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cpython/Modules/_functoolsmodule.c

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#include "Python.h"
#include "structmember.h"
/* _functools module written and maintained
by Hye-Shik Chang <perky@FreeBSD.org>
with adaptations by Raymond Hettinger <python@rcn.com>
Copyright (c) 2004, 2005, 2006 Python Software Foundation.
All rights reserved.
*/
/* partial object **********************************************************/
typedef struct {
PyObject_HEAD
PyObject *fn;
PyObject *args;
PyObject *kw;
PyObject *dict;
PyObject *weakreflist; /* List of weak references */
} partialobject;
static PyTypeObject partial_type;
static PyObject *
partial_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
PyObject *func;
partialobject *pto;
if (PyTuple_GET_SIZE(args) < 1) {
PyErr_SetString(PyExc_TypeError,
"type 'partial' takes at least one argument");
return NULL;
}
func = PyTuple_GET_ITEM(args, 0);
if (!PyCallable_Check(func)) {
PyErr_SetString(PyExc_TypeError,
"the first argument must be callable");
return NULL;
}
/* create partialobject structure */
pto = (partialobject *)type->tp_alloc(type, 0);
if (pto == NULL)
return NULL;
pto->fn = func;
Py_INCREF(func);
pto->args = PyTuple_GetSlice(args, 1, PY_SSIZE_T_MAX);
if (pto->args == NULL) {
pto->kw = NULL;
Py_DECREF(pto);
return NULL;
}
if (kw != NULL) {
pto->kw = PyDict_Copy(kw);
if (pto->kw == NULL) {
Py_DECREF(pto);
return NULL;
}
} else {
pto->kw = Py_None;
Py_INCREF(Py_None);
}
pto->weakreflist = NULL;
pto->dict = NULL;
return (PyObject *)pto;
}
static void
partial_dealloc(partialobject *pto)
{
PyObject_GC_UnTrack(pto);
if (pto->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) pto);
Py_XDECREF(pto->fn);
Py_XDECREF(pto->args);
Py_XDECREF(pto->kw);
Py_XDECREF(pto->dict);
Py_TYPE(pto)->tp_free(pto);
}
static PyObject *
partial_call(partialobject *pto, PyObject *args, PyObject *kw)
{
PyObject *ret;
PyObject *argappl = NULL, *kwappl = NULL;
assert (PyCallable_Check(pto->fn));
assert (PyTuple_Check(pto->args));
assert (pto->kw == Py_None || PyDict_Check(pto->kw));
if (PyTuple_GET_SIZE(pto->args) == 0) {
argappl = args;
Py_INCREF(args);
} else if (PyTuple_GET_SIZE(args) == 0) {
argappl = pto->args;
Py_INCREF(pto->args);
} else {
argappl = PySequence_Concat(pto->args, args);
if (argappl == NULL)
return NULL;
}
if (pto->kw == Py_None) {
kwappl = kw;
Py_XINCREF(kw);
} else {
kwappl = PyDict_Copy(pto->kw);
if (kwappl == NULL) {
Py_DECREF(argappl);
return NULL;
}
if (kw != NULL) {
if (PyDict_Merge(kwappl, kw, 1) != 0) {
Py_DECREF(argappl);
Py_DECREF(kwappl);
return NULL;
}
}
}
ret = PyObject_Call(pto->fn, argappl, kwappl);
Py_DECREF(argappl);
Py_XDECREF(kwappl);
return ret;
}
static int
partial_traverse(partialobject *pto, visitproc visit, void *arg)
{
Py_VISIT(pto->fn);
Py_VISIT(pto->args);
Py_VISIT(pto->kw);
Py_VISIT(pto->dict);
return 0;
}
PyDoc_STRVAR(partial_doc,
"partial(func, *args, **keywords) - new function with partial application\n\
of the given arguments and keywords.\n");
#define OFF(x) offsetof(partialobject, x)
static PyMemberDef partial_memberlist[] = {
{"func", T_OBJECT, OFF(fn), READONLY,
"function object to use in future partial calls"},
{"args", T_OBJECT, OFF(args), READONLY,
"tuple of arguments to future partial calls"},
{"keywords", T_OBJECT, OFF(kw), READONLY,
"dictionary of keyword arguments to future partial calls"},
{NULL} /* Sentinel */
};
static PyObject *
partial_get_dict(partialobject *pto)
{
if (pto->dict == NULL) {
pto->dict = PyDict_New();
if (pto->dict == NULL)
return NULL;
}
Py_INCREF(pto->dict);
return pto->dict;
}
static int
partial_set_dict(partialobject *pto, PyObject *value)
{
PyObject *tmp;
/* It is illegal to del p.__dict__ */
if (value == NULL) {
PyErr_SetString(PyExc_TypeError,
"a partial object's dictionary may not be deleted");
return -1;
}
/* Can only set __dict__ to a dictionary */
if (!PyDict_Check(value)) {
PyErr_SetString(PyExc_TypeError,
"setting partial object's dictionary to a non-dict");
return -1;
}
tmp = pto->dict;
Py_INCREF(value);
pto->dict = value;
Py_XDECREF(tmp);
return 0;
}
static PyGetSetDef partial_getsetlist[] = {
{"__dict__", (getter)partial_get_dict, (setter)partial_set_dict},
{NULL} /* Sentinel */
};
/* Pickle strategy:
__reduce__ by itself doesn't support getting kwargs in the unpickle
operation so we define a __setstate__ that replaces all the information
about the partial. If we only replaced part of it someone would use
it as a hook to do strange things.
*/
static PyObject *
partial_reduce(partialobject *pto, PyObject *unused)
{
return Py_BuildValue("O(O)(OOOO)", Py_TYPE(pto), pto->fn, pto->fn,
pto->args, pto->kw,
pto->dict ? pto->dict : Py_None);
}
static PyObject *
partial_setstate(partialobject *pto, PyObject *args)
{
PyObject *fn, *fnargs, *kw, *dict;
if (!PyArg_ParseTuple(args, "(OOOO):__setstate__",
&fn, &fnargs, &kw, &dict))
return NULL;
Py_XDECREF(pto->fn);
Py_XDECREF(pto->args);
Py_XDECREF(pto->kw);
Py_XDECREF(pto->dict);
pto->fn = fn;
pto->args = fnargs;
pto->kw = kw;
if (dict != Py_None) {
pto->dict = dict;
Py_INCREF(dict);
} else {
pto->dict = NULL;
}
Py_INCREF(fn);
Py_INCREF(fnargs);
Py_INCREF(kw);
Py_RETURN_NONE;
}
static PyMethodDef partial_methods[] = {
{"__reduce__", (PyCFunction)partial_reduce, METH_NOARGS},
{"__setstate__", (PyCFunction)partial_setstate, METH_VARARGS},
{NULL, NULL} /* sentinel */
};
static PyTypeObject partial_type = {
PyVarObject_HEAD_INIT(NULL, 0)
"functools.partial", /* tp_name */
sizeof(partialobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)partial_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
(ternaryfunc)partial_call, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
PyObject_GenericSetAttr, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
Py_TPFLAGS_BASETYPE, /* tp_flags */
partial_doc, /* tp_doc */
(traverseproc)partial_traverse, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(partialobject, weakreflist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
partial_methods, /* tp_methods */
partial_memberlist, /* tp_members */
partial_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
offsetof(partialobject, dict), /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
partial_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
};
/* reduce (used to be a builtin) ********************************************/
static PyObject *
functools_reduce(PyObject *self, PyObject *args)
{
PyObject *seq, *func, *result = NULL, *it;
if (!PyArg_UnpackTuple(args, "reduce", 2, 3, &func, &seq, &result))
return NULL;
if (result != NULL)
Py_INCREF(result);
it = PyObject_GetIter(seq);
if (it == NULL) {
if (PyErr_ExceptionMatches(PyExc_TypeError))
PyErr_SetString(PyExc_TypeError,
"reduce() arg 2 must support iteration");
Py_XDECREF(result);
return NULL;
}
if ((args = PyTuple_New(2)) == NULL)
goto Fail;
for (;;) {
PyObject *op2;
if (args->ob_refcnt > 1) {
Py_DECREF(args);
if ((args = PyTuple_New(2)) == NULL)
goto Fail;
}
op2 = PyIter_Next(it);
if (op2 == NULL) {
if (PyErr_Occurred())
goto Fail;
break;
}
if (result == NULL)
result = op2;
else {
PyTuple_SetItem(args, 0, result);
PyTuple_SetItem(args, 1, op2);
if ((result = PyEval_CallObject(func, args)) == NULL)
goto Fail;
}
}
Py_DECREF(args);
if (result == NULL)
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;
}
PyDoc_STRVAR(functools_reduce_doc,
"reduce(function, sequence[, initial]) -> value\n\
\n\
Apply a function of two arguments cumulatively to the items of a sequence,\n\
from left to right, so as to reduce the sequence to a single value.\n\
For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates\n\
((((1+2)+3)+4)+5). If initial is present, it is placed before the items\n\
of the sequence in the calculation, and serves as a default when the\n\
sequence is empty.");
/* module level code ********************************************************/
PyDoc_STRVAR(module_doc,
"Tools that operate on functions.");
static PyMethodDef module_methods[] = {
{"reduce", functools_reduce, METH_VARARGS, functools_reduce_doc},
{NULL, NULL} /* sentinel */
};
static struct PyModuleDef _functoolsmodule = {
PyModuleDef_HEAD_INIT,
"_functools",
module_doc,
-1,
module_methods,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC
PyInit__functools(void)
{
int i;
PyObject *m;
char *name;
PyTypeObject *typelist[] = {
&partial_type,
NULL
};
m = PyModule_Create(&_functoolsmodule);
if (m == NULL)
return NULL;
for (i=0 ; typelist[i] != NULL ; i++) {
if (PyType_Ready(typelist[i]) < 0) {
Py_DECREF(m);
return NULL;
}
name = strchr(typelist[i]->tp_name, '.');
assert (name != NULL);
Py_INCREF(typelist[i]);
PyModule_AddObject(m, name+1, (PyObject *)typelist[i]);
}
return m;
}
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