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Generalize reduce() to work with iterators.

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NEEDS DOC CHANGES.
This commit is contained in:
Tim Peters 2001-05-04 04:39:21 +00:00
parent 8bc10b0c57
commit 15d81efb8a
3 changed files with 33 additions and 12 deletions
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31
Python/bltinmodule.c
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@ -1851,26 +1851,25 @@ is printed without a trailing newline before reading.";
static PyObject *
builtin_reduce(PyObject *self, PyObject *args)
{
PyObject *seq, *func, *result = NULL;
PySequenceMethods *sqf;
register int i;
PyObject *seq, *func, *result = NULL, *it;
if (!PyArg_ParseTuple(args, "OO|O:reduce", &func, &seq, &result))
return NULL;
if (result != NULL)
Py_INCREF(result);
sqf = seq->ob_type->tp_as_sequence;
if (sqf == NULL || sqf->sq_item == NULL) {
it = PyObject_GetIter(seq);
if (it == NULL) {
PyErr_SetString(PyExc_TypeError,
"reduce() arg 2 must be a sequence");
"reduce() arg 2 must support iteration");
Py_XDECREF(result);
return NULL;
}
if ((args = PyTuple_New(2)) == NULL)
goto Fail;
for (i = 0; ; ++i) {
for (;;) {
PyObject *op2;
if (args->ob_refcnt > 1) {
@ -1879,12 +1878,18 @@ builtin_reduce(PyObject *self, PyObject *args)
goto Fail;
}
if ((op2 = (*sqf->sq_item)(seq, i)) == NULL) {
if (PyErr_ExceptionMatches(PyExc_IndexError)) {
PyErr_Clear();
break;
op2 = PyIter_Next(it);
if (op2 == NULL) {
/* StopIteration is *implied* by a NULL return from
* PyIter_Next() if PyErr_Occurred() is false.
*/
if (PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_StopIteration))
PyErr_Clear();
else
goto Fail;
}
goto Fail;
break;
}
if (result == NULL)
@ -1903,11 +1908,13 @@ builtin_reduce(PyObject *self, PyObject *args)
PyErr_SetString(PyExc_TypeError,
"reduce() of empty sequence with no initial value");
Py_DECREF(it);
return result;
Fail:
Py_XDECREF(args);
Py_XDECREF(result);
Py_DECREF(it);
return NULL;
}