Modules/xreadlinesmodule.c

   1 #include "Python.h"
   2
   3 static char xreadlines_doc [] =
   4 "xreadlines(f)\n\
   5 \n\
   6 Return an xreadlines object for the file f.";
   7
   8 typedef struct {
   9         PyObject_HEAD
  10         PyObject *file;
  11         PyObject *lines;
  12         int lineslen;
  13         int lineno;
  14         int abslineno;
  15 } PyXReadlinesObject;
  16
  17 staticforward PyTypeObject XReadlinesObject_Type;
  18
  19 static void
  20 xreadlines_dealloc(PyXReadlinesObject *op)
  21 {
  22         Py_XDECREF(op->file);
  23         Py_XDECREF(op->lines);
  24         PyObject_DEL(op);
  25 }
  26
  27 /* A larger chunk size doesn't seem to make a difference */
  28 #define CHUNKSIZE  8192
  29
  30 static PyXReadlinesObject *
  31 newreadlinesobject(PyObject *file)
  32 {
  33         PyXReadlinesObject *op;
  34         op = PyObject_NEW(PyXReadlinesObject, &XReadlinesObject_Type);
  35         if (op == NULL)
  36                 return NULL;
  37         Py_XINCREF(file);
  38         op->file = file;
  39         op->lines = NULL;
  40         op->abslineno = op->lineno = op->lineslen = 0;
  41         return op;
  42 }
  43
  44 static PyObject *
  45 xreadlines(PyObject *self, PyObject *args)
  46 {
  47         PyObject *file;
  48         PyXReadlinesObject *ret;
  49
  50         if (!PyArg_ParseTuple(args, "O:xreadlines", &file))
  51                 return NULL;
  52         ret = newreadlinesobject(file);
  53         Py_XINCREF(ret);
  54         return (PyObject*)ret;
  55 }
  56
  57 static PyObject *
  58 xreadlines_item(PyXReadlinesObject *a, int i)
  59 {
  60         if (i != a->abslineno) {
  61                 PyErr_SetString(PyExc_RuntimeError,
  62                         "xreadlines object accessed out of order");
  63                 return NULL;
  64         }
  65         if (a->lineno >= a->lineslen) {
  66                 Py_XDECREF(a->lines);
  67                 a->lines = PyObject_CallMethod(a->file, "readlines", "(i)",
  68                                                CHUNKSIZE);
  69                 if (a->lines == NULL)
  70                         return NULL;
  71                 a->lineno = 0;
  72                 if ((a->lineslen = PySequence_Size(a->lines)) < 0)
  73                         return NULL;
  74         }
  75         a->abslineno++;
  76         return PySequence_GetItem(a->lines, a->lineno++);
  77 }
  78
  79 static PySequenceMethods xreadlines_as_sequence = {
  80         0, /*sq_length*/
  81         0, /*sq_concat*/
  82         0, /*sq_repeat*/
  83         (intargfunc)xreadlines_item, /*sq_item*/
  84 };
  85
  86 static PyTypeObject XReadlinesObject_Type = {
  87         PyObject_HEAD_INIT(NULL)
  88         0,
  89         "xreadlines",
  90         sizeof(PyXReadlinesObject) + PyGC_HEAD_SIZE,
  91         0,
  92         (destructor)xreadlines_dealloc, /*tp_dealloc*/
  93         0, /*tp_print*/
  94         0, /*tp_getattr*/
  95         0, /*tp_setattr*/
  96         0, /*tp_compare*/
  97         0, /*tp_repr*/
  98         0, /*tp_as_number*/
  99         &xreadlines_as_sequence, /*tp_as_sequence*/
 100         0,              /*tp_as_mapping*/
 101         0,              /*tp_hash*/
 102         0,              /*tp_call*/
 103         0,              /*tp_str*/
 104         0,              /*tp_getattro*/
 105         0,              /*tp_setattro*/
 106         0,              /*tp_as_buffer*/
 107         Py_TPFLAGS_DEFAULT,     /*tp_flags*/
 108         0,              /* tp_doc */
 109 };
 110
 111 static PyMethodDef xreadlines_methods[] = {
 112         {"xreadlines", xreadlines, METH_VARARGS, xreadlines_doc},
 113         {NULL, NULL}
 114 };
 115
 116 DL_EXPORT(void)
 117 initxreadlines(void)
 118 {
 119         PyObject *m;
 120
 121         XReadlinesObject_Type.ob_type = &PyType_Type;
 122         m = Py_InitModule("xreadlines", xreadlines_methods);
 123 }