mirror of https://github.com/python/cpython
304 lines
8.5 KiB
C
304 lines
8.5 KiB
C
/* enumerate object */
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#include "Python.h"
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typedef struct {
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PyObject_HEAD
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long en_index; /* current index of enumeration */
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PyObject* en_sit; /* secondary iterator of enumeration */
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PyObject* en_result; /* result tuple */
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} enumobject;
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static PyObject *
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enum_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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{
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enumobject *en;
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PyObject *seq = NULL;
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static char *kwlist[] = {"sequence", 0};
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:enumerate", kwlist,
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&seq))
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return NULL;
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en = (enumobject *)type->tp_alloc(type, 0);
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if (en == NULL)
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return NULL;
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en->en_index = 0;
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en->en_sit = PyObject_GetIter(seq);
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if (en->en_sit == NULL) {
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Py_DECREF(en);
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return NULL;
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}
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en->en_result = PyTuple_Pack(2, Py_None, Py_None);
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if (en->en_result == NULL) {
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Py_DECREF(en);
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return NULL;
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}
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return (PyObject *)en;
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}
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static void
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enum_dealloc(enumobject *en)
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{
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PyObject_GC_UnTrack(en);
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Py_XDECREF(en->en_sit);
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Py_XDECREF(en->en_result);
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en->ob_type->tp_free(en);
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}
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static int
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enum_traverse(enumobject *en, visitproc visit, void *arg)
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{
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int err;
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if (en->en_sit) {
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err = visit(en->en_sit, arg);
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if (err)
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return err;
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}
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if (en->en_result) {
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err = visit(en->en_result, arg);
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if (err)
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return err;
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}
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return 0;
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}
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static PyObject *
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enum_next(enumobject *en)
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{
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PyObject *next_index;
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PyObject *next_item;
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PyObject *result = en->en_result;
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PyObject *it = en->en_sit;
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next_item = (*it->ob_type->tp_iternext)(it);
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if (next_item == NULL)
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return NULL;
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next_index = PyInt_FromLong(en->en_index);
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if (next_index == NULL) {
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Py_DECREF(next_item);
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return NULL;
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}
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en->en_index++;
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if (result->ob_refcnt == 1) {
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Py_INCREF(result);
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Py_DECREF(PyTuple_GET_ITEM(result, 0));
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Py_DECREF(PyTuple_GET_ITEM(result, 1));
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} else {
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result = PyTuple_New(2);
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if (result == NULL) {
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Py_DECREF(next_index);
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Py_DECREF(next_item);
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return NULL;
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}
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}
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PyTuple_SET_ITEM(result, 0, next_index);
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PyTuple_SET_ITEM(result, 1, next_item);
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return result;
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}
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PyDoc_STRVAR(enum_doc,
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"enumerate(iterable) -> iterator for index, value of iterable\n"
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"\n"
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"Return an enumerate object. iterable must be an other object that supports\n"
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"iteration. The enumerate object yields pairs containing a count (from\n"
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"zero) and a value yielded by the iterable argument. enumerate is useful\n"
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"for obtaining an indexed list: (0, seq[0]), (1, seq[1]), (2, seq[2]), ...");
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PyTypeObject PyEnum_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0, /* ob_size */
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"enumerate", /* tp_name */
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sizeof(enumobject), /* tp_basicsize */
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0, /* tp_itemsize */
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/* methods */
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(destructor)enum_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
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Py_TPFLAGS_BASETYPE, /* tp_flags */
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enum_doc, /* tp_doc */
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(traverseproc)enum_traverse, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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PyObject_SelfIter, /* tp_iter */
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(iternextfunc)enum_next, /* tp_iternext */
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0, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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0, /* tp_init */
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PyType_GenericAlloc, /* tp_alloc */
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enum_new, /* tp_new */
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PyObject_GC_Del, /* tp_free */
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};
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/* Reversed Object ***************************************************************/
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typedef struct {
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PyObject_HEAD
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Py_ssize_t index;
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PyObject* seq;
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} reversedobject;
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static PyObject *
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reversed_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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{
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Py_ssize_t n;
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PyObject *seq;
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reversedobject *ro;
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if (!PyArg_UnpackTuple(args, "reversed", 1, 1, &seq))
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return NULL;
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if (PyObject_HasAttrString(seq, "__reversed__"))
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return PyObject_CallMethod(seq, "__reversed__", NULL);
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if (!PySequence_Check(seq)) {
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PyErr_SetString(PyExc_TypeError,
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"argument to reversed() must be a sequence");
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return NULL;
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}
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n = PySequence_Size(seq);
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if (n == -1)
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return NULL;
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ro = (reversedobject *)type->tp_alloc(type, 0);
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if (ro == NULL)
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return NULL;
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ro->index = n-1;
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Py_INCREF(seq);
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ro->seq = seq;
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return (PyObject *)ro;
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}
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static void
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reversed_dealloc(reversedobject *ro)
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{
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PyObject_GC_UnTrack(ro);
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Py_XDECREF(ro->seq);
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ro->ob_type->tp_free(ro);
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}
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static int
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reversed_traverse(reversedobject *ro, visitproc visit, void *arg)
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{
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if (ro->seq)
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return visit((PyObject *)(ro->seq), arg);
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return 0;
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}
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static PyObject *
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reversed_next(reversedobject *ro)
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{
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PyObject *item;
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Py_ssize_t index = ro->index;
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if (index >= 0) {
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item = PySequence_GetItem(ro->seq, index);
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if (item != NULL) {
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ro->index--;
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return item;
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}
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if (PyErr_ExceptionMatches(PyExc_IndexError) ||
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PyErr_ExceptionMatches(PyExc_StopIteration))
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PyErr_Clear();
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}
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ro->index = -1;
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Py_CLEAR(ro->seq);
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return NULL;
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}
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PyDoc_STRVAR(reversed_doc,
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"reversed(sequence) -> reverse iterator over values of the sequence\n"
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"\n"
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"Return a reverse iterator");
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static PyObject *
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reversed_len(reversedobject *ro)
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{
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Py_ssize_t position, seqsize;
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if (ro->seq == NULL)
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return PyInt_FromLong(0);
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seqsize = PySequence_Size(ro->seq);
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if (seqsize == -1)
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return NULL;
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position = ro->index + 1;
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return PyInt_FromSsize_t((seqsize < position) ? 0 : position);
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}
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PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
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static PyMethodDef reversediter_methods[] = {
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{"__length_hint__", (PyCFunction)reversed_len, METH_NOARGS, length_hint_doc},
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{NULL, NULL} /* sentinel */
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};
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PyTypeObject PyReversed_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0, /* ob_size */
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"reversed", /* tp_name */
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sizeof(reversedobject), /* tp_basicsize */
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0, /* tp_itemsize */
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/* methods */
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(destructor)reversed_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
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Py_TPFLAGS_BASETYPE, /* tp_flags */
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reversed_doc, /* tp_doc */
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(traverseproc)reversed_traverse,/* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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PyObject_SelfIter, /* tp_iter */
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(iternextfunc)reversed_next, /* tp_iternext */
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reversediter_methods, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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0, /* tp_init */
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PyType_GenericAlloc, /* tp_alloc */
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reversed_new, /* tp_new */
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PyObject_GC_Del, /* tp_free */
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};
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