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Convert iterator __len__() methods to a private API.

This commit is contained in:
Raymond Hettinger 2005-09-24 21:23:05 +00:00
parent 9ceebd5445
commit 6b27cda643
16 changed files with 169 additions and 94 deletions
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15
Include/abstract.h
View File

@ -422,6 +422,21 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
PyAPI_FUNC(int) PyObject_Length(PyObject *o);
#define PyObject_Length PyObject_Size
PyAPI_FUNC(int) _PyObject_LengthCue(PyObject *o);
/*
Return the size of object o. If the object, o, provides
both sequence and mapping protocols, the sequence size is
returned. On error, -1 is returned. If the object provides
a _length_cue() method, its value is returned. This is the
equivalent to the Python expression:
try:
return len(o)
except (AttributeError, TypeError):
if hasattr(o, '_length_cue'):
return o._length_cue()
raise
*/
PyAPI_FUNC(PyObject *) PyObject_GetItem(PyObject *o, PyObject *key);

1
Lib/test/test_enumerate.py
View File

@ -144,6 +144,7 @@ class TestReversed(unittest.TestCase):
def test_len(self):
# This is an implementation detail, not an interface requirement
from test.test_iterlen import len
for s in ('hello', tuple('hello'), list('hello'), xrange(5)):
self.assertEqual(len(reversed(s)), len(s))
r = reversed(s)

12
Lib/test/test_iterlen.py
View File

@ -43,12 +43,22 @@ enumerate(iter('abc')).
import unittest
from test import test_support
from itertools import repeat, count
from itertools import repeat
from collections import deque
from UserList import UserList
from __builtin__ import len as _len
n = 10
def len(obj):
try:
return _len(obj)
except TypeError:
try:
return obj._length_cue()
except AttributeError:
raise TypeError
class TestInvariantWithoutMutations(unittest.TestCase):
def test_invariant(self):

1
Lib/test/test_itertools.py
View File

@ -670,6 +670,7 @@ class TestVariousIteratorArgs(unittest.TestCase):
class LengthTransparency(unittest.TestCase):
def test_repeat(self):
from test.test_iterlen import len
self.assertEqual(len(repeat(None, 50)), 50)
self.assertRaises(TypeError, len, repeat(None))

4
Misc/NEWS
View File

@ -12,6 +12,10 @@ What's New in Python 2.5 alpha 1?
Core and builtins
-----------------
- All iterators now have a Boolean value of true. Formerly, some iterators
supported a __len__() method which evaluated to False when the iterator
was empty.
- On 64-bit platforms, when __len__() returns a value that cannot be
represented as a C int, raise OverflowError.

18
Modules/collectionsmodule.c
View File

@ -935,15 +935,17 @@ dequeiter_next(dequeiterobject *it)
return item;
}
static int
static PyObject *
dequeiter_len(dequeiterobject *it)
{
return it->counter;
return PyInt_FromLong(it->counter);
}
static PySequenceMethods dequeiter_as_sequence = {
(inquiry)dequeiter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef dequeiter_methods[] = {
{"_length_cue", (PyCFunction)dequeiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject dequeiter_type = {
@ -960,7 +962,7 @@ PyTypeObject dequeiter_type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&dequeiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -976,6 +978,7 @@ PyTypeObject dequeiter_type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)dequeiter_next, /* tp_iternext */
dequeiter_methods, /* tp_methods */
0,
};
@ -1042,7 +1045,7 @@ PyTypeObject dequereviter_type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&dequeiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -1058,6 +1061,7 @@ PyTypeObject dequereviter_type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)dequereviter_next, /* tp_iternext */
dequeiter_methods, /* tp_methods */
0,
};

20
Modules/itertoolsmodule.c
View File

@ -2336,17 +2336,21 @@ repeat_repr(repeatobject *ro)
return result;
}
static int
static PyObject *
repeat_len(repeatobject *ro)
{
if (ro->cnt == -1)
if (ro->cnt == -1) {
PyErr_SetString(PyExc_TypeError, "len() of unsized object");
return (int)(ro->cnt);
return NULL;
}
return PyInt_FromLong(ro->cnt);
}
static PySequenceMethods repeat_as_sequence = {
(inquiry)repeat_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef repeat_methods[] = {
{"_length_cue", (PyCFunction)repeat_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyDoc_STRVAR(repeat_doc,
@ -2368,7 +2372,7 @@ static PyTypeObject repeat_type = {
0, /* tp_compare */
(reprfunc)repeat_repr, /* tp_repr */
0, /* tp_as_number */
&repeat_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -2385,7 +2389,7 @@ static PyTypeObject repeat_type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)repeat_next, /* tp_iternext */
0, /* tp_methods */
repeat_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */

27
Objects/abstract.c
View File

@ -81,6 +81,31 @@ PyObject_Length(PyObject *o)
}
#define PyObject_Length PyObject_Size
int
_PyObject_LengthCue(PyObject *o)
{
int rv = PyObject_Size(o);
if (rv != -1)
return rv;
if (PyErr_ExceptionMatches(PyExc_TypeError) ||
PyErr_ExceptionMatches(PyExc_AttributeError)) {
PyObject *err_type, *err_value, *err_tb, *ro;
PyErr_Fetch(&err_type, &err_value, &err_tb);
ro = PyObject_CallMethod(o, "_length_cue", NULL);
if (ro != NULL) {
rv = (int)PyInt_AsLong(ro);
Py_DECREF(ro);
Py_XDECREF(err_type);
Py_XDECREF(err_value);
Py_XDECREF(err_tb);
return rv;
}
PyErr_Restore(err_type, err_value, err_tb);
}
return -1;
}
PyObject *
PyObject_GetItem(PyObject *o, PyObject *key)
{
@ -1399,7 +1424,7 @@ PySequence_Tuple(PyObject *v)
return NULL;
/* Guess result size and allocate space. */
n = PyObject_Size(v);
n = _PyObject_LengthCue(v);
if (n < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {

27
Objects/dictobject.c
View File

@ -2054,17 +2054,20 @@ dictiter_dealloc(dictiterobject *di)
PyObject_Del(di);
}
static int
static PyObject *
dictiter_len(dictiterobject *di)
{
int len = 0;
if (di->di_dict != NULL && di->di_used == di->di_dict->ma_used)
return di->len;
return 0;
len = di->len;
return PyInt_FromLong(len);
}
static PySequenceMethods dictiter_as_sequence = {
(inquiry)dictiter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef dictiter_methods[] = {
{"_length_cue", (PyCFunction)dictiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
static PyObject *dictiter_iternextkey(dictiterobject *di)
@ -2120,7 +2123,7 @@ PyTypeObject PyDictIterKey_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&dictiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -2136,6 +2139,8 @@ PyTypeObject PyDictIterKey_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)dictiter_iternextkey, /* tp_iternext */
dictiter_methods, /* tp_methods */
0,
};
static PyObject *dictiter_iternextvalue(dictiterobject *di)
@ -2191,7 +2196,7 @@ PyTypeObject PyDictIterValue_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&dictiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -2207,6 +2212,8 @@ PyTypeObject PyDictIterValue_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)dictiter_iternextvalue, /* tp_iternext */
dictiter_methods, /* tp_methods */
0,
};
static PyObject *dictiter_iternextitem(dictiterobject *di)
@ -2276,7 +2283,7 @@ PyTypeObject PyDictIterItem_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&dictiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -2292,4 +2299,6 @@ PyTypeObject PyDictIterItem_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)dictiter_iternextitem, /* tp_iternext */
dictiter_methods, /* tp_methods */
0,
};

20
Objects/enumobject.c
View File

@ -239,23 +239,25 @@ PyDoc_STRVAR(reversed_doc,
"\n"
"Return a reverse iterator");
static int
static PyObject *
reversed_len(reversedobject *ro)
{
int position, seqsize;
if (ro->seq == NULL)
return 0;
return PyInt_FromLong(0);
seqsize = PySequence_Size(ro->seq);
if (seqsize == -1)
return -1;
return NULL;
position = ro->index + 1;
return (seqsize < position) ? 0 : position;
return PyInt_FromLong((seqsize < position) ? 0 : position);
}
static PySequenceMethods reversed_as_sequence = {
(inquiry)reversed_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef reversediter_methods[] = {
{"_length_cue", (PyCFunction)reversed_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyReversed_Type = {
@ -272,7 +274,7 @@ PyTypeObject PyReversed_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&reversed_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -289,7 +291,7 @@ PyTypeObject PyReversed_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)reversed_next, /* tp_iternext */
0, /* tp_methods */
reversediter_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */

31
Objects/iterobject.c
View File

@ -71,7 +71,7 @@ iter_iternext(PyObject *iterator)
return NULL;
}
static int
static PyObject *
iter_len(seqiterobject *it)
{
int seqsize, len;
@ -79,17 +79,19 @@ iter_len(seqiterobject *it)
if (it->it_seq) {
seqsize = PySequence_Size(it->it_seq);
if (seqsize == -1)
return -1;
return NULL;
len = seqsize - it->it_index;
if (len >= 0)
return len;
return PyInt_FromLong(len);
}
return 0;
return PyInt_FromLong(0);
}
static PySequenceMethods iter_as_sequence = {
(inquiry)iter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef seqiter_methods[] = {
{"_length_cue", (PyCFunction)iter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PySeqIter_Type = {
@ -106,7 +108,7 @@ PyTypeObject PySeqIter_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&iter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -122,13 +124,8 @@ PyTypeObject PySeqIter_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)iter_iternext, /* tp_iternext */
0, /* tp_methods */
seqiter_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
};
/* -------------------------------------- */
@ -236,10 +233,4 @@ PyTypeObject PyCallIter_Type = {
PyObject_SelfIter, /* tp_iter */
(iternextfunc)calliter_iternext, /* 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 */
};

25
Objects/listobject.c
View File

@ -775,7 +775,7 @@ listextend(PyListObject *self, PyObject *b)
iternext = *it->ob_type->tp_iternext;
/* Guess a result list size. */
n = PyObject_Size(b);
n = _PyObject_LengthCue(b);
if (n < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {
@ -2764,21 +2764,23 @@ listiter_next(listiterobject *it)
return NULL;
}
static int
static PyObject *
listiter_len(listiterobject *it)
{
int len;
if (it->it_seq) {
len = PyList_GET_SIZE(it->it_seq) - it->it_index;
if (len >= 0)
return len;
return PyInt_FromLong((long)len);
}
return 0;
return PyInt_FromLong(0);
}
static PySequenceMethods listiter_as_sequence = {
(inquiry)listiter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef listiter_methods[] = {
{"_length_cue", (PyCFunction)listiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyListIter_Type = {
@ -2795,7 +2797,7 @@ PyTypeObject PyListIter_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&listiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -2811,13 +2813,8 @@ PyTypeObject PyListIter_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)listiter_next, /* tp_iternext */
0, /* tp_methods */
listiter_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
};
/*********************** List Reverse Iterator **************************/

18
Objects/rangeobject.c
View File

@ -262,17 +262,18 @@ rangeiter_next(rangeiterobject *r)
return NULL;
}
static int
static PyObject *
rangeiter_len(rangeiterobject *r)
{
return r->len - r->index;
return PyInt_FromLong(r->len - r->index);
}
static PySequenceMethods rangeiter_as_sequence = {
(inquiry)rangeiter_len, /* sq_length */
0, /* sq_concat */
};
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef rangeiter_methods[] = {
{"_length_cue", (PyCFunction)rangeiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
static PyTypeObject Pyrangeiter_Type = {
PyObject_HEAD_INIT(&PyType_Type)
@ -288,7 +289,7 @@ static PyTypeObject Pyrangeiter_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&rangeiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -304,5 +305,6 @@ static PyTypeObject Pyrangeiter_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)rangeiter_next, /* tp_iternext */
0, /* tp_methods */
rangeiter_methods, /* tp_methods */
0,
};

19
Objects/setobject.c
View File

@ -749,17 +749,20 @@ setiter_dealloc(setiterobject *si)
PyObject_Del(si);
}
static int
static PyObject *
setiter_len(setiterobject *si)
{
int len = 0;
if (si->si_set != NULL && si->si_used == si->si_set->used)
return si->len;
return 0;
len = si->len;
return PyInt_FromLong(len);
}
static PySequenceMethods setiter_as_sequence = {
(inquiry)setiter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef setiter_methods[] = {
{"_length_cue", (PyCFunction)setiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
static PyObject *setiter_iternext(setiterobject *si)
@ -814,7 +817,7 @@ static PyTypeObject PySetIter_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&setiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -830,6 +833,8 @@ static PyTypeObject PySetIter_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)setiter_iternext, /* tp_iternext */
setiter_methods, /* tp_methods */
0,
};
static int

19
Objects/tupleobject.c
View File

@ -851,17 +851,20 @@ tupleiter_next(tupleiterobject *it)
return NULL;
}
static int
static PyObject *
tupleiter_len(tupleiterobject *it)
{
int len = 0;
if (it->it_seq)
return PyTuple_GET_SIZE(it->it_seq) - it->it_index;
return 0;
len = PyTuple_GET_SIZE(it->it_seq) - it->it_index;
return PyInt_FromLong(len);
}
static PySequenceMethods tupleiter_as_sequence = {
(inquiry)tupleiter_len, /* sq_length */
0, /* sq_concat */
PyDoc_STRVAR(length_cue_doc, "Private method returning an estimate of len(list(it)).");
static PyMethodDef tupleiter_methods[] = {
{"_length_cue", (PyCFunction)tupleiter_len, METH_NOARGS, length_cue_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyTupleIter_Type = {
@ -878,7 +881,7 @@ PyTypeObject PyTupleIter_Type = {
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
&tupleiter_as_sequence, /* tp_as_sequence */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
@ -894,4 +897,6 @@ PyTypeObject PyTupleIter_Type = {
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)tupleiter_next, /* tp_iternext */
tupleiter_methods, /* tp_methods */
0,
};

6
Python/bltinmodule.c
View File

@ -221,7 +221,7 @@ builtin_filter(PyObject *self, PyObject *args)
goto Fail_arg;
/* Guess a result list size. */
len = PyObject_Size(seq);
len = _PyObject_LengthCue(seq);
if (len < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {
@ -873,7 +873,7 @@ builtin_map(PyObject *self, PyObject *args)
}
/* Update len. */
curlen = PyObject_Size(curseq);
curlen = _PyObject_LengthCue(curseq);
if (curlen < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {
@ -2108,7 +2108,7 @@ builtin_zip(PyObject *self, PyObject *args)
len = -1; /* unknown */
for (i = 0; i < itemsize; ++i) {
PyObject *item = PyTuple_GET_ITEM(args, i);
int thislen = PyObject_Size(item);
int thislen = _PyObject_LengthCue(item);
if (thislen < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {