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Iterators phase 1. This comprises:

Browse source 
new slot tp_iter in type object, plus new flag Py_TPFLAGS_HAVE_ITER
new C API PyObject_GetIter(), calls tp_iter
new builtin iter(), with two forms: iter(obj), and iter(function, sentinel)
new internal object types iterobject and calliterobject
new exception StopIteration
new opcodes for "for" loops, GET_ITER and FOR_ITER (also supported by dis.py)
new magic number for .pyc files
new special method for instances: __iter__() returns an iterator
iteration over dictionaries: "for x in dict" iterates over the keys
iteration over files: "for x in file" iterates over lines

TODO:

documentation
test suite
decide whether to use a different way to spell iter(function, sentinal)
decide whether "for key in dict" is a good idea
use iterators in map/filter/reduce, min/max, and elsewhere (in/not in?)
speed tuning (make next() a slot tp_next???)
This commit is contained in:
Guido van Rossum 2001-04-20 19:13:02 +00:00
parent 12e73bb2f0
commit 59d1d2b434
16 changed files with 256 additions and 25 deletions
Download patch file Download diff file Expand all files Collapse all files

103
Objects/dictobject.c
View file

@ -1324,6 +1324,8 @@ static PySequenceMethods dict_as_sequence = {
0, /* sq_inplace_repeat */
};
staticforward PyObject *dictiter_new(dictobject *);
PyTypeObject PyDict_Type = {
PyObject_HEAD_INIT(&PyType_Type)
0,
@ -1350,6 +1352,8 @@ PyTypeObject PyDict_Type = {
(traverseproc)dict_traverse, /* tp_traverse */
(inquiry)dict_tp_clear, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
(getiterfunc)dictiter_new, /* tp_iter */
};
/* For backward compatibility with old dictionary interface */
@ -1392,3 +1396,102 @@ PyDict_DelItemString(PyObject *v, char *key)
Py_DECREF(kv);
return err;
}
/* Dictionary iterator type */
extern PyTypeObject PyDictIter_Type; /* Forward */
typedef struct {
PyObject_HEAD
dictobject *di_dict;
int di_size;
int di_pos;
} dictiterobject;
static PyObject *
dictiter_new(dictobject *dict)
{
dictiterobject *di;
di = PyObject_NEW(dictiterobject, &PyDictIter_Type);
if (di == NULL)
return NULL;
Py_INCREF(dict);
di->di_dict = dict;
di->di_size = dict->ma_size;
di->di_pos = 0;
return (PyObject *)di;
}
static void
dictiter_dealloc(dictiterobject *di)
{
Py_DECREF(di->di_dict);
PyObject_DEL(di);
}
static PyObject *
dictiter_next(dictiterobject *di, PyObject *args)
{
PyObject *key;
if (di->di_size != di->di_dict->ma_size) {
PyErr_SetString(PyExc_RuntimeError,
"dictionary changed size during iteration");
return NULL;
}
if (PyDict_Next((PyObject *)(di->di_dict), &di->di_pos, &key, NULL)) {
Py_INCREF(key);
return key;
}
PyErr_SetObject(PyExc_StopIteration, Py_None);
return NULL;
}
static PyObject *
dictiter_getiter(PyObject *it)
{
Py_INCREF(it);
return it;
}
static PyMethodDef dictiter_methods[] = {
{"next", (PyCFunction)dictiter_next, METH_VARARGS,
"it.next() -- get the next value, or raise StopIteration"},
{NULL, NULL} /* sentinel */
};
static PyObject *
dictiter_getattr(dictiterobject *it, char *name)
{
return Py_FindMethod(dictiter_methods, (PyObject *)it, name);
}
PyTypeObject PyDictIter_Type = {
PyObject_HEAD_INIT(&PyType_Type)
0, /* ob_size */
"dictionary-iterator", /* tp_name */
sizeof(dictiterobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)dictiter_dealloc, /* tp_dealloc */
0, /* tp_print */
(getattrfunc)dictiter_getattr, /* 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 */
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
(getiterfunc)dictiter_getiter, /* tp_iter */
};