Objects/tupleobject.c - platform/external/python/cpython2 - Gitiles


 /* Tuple object implementation */

 #include "Python.h"

 /* Speed optimization to avoid frequent malloc/free of small tuples */
 #ifndef MAXSAVESIZE
 #define MAXSAVESIZE	20  /* Largest tuple to save on free list */
 #endif
 #ifndef MAXSAVEDTUPLES
 #define MAXSAVEDTUPLES  2000  /* Maximum number of tuples of each size to save */
 #endif

 #if MAXSAVESIZE > 0
 /* Entries 1 up to MAXSAVESIZE are free lists, entry 0 is the empty
    tuple () of which at most one instance will be allocated.
 */
 static PyTupleObject *free_tuples[MAXSAVESIZE];
 static int num_free_tuples[MAXSAVESIZE];
 #endif
 #ifdef COUNT_ALLOCS
 int fast_tuple_allocs;
 int tuple_zero_allocs;
 #endif

 PyObject *
 PyTuple_New(register int size)
 {
 	register PyTupleObject *op;
 	if (size < 0) {
 		PyErr_BadInternalCall();
 		return NULL;
 	}
 #if MAXSAVESIZE > 0
 	if (size == 0 && free_tuples[0]) {
 		op = free_tuples[0];
 		Py_INCREF(op);
 #ifdef COUNT_ALLOCS
 		tuple_zero_allocs++;
 #endif
 		return (PyObject *) op;
 	}
 	if (0 < size && size < MAXSAVESIZE &&
 	    (op = free_tuples[size]) != NULL)
 	{
 		free_tuples[size] = (PyTupleObject *) op->ob_item[0];
 		num_free_tuples[size]--;
 #ifdef COUNT_ALLOCS
 		fast_tuple_allocs++;
 #endif
 		/* Inline PyObject_InitVar */
 #ifdef Py_TRACE_REFS
 		op->ob_size = size;
 		op->ob_type = &PyTuple_Type;
 #endif
 		_Py_NewReference((PyObject *)op);
 	}
 	else
 #endif
 	{
 		int nbytes = size * sizeof(PyObject *);
 		/* Check for overflow */
 		if (nbytes / sizeof(PyObject *) != (size_t)size ||
 		    (nbytes += sizeof(PyTupleObject) - sizeof(PyObject *))
 		    <= 0)
 		{
 			return PyErr_NoMemory();
 		}
 		op = PyObject_GC_NewVar(PyTupleObject, &PyTuple_Type, size);
 		if (op == NULL)
 			return NULL;
 	}
 	memset(op->ob_item, 0, sizeof(*op->ob_item) * size);
 #if MAXSAVESIZE > 0
 	if (size == 0) {
 		free_tuples[0] = op;
 		++num_free_tuples[0];
 		Py_INCREF(op);	/* extra INCREF so that this is never freed */
 	}
 #endif
 	_PyObject_GC_TRACK(op);
 	return (PyObject *) op;
 }

 int
 PyTuple_Size(register PyObject *op)
 {
 	if (!PyTuple_Check(op)) {
 		PyErr_BadInternalCall();
 		return -1;
 	}
 	else
 		return ((PyTupleObject *)op)->ob_size;
 }

 PyObject *
 PyTuple_GetItem(register PyObject *op, register int i)
 {
 	if (!PyTuple_Check(op)) {
 		PyErr_BadInternalCall();
 		return NULL;
 	}
 	if (i < 0 || i >= ((PyTupleObject *)op) -> ob_size) {
 		PyErr_SetString(PyExc_IndexError, "tuple index out of range");
 		return NULL;
 	}
 	return ((PyTupleObject *)op) -> ob_item[i];
 }

 int
 PyTuple_SetItem(register PyObject *op, register int i, PyObject *newitem)
 {
 	register PyObject *olditem;
 	register PyObject **p;
 	if (!PyTuple_Check(op) || op->ob_refcnt != 1) {
 		Py_XDECREF(newitem);
 		PyErr_BadInternalCall();
 		return -1;
 	}
 	if (i < 0 || i >= ((PyTupleObject *)op) -> ob_size) {
 		Py_XDECREF(newitem);
 		PyErr_SetString(PyExc_IndexError,
 				"tuple assignment index out of range");
 		return -1;
 	}
 	p = ((PyTupleObject *)op) -> ob_item + i;
 	olditem = *p;
 	*p = newitem;
 	Py_XDECREF(olditem);
 	return 0;
 }

 /* Methods */

 static void
 tupledealloc(register PyTupleObject *op)
 {
 	register int i;
 	register int len =  op->ob_size;
 	PyObject_GC_UnTrack(op);
 	Py_TRASHCAN_SAFE_BEGIN(op)
 	if (len > 0) {
 		i = len;
 		while (--i >= 0)
 			Py_XDECREF(op->ob_item[i]);
 #if MAXSAVESIZE > 0
 		if (len < MAXSAVESIZE &&
 		    num_free_tuples[len] < MAXSAVEDTUPLES &&
 		    op->ob_type == &PyTuple_Type)
 		{
 			op->ob_item[0] = (PyObject *) free_tuples[len];
 			num_free_tuples[len]++;
 			free_tuples[len] = op;
 			goto done; /* return */
 		}
 #endif
 	}
 	op->ob_type->tp_free((PyObject *)op);
 done:
 	Py_TRASHCAN_SAFE_END(op)
 }

 static int
 tupleprint(PyTupleObject *op, FILE *fp, int flags)
 {
 	int i;
 	fprintf(fp, "(");
 	for (i = 0; i < op->ob_size; i++) {
 		if (i > 0)
 			fprintf(fp, ", ");
 		if (PyObject_Print(op->ob_item[i], fp, 0) != 0)
 			return -1;
 	}
 	if (op->ob_size == 1)
 		fprintf(fp, ",");
 	fprintf(fp, ")");
 	return 0;
 }

 static PyObject *
 tuplerepr(PyTupleObject *v)
 {
 	int i, n;
 	PyObject *s, *temp;
 	PyObject *pieces, *result = NULL;

 	n = v->ob_size;
 	if (n == 0)
 		return PyString_FromString("()");

 	pieces = PyTuple_New(n);
 	if (pieces == NULL)
 		return NULL;

 	/* Do repr() on each element. */
 	for (i = 0; i < n; ++i) {
 		s = PyObject_Repr(v->ob_item[i]);
 		if (s == NULL)
 			goto Done;
 		PyTuple_SET_ITEM(pieces, i, s);
 	}

 	/* Add "()" decorations to the first and last items. */
 	assert(n > 0);
 	s = PyString_FromString("(");
 	if (s == NULL)
 		goto Done;
 	temp = PyTuple_GET_ITEM(pieces, 0);
 	PyString_ConcatAndDel(&s, temp);
 	PyTuple_SET_ITEM(pieces, 0, s);
 	if (s == NULL)
 		goto Done;

 	s = PyString_FromString(n == 1 ? ",)" : ")");
 	if (s == NULL)
 		goto Done;
 	temp = PyTuple_GET_ITEM(pieces, n-1);
 	PyString_ConcatAndDel(&temp, s);
 	PyTuple_SET_ITEM(pieces, n-1, temp);
 	if (temp == NULL)
 		goto Done;

 	/* Paste them all together with ", " between. */
 	s = PyString_FromString(", ");
 	if (s == NULL)
 		goto Done;
 	result = _PyString_Join(s, pieces);
 	Py_DECREF(s);

 Done:
 	Py_DECREF(pieces);
 	return result;
 }

 static long
 tuplehash(PyTupleObject *v)
 {
 	register long x, y;
 	register int len = v->ob_size;
 	register PyObject **p;
 	x = 0x345678L;
 	p = v->ob_item;
 	while (--len >= 0) {
 		y = PyObject_Hash(*p++);
 		if (y == -1)
 			return -1;
 		x = (1000003*x) ^ y;
 	}
 	x ^= v->ob_size;
 	if (x == -1)
 		x = -2;
 	return x;
 }

 static int
 tuplelength(PyTupleObject *a)
 {
 	return a->ob_size;
 }

 static int
 tuplecontains(PyTupleObject *a, PyObject *el)
 {
 	int i, cmp;

 	for (i = 0, cmp = 0 ; cmp == 0 && i < a->ob_size; ++i)
 		cmp = PyObject_RichCompareBool(el, PyTuple_GET_ITEM(a, i),
 						   Py_EQ);
 	return cmp;
 }

 static PyObject *
 tupleitem(register PyTupleObject *a, register int i)
 {
 	if (i < 0 || i >= a->ob_size) {
 		PyErr_SetString(PyExc_IndexError, "tuple index out of range");
 		return NULL;
 	}
 	Py_INCREF(a->ob_item[i]);
 	return a->ob_item[i];
 }

 static PyObject *
 tupleslice(register PyTupleObject *a, register int ilow, register int ihigh)
 {
 	register PyTupleObject *np;
 	register int i;
 	if (ilow < 0)
 		ilow = 0;
 	if (ihigh > a->ob_size)
 		ihigh = a->ob_size;
 	if (ihigh < ilow)
 		ihigh = ilow;
 	if (ilow == 0 && ihigh == a->ob_size && PyTuple_CheckExact(a)) {
 		Py_INCREF(a);
 		return (PyObject *)a;
 	}
 	np = (PyTupleObject *)PyTuple_New(ihigh - ilow);
 	if (np == NULL)
 		return NULL;
 	for (i = ilow; i < ihigh; i++) {
 		PyObject *v = a->ob_item[i];
 		Py_INCREF(v);
 		np->ob_item[i - ilow] = v;
 	}
 	return (PyObject *)np;
 }

 PyObject *
 PyTuple_GetSlice(PyObject *op, int i, int j)
 {
 	if (op == NULL || !PyTuple_Check(op)) {
 		PyErr_BadInternalCall();
 		return NULL;
 	}
 	return tupleslice((PyTupleObject *)op, i, j);
 }

 static PyObject *
 tupleconcat(register PyTupleObject *a, register PyObject *bb)
 {
 	register int size;
 	register int i;
 	PyTupleObject *np;
 	if (!PyTuple_Check(bb)) {
 		PyErr_Format(PyExc_TypeError,
        		     "can only concatenate tuple (not \"%.200s\") to tuple",
 			     bb->ob_type->tp_name);
 		return NULL;
 	}
 #define b ((PyTupleObject *)bb)
 	size = a->ob_size + b->ob_size;
 	if (size < 0)
 		return PyErr_NoMemory();
 	np = (PyTupleObject *) PyTuple_New(size);
 	if (np == NULL) {
 		return NULL;
 	}
 	for (i = 0; i < a->ob_size; i++) {
 		PyObject *v = a->ob_item[i];
 		Py_INCREF(v);
 		np->ob_item[i] = v;
 	}
 	for (i = 0; i < b->ob_size; i++) {
 		PyObject *v = b->ob_item[i];
 		Py_INCREF(v);
 		np->ob_item[i + a->ob_size] = v;
 	}
 	return (PyObject *)np;
 #undef b
 }

 static PyObject *
 tuplerepeat(PyTupleObject *a, int n)
 {
 	int i, j;
 	int size;
 	PyTupleObject *np;
 	PyObject **p;
 	if (n < 0)
 		n = 0;
 	if (a->ob_size == 0 || n == 1) {
 		if (PyTuple_CheckExact(a)) {
 			/* Since tuples are immutable, we can return a shared
 			   copy in this case */
 			Py_INCREF(a);
 			return (PyObject *)a;
 		}
 		if (a->ob_size == 0)
 			return PyTuple_New(0);
 	}
 	size = a->ob_size * n;
 	if (size/a->ob_size != n)
 		return PyErr_NoMemory();
 	np = (PyTupleObject *) PyTuple_New(size);
 	if (np == NULL)
 		return NULL;
 	p = np->ob_item;
 	for (i = 0; i < n; i++) {
 		for (j = 0; j < a->ob_size; j++) {
 			*p = a->ob_item[j];
 			Py_INCREF(*p);
 			p++;
 		}
 	}
 	return (PyObject *) np;
 }

 static int
 tupletraverse(PyTupleObject *o, visitproc visit, void *arg)
 {
 	int i, err;
 	PyObject *x;

 	for (i = o->ob_size; --i >= 0; ) {
 		x = o->ob_item[i];
 		if (x != NULL) {
 			err = visit(x, arg);
 			if (err)
 				return err;
 		}
 	}
 	return 0;
 }

 static PyObject *
 tuplerichcompare(PyObject *v, PyObject *w, int op)
 {
 	PyTupleObject *vt, *wt;
 	int i;
 	int vlen, wlen;

 	if (!PyTuple_Check(v) || !PyTuple_Check(w)) {
 		Py_INCREF(Py_NotImplemented);
 		return Py_NotImplemented;
 	}

 	vt = (PyTupleObject *)v;
 	wt = (PyTupleObject *)w;

 	vlen = vt->ob_size;
 	wlen = wt->ob_size;

 	/* Note:  the corresponding code for lists has an "early out" test
 	 * here when op is EQ or NE and the lengths differ.  That pays there,
 	 * but Tim was unable to find any real code where EQ/NE tuple
 	 * compares don't have the same length, so testing for it here would
 	 * have cost without benefit.
 	 */

 	/* Search for the first index where items are different.
 	 * Note that because tuples are immutable, it's safe to reuse
 	 * vlen and wlen across the comparison calls.
 	 */
 	for (i = 0; i < vlen && i < wlen; i++) {
 		int k = PyObject_RichCompareBool(vt->ob_item[i],
 						 wt->ob_item[i], Py_EQ);
 		if (k < 0)
 			return NULL;
 		if (!k)
 			break;
 	}

 	if (i >= vlen || i >= wlen) {
 		/* No more items to compare -- compare sizes */
 		int cmp;
 		PyObject *res;
 		switch (op) {
 		case Py_LT: cmp = vlen <  wlen; break;
 		case Py_LE: cmp = vlen <= wlen; break;
 		case Py_EQ: cmp = vlen == wlen; break;
 		case Py_NE: cmp = vlen != wlen; break;
 		case Py_GT: cmp = vlen >  wlen; break;
 		case Py_GE: cmp = vlen >= wlen; break;
 		default: return NULL; /* cannot happen */
 		}
 		if (cmp)
 			res = Py_True;
 		else
 			res = Py_False;
 		Py_INCREF(res);
 		return res;
 	}

 	/* We have an item that differs -- shortcuts for EQ/NE */
 	if (op == Py_EQ) {
 		Py_INCREF(Py_False);
 		return Py_False;
 	}
 	if (op == Py_NE) {
 		Py_INCREF(Py_True);
 		return Py_True;
 	}

 	/* Compare the final item again using the proper operator */
 	return PyObject_RichCompare(vt->ob_item[i], wt->ob_item[i], op);
 }

 static PyObject *
 tuple_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);

 static PyObject *
 tuple_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
 	PyObject *arg = NULL;
 	static char *kwlist[] = {"sequence", 0};

 	if (type != &PyTuple_Type)
 		return tuple_subtype_new(type, args, kwds);
 	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O:tuple", kwlist, &arg))
 		return NULL;

 	if (arg == NULL)
 		return PyTuple_New(0);
 	else
 		return PySequence_Tuple(arg);
 }

 static PyObject *
 tuple_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
 	PyObject *tmp, *new, *item;
 	int i, n;

 	assert(PyType_IsSubtype(type, &PyTuple_Type));
 	tmp = tuple_new(&PyTuple_Type, args, kwds);
 	if (tmp == NULL)
 		return NULL;
 	assert(PyTuple_Check(tmp));
 	new = type->tp_alloc(type, n = PyTuple_GET_SIZE(tmp));
 	if (new == NULL)
 		return NULL;
 	for (i = 0; i < n; i++) {
 		item = PyTuple_GET_ITEM(tmp, i);
 		Py_INCREF(item);
 		PyTuple_SET_ITEM(new, i, item);
 	}
 	Py_DECREF(tmp);
 	return new;
 }

 PyDoc_STRVAR(tuple_doc,
 "tuple() -> an empty tuple\n"
 "tuple(sequence) -> tuple initialized from sequence's items\n"
 "\n"
 "If the argument is a tuple, the return value is the same object.");

 static PySequenceMethods tuple_as_sequence = {
 	(inquiry)tuplelength,			/* sq_length */
 	(binaryfunc)tupleconcat,		/* sq_concat */
 	(intargfunc)tuplerepeat,		/* sq_repeat */
 	(intargfunc)tupleitem,			/* sq_item */
 	(intintargfunc)tupleslice,		/* sq_slice */
 	0,					/* sq_ass_item */
 	0,					/* sq_ass_slice */
 	(objobjproc)tuplecontains,		/* sq_contains */
 };

 static PyObject*
 tuplesubscript(PyTupleObject* self, PyObject* item)
 {
 	if (PyInt_Check(item)) {
 		long i = PyInt_AS_LONG(item);
 		if (i < 0)
 			i += PyTuple_GET_SIZE(self);
 		return tupleitem(self, i);
 	}
 	else if (PyLong_Check(item)) {
 		long i = PyLong_AsLong(item);
 		if (i == -1 && PyErr_Occurred())
 			return NULL;
 		if (i < 0)
 			i += PyTuple_GET_SIZE(self);
 		return tupleitem(self, i);
 	}
 	else if (PySlice_Check(item)) {
 		int start, stop, step, slicelength, cur, i;
 		PyObject* result;
 		PyObject* it;

 		if (PySlice_GetIndicesEx((PySliceObject*)item,
 				 PyTuple_GET_SIZE(self),
 				 &start, &stop, &step, &slicelength) < 0) {
 			return NULL;
 		}

 		if (slicelength <= 0) {
 			return PyTuple_New(0);
 		}
 		else {
 			result = PyTuple_New(slicelength);

 			for (cur = start, i = 0; i < slicelength;
 			     cur += step, i++) {
 				it = PyTuple_GET_ITEM(self, cur);
 				Py_INCREF(it);
 				PyTuple_SET_ITEM(result, i, it);
 			}

 			return result;
 		}
 	}
 	else {
 		PyErr_SetString(PyExc_TypeError,
 				"tuple indices must be integers");
 		return NULL;
 	}
 }

 static PyMappingMethods tuple_as_mapping = {
 	(inquiry)tuplelength,
 	(binaryfunc)tuplesubscript,
 	0
 };

 static PyObject *tuple_iter(PyObject *seq);

 PyTypeObject PyTuple_Type = {
 	PyObject_HEAD_INIT(&PyType_Type)
 	0,
 	"tuple",
 	sizeof(PyTupleObject) - sizeof(PyObject *),
 	sizeof(PyObject *),
 	(destructor)tupledealloc,		/* tp_dealloc */
 	(printfunc)tupleprint,			/* tp_print */
 	0,					/* tp_getattr */
 	0,					/* tp_setattr */
 	0,					/* tp_compare */
 	(reprfunc)tuplerepr,			/* tp_repr */
 	0,					/* tp_as_number */
 	&tuple_as_sequence,			/* tp_as_sequence */
 	&tuple_as_mapping,			/* tp_as_mapping */
 	(hashfunc)tuplehash,			/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */
 	PyObject_GenericGetAttr,		/* tp_getattro */
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
 		Py_TPFLAGS_BASETYPE,		/* tp_flags */
 	tuple_doc,				/* tp_doc */
  	(traverseproc)tupletraverse,		/* tp_traverse */
 	0,					/* tp_clear */
 	tuplerichcompare,			/* tp_richcompare */
 	0,					/* tp_weaklistoffset */
 	tuple_iter,	    			/* tp_iter */
 	0,					/* tp_iternext */
 	0,					/* tp_methods */
 	0,					/* tp_members */
 	0,					/* tp_getset */
 	0,					/* tp_base */
 	0,					/* tp_dict */
 	0,					/* tp_descr_get */
 	0,					/* tp_descr_set */
 	0,					/* tp_dictoffset */
 	0,					/* tp_init */
 	0,					/* tp_alloc */
 	tuple_new,				/* tp_new */
 	PyObject_GC_Del,        		/* tp_free */
 };

 /* The following function breaks the notion that tuples are immutable:
    it changes the size of a tuple.  We get away with this only if there
    is only one module referencing the object.  You can also think of it
    as creating a new tuple object and destroying the old one, only more
    efficiently.  In any case, don't use this if the tuple may already be
    known to some other part of the code. */

 int
 _PyTuple_Resize(PyObject **pv, int newsize)
 {
 	register PyTupleObject *v;
 	register PyTupleObject *sv;
 	int i;
 	int oldsize;

 	v = (PyTupleObject *) *pv;
 	if (v == NULL || v->ob_type != &PyTuple_Type ||
 	    (v->ob_size != 0 && v->ob_refcnt != 1)) {
 		*pv = 0;
 		Py_XDECREF(v);
 		PyErr_BadInternalCall();
 		return -1;
 	}
 	oldsize = v->ob_size;
 	if (oldsize == newsize)
 		return 0;

 	if (oldsize == 0) {
 		/* Empty tuples are often shared, so we should never
 		   resize them in-place even if we do own the only
 		   (current) reference */
 		Py_DECREF(v);
 		*pv = PyTuple_New(newsize);
 		return *pv == NULL ? -1 : 0;
 	}

 	/* XXX UNREF/NEWREF interface should be more symmetrical */
 	_Py_DEC_REFTOTAL;
 	_PyObject_GC_UNTRACK(v);
 	_Py_ForgetReference((PyObject *) v);
 	/* DECREF items deleted by shrinkage */
 	for (i = newsize; i < oldsize; i++) {
 		Py_XDECREF(v->ob_item[i]);
 		v->ob_item[i] = NULL;
 	}
 	sv = PyObject_GC_Resize(PyTupleObject, v, newsize);
 	if (sv == NULL) {
 		*pv = NULL;
 		PyObject_GC_Del(v);
 		return -1;
 	}
 	_Py_NewReference((PyObject *) sv);
 	/* Zero out items added by growing */
 	if (newsize > oldsize)
 		memset(&sv->ob_item[oldsize], 0,
 		       sizeof(*sv->ob_item) * (newsize - oldsize));
 	*pv = (PyObject *) sv;
 	_PyObject_GC_TRACK(sv);
 	return 0;
 }

 void
 PyTuple_Fini(void)
 {
 #if MAXSAVESIZE > 0
 	int i;

 	Py_XDECREF(free_tuples[0]);
 	free_tuples[0] = NULL;

 	for (i = 1; i < MAXSAVESIZE; i++) {
 		PyTupleObject *p, *q;
 		p = free_tuples[i];
 		free_tuples[i] = NULL;
 		while (p) {
 			q = p;
 			p = (PyTupleObject *)(p->ob_item[0]);
 			PyObject_GC_Del(q);
 		}
 	}
 #endif
 }

 /*********************** Tuple Iterator **************************/

 typedef struct {
 	PyObject_HEAD
 	long it_index;
 	PyTupleObject *it_seq; /* Set to NULL when iterator is exhausted */
 } tupleiterobject;

 PyTypeObject PyTupleIter_Type;

 static PyObject *
 tuple_iter(PyObject *seq)
 {
 	tupleiterobject *it;

 	if (!PyTuple_Check(seq)) {
 		PyErr_BadInternalCall();
 		return NULL;
 	}
 	it = PyObject_GC_New(tupleiterobject, &PyTupleIter_Type);
 	if (it == NULL)
 		return NULL;
 	it->it_index = 0;
 	Py_INCREF(seq);
 	it->it_seq = (PyTupleObject *)seq;
 	_PyObject_GC_TRACK(it);
 	return (PyObject *)it;
 }

 static void
 tupleiter_dealloc(tupleiterobject *it)
 {
 	_PyObject_GC_UNTRACK(it);
 	Py_XDECREF(it->it_seq);
 	PyObject_GC_Del(it);
 }

 static int
 tupleiter_traverse(tupleiterobject *it, visitproc visit, void *arg)
 {
 	if (it->it_seq == NULL)
 		return 0;
 	return visit((PyObject *)it->it_seq, arg);
 }


 static PyObject *
 tupleiter_getiter(PyObject *it)
 {
 	Py_INCREF(it);
 	return it;
 }

 static PyObject *
 tupleiter_next(tupleiterobject *it)
 {
 	PyTupleObject *seq;
 	PyObject *item;

 	assert(it != NULL);
 	seq = it->it_seq;
 	if (seq == NULL)
 		return NULL;
 	assert(PyTuple_Check(seq));

 	if (it->it_index < PyTuple_GET_SIZE(seq)) {
 		item = PyTuple_GET_ITEM(seq, it->it_index);
 		++it->it_index;
 		Py_INCREF(item);
 		return item;
 	}

 	Py_DECREF(seq);
 	it->it_seq = NULL;
 	return NULL;
 }

 PyTypeObject PyTupleIter_Type = {
 	PyObject_HEAD_INIT(&PyType_Type)
 	0,					/* ob_size */
 	"tupleiterator",			/* tp_name */
 	sizeof(tupleiterobject),		/* tp_basicsize */
 	0,					/* tp_itemsize */
 	/* methods */
 	(destructor)tupleiter_dealloc,		/* tp_dealloc */
 	0,					/* tp_print */
 	0,					/* tp_getattr */
 	0,					/* tp_setattr */
 	0,					/* tp_compare */
 	0,					/* tp_repr */
 	0,					/* tp_as_number */
 	0,					/* tp_as_sequence */
 	0,					/* tp_as_mapping */
 	0,					/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */
 	PyObject_GenericGetAttr,		/* tp_getattro */
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
 	0,					/* tp_doc */
 	(traverseproc)tupleiter_traverse,	/* tp_traverse */
 	0,					/* tp_clear */
 	0,					/* tp_richcompare */
 	0,					/* tp_weaklistoffset */
 	(getiterfunc)tupleiter_getiter,		/* tp_iter */
 	(iternextfunc)tupleiter_next,		/* tp_iternext */
 };

	/* Tuple object implementation */

	#include "Python.h"

	/* Speed optimization to avoid frequent malloc/free of small tuples */
	#ifndef MAXSAVESIZE
	#define MAXSAVESIZE 20 /* Largest tuple to save on free list */
	#endif
	#ifndef MAXSAVEDTUPLES
	#define MAXSAVEDTUPLES 2000 /* Maximum number of tuples of each size to save */
	#endif

	#if MAXSAVESIZE > 0
	/* Entries 1 up to MAXSAVESIZE are free lists, entry 0 is the empty
	tuple () of which at most one instance will be allocated.
	*/
	static PyTupleObject *free_tuples[MAXSAVESIZE];
	static int num_free_tuples[MAXSAVESIZE];
	#endif
	#ifdef COUNT_ALLOCS
	int fast_tuple_allocs;
	int tuple_zero_allocs;
	#endif

	PyObject *
	PyTuple_New(register int size)
	{
	register PyTupleObject *op;
	if (size < 0) {
	PyErr_BadInternalCall();
	return NULL;
	}
	#if MAXSAVESIZE > 0
	if (size == 0 && free_tuples[0]) {
	op = free_tuples[0];
	Py_INCREF(op);
	#ifdef COUNT_ALLOCS
	tuple_zero_allocs++;
	#endif
	return (PyObject *) op;
	}
	if (0 < size && size < MAXSAVESIZE &&
	(op = free_tuples[size]) != NULL)
	{
	free_tuples[size] = (PyTupleObject *) op->ob_item[0];
	num_free_tuples[size]--;
	#ifdef COUNT_ALLOCS
	fast_tuple_allocs++;
	#endif
	/* Inline PyObject_InitVar */
	#ifdef Py_TRACE_REFS
	op->ob_size = size;
	op->ob_type = &PyTuple_Type;
	#endif
	_Py_NewReference((PyObject *)op);
	}
	else
	#endif
	{
	int nbytes = size * sizeof(PyObject *);
	/* Check for overflow */
	if (nbytes / sizeof(PyObject *) != (size_t)size \|\|
	(nbytes += sizeof(PyTupleObject) - sizeof(PyObject *))
	<= 0)
	{
	return PyErr_NoMemory();
	}
	op = PyObject_GC_NewVar(PyTupleObject, &PyTuple_Type, size);
	if (op == NULL)
	return NULL;
	}
	memset(op->ob_item, 0, sizeof(op->ob_item) size);
	#if MAXSAVESIZE > 0
	if (size == 0) {
	free_tuples[0] = op;
	++num_free_tuples[0];
	Py_INCREF(op); /* extra INCREF so that this is never freed */
	}
	#endif
	_PyObject_GC_TRACK(op);
	return (PyObject *) op;
	}

	int
	PyTuple_Size(register PyObject *op)
	{
	if (!PyTuple_Check(op)) {
	PyErr_BadInternalCall();
	return -1;
	}
	else
	return ((PyTupleObject *)op)->ob_size;
	}

	PyObject *
	PyTuple_GetItem(register PyObject *op, register int i)
	{
	if (!PyTuple_Check(op)) {
	PyErr_BadInternalCall();
	return NULL;
	}
	if (i < 0 \|\| i >= ((PyTupleObject *)op) -> ob_size) {
	PyErr_SetString(PyExc_IndexError, "tuple index out of range");
	return NULL;
	}
	return ((PyTupleObject *)op) -> ob_item[i];
	}

	int
	PyTuple_SetItem(register PyObject op, register int i, PyObject newitem)
	{
	register PyObject *olditem;
	register PyObject **p;
	if (!PyTuple_Check(op) \|\| op->ob_refcnt != 1) {
	Py_XDECREF(newitem);
	PyErr_BadInternalCall();
	return -1;
	}
	if (i < 0 \|\| i >= ((PyTupleObject *)op) -> ob_size) {
	Py_XDECREF(newitem);
	PyErr_SetString(PyExc_IndexError,
	"tuple assignment index out of range");
	return -1;
	}
	p = ((PyTupleObject *)op) -> ob_item + i;
	olditem = *p;
	*p = newitem;
	Py_XDECREF(olditem);
	return 0;
	}

	/* Methods */

	static void
	tupledealloc(register PyTupleObject *op)
	{
	register int i;
	register int len = op->ob_size;
	PyObject_GC_UnTrack(op);
	Py_TRASHCAN_SAFE_BEGIN(op)
	if (len > 0) {
	i = len;
	while (--i >= 0)
	Py_XDECREF(op->ob_item[i]);
	#if MAXSAVESIZE > 0
	if (len < MAXSAVESIZE &&
	num_free_tuples[len] < MAXSAVEDTUPLES &&
	op->ob_type == &PyTuple_Type)
	{
	op->ob_item[0] = (PyObject *) free_tuples[len];
	num_free_tuples[len]++;
	free_tuples[len] = op;
	goto done; /* return */
	}
	#endif
	}
	op->ob_type->tp_free((PyObject *)op);
	done:
	Py_TRASHCAN_SAFE_END(op)
	}

	static int
	tupleprint(PyTupleObject op, FILE fp, int flags)
	{
	int i;
	fprintf(fp, "(");
	for (i = 0; i < op->ob_size; i++) {
	if (i > 0)
	fprintf(fp, ", ");
	if (PyObject_Print(op->ob_item[i], fp, 0) != 0)
	return -1;
	}
	if (op->ob_size == 1)
	fprintf(fp, ",");
	fprintf(fp, ")");
	return 0;
	}

	static PyObject *
	tuplerepr(PyTupleObject *v)
	{
	int i, n;
	PyObject s, temp;
	PyObject pieces, result = NULL;

	n = v->ob_size;
	if (n == 0)
	return PyString_FromString("()");

	pieces = PyTuple_New(n);
	if (pieces == NULL)
	return NULL;

	/* Do repr() on each element. */
	for (i = 0; i < n; ++i) {
	s = PyObject_Repr(v->ob_item[i]);
	if (s == NULL)
	goto Done;
	PyTuple_SET_ITEM(pieces, i, s);
	}

	/* Add "()" decorations to the first and last items. */
	assert(n > 0);
	s = PyString_FromString("(");
	if (s == NULL)
	goto Done;
	temp = PyTuple_GET_ITEM(pieces, 0);
	PyString_ConcatAndDel(&s, temp);
	PyTuple_SET_ITEM(pieces, 0, s);
	if (s == NULL)
	goto Done;

	s = PyString_FromString(n == 1 ? ",)" : ")");
	if (s == NULL)
	goto Done;
	temp = PyTuple_GET_ITEM(pieces, n-1);
	PyString_ConcatAndDel(&temp, s);
	PyTuple_SET_ITEM(pieces, n-1, temp);
	if (temp == NULL)
	goto Done;

	/* Paste them all together with ", " between. */
	s = PyString_FromString(", ");
	if (s == NULL)
	goto Done;
	result = _PyString_Join(s, pieces);
	Py_DECREF(s);

	Done:
	Py_DECREF(pieces);
	return result;
	}

	static long
	tuplehash(PyTupleObject *v)
	{
	register long x, y;
	register int len = v->ob_size;
	register PyObject **p;
	x = 0x345678L;
	p = v->ob_item;
	while (--len >= 0) {
	y = PyObject_Hash(*p++);
	if (y == -1)
	return -1;
	x = (1000003*x) ^ y;
	}
	x ^= v->ob_size;
	if (x == -1)
	x = -2;
	return x;
	}

	static int
	tuplelength(PyTupleObject *a)
	{
	return a->ob_size;
	}

	static int
	tuplecontains(PyTupleObject a, PyObject el)
	{
	int i, cmp;

	for (i = 0, cmp = 0 ; cmp == 0 && i < a->ob_size; ++i)
	cmp = PyObject_RichCompareBool(el, PyTuple_GET_ITEM(a, i),
	Py_EQ);
	return cmp;
	}

	static PyObject *
	tupleitem(register PyTupleObject *a, register int i)
	{
	if (i < 0 \|\| i >= a->ob_size) {
	PyErr_SetString(PyExc_IndexError, "tuple index out of range");
	return NULL;
	}
	Py_INCREF(a->ob_item[i]);
	return a->ob_item[i];
	}

	static PyObject *
	tupleslice(register PyTupleObject *a, register int ilow, register int ihigh)
	{
	register PyTupleObject *np;
	register int i;
	if (ilow < 0)
	ilow = 0;
	if (ihigh > a->ob_size)
	ihigh = a->ob_size;
	if (ihigh < ilow)
	ihigh = ilow;
	if (ilow == 0 && ihigh == a->ob_size && PyTuple_CheckExact(a)) {
	Py_INCREF(a);
	return (PyObject *)a;
	}
	np = (PyTupleObject *)PyTuple_New(ihigh - ilow);
	if (np == NULL)
	return NULL;
	for (i = ilow; i < ihigh; i++) {
	PyObject *v = a->ob_item[i];
	Py_INCREF(v);
	np->ob_item[i - ilow] = v;
	}
	return (PyObject *)np;
	}

	PyObject *
	PyTuple_GetSlice(PyObject *op, int i, int j)
	{
	if (op == NULL \|\| !PyTuple_Check(op)) {
	PyErr_BadInternalCall();
	return NULL;
	}
	return tupleslice((PyTupleObject *)op, i, j);
	}

	static PyObject *
	tupleconcat(register PyTupleObject a, register PyObject bb)
	{
	register int size;
	register int i;
	PyTupleObject *np;
	if (!PyTuple_Check(bb)) {
	PyErr_Format(PyExc_TypeError,
	"can only concatenate tuple (not \"%.200s\") to tuple",
	bb->ob_type->tp_name);
	return NULL;
	}
	#define b ((PyTupleObject *)bb)
	size = a->ob_size + b->ob_size;
	if (size < 0)
	return PyErr_NoMemory();
	np = (PyTupleObject *) PyTuple_New(size);
	if (np == NULL) {
	return NULL;
	}
	for (i = 0; i < a->ob_size; i++) {
	PyObject *v = a->ob_item[i];
	Py_INCREF(v);
	np->ob_item[i] = v;
	}
	for (i = 0; i < b->ob_size; i++) {
	PyObject *v = b->ob_item[i];
	Py_INCREF(v);
	np->ob_item[i + a->ob_size] = v;
	}
	return (PyObject *)np;
	#undef b
	}

	static PyObject *
	tuplerepeat(PyTupleObject *a, int n)
	{
	int i, j;
	int size;
	PyTupleObject *np;
	PyObject **p;
	if (n < 0)
	n = 0;
	if (a->ob_size == 0 \|\| n == 1) {
	if (PyTuple_CheckExact(a)) {
	/* Since tuples are immutable, we can return a shared
	copy in this case */
	Py_INCREF(a);
	return (PyObject *)a;
	}
	if (a->ob_size == 0)
	return PyTuple_New(0);
	}
	size = a->ob_size * n;
	if (size/a->ob_size != n)
	return PyErr_NoMemory();
	np = (PyTupleObject *) PyTuple_New(size);
	if (np == NULL)
	return NULL;
	p = np->ob_item;
	for (i = 0; i < n; i++) {
	for (j = 0; j < a->ob_size; j++) {
	*p = a->ob_item[j];
	Py_INCREF(*p);
	p++;
	}
	}
	return (PyObject *) np;
	}

	static int
	tupletraverse(PyTupleObject o, visitproc visit, void arg)
	{
	int i, err;
	PyObject *x;

	for (i = o->ob_size; --i >= 0; ) {
	x = o->ob_item[i];
	if (x != NULL) {
	err = visit(x, arg);
	if (err)
	return err;
	}
	}
	return 0;
	}

	static PyObject *
	tuplerichcompare(PyObject v, PyObject w, int op)
	{
	PyTupleObject vt, wt;
	int i;
	int vlen, wlen;

	if (!PyTuple_Check(v) \|\| !PyTuple_Check(w)) {
	Py_INCREF(Py_NotImplemented);
	return Py_NotImplemented;
	}

	vt = (PyTupleObject *)v;
	wt = (PyTupleObject *)w;

	vlen = vt->ob_size;
	wlen = wt->ob_size;

	/* Note: the corresponding code for lists has an "early out" test
	* here when op is EQ or NE and the lengths differ. That pays there,
	* but Tim was unable to find any real code where EQ/NE tuple
	* compares don't have the same length, so testing for it here would
	* have cost without benefit.
	*/

	/* Search for the first index where items are different.
	* Note that because tuples are immutable, it's safe to reuse
	* vlen and wlen across the comparison calls.
	*/
	for (i = 0; i < vlen && i < wlen; i++) {
	int k = PyObject_RichCompareBool(vt->ob_item[i],
	wt->ob_item[i], Py_EQ);
	if (k < 0)
	return NULL;
	if (!k)
	break;
	}

	if (i >= vlen \|\| i >= wlen) {
	/* No more items to compare -- compare sizes */
	int cmp;
	PyObject *res;
	switch (op) {
	case Py_LT: cmp = vlen < wlen; break;
	case Py_LE: cmp = vlen <= wlen; break;
	case Py_EQ: cmp = vlen == wlen; break;
	case Py_NE: cmp = vlen != wlen; break;
	case Py_GT: cmp = vlen > wlen; break;
	case Py_GE: cmp = vlen >= wlen; break;
	default: return NULL; /* cannot happen */
	}
	if (cmp)
	res = Py_True;
	else
	res = Py_False;
	Py_INCREF(res);
	return res;
	}

	/* We have an item that differs -- shortcuts for EQ/NE */
	if (op == Py_EQ) {
	Py_INCREF(Py_False);
	return Py_False;
	}
	if (op == Py_NE) {
	Py_INCREF(Py_True);
	return Py_True;
	}

	/* Compare the final item again using the proper operator */
	return PyObject_RichCompare(vt->ob_item[i], wt->ob_item[i], op);
	}

	static PyObject *
	tuple_subtype_new(PyTypeObject type, PyObject args, PyObject *kwds);

	static PyObject *
	tuple_new(PyTypeObject type, PyObject args, PyObject *kwds)
	{
	PyObject *arg = NULL;
	static char *kwlist[] = {"sequence", 0};

	if (type != &PyTuple_Type)
	return tuple_subtype_new(type, args, kwds);
	if (!PyArg_ParseTupleAndKeywords(args, kwds, "\|O:tuple", kwlist, &arg))
	return NULL;

	if (arg == NULL)
	return PyTuple_New(0);
	else
	return PySequence_Tuple(arg);
	}

	static PyObject *
	tuple_subtype_new(PyTypeObject type, PyObject args, PyObject *kwds)
	{
	PyObject tmp, new, *item;
	int i, n;

	assert(PyType_IsSubtype(type, &PyTuple_Type));
	tmp = tuple_new(&PyTuple_Type, args, kwds);
	if (tmp == NULL)
	return NULL;
	assert(PyTuple_Check(tmp));
	new = type->tp_alloc(type, n = PyTuple_GET_SIZE(tmp));
	if (new == NULL)
	return NULL;
	for (i = 0; i < n; i++) {
	item = PyTuple_GET_ITEM(tmp, i);
	Py_INCREF(item);
	PyTuple_SET_ITEM(new, i, item);
	}
	Py_DECREF(tmp);
	return new;
	}

	PyDoc_STRVAR(tuple_doc,
	"tuple() -> an empty tuple\n"
	"tuple(sequence) -> tuple initialized from sequence's items\n"
	"\n"
	"If the argument is a tuple, the return value is the same object.");

	static PySequenceMethods tuple_as_sequence = {
	(inquiry)tuplelength, /* sq_length */
	(binaryfunc)tupleconcat, /* sq_concat */
	(intargfunc)tuplerepeat, /* sq_repeat */
	(intargfunc)tupleitem, /* sq_item */
	(intintargfunc)tupleslice, /* sq_slice */
	0, /* sq_ass_item */
	0, /* sq_ass_slice */
	(objobjproc)tuplecontains, /* sq_contains */
	};

	static PyObject*
	tuplesubscript(PyTupleObject* self, PyObject* item)
	{
	if (PyInt_Check(item)) {
	long i = PyInt_AS_LONG(item);
	if (i < 0)
	i += PyTuple_GET_SIZE(self);
	return tupleitem(self, i);
	}
	else if (PyLong_Check(item)) {
	long i = PyLong_AsLong(item);
	if (i == -1 && PyErr_Occurred())
	return NULL;
	if (i < 0)
	i += PyTuple_GET_SIZE(self);
	return tupleitem(self, i);
	}
	else if (PySlice_Check(item)) {
	int start, stop, step, slicelength, cur, i;
	PyObject* result;
	PyObject* it;

	if (PySlice_GetIndicesEx((PySliceObject*)item,
	PyTuple_GET_SIZE(self),
	&start, &stop, &step, &slicelength) < 0) {
	return NULL;
	}

	if (slicelength <= 0) {
	return PyTuple_New(0);
	}
	else {
	result = PyTuple_New(slicelength);

	for (cur = start, i = 0; i < slicelength;
	cur += step, i++) {
	it = PyTuple_GET_ITEM(self, cur);
	Py_INCREF(it);
	PyTuple_SET_ITEM(result, i, it);
	}

	return result;
	}
	}
	else {
	PyErr_SetString(PyExc_TypeError,
	"tuple indices must be integers");
	return NULL;
	}
	}

	static PyMappingMethods tuple_as_mapping = {
	(inquiry)tuplelength,
	(binaryfunc)tuplesubscript,
	0
	};

	static PyObject tuple_iter(PyObject seq);

	PyTypeObject PyTuple_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"tuple",
	sizeof(PyTupleObject) - sizeof(PyObject *),
	sizeof(PyObject *),
	(destructor)tupledealloc, /* tp_dealloc */
	(printfunc)tupleprint, /* tp_print */
	0, /* tp_getattr */
	0, /* tp_setattr */
	0, /* tp_compare */
	(reprfunc)tuplerepr, /* tp_repr */
	0, /* tp_as_number */
	&tuple_as_sequence, /* tp_as_sequence */
	&tuple_as_mapping, /* tp_as_mapping */
	(hashfunc)tuplehash, /* tp_hash */
	0, /* tp_call */
	0, /* tp_str */
	PyObject_GenericGetAttr, /* tp_getattro */
	0, /* tp_setattro */
	0, /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT \| Py_TPFLAGS_HAVE_GC \|
	Py_TPFLAGS_BASETYPE, /* tp_flags */
	tuple_doc, /* tp_doc */
	(traverseproc)tupletraverse, /* tp_traverse */
	0, /* tp_clear */
	tuplerichcompare, /* tp_richcompare */
	0, /* tp_weaklistoffset */
	tuple_iter, /* tp_iter */
	0, /* tp_iternext */
	0, /* tp_methods */
	0, /* tp_members */
	0, /* tp_getset */
	0, /* tp_base */
	0, /* tp_dict */
	0, /* tp_descr_get */
	0, /* tp_descr_set */
	0, /* tp_dictoffset */
	0, /* tp_init */
	0, /* tp_alloc */
	tuple_new, /* tp_new */
	PyObject_GC_Del, /* tp_free */
	};

	/* The following function breaks the notion that tuples are immutable:
	it changes the size of a tuple. We get away with this only if there
	is only one module referencing the object. You can also think of it
	as creating a new tuple object and destroying the old one, only more
	efficiently. In any case, don't use this if the tuple may already be
	known to some other part of the code. */

	int
	_PyTuple_Resize(PyObject **pv, int newsize)
	{
	register PyTupleObject *v;
	register PyTupleObject *sv;
	int i;
	int oldsize;

	v = (PyTupleObject ) pv;
	if (v == NULL \|\| v->ob_type != &PyTuple_Type \|\|
	(v->ob_size != 0 && v->ob_refcnt != 1)) {
	*pv = 0;
	Py_XDECREF(v);
	PyErr_BadInternalCall();
	return -1;
	}
	oldsize = v->ob_size;
	if (oldsize == newsize)
	return 0;

	if (oldsize == 0) {
	/* Empty tuples are often shared, so we should never
	resize them in-place even if we do own the only
	(current) reference */
	Py_DECREF(v);
	*pv = PyTuple_New(newsize);
	return *pv == NULL ? -1 : 0;
	}

	/* XXX UNREF/NEWREF interface should be more symmetrical */
	_Py_DEC_REFTOTAL;
	_PyObject_GC_UNTRACK(v);
	_Py_ForgetReference((PyObject *) v);
	/* DECREF items deleted by shrinkage */
	for (i = newsize; i < oldsize; i++) {
	Py_XDECREF(v->ob_item[i]);
	v->ob_item[i] = NULL;
	}
	sv = PyObject_GC_Resize(PyTupleObject, v, newsize);
	if (sv == NULL) {
	*pv = NULL;
	PyObject_GC_Del(v);
	return -1;
	}
	_Py_NewReference((PyObject *) sv);
	/* Zero out items added by growing */
	if (newsize > oldsize)
	memset(&sv->ob_item[oldsize], 0,
	sizeof(sv->ob_item) (newsize - oldsize));
	pv = (PyObject ) sv;
	_PyObject_GC_TRACK(sv);
	return 0;
	}

	void
	PyTuple_Fini(void)
	{
	#if MAXSAVESIZE > 0
	int i;

	Py_XDECREF(free_tuples[0]);
	free_tuples[0] = NULL;

	for (i = 1; i < MAXSAVESIZE; i++) {
	PyTupleObject p, q;
	p = free_tuples[i];
	free_tuples[i] = NULL;
	while (p) {
	q = p;
	p = (PyTupleObject *)(p->ob_item[0]);
	PyObject_GC_Del(q);
	}
	}
	#endif
	}

	/********************* Tuple Iterator ************************/

	typedef struct {
	PyObject_HEAD
	long it_index;
	PyTupleObject it_seq; / Set to NULL when iterator is exhausted */
	} tupleiterobject;

	PyTypeObject PyTupleIter_Type;

	static PyObject *
	tuple_iter(PyObject *seq)
	{
	tupleiterobject *it;

	if (!PyTuple_Check(seq)) {
	PyErr_BadInternalCall();
	return NULL;
	}
	it = PyObject_GC_New(tupleiterobject, &PyTupleIter_Type);
	if (it == NULL)
	return NULL;
	it->it_index = 0;
	Py_INCREF(seq);
	it->it_seq = (PyTupleObject *)seq;
	_PyObject_GC_TRACK(it);
	return (PyObject *)it;
	}

	static void
	tupleiter_dealloc(tupleiterobject *it)
	{
	_PyObject_GC_UNTRACK(it);
	Py_XDECREF(it->it_seq);
	PyObject_GC_Del(it);
	}

	static int
	tupleiter_traverse(tupleiterobject it, visitproc visit, void arg)
	{
	if (it->it_seq == NULL)
	return 0;
	return visit((PyObject *)it->it_seq, arg);
	}


	static PyObject *
	tupleiter_getiter(PyObject *it)
	{
	Py_INCREF(it);
	return it;
	}

	static PyObject *
	tupleiter_next(tupleiterobject *it)
	{
	PyTupleObject *seq;
	PyObject *item;

	assert(it != NULL);
	seq = it->it_seq;
	if (seq == NULL)
	return NULL;
	assert(PyTuple_Check(seq));

	if (it->it_index < PyTuple_GET_SIZE(seq)) {
	item = PyTuple_GET_ITEM(seq, it->it_index);
	++it->it_index;
	Py_INCREF(item);
	return item;
	}

	Py_DECREF(seq);
	it->it_seq = NULL;
	return NULL;
	}

	PyTypeObject PyTupleIter_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0, /* ob_size */
	"tupleiterator", /* tp_name */
	sizeof(tupleiterobject), /* tp_basicsize */
	0, /* tp_itemsize */
	/* methods */
	(destructor)tupleiter_dealloc, /* tp_dealloc */
	0, /* tp_print */
	0, /* tp_getattr */
	0, /* tp_setattr */
	0, /* tp_compare */
	0, /* tp_repr */
	0, /* tp_as_number */
	0, /* tp_as_sequence */
	0, /* tp_as_mapping */
	0, /* tp_hash */
	0, /* tp_call */
	0, /* tp_str */
	PyObject_GenericGetAttr, /* tp_getattro */
	0, /* tp_setattro */
	0, /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT \| Py_TPFLAGS_HAVE_GC,/* tp_flags */
	0, /* tp_doc */
	(traverseproc)tupleiter_traverse, /* tp_traverse */
	0, /* tp_clear */
	0, /* tp_richcompare */
	0, /* tp_weaklistoffset */
	(getiterfunc)tupleiter_getiter, /* tp_iter */
	(iternextfunc)tupleiter_next, /* tp_iternext */
	};