--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cos/python/Objects/tupleobject.c	Tue Dec 27 18:59:02 2011 +0100
@@ -0,0 +1,907 @@
+
+/* Tuple object implementation */
+
+#include "Python.h"
+
+PyObject *
+PyTuple_New(register Py_ssize_t size)
+{
+    register PyTupleObject *op;
+    Py_ssize_t i;
+    if (size < 0) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
+    {
+        Py_ssize_t nbytes = size * sizeof(PyObject *);
+        /* Check for overflow */
+        if (nbytes / sizeof(PyObject *) != (size_t)size ||
+            (nbytes > PY_SSIZE_T_MAX - sizeof(PyTupleObject) - sizeof(PyObject *)))
+        {
+            return PyErr_NoMemory();
+        }
+        /* nbytes += sizeof(PyTupleObject) - sizeof(PyObject *); */
+
+        op = PyObject_GC_NewVar(PyTupleObject, &PyTuple_Type, size);
+        if (op == NULL)
+            return NULL;
+    }
+    for (i=0; i < size; i++)
+        op->ob_item[i] = NULL;
+    _PyObject_GC_TRACK(op);
+    return (PyObject *) op;
+}
+
+Py_ssize_t
+PyTuple_Size(register PyObject *op)
+{
+    if (!PyTuple_Check(op)) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
+    else
+        return Py_SIZE(op);
+}
+
+PyObject *
+PyTuple_GetItem(register PyObject *op, register Py_ssize_t i)
+{
+    if (!PyTuple_Check(op)) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
+    if (i < 0 || i >= Py_SIZE(op)) {
+        PyErr_SetString(PyExc_IndexError, "tuple index out of range");
+        return NULL;
+    }
+    return ((PyTupleObject *)op) -> ob_item[i];
+}
+
+int
+PyTuple_SetItem(register PyObject *op, register Py_ssize_t 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 >= Py_SIZE(op)) {
+        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;
+}
+
+void
+_PyTuple_MaybeUntrack(PyObject *op)
+{
+    PyTupleObject *t;
+    Py_ssize_t i, n;
+
+    if (!PyTuple_CheckExact(op) || !_PyObject_GC_IS_TRACKED(op))
+        return;
+    t = (PyTupleObject *) op;
+    n = Py_SIZE(t);
+    for (i = 0; i < n; i++) {
+        PyObject *elt = PyTuple_GET_ITEM(t, i);
+        /* Tuple with NULL elements aren't
+           fully constructed, don't untrack
+           them yet. */
+        if (!elt ||
+            _PyObject_GC_MAY_BE_TRACKED(elt))
+            return;
+    }
+    _PyObject_GC_UNTRACK(op);
+}
+
+PyObject *
+PyTuple_Pack(Py_ssize_t n, ...)
+{
+    Py_ssize_t i;
+    PyObject *o;
+    PyObject *result;
+    PyObject **items;
+    va_list vargs;
+
+    va_start(vargs, n);
+    result = PyTuple_New(n);
+    if (result == NULL)
+        return NULL;
+    items = ((PyTupleObject *)result)->ob_item;
+    for (i = 0; i < n; i++) {
+        o = va_arg(vargs, PyObject *);
+        Py_INCREF(o);
+        items[i] = o;
+    }
+    va_end(vargs);
+    return result;
+}
+
+
+/* Methods */
+
+static void
+tupledealloc(register PyTupleObject *op)
+{
+    register Py_ssize_t i;
+    register Py_ssize_t len =  Py_SIZE(op);
+    PyObject_GC_UnTrack(op);
+    Py_TRASHCAN_SAFE_BEGIN(op)
+    if (len > 0) {
+        i = len;
+        while (--i >= 0)
+            Py_XDECREF(op->ob_item[i]);
+    }
+    Py_TYPE(op)->tp_free((PyObject *)op);
+done:
+    Py_TRASHCAN_SAFE_END(op)
+}
+
+static PyObject *
+tuplerepr(PyTupleObject *v)
+{
+    Py_ssize_t i, n;
+    PyObject *s = NULL;
+    _PyAccu acc;
+    static PyObject *sep = NULL;
+
+    n = Py_SIZE(v);
+    if (n == 0)
+        return PyUnicode_FromString("()");
+
+    if (sep == NULL) {
+        sep = PyUnicode_FromString(", ");
+        if (sep == NULL)
+            return NULL;
+    }
+
+    /* While not mutable, it is still possible to end up with a cycle in a
+       tuple through an object that stores itself within a tuple (and thus
+       infinitely asks for the repr of itself). This should only be
+       possible within a type. */
+    i = Py_ReprEnter((PyObject *)v);
+    if (i != 0) {
+        return i > 0 ? PyUnicode_FromString("(...)") : NULL;
+    }
+
+    if (_PyAccu_Init(&acc))
+        goto error;
+
+    s = PyUnicode_FromString("(");
+    if (s == NULL || _PyAccu_Accumulate(&acc, s))
+        goto error;
+    Py_CLEAR(s);
+
+    /* Do repr() on each element. */
+    for (i = 0; i < n; ++i) {
+        if (Py_EnterRecursiveCall(" while getting the repr of a tuple"))
+            goto error;
+        s = PyObject_Repr(v->ob_item[i]);
+        Py_LeaveRecursiveCall();
+        if (i > 0 && _PyAccu_Accumulate(&acc, sep))
+            goto error;
+        if (s == NULL || _PyAccu_Accumulate(&acc, s))
+            goto error;
+        Py_CLEAR(s);
+    }
+    if (n > 1)
+        s = PyUnicode_FromString(")");
+    else
+        s = PyUnicode_FromString(",)");
+    if (s == NULL || _PyAccu_Accumulate(&acc, s))
+        goto error;
+    Py_CLEAR(s);
+
+    Py_ReprLeave((PyObject *)v);
+    return _PyAccu_Finish(&acc);
+
+error:
+    _PyAccu_Destroy(&acc);
+    Py_XDECREF(s);
+    Py_ReprLeave((PyObject *)v);
+    return NULL;
+}
+
+/* The addend 82520, was selected from the range(0, 1000000) for
+   generating the greatest number of prime multipliers for tuples
+   upto length eight:
+
+     1082527, 1165049, 1082531, 1165057, 1247581, 1330103, 1082533,
+     1330111, 1412633, 1165069, 1247599, 1495177, 1577699
+*/
+
+static Py_hash_t
+tuplehash(PyTupleObject *v)
+{
+    register Py_uhash_t x;
+    register Py_hash_t y;
+    register Py_ssize_t len = Py_SIZE(v);
+    register PyObject **p;
+    Py_uhash_t mult = 1000003;
+    x = 0x345678;
+    p = v->ob_item;
+    while (--len >= 0) {
+        y = PyObject_Hash(*p++);
+        if (y == -1)
+            return -1;
+        x = (x ^ y) * mult;
+        /* the cast might truncate len; that doesn't change hash stability */
+        mult += (Py_hash_t)(82520L + len + len);
+    }
+    x += 97531L;
+    if (x == (Py_uhash_t)-1)
+        x = -2;
+    return x;
+}
+
+static Py_ssize_t
+tuplelength(PyTupleObject *a)
+{
+    return Py_SIZE(a);
+}
+
+static int
+tuplecontains(PyTupleObject *a, PyObject *el)
+{
+    Py_ssize_t i;
+    int cmp;
+
+    for (i = 0, cmp = 0 ; cmp == 0 && i < Py_SIZE(a); ++i)
+        cmp = PyObject_RichCompareBool(el, PyTuple_GET_ITEM(a, i),
+                                           Py_EQ);
+    return cmp;
+}
+
+static PyObject *
+tupleitem(register PyTupleObject *a, register Py_ssize_t i)
+{
+    if (i < 0 || i >= Py_SIZE(a)) {
+        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 Py_ssize_t ilow,
+           register Py_ssize_t ihigh)
+{
+    register PyTupleObject *np;
+    PyObject **src, **dest;
+    register Py_ssize_t i;
+    Py_ssize_t len;
+    if (ilow < 0)
+        ilow = 0;
+    if (ihigh > Py_SIZE(a))
+        ihigh = Py_SIZE(a);
+    if (ihigh < ilow)
+        ihigh = ilow;
+    if (ilow == 0 && ihigh == Py_SIZE(a) && PyTuple_CheckExact(a)) {
+        Py_INCREF(a);
+        return (PyObject *)a;
+    }
+    len = ihigh - ilow;
+    np = (PyTupleObject *)PyTuple_New(len);
+    if (np == NULL)
+        return NULL;
+    src = a->ob_item + ilow;
+    dest = np->ob_item;
+    for (i = 0; i < len; i++) {
+        PyObject *v = src[i];
+        Py_INCREF(v);
+        dest[i] = v;
+    }
+    return (PyObject *)np;
+}
+
+PyObject *
+PyTuple_GetSlice(PyObject *op, Py_ssize_t i, Py_ssize_t 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 Py_ssize_t size;
+    register Py_ssize_t i;
+    PyObject **src, **dest;
+    PyTupleObject *np;
+    if (!PyTuple_Check(bb)) {
+        PyErr_Format(PyExc_TypeError,
+             "can only concatenate tuple (not \"%.200s\") to tuple",
+                 Py_TYPE(bb)->tp_name);
+        return NULL;
+    }
+#define b ((PyTupleObject *)bb)
+    size = Py_SIZE(a) + Py_SIZE(b);
+    if (size < 0)
+        return PyErr_NoMemory();
+    np = (PyTupleObject *) PyTuple_New(size);
+    if (np == NULL) {
+        return NULL;
+    }
+    src = a->ob_item;
+    dest = np->ob_item;
+    for (i = 0; i < Py_SIZE(a); i++) {
+        PyObject *v = src[i];
+        Py_INCREF(v);
+        dest[i] = v;
+    }
+    src = b->ob_item;
+    dest = np->ob_item + Py_SIZE(a);
+    for (i = 0; i < Py_SIZE(b); i++) {
+        PyObject *v = src[i];
+        Py_INCREF(v);
+        dest[i] = v;
+    }
+    return (PyObject *)np;
+#undef b
+}
+
+static PyObject *
+tuplerepeat(PyTupleObject *a, Py_ssize_t n)
+{
+    Py_ssize_t i, j;
+    Py_ssize_t size;
+    PyTupleObject *np;
+    PyObject **p, **items;
+    if (n < 0)
+        n = 0;
+    if (Py_SIZE(a) == 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 (Py_SIZE(a) == 0)
+            return PyTuple_New(0);
+    }
+    size = Py_SIZE(a) * n;
+    if (size/Py_SIZE(a) != n)
+        return PyErr_NoMemory();
+    np = (PyTupleObject *) PyTuple_New(size);
+    if (np == NULL)
+        return NULL;
+    p = np->ob_item;
+    items = a->ob_item;
+    for (i = 0; i < n; i++) {
+        for (j = 0; j < Py_SIZE(a); j++) {
+            *p = items[j];
+            Py_INCREF(*p);
+            p++;
+        }
+    }
+    return (PyObject *) np;
+}
+
+static PyObject *
+tupleindex(PyTupleObject *self, PyObject *args)
+{
+    Py_ssize_t i, start=0, stop=Py_SIZE(self);
+    PyObject *v;
+
+    if (!PyArg_ParseTuple(args, "O|O&O&:index", &v,
+                                _PyEval_SliceIndex, &start,
+                                _PyEval_SliceIndex, &stop))
+        return NULL;
+    if (start < 0) {
+        start += Py_SIZE(self);
+        if (start < 0)
+            start = 0;
+    }
+    if (stop < 0) {
+        stop += Py_SIZE(self);
+        if (stop < 0)
+            stop = 0;
+    }
+    for (i = start; i < stop && i < Py_SIZE(self); i++) {
+        int cmp = PyObject_RichCompareBool(self->ob_item[i], v, Py_EQ);
+        if (cmp > 0)
+            return PyLong_FromSsize_t(i);
+        else if (cmp < 0)
+            return NULL;
+    }
+    PyErr_SetString(PyExc_ValueError, "tuple.index(x): x not in tuple");
+    return NULL;
+}
+
+static PyObject *
+tuplecount(PyTupleObject *self, PyObject *v)
+{
+    Py_ssize_t count = 0;
+    Py_ssize_t i;
+
+    for (i = 0; i < Py_SIZE(self); i++) {
+        int cmp = PyObject_RichCompareBool(self->ob_item[i], v, Py_EQ);
+        if (cmp > 0)
+            count++;
+        else if (cmp < 0)
+            return NULL;
+    }
+    return PyLong_FromSsize_t(count);
+}
+
+static int
+tupletraverse(PyTupleObject *o, visitproc visit, void *arg)
+{
+    Py_ssize_t i;
+
+    for (i = Py_SIZE(o); --i >= 0; )
+        Py_VISIT(o->ob_item[i]);
+    return 0;
+}
+
+static PyObject *
+tuplerichcompare(PyObject *v, PyObject *w, int op)
+{
+    PyTupleObject *vt, *wt;
+    Py_ssize_t i;
+    Py_ssize_t vlen, wlen;
+
+    if (!PyTuple_Check(v) || !PyTuple_Check(w))
+        Py_RETURN_NOTIMPLEMENTED;
+
+    vt = (PyTupleObject *)v;
+    wt = (PyTupleObject *)w;
+
+    vlen = Py_SIZE(vt);
+    wlen = Py_SIZE(wt);
+
+    /* 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, *newobj, *item;
+    Py_ssize_t i, n;
+
+    assert(PyType_IsSubtype(type, &PyTuple_Type));
+    tmp = tuple_new(&PyTuple_Type, args, kwds);
+    if (tmp == NULL)
+        return NULL;
+    assert(PyTuple_Check(tmp));
+    newobj = type->tp_alloc(type, n = PyTuple_GET_SIZE(tmp));
+    if (newobj == NULL)
+        return NULL;
+    for (i = 0; i < n; i++) {
+        item = PyTuple_GET_ITEM(tmp, i);
+        Py_INCREF(item);
+        PyTuple_SET_ITEM(newobj, i, item);
+    }
+    Py_DECREF(tmp);
+    return newobj;
+}
+
+PyDoc_STRVAR(tuple_doc,
+"tuple() -> empty tuple\n\
+tuple(iterable) -> tuple initialized from iterable's items\n\
+\n\
+If the argument is a tuple, the return value is the same object.");
+
+static PySequenceMethods tuple_as_sequence = {
+    (lenfunc)tuplelength,                       /* sq_length */
+    (binaryfunc)tupleconcat,                    /* sq_concat */
+    (ssizeargfunc)tuplerepeat,                  /* sq_repeat */
+    (ssizeargfunc)tupleitem,                    /* sq_item */
+    0,                                          /* sq_slice */
+    0,                                          /* sq_ass_item */
+    0,                                          /* sq_ass_slice */
+    (objobjproc)tuplecontains,                  /* sq_contains */
+};
+
+static PyObject*
+tuplesubscript(PyTupleObject* self, PyObject* item)
+{
+    if (PyIndex_Check(item)) {
+        Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
+        if (i == -1 && PyErr_Occurred())
+            return NULL;
+        if (i < 0)
+            i += PyTuple_GET_SIZE(self);
+        return tupleitem(self, i);
+    }
+    else if (PySlice_Check(item)) {
+        Py_ssize_t start, stop, step, slicelength, cur, i;
+        PyObject* result;
+        PyObject* it;
+        PyObject **src, **dest;
+
+        if (PySlice_GetIndicesEx(item,
+                         PyTuple_GET_SIZE(self),
+                         &start, &stop, &step, &slicelength) < 0) {
+            return NULL;
+        }
+
+        if (slicelength <= 0) {
+            return PyTuple_New(0);
+        }
+        else if (start == 0 && step == 1 &&
+                 slicelength == PyTuple_GET_SIZE(self) &&
+                 PyTuple_CheckExact(self)) {
+            Py_INCREF(self);
+            return (PyObject *)self;
+        }
+        else {
+            result = PyTuple_New(slicelength);
+            if (!result) return NULL;
+
+            src = self->ob_item;
+            dest = ((PyTupleObject *)result)->ob_item;
+            for (cur = start, i = 0; i < slicelength;
+                 cur += step, i++) {
+                it = src[cur];
+                Py_INCREF(it);
+                dest[i] = it;
+            }
+
+            return result;
+        }
+    }
+    else {
+        PyErr_Format(PyExc_TypeError,
+                     "tuple indices must be integers, not %.200s",
+                     Py_TYPE(item)->tp_name);
+        return NULL;
+    }
+}
+
+static PyObject *
+tuple_getnewargs(PyTupleObject *v)
+{
+    return Py_BuildValue("(N)", tupleslice(v, 0, Py_SIZE(v)));
+
+}
+
+static PyObject *
+tuple_sizeof(PyTupleObject *self)
+{
+    Py_ssize_t res;
+
+    res = PyTuple_Type.tp_basicsize + Py_SIZE(self) * sizeof(PyObject *);
+    return PyLong_FromSsize_t(res);
+}
+
+PyDoc_STRVAR(index_doc,
+"T.index(value, [start, [stop]]) -> integer -- return first index of value.\n"
+"Raises ValueError if the value is not present."
+);
+PyDoc_STRVAR(count_doc,
+"T.count(value) -> integer -- return number of occurrences of value");
+PyDoc_STRVAR(sizeof_doc,
+"T.__sizeof__() -- size of T in memory, in bytes");
+
+static PyMethodDef tuple_methods[] = {
+    {"__getnewargs__",          (PyCFunction)tuple_getnewargs,  METH_NOARGS},
+    {"__sizeof__",      (PyCFunction)tuple_sizeof, METH_NOARGS, sizeof_doc},
+    {"index",           (PyCFunction)tupleindex,  METH_VARARGS, index_doc},
+    {"count",           (PyCFunction)tuplecount,  METH_O, count_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
+static PyMappingMethods tuple_as_mapping = {
+    (lenfunc)tuplelength,
+    (binaryfunc)tuplesubscript,
+    0
+};
+
+static PyObject *tuple_iter(PyObject *seq);
+
+PyTypeObject PyTuple_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    "tuple",
+    sizeof(PyTupleObject) - sizeof(PyObject *),
+    sizeof(PyObject *),
+    (destructor)tupledealloc,                   /* tp_dealloc */
+    0,                                          /* tp_print */
+    0,                                          /* tp_getattr */
+    0,                                          /* tp_setattr */
+    0,                                          /* tp_reserved */
+    (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 | Py_TPFLAGS_TUPLE_SUBCLASS, /* 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 */
+    tuple_methods,                              /* 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, Py_ssize_t newsize)
+{
+    register PyTupleObject *v;
+    register PyTupleObject *sv;
+    Py_ssize_t i;
+    Py_ssize_t oldsize;
+
+    v = (PyTupleObject *) *pv;
+    if (v == NULL || Py_TYPE(v) != &PyTuple_Type ||
+        (Py_SIZE(v) != 0 && Py_REFCNT(v) != 1)) {
+        *pv = 0;
+        Py_XDECREF(v);
+        PyErr_BadInternalCall();
+        return -1;
+    }
+    oldsize = Py_SIZE(v);
+    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;
+    if (_PyObject_GC_IS_TRACKED(v))
+        _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;
+}
+
+int
+PyTuple_ClearFreeList(void)
+{
+    int freelist_size = 0;
+    return freelist_size;
+}
+
+void
+PyTuple_Fini(void)
+{
+}
+
+/*********************** Tuple Iterator **************************/
+
+typedef struct {
+    PyObject_HEAD
+    long it_index;
+    PyTupleObject *it_seq; /* Set to NULL when iterator is exhausted */
+} tupleiterobject;
+
+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)
+{
+    Py_VISIT(it->it_seq);
+    return 0;
+}
+
+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;
+}
+
+static PyObject *
+tupleiter_len(tupleiterobject *it)
+{
+    Py_ssize_t len = 0;
+    if (it->it_seq)
+        len = PyTuple_GET_SIZE(it->it_seq) - it->it_index;
+    return PyLong_FromSsize_t(len);
+}
+
+PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
+
+static PyMethodDef tupleiter_methods[] = {
+    {"__length_hint__", (PyCFunction)tupleiter_len, METH_NOARGS, length_hint_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
+PyTypeObject PyTupleIter_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    "tuple_iterator",                           /* 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_reserved */
+    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 */
+    PyObject_SelfIter,                          /* tp_iter */
+    (iternextfunc)tupleiter_next,               /* tp_iternext */
+    tupleiter_methods,                          /* tp_methods */
+    0,
+};
+
+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;
+}