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cpython/Objects/enumobject.c

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/* enumerate object */
#include "Python.h"
#include "pycore_call.h" // _PyObject_CallNoArgs()
#include "pycore_long.h" // _PyLong_GetOne()
#include "pycore_modsupport.h" // _PyArg_NoKwnames()
#include "pycore_object.h" // _PyObject_GC_TRACK()
#include "pycore_unicodeobject.h" // _PyUnicode_EqualToASCIIString
#include "pycore_tuple.h" // _PyTuple_Recycle()
#include "clinic/enumobject.c.h"
/*[clinic input]
class enumerate "enumobject *" "&PyEnum_Type"
class reversed "reversedobject *" "&PyReversed_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=d2dfdf1a88c88975]*/
typedef struct {
PyObject_HEAD
Py_ssize_t en_index; /* current index of enumeration */
PyObject* en_sit; /* secondary iterator of enumeration */
PyObject* en_result; /* result tuple */
PyObject* en_longindex; /* index for sequences >= PY_SSIZE_T_MAX */
PyObject* one; /* borrowed reference */
} enumobject;
#define _enumobject_CAST(op) ((enumobject *)(op))
/*[clinic input]
@classmethod
enumerate.__new__ as enum_new
iterable: object
an object supporting iteration
start: object = 0
Return an enumerate object.
The enumerate object yields pairs containing a count (from start, which
defaults to zero) and a value yielded by the iterable argument.
enumerate is useful for obtaining an indexed list:
(0, seq[0]), (1, seq[1]), (2, seq[2]), ...
[clinic start generated code]*/
static PyObject *
enum_new_impl(PyTypeObject *type, PyObject *iterable, PyObject *start)
/*[clinic end generated code: output=e95e6e439f812c10 input=782e4911efcb8acf]*/
{
enumobject *en;
en = (enumobject *)type->tp_alloc(type, 0);
if (en == NULL)
return NULL;
if (start != NULL) {
start = PyNumber_Index(start);
if (start == NULL) {
Py_DECREF(en);
return NULL;
}
assert(PyLong_Check(start));
en->en_index = PyLong_AsSsize_t(start);
if (en->en_index == -1 && PyErr_Occurred()) {
PyErr_Clear();
en->en_index = PY_SSIZE_T_MAX;
en->en_longindex = start;
} else {
en->en_longindex = NULL;
Py_DECREF(start);
}
} else {
en->en_index = 0;
en->en_longindex = NULL;
}
en->en_sit = PyObject_GetIter(iterable);
if (en->en_sit == NULL) {
Py_DECREF(en);
return NULL;
}
en->en_result = PyTuple_Pack(2, Py_None, Py_None);
if (en->en_result == NULL) {
Py_DECREF(en);
return NULL;
}
en->one = _PyLong_GetOne(); /* borrowed reference */
return (PyObject *)en;
}
static int check_keyword(PyObject *kwnames, int index,
const char *name)
{
PyObject *kw = PyTuple_GET_ITEM(kwnames, index);
if (!_PyUnicode_EqualToASCIIString(kw, name)) {
PyErr_Format(PyExc_TypeError,
"'%S' is an invalid keyword argument for enumerate()", kw);
return 0;
}
return 1;
}
// TODO: Use AC when bpo-43447 is supported
static PyObject *
enumerate_vectorcall(PyObject *type, PyObject *const *args,
size_t nargsf, PyObject *kwnames)
{
PyTypeObject *tp = _PyType_CAST(type);
Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
Py_ssize_t nkwargs = 0;
if (kwnames != NULL) {
nkwargs = PyTuple_GET_SIZE(kwnames);
}
// Manually implement enumerate(iterable, start=...)
if (nargs + nkwargs == 2) {
if (nkwargs == 1) {
if (!check_keyword(kwnames, 0, "start")) {
return NULL;
}
} else if (nkwargs == 2) {
PyObject *kw0 = PyTuple_GET_ITEM(kwnames, 0);
if (_PyUnicode_EqualToASCIIString(kw0, "start")) {
if (!check_keyword(kwnames, 1, "iterable")) {
return NULL;
}
return enum_new_impl(tp, args[1], args[0]);
}
if (!check_keyword(kwnames, 0, "iterable") ||
!check_keyword(kwnames, 1, "start")) {
return NULL;
}
}
return enum_new_impl(tp, args[0], args[1]);
}
if (nargs + nkwargs == 1) {
if (nkwargs == 1 && !check_keyword(kwnames, 0, "iterable")) {
return NULL;
}
return enum_new_impl(tp, args[0], NULL);
}
if (nargs == 0) {
PyErr_SetString(PyExc_TypeError,
"enumerate() missing required argument 'iterable'");
return NULL;
}
PyErr_Format(PyExc_TypeError,
"enumerate() takes at most 2 arguments (%d given)", nargs + nkwargs);
return NULL;
}
static void
enum_dealloc(PyObject *op)
{
enumobject *en = _enumobject_CAST(op);
PyObject_GC_UnTrack(en);
Py_XDECREF(en->en_sit);
Py_XDECREF(en->en_result);
Py_XDECREF(en->en_longindex);
Py_TYPE(en)->tp_free(en);
}
static int
enum_traverse(PyObject *op, visitproc visit, void *arg)
{
enumobject *en = _enumobject_CAST(op);
Py_VISIT(en->en_sit);
Py_VISIT(en->en_result);
Py_VISIT(en->en_longindex);
return 0;
}
// increment en_longindex with lock held, return the next index to be used
// or NULL on error
static inline PyObject *
increment_longindex_lock_held(enumobject *en)
{
PyObject *next_index = en->en_longindex;
if (next_index == NULL) {
next_index = PyLong_FromSsize_t(PY_SSIZE_T_MAX);
if (next_index == NULL) {
return NULL;
}
}
assert(next_index != NULL);
PyObject *stepped_up = PyNumber_Add(next_index, en->one);
if (stepped_up == NULL) {
return NULL;
}
en->en_longindex = stepped_up;
return next_index;
}
static PyObject *
enum_next_long(enumobject *en, PyObject* next_item)
{
PyObject *result = en->en_result;
PyObject *next_index;
PyObject *old_index;
PyObject *old_item;
Py_BEGIN_CRITICAL_SECTION(en);
next_index = increment_longindex_lock_held(en);
Py_END_CRITICAL_SECTION();
if (next_index == NULL) {
Py_DECREF(next_item);
return NULL;
}
if (_PyObject_IsUniquelyReferenced(result)) {
Py_INCREF(result);
old_index = PyTuple_GET_ITEM(result, 0);
old_item = PyTuple_GET_ITEM(result, 1);
PyTuple_SET_ITEM(result, 0, next_index);
PyTuple_SET_ITEM(result, 1, next_item);
Py_DECREF(old_index);
Py_DECREF(old_item);
// bpo-42536: The GC may have untracked this result tuple. Since we're
// recycling it, make sure it's tracked again:
_PyTuple_Recycle(result);
return result;
}
result = PyTuple_New(2);
if (result == NULL) {
Py_DECREF(next_index);
Py_DECREF(next_item);
return NULL;
}
PyTuple_SET_ITEM(result, 0, next_index);
PyTuple_SET_ITEM(result, 1, next_item);
return result;
}
static PyObject *
enum_next(PyObject *op)
{
enumobject *en = _enumobject_CAST(op);
PyObject *next_index;
PyObject *next_item;
PyObject *result = en->en_result;
PyObject *it = en->en_sit;
PyObject *old_index;
PyObject *old_item;
next_item = (*Py_TYPE(it)->tp_iternext)(it);
if (next_item == NULL)
return NULL;
Py_ssize_t en_index = FT_ATOMIC_LOAD_SSIZE_RELAXED(en->en_index);
if (en_index == PY_SSIZE_T_MAX)
return enum_next_long(en, next_item);
next_index = PyLong_FromSsize_t(en_index);
if (next_index == NULL) {
Py_DECREF(next_item);
return NULL;
}
FT_ATOMIC_STORE_SSIZE_RELAXED(en->en_index, en_index + 1);
if (_PyObject_IsUniquelyReferenced(result)) {
Py_INCREF(result);
old_index = PyTuple_GET_ITEM(result, 0);
old_item = PyTuple_GET_ITEM(result, 1);
PyTuple_SET_ITEM(result, 0, next_index);
PyTuple_SET_ITEM(result, 1, next_item);
Py_DECREF(old_index);
Py_DECREF(old_item);
// bpo-42536: The GC may have untracked this result tuple. Since we're
// recycling it, make sure it's tracked again:
_PyTuple_Recycle(result);
return result;
}
result = PyTuple_New(2);
if (result == NULL) {
Py_DECREF(next_index);
Py_DECREF(next_item);
return NULL;
}
PyTuple_SET_ITEM(result, 0, next_index);
PyTuple_SET_ITEM(result, 1, next_item);
return result;
}
static PyObject *
enum_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))
{
enumobject *en = _enumobject_CAST(op);
PyObject *result;
Py_BEGIN_CRITICAL_SECTION(en);
if (en->en_longindex != NULL)
result = Py_BuildValue("O(OO)", Py_TYPE(en), en->en_sit, en->en_longindex);
else
result = Py_BuildValue("O(On)", Py_TYPE(en), en->en_sit, en->en_index);
Py_END_CRITICAL_SECTION();
return result;
}
PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
static PyMethodDef enum_methods[] = {
{"__reduce__", enum_reduce, METH_NOARGS, reduce_doc},
{"__class_getitem__", Py_GenericAlias,
METH_O|METH_CLASS, PyDoc_STR("See PEP 585")},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyEnum_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"enumerate", /* tp_name */
sizeof(enumobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
enum_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
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 |
Py_TPFLAGS_BASETYPE, /* tp_flags */
enum_new__doc__, /* tp_doc */
enum_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
enum_next, /* tp_iternext */
enum_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 */
PyType_GenericAlloc, /* tp_alloc */
enum_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
.tp_vectorcall = enumerate_vectorcall
};
/* Reversed Object ***************************************************************/
typedef struct {
PyObject_HEAD
Py_ssize_t index;
PyObject* seq;
} reversedobject;
#define _reversedobject_CAST(op) ((reversedobject *)(op))
/*[clinic input]
@classmethod
reversed.__new__ as reversed_new
sequence as seq: object
/
Return a reverse iterator over the values of the given sequence.
[clinic start generated code]*/
static PyObject *
reversed_new_impl(PyTypeObject *type, PyObject *seq)
/*[clinic end generated code: output=f7854cc1df26f570 input=aeb720361e5e3f1d]*/
{
Py_ssize_t n;
PyObject *reversed_meth;
reversedobject *ro;
reversed_meth = _PyObject_LookupSpecial(seq, &_Py_ID(__reversed__));
if (reversed_meth == Py_None) {
Py_DECREF(reversed_meth);
PyErr_Format(PyExc_TypeError,
"'%.200s' object is not reversible",
Py_TYPE(seq)->tp_name);
return NULL;
}
if (reversed_meth != NULL) {
PyObject *res = _PyObject_CallNoArgs(reversed_meth);
Py_DECREF(reversed_meth);
return res;
}
else if (PyErr_Occurred())
return NULL;
if (!PySequence_Check(seq)) {
PyErr_Format(PyExc_TypeError,
"'%.200s' object is not reversible",
Py_TYPE(seq)->tp_name);
return NULL;
}
n = PySequence_Size(seq);
if (n == -1)
return NULL;
ro = (reversedobject *)type->tp_alloc(type, 0);
if (ro == NULL)
return NULL;
ro->index = n-1;
ro->seq = Py_NewRef(seq);
return (PyObject *)ro;
}
static PyObject *
reversed_vectorcall(PyObject *type, PyObject * const*args,
size_t nargsf, PyObject *kwnames)
{
if (!_PyArg_NoKwnames("reversed", kwnames)) {
return NULL;
}
Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
if (!_PyArg_CheckPositional("reversed", nargs, 1, 1)) {
return NULL;
}
return reversed_new_impl(_PyType_CAST(type), args[0]);
}
static void
reversed_dealloc(PyObject *op)
{
reversedobject *ro = _reversedobject_CAST(op);
PyObject_GC_UnTrack(ro);
Py_XDECREF(ro->seq);
Py_TYPE(ro)->tp_free(ro);
}
static int
reversed_traverse(PyObject *op, visitproc visit, void *arg)
{
reversedobject *ro = _reversedobject_CAST(op);
Py_VISIT(ro->seq);
return 0;
}
static PyObject *
reversed_next(PyObject *op)
{
reversedobject *ro = _reversedobject_CAST(op);
PyObject *item;
Py_ssize_t index = FT_ATOMIC_LOAD_SSIZE_RELAXED(ro->index);
if (index >= 0) {
item = PySequence_GetItem(ro->seq, index);
if (item != NULL) {
FT_ATOMIC_STORE_SSIZE_RELAXED(ro->index, index - 1);
return item;
}
if (PyErr_ExceptionMatches(PyExc_IndexError) ||
PyErr_ExceptionMatches(PyExc_StopIteration))
PyErr_Clear();
}
FT_ATOMIC_STORE_SSIZE_RELAXED(ro->index, -1);
#ifndef Py_GIL_DISABLED
Py_CLEAR(ro->seq);
#endif
return NULL;
}
static PyObject *
reversed_len(PyObject *op, PyObject *Py_UNUSED(ignored))
{
reversedobject *ro = _reversedobject_CAST(op);
Py_ssize_t position, seqsize;
Py_ssize_t index = FT_ATOMIC_LOAD_SSIZE_RELAXED(ro->index);
if (index == -1)
return PyLong_FromLong(0);
assert(ro->seq != NULL);
seqsize = PySequence_Size(ro->seq);
if (seqsize == -1)
return NULL;
position = index + 1;
return PyLong_FromSsize_t((seqsize < position) ? 0 : position);
}
PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
static PyObject *
reversed_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))
{
reversedobject *ro = _reversedobject_CAST(op);
Py_ssize_t index = FT_ATOMIC_LOAD_SSIZE_RELAXED(ro->index);
if (index != -1) {
return Py_BuildValue("O(O)n", Py_TYPE(ro), ro->seq, ro->index);
}
else {
return Py_BuildValue("O(())", Py_TYPE(ro));
}
}
static PyObject *
reversed_setstate(PyObject *op, PyObject *state)
{
reversedobject *ro = _reversedobject_CAST(op);
Py_ssize_t index = PyLong_AsSsize_t(state);
if (index == -1 && PyErr_Occurred())
return NULL;
Py_ssize_t ro_index = FT_ATOMIC_LOAD_SSIZE_RELAXED(ro->index);
// if the iterator is exhausted we do not set the state
// this is for backwards compatibility reasons. in practice this situation
// will not occur, see gh-120971
if (ro_index != -1) {
Py_ssize_t n = PySequence_Size(ro->seq);
if (n < 0)
return NULL;
if (index < -1)
index = -1;
else if (index > n-1)
index = n-1;
FT_ATOMIC_STORE_SSIZE_RELAXED(ro->index, index);
}
Py_RETURN_NONE;
}
PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
static PyMethodDef reversediter_methods[] = {
{"__length_hint__", reversed_len, METH_NOARGS, length_hint_doc},
{"__reduce__", reversed_reduce, METH_NOARGS, reduce_doc},
{"__setstate__", reversed_setstate, METH_O, setstate_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyReversed_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"reversed", /* tp_name */
sizeof(reversedobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
reversed_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
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 |
Py_TPFLAGS_BASETYPE, /* tp_flags */
reversed_new__doc__, /* tp_doc */
reversed_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
reversed_next, /* tp_iternext */
reversediter_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 */
PyType_GenericAlloc, /* tp_alloc */
reversed_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
.tp_vectorcall = reversed_vectorcall,
};
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