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