range: lean and mean

Objects/rangeobject.c

 /* Range object implementation */
 
 #include "Python.h"
 #include "structmember.h"
 
 /* Support objects whose length is > PY_SSIZE_T_MAX.
 
    This could be sped up for small PyLongs if they fit in an Py_ssize_t.
    This only matters on Win64.  Though we could use PY_LONG_LONG which
    would presumably help perf.
@@ skipping 104 matching lines @@
 static void
 range_dealloc(rangeobject *r)
 {
     Py_DECREF(r->start);
     Py_DECREF(r->stop);
     Py_DECREF(r->step);
     Py_DECREF(r->length);
     PyObject_Del(r);
 }
 
+/*Return number of items in range (lo, hi, step), when arguments are
+* PyLong objects. step > 0 required. Return a PyLong with the length.
+* Return NULL when there is an error.*/
 static PyObject *
 range_compute_length(PyObject *start, PyObject *stop, PyObject *step)
 {
     /* -------------------------------------------------------------
     Algorithm is equal to that of get_len_of_range(), but it operates
     on PyObjects (which are assumed to be PyLong or PyInt objects).
     ---------------------------------------------------------------*/
     int cmp_result, cmp_call;
     PyObject *lo, *hi;
     PyObject *diff = NULL;
@@ skipping 520 matching lines @@
         return NULL;
     }
 
     return (PyObject *)it;
 
 create_failure:
     Py_XDECREF(len);
     PyObject_Del(it);
     return NULL;
 }