /*
 852 More conventions
 853 ================
 854
 855 Argument Checking
 856 -----------------
 857
 858 Functions that take objects as arguments normally don't check for nil
 859 arguments, but they do check the type of the argument, and return an
 860 error if the function doesn't apply to the type.
 861
 862 Failure Modes
 863 -------------
 864
 865 Functions may fail for a variety of reasons, including running out of
 866 memory.  This is communicated to the caller in two ways: an error string
 867 is set (see errors.h), and the function result differs: functions that
 868 normally return a pointer return NULL for failure, functions returning
 869 an integer return -1 (which could be a legal return value too!), and
 870 other functions return 0 for success and -1 for failure.
 871 Callers should always check for errors before using the result.  If
 872 an error was set, the caller must either explicitly clear it, or pass
 873 the error on to its caller.
 874
 875 Reference Counts
 876 ----------------
 877
 878 It takes a while to get used to the proper usage of reference counts.
 879
 880 Functions that create an object set the reference count to 1; such new
 881 objects must be stored somewhere or destroyed again with Py_DECREF().
 882 Some functions that 'store' objects, such as PyTuple_SetItem() and
 883 PyList_SetItem(),
 884 don't increment the reference count of the object, since the most
 885 frequent use is to store a fresh object.  Functions that 'retrieve'
 886 objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
 887 don't increment
 888 the reference count, since most frequently the object is only looked at
 889 quickly.  Thus, to retrieve an object and store it again, the caller
 890 must call Py_INCREF() explicitly.
 891
 892 NOTE: functions that 'consume' a reference count, like
 893 PyList_SetItem(), consume the reference even if the object wasn't
 894 successfully stored, to simplify error handling.
 895
 896 It seems attractive to make other functions that take an object as
 897 argument consume a reference count; however, this may quickly get
 898 confusing (even the current practice is already confusing).  Consider
 899 it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
 900 times.
 901 */
 902
 903
 904 /* Trashcan mechanism, thanks to Christian Tismer.
 905
 906 When deallocating a container object, it's possible to trigger an unbounded
 907 chain of deallocations, as each Py_DECREF in turn drops the refcount on "the
 908 next" object in the chain to 0.  This can easily lead to stack faults, and
 909 especially in threads (which typically have less stack space to work with).
 910
 911 A container object that participates in cyclic gc can avoid this by
 912 bracketing the body of its tp_dealloc function with a pair of macros:
 913
 914 static void
 915 mytype_dealloc(mytype *p)
 916 {
 917         ... declarations go here ...
 918
 919         PyObject_GC_UnTrack(p);    // must untrack first
 920         Py_TRASHCAN_SAFE_BEGIN(p)
 921         ... The body of the deallocator goes here, including all calls ...
 922         ... to Py_DECREF on contained objects.                         ...
 923         Py_TRASHCAN_SAFE_END(p)
 924 }
 925
 926 CAUTION:  Never return from the middle of the body!  If the body needs to
 927 "get out early", put a label immediately before the Py_TRASHCAN_SAFE_END
 928 call, and goto it.  Else the call-depth counter (see below) will stay
 929 above 0 forever, and the trashcan will never get emptied.
 930
 931 How it works:  The BEGIN macro increments a call-depth counter.  So long
 932 as this counter is small, the body of the deallocator is run directly without
 933 further ado.  But if the counter gets large, it instead adds p to a list of
 934 objects to be deallocated later, skips the body of the deallocator, and
 935 resumes execution after the END macro.  The tp_dealloc routine then returns
 936 without deallocating anything (and so unbounded call-stack depth is avoided).
 937
 938 When the call stack finishes unwinding again, code generated by the END macro
 939 notices this, and calls another routine to deallocate all the objects that
 940 may have been added to the list of deferred deallocations.  In effect, a
 941 chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces,
 942 with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL.
 943 */
 944
 945 PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*);
 946 PyAPI_FUNC(void) _PyTrash_destroy_chain(void);
 947 PyAPI_DATA(int) _PyTrash_delete_nesting;
 948 PyAPI_DATA(PyObject *) _PyTrash_delete_later;
 949
 950 #define PyTrash_UNWIND_LEVEL 50
 951
 952 #define Py_TRASHCAN_SAFE_BEGIN(op) \
 953         if (_PyTrash_delete_nesting < PyTrash_UNWIND_LEVEL) { \
 954                 ++_PyTrash_delete_nesting;
 955                 /* The body of the deallocator is here. */
 956 #define Py_TRASHCAN_SAFE_END(op) \
 957                 --_PyTrash_delete_nesting; \
 958                 if (_PyTrash_delete_later && _PyTrash_delete_nesting <= 0) \
 959                         _PyTrash_destroy_chain(); \
 960         } \
 961         else \
 962                 _PyTrash_deposit_object((PyObject*)op);
 963
 964 #ifdef __cplusplus
 965 }
 966 #endif
 967 #endif /* !Py_OBJECT_H */