/* Iterator objects */

#include "Python.h"

typedef struct {

	PyObject_HEAD

	long      it_index;

	PyObject *it_seq; /* Set to NULL when iterator is exhausted */

} seqiterobject;

PyObject *

PySeqIter_New(PyObject *seq)

{

	seqiterobject *it;

	if (!PySequence_Check(seq)) {

		PyErr_BadInternalCall();

		return NULL;

	}	

	it = PyObject_GC_New(seqiterobject, &PySeqIter_Type);

	if (it == NULL)

		return NULL;

	it->it_index = 0;

	Py_INCREF(seq);

	it->it_seq = seq;

	_PyObject_GC_TRACK(it);

	return (PyObject *)it;

}

static void

iter_dealloc(seqiterobject *it)

{

	_PyObject_GC_UNTRACK(it);

	Py_XDECREF(it->it_seq);

	PyObject_GC_Del(it);

}

static int

iter_traverse(seqiterobject *it, visitproc visit, void *arg)

{

	Py_VISIT(it->it_seq);

	return 0;

}

static PyObject *

iter_iternext(PyObject *iterator)

{

	seqiterobject *it;

	PyObject *seq;

	PyObject *result;

	assert(PySeqIter_Check(iterator));

	it = (seqiterobject *)iterator;

	seq = it->it_seq;

	if (seq == NULL)

		return NULL;

	result = PySequence_GetItem(seq, it->it_index);

	if (result != NULL) {

		it->it_index++;

		return result;

	}

	if (PyErr_ExceptionMatches(PyExc_IndexError) ||

	    PyErr_ExceptionMatches(PyExc_StopIteration))

	{

		PyErr_Clear();

		Py_DECREF(seq);

		it->it_seq = NULL;

	}

	return NULL;

}

static PyObject *

iter_len(seqiterobject *it)

{

	Py_ssize_t seqsize, len;

	if (it->it_seq) {

		seqsize = PySequence_Size(it->it_seq);

		if (seqsize == -1)

			return NULL;

		len = seqsize - it->it_index;

		if (len >= 0)

			return PyInt_FromSsize_t(len);

	}

	return PyInt_FromLong(0);

}

PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");

static PyMethodDef seqiter_methods[] = {

	{"__length_hint__", (PyCFunction)iter_len, METH_NOARGS, length_hint_doc},

 	{NULL,		NULL}		/* sentinel */

};

PyTypeObject PySeqIter_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"iterator",				/* tp_name */

	sizeof(seqiterobject),			/* tp_basicsize */

	0,					/* tp_itemsize */

	/* methods */

	(destructor)iter_dealloc, 		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* 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 */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */

 	0,					/* tp_doc */

 	(traverseproc)iter_traverse,		/* tp_traverse */

 	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	PyObject_SelfIter,			/* tp_iter */

	iter_iternext,				/* tp_iternext */

	seqiter_methods,			/* tp_methods */

	0,					/* tp_members */

};

/* -------------------------------------- */

typedef struct {

	PyObject_HEAD

	PyObject *it_callable; /* Set to NULL when iterator is exhausted */

	PyObject *it_sentinel; /* Set to NULL when iterator is exhausted */

} calliterobject;

PyObject *

PyCallIter_New(PyObject *callable, PyObject *sentinel)

{

	calliterobject *it;

	it = PyObject_GC_New(calliterobject, &PyCallIter_Type);

	if (it == NULL)

		return NULL;

	Py_INCREF(callable);

	it->it_callable = callable;

	Py_INCREF(sentinel);

	it->it_sentinel = sentinel;

	_PyObject_GC_TRACK(it);

	return (PyObject *)it;

}

static void

calliter_dealloc(calliterobject *it)

{

	_PyObject_GC_UNTRACK(it);

	Py_XDECREF(it->it_callable);

	Py_XDECREF(it->it_sentinel);

	PyObject_GC_Del(it);

}

static int

calliter_traverse(calliterobject *it, visitproc visit, void *arg)

{

	Py_VISIT(it->it_callable);

	Py_VISIT(it->it_sentinel);

	return 0;

}

static PyObject *

calliter_iternext(calliterobject *it)

{

	if (it->it_callable != NULL) {

		PyObject *args = PyTuple_New(0);

		PyObject *result;

		if (args == NULL)

			return NULL;

		result = PyObject_Call(it->it_callable, args, NULL);

		Py_DECREF(args);

		if (result != NULL) {

			int ok;

			ok = PyObject_RichCompareBool(result,

						      it->it_sentinel,

						      Py_EQ);

			if (ok == 0)

				return result; /* Common case, fast path */

			Py_DECREF(result);

			if (ok > 0) {

				Py_CLEAR(it->it_callable);

				Py_CLEAR(it->it_sentinel);

			}

		}

		else if (PyErr_ExceptionMatches(PyExc_StopIteration)) {

			PyErr_Clear();

			Py_CLEAR(it->it_callable);

			Py_CLEAR(it->it_sentinel);

		}

	}

	return NULL;

}

PyTypeObject PyCallIter_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"callable-iterator",			/* tp_name */

	sizeof(calliterobject),			/* tp_basicsize */

	0,					/* tp_itemsize */

	/* methods */

	(destructor)calliter_dealloc, 		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* 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 */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */

	0,					/* tp_doc */

	(traverseproc)calliter_traverse,	/* tp_traverse */

	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	PyObject_SelfIter,			/* tp_iter */

	(iternextfunc)calliter_iternext,	/* tp_iternext */

	0,					/* tp_methods */

};