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/* David Leonard <david.leonard@csee.uq.edu.au>, 1999. Public domain. */
/* $Id: linkedlist.c,v 1.6 2001/05/12 08:08:39 leonard Exp $ */
/*
* read-only linked list type template.
* These utility functions construct python object types that provide
* a sequence interface to a linked list in C. Three C functions are
* provided to the template: first, next, and item. The first two manipulate
* pointers, while the third generate a python object from a C pointer.
* All pointers are void *.
*/
#include "common.h"
#include "linkedlist.h"
static PyObject *repr(PyObject *obj);
static PyObject *length(PyObject *obj);
static PyObject *item(PyObject *obj, int index);
#define LINKCLASS(obj) \
((LinkedListType *)((obj)->ob_type))
#define FIRST(obj) \
(*LINKCLASS(obj)->llt_firstfn)((obj))
#define NEXT(obj, pos) \
(*LINKCLASS(obj)->llt_nextfn)((obj), pos)
#define ITEM(obj, pos) \
(*LINKCLASS(obj)->llt_itemfn)((obj), pos)
/*
* Create a new instance of the linked list. The caller should keep
* the head pointer somewhere for when FIRST() is called later.
*/
PyObject *
LinkedList_new(type)
LinkedListType *type;
{
return (PyObject *)PyObject_NEW(LinkedListObject, &type->llt_type);
}
/* Dodgy representation: much of this from listobject.c */
static PyObject *
repr(obj)
PyObject *obj;
{
LinkedListObject *self = (LinkedListObject *)obj;
PyObject *s, *comma, *itm;
void *pos;
int i;
i = Py_ReprEnter((PyObject *)self);
if (i != 0) {
if (i > 0)
return PyString_FromString("<...>");
return NULL;
}
s = PyString_FromString("<");
comma = PyString_FromString(", ");
for (i = 0, pos = FIRST(self); pos; pos = NEXT(self, pos), i++) {
if (i > 0)
PyString_Concat(&s, comma);
itm = ITEM(self, pos);
PyString_ConcatAndDel(&s, PyObject_Repr(itm));
}
Py_XDECREF(comma);
PyString_ConcatAndDel(&s, PyString_FromString(">"));
Py_ReprLeave((PyObject *)self);
return s;
}
/* Inefficiently find the length of the list */
static PyObject *
length(obj)
PyObject *obj;
{
LinkedListObject *self = (LinkedListObject *)obj;
int len;
void *pos;
len = 0;
for (pos = FIRST(self); pos != NULL; pos = NEXT(self, pos))
len++;
return PyInt_FromLong(len);
}
/* Inefficiently access an item in the list */
static PyObject *
item(obj, index)
PyObject *obj;
int index;
{
LinkedListObject *self = (LinkedListObject *)obj;
void *pos;
pos = FIRST(self);
while (pos && index) {
pos = NEXT(self, pos);
index--;
}
if (pos && index == 0)
return ITEM(self, pos);
PyErr_SetObject(PyExc_IndexError, PyInt_FromLong(index));
return NULL;
}
static PySequenceMethods default_methods = {
(inquiry)length, /* sq_length */
(binaryfunc)0, /* sq_concat */
(intargfunc)0, /* sq_repeat */
(intargfunc)item, /* sq_item */
(intintargfunc)0, /* sq_slice */
(intobjargproc)0, /* sq_ass_item */
(intintobjargproc)0, /* sq_ass_slice */
};
static PyTypeObject default_type = {
#if defined(WIN32) || defined(__CYGWIN__)
/* see http://www.python.org/doc/FAQ.html#3.24 */
PyObject_HEAD_INIT(NULL)
#else /* ! WIN32 */
PyObject_HEAD_INIT(&PyType_Type)
#endif /* ! WIN32 */
0, /*ob_size*/
0, /*tp_name*/
0, /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
(destructor)0, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
(reprfunc)repr, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash*/
};
/*
* Create a new linked-list object type.
* Caller must set tp_dealloc.
*/
void
LinkedList_inittype(type, name, size, firstfn, nextfn, itemfn, dealloc)
LinkedListType *type;
char *name;
size_t size;
firstfunc firstfn;
nextfunc nextfn;
itemfunc itemfn;
destructor dealloc;
{
memcpy(&type->llt_type, &default_type, sizeof type->llt_type);
memcpy(&type->llt_sequence, &default_methods,
sizeof type->llt_sequence);
type->llt_firstfn = firstfn;
type->llt_nextfn = nextfn;
type->llt_itemfn = itemfn;
type->llt_type.tp_as_sequence = &type->llt_sequence;
type->llt_type.ob_size = size;
type->llt_type.tp_dealloc = dealloc;
}
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