yap-6.3/packages/python/pybips.c

/**
 *
 * @section Python Built-Ins
 *
 * The Python engine includes a large number of Python built-ins. Some
 * of them are interfaced here.
 */

//@{

#include "py4yap.h"

static PyObject *finalLookup(PyObject *i, const char *s) {
  PyObject *rc;
  if (i == NULL)
    return NULL;
  if (strcmp(s, "none") == 0)
    return Py_None;
  if (PyDict_Check(i)) {
    if ((rc = PyDict_GetItemString(i, s)))
      return rc;
  }
  if (PyModule_Check(i)) {
    if ((rc = PyDict_GetItemString(i, s)))
      return rc;
  }
  if (PyObject_HasAttrString(i, s)) {
    return PyObject_GetAttrString(i, s);
  }
  return NULL;
}

PyObject *PythonLookupSpecial(const char *s) {
  if (s == NULL)
    return NULL;
  if (strcmp(s, "true") == 0) {
    return Py_True;
  }
  if (strcmp(s, "false") == 0) {
    return Py_False;
  }
  if (strcmp(s, "[]") == 0) {
    return PyList_New(0);
  }
  if (strcmp(s, "{}") == 0) {
    return PyDict_New();
    /* return __main__,s */
  }
  return NULL;
}

PyObject *lookupPySymbol(const char *sp, PyObject *pContext, PyObject **duc) {
  PyObject *out = NULL;
  if (!sp)
    return NULL;
  if ((out = finalLookup(pContext, sp))) {
    return out;
  }
  if ((out = finalLookup(py_Context, sp))) {
    return out;
  }
  PyObject *py_Builtin = PyEval_GetBuiltins();
  if ((out = finalLookup(py_Builtin, sp))) {
    return out;
  }
  PyObject *py_Local = PyEval_GetLocals();
  if ((out = finalLookup(py_Local, sp)) && out != Py_None) {
    return out;
  }
  PyObject *py_Global = PyEval_GetGlobals();
  if ((out = finalLookup(py_Global, sp))) {
    return out;
  }
  if ((out = finalLookup(py_ModDict, sp))) {
    return out;
  }
  if ((out = finalLookup(py_Main, sp))) {
    return out;
  }
  return NULL;
}

PyObject *PythonLookup(const char *s, PyObject *oo) {
  PyObject *o;
  if ((o = PythonLookupSpecial(s)))
    return o;
  if ((o = lookupPySymbol(s, oo, NULL)) == NULL)
    return NULL;
  else {
    Py_INCREF(o);
    return o;
  }
}

PyObject *

find_obj(PyObject *ob, term_t l, bool eval) {
  YAP_Term hd, yt;

  py_Context = NULL;
  yt = YAP_GetFromSlot(l);
  // Yap_DebugPlWriteln(yt);
  while (YAP_IsPairTerm(yt)) {
    hd = YAP_HeadOfTerm(yt);
    yt = YAP_TailOfTerm(yt);
    YAP_PutInSlot(l, yt);
    ob = yap_to_python(hd, true, ob, false);
    if (!ob) {
      return Py_None;
    }
  }
  return ob;
}

/**
 * Python abs
 *
 * @param t Prolog term with a number
 *
 * @return a Python object with the number's absolute value
 */

static PyObject *bip_abs(term_t t) {
  PyObject *pVal, *nVal;

  AOK(PL_get_arg(1, t, t), NULL);
  pVal = term_to_python(t, true, NULL, true);
  pVal = CHECKNULL(t, pVal);
  nVal = PyNumber_Absolute(pVal);
  Py_DecRef(pVal);
  return nVal;
}

/**
 * Python all
 *
 * @param t Prolog term with a previously constructed Python iterator
> *
 * @return the Python boolean `True` if all elements of the iterator are `True`,
 *    `False`  otherwise.
 */
static PyObject *bip_all(term_t t) {
  PyObject *it, *item, *v;
  PyObject *(*iternext)(PyObject *);
  int cmp;

  AOK(PL_get_arg(1, t, t), NULL);
  (v = term_to_python(t, true, NULL, true));
  v = CHECKNULL(t, v);
  it = PyObject_GetIter(v);
  if (CHECKNULL(t, it) == NULL)
    return Py_None;
  iternext = *Py_TYPE(it)->tp_iternext;

  if (PyErr_Occurred()) {
    if (PyErr_ExceptionMatches(PyExc_StopIteration))
      PyErr_Clear();
    else
      return Py_None;
  }
  //  PyObject_Print(v, stderr, 0);
  for (;;) {
    item = iternext(it);
    if (CHECKNULL(t, item) == NULL)
      break;
    cmp = PyObject_IsTrue(item);
    Py_DECREF(item);
    if (cmp < 0) {
      Py_DECREF(it);
      return Py_None;
    }
    if (cmp == 0) {
      Py_DECREF(it);
      return Py_False;
    }
  }
  Py_DECREF(it);
  return Py_True;
}

/**
 * Python any
 *
 * @param t Prolog term with a previously constructed Python iterator
 *
 * @return the Python boolean `True` if any element of the iterator is `True`,
 *    `False`  if all of them are false.
 */
static PyObject *bip_any(term_t t) {
  PyObject *it, *item, *v;
  PyObject *(*iternext)(PyObject *);
  int cmp;

  AOK(PL_get_arg(1, t, t), NULL);
  v = term_to_python(t, true, NULL, true);
  it = PyObject_GetIter(v);
  if (CHECKNULL(t, it) == NULL)
    return Py_None;
  iternext = *Py_TYPE(it)->tp_iternext;

  for (;;) {
    item = iternext(it);
    if (CHECKNULL(t, item) == NULL)
      break;
    cmp = PyObject_IsTrue(item);
    Py_DECREF(item);
    if (cmp < 0) {
      Py_DECREF(it);
      return Py_None;
    }
    if (cmp == 1) {
      Py_DECREF(it);
      Py_RETURN_TRUE;
    }
  }
  Py_DECREF(it);
  if (PyErr_Occurred()) {
    if (PyErr_ExceptionMatches(PyExc_StopIteration))
      PyErr_Clear();
    else
      return CHECKNULL(t, NULL);
  }
  Py_RETURN_FALSE;
}

static PyObject *bip_bin(term_t t) {
  PyObject *v;

  AOK(PL_get_arg(1, t, t), NULL);
  v = term_to_python(t, true, NULL, true);
  return PyNumber_ToBase(v, 2);
}

static PyObject *bip_float(term_t t, bool eval) {
  PyObject *pVal, *o;

  AOK(PL_get_arg(1, t, t), NULL);
  pVal = term_to_python(t, eval, NULL, eval);
  if (PyLong_Check(pVal)) {
    o = PyFloat_FromDouble(PyLong_AsLong(pVal));
#if PY_MAJOR_VERSION < 3
  } else if (PyInt_Check(pVal)) {
    o = PyFloat_FromDouble(PyInt_AsLong(pVal));
#endif
  } else if (PyFloat_Check(pVal)) {
    return pVal;
  } else
    return Py_None;
  Py_DECREF(pVal);
  return o;
}

static PyObject *bip_int(term_t t) {
  PyObject *pVal, *o;

  AOK(PL_get_arg(1, t, t), NULL);
  pVal = term_to_python(t, true, NULL, true);
#if PY_MAJOR_VERSION < 3
  if (PyLong_Check(pVal)) {
    o = PyInt_FromLong(PyLong_AsLong(pVal));
  } else if (PyInt_Check(pVal)) {
    return pVal;
#else
  if (PyLong_Check(pVal)) {
    return pVal;
#endif
  } else if (PyFloat_Check(pVal)) {
#if PY_MAJOR_VERSION < 3
    o = PyInt_FromLong(PyFloat_AsDouble(pVal));
#else
    o = PyLong_FromDouble(PyFloat_AsDouble(pVal));
#endif
  } else
    return Py_None;
  Py_DECREF(pVal);
  return o;
}

static PyObject *bip_long(term_t t) {
  PyObject *pVal, *o;

  AOK(PL_get_arg(1, t, t), NULL);
  pVal = term_to_python(t, true, NULL, true);
  if (PyLong_Check(pVal)) {
    return pVal;
#if PY_MAJOR_VERSION < 3
  } else if (PyInt_Check(pVal)) {
    o = PyLong_FromLong(PyInt_AsLong(pVal));
#endif
  } else if (PyFloat_Check(pVal)) {
    o = pVal;
  } else
    return Py_None;
  Py_DECREF(pVal);
  return o;
}

static PyObject *bip_iter(term_t t) {
  PyObject *v;

  AOK(PL_get_arg(1, t, t), NULL);
  v = term_to_python(t, true, NULL, true);
  return PyObject_GetIter(v);
}

static PyObject *bip_ord(term_t t) {
  PyObject *pVal;
  Py_ssize_t size;

  AOK(PL_get_arg(1, t, t), NULL);
  pVal = term_to_python(t, true, NULL, true);
  if (PyUnicode_Check(pVal)) {
#if PY_MAJOR_VERSION < 3
    size = PyUnicode_GET_SIZE(pVal);
#else
    size = PyUnicode_GetLength(pVal);
#endif
    if (size == 1) {
#if PY_MAJOR_VERSION < 3
      long ord = (long)*PyUnicode_AS_UNICODE(pVal);
      return PyInt_FromLong(ord);
#else
      Py_UCS4 ord = PyUnicode_ReadChar(pVal, 0);
      return PyLong_FromLong(ord);
#endif
    }
    return Py_None;
  } else if (PyByteArray_Check(pVal)) {
    char *s = PyByteArray_AsString(pVal);

    if (s[1])
      return Py_None;
#if PY_MAJOR_VERSION < 3
    return PyInt_FromLong(s[0]);
  } else if (PyString_Check(pVal)) {
    char *s = PyString_AsString(pVal);

    if (s[1])
      return Py_None;
    return PyInt_FromLong(s[0]);
#else
    return PyLong_FromLong(s[0]);
#endif
  } else
    return NULL;
}

static PyObject *bip_sum(term_t t) {
  PyObject *seq;
  PyObject *result = NULL;
  PyObject *temp, *item, *iter;

  AOK(PL_get_arg(1, t, t), NULL);
  seq = term_to_python(t, true, NULL, true);
  iter = PyObject_GetIter(seq);
  if (iter == NULL)
    return NULL;

  if (result == NULL) {
#if PY_MAJOR_VERSION < 3
    result = PyInt_FromLong(0);
#else
    result = PyLong_FromLong(0);
#endif
    if (result == NULL) {
      Py_DECREF(iter);
      return NULL;
    }
  } else {
#if PY_MAJOR_VERSION < 3
    /* reject string values for 'start' parameter */
    if (PyObject_TypeCheck(result, &PyBaseString_Type)) {
      PyErr_SetString(PyExc_TypeError,
                      "sum() can't sum strings [use ''.join(seq) instead]");
      Py_DECREF(iter);
      return NULL;
    }
    Py_INCREF(result);
#endif
  }

#ifndef SLOW_SUM
/* Fast addition by keeping temporary sums in C instead of new Python objects.
   Assumes all inputs are the same type.  If the assumption fails, default
   to the more general routine.
*/
#if PY_MAJOR_VERSION < 3
  if (PyInt_CheckExact(result)) {
    long i_result = PyInt_AS_LONG(result);
#else
  if (PyLong_CheckExact(result)) {
    long i_result = PyLong_AS_LONG(result);
#endif
    Py_DECREF(result);
    result = NULL;
    while (result == NULL) {
      item = PyIter_Next(iter);
      if (item == NULL) {
        Py_DECREF(iter);
        if (PyErr_Occurred())
          return NULL;
#if PY_MAJOR_VERSION < 3
        return PyInt_FromLong(i_result);
#else
        return PyLong_FromLong(i_result);
#endif
      }
#if PY_MAJOR_VERSION < 3
      if (PyInt_CheckExact(item)) {
        long b = PyInt_AS_LONG(item);
#else
      if (PyLong_CheckExact(item)) {
        long b = PyLong_AS_LONG(item);
#endif
        long x = i_result + b;
        if ((x ^ i_result) >= 0 || (x ^ b) >= 0) {
          i_result = x;
          Py_DECREF(item);
          continue;
        }
      }
/* Either overflowed or is not an int. Restore real objects and process normally
 */
#if PY_MAJOR_VERSION < 3
      result = PyInt_FromLong(i_result);
#else
      result = PyLong_FromLong(i_result);
#endif
      temp = PyNumber_Add(result, item);
      Py_DECREF(result);
      Py_DECREF(item);
      result = temp;
      if (result == NULL) {
        Py_DECREF(iter);
        return NULL;
      }
    }
  }

  if (PyFloat_CheckExact(result)) {
    double f_result = PyFloat_AS_DOUBLE(result);
    Py_DECREF(result);
    result = NULL;
    while (result == NULL) {
      item = PyIter_Next(iter);
      if (item == NULL) {
        Py_DECREF(iter);
        if (PyErr_Occurred())
          return NULL;
        return PyFloat_FromDouble(f_result);
      }
      if (PyFloat_CheckExact(item)) {
        PyFPE_START_PROTECT("add", Py_DECREF(item); Py_DECREF(iter); return 0)
            f_result += PyFloat_AS_DOUBLE(item);
        PyFPE_END_PROTECT(f_result) Py_DECREF(item);
        continue;
      }
#if PY_MAJOR_VERSION < 3
      if (PyInt_CheckExact(item)) {
        764PyFPE_START_PROTECT("add", Py_DECREF(item); Py_DECREF(iter);
                               return 0)f_result += (double)PyInt_AS_LONG(item);
        PyFPE_END_PROTECT(f_result) Py_DECREF(item);
        continue;
      }
#else
      if (PyLong_CheckExact(item)) {
        PyFPE_START_PROTECT("add", Py_DECREF(item); Py_DECREF(iter); return 0)
            f_result += PyLong_AsDouble(item);
        PyFPE_END_PROTECT(f_result) Py_DECREF(item);
        continue;
      }
#endif
      result = PyFloat_FromDouble(f_result);
      temp = PyNumber_Add(result, item);
      Py_DECREF(result);
      Py_DECREF(item);
      result = temp;
      if (result == NULL) {
        Py_DECREF(iter);
        return NULL;
      }
    }
#endif
  }

  for (;;) {
    item = PyIter_Next(iter);
    if (item == NULL) {
      /* error, or end-of-sequence */
      if (PyErr_Occurred()) {
        Py_DECREF(result);
        result = NULL;
      }
      break;
    }
    /* It's tempting to use PyNumber_InPlaceAdd instead of
       PyNumber_Add here, to avoid quadratic running time
       when doing 'sum(list_of_lists, [])'.  However, this
       would produce a change in behaviour: a snippet like

       empty = []
       sum([[x] for x in range(10)], empty)

       would change the value of empty. */
    temp = PyNumber_Add(result, item);
    Py_DECREF(result);
    Py_DECREF(item);
    result = temp;
    if (result == NULL)
      break;
  }
  Py_DECREF(iter);
  return result;
}

//@}

static long get_int(term_t arg, bool eval) {
  long low;

  if (!PL_get_long(arg, &low)) {
    PyObject *low = term_to_python(arg, eval, NULL, eval);
    if (PyLong_Check(low)) {
      return PyLong_AsLong(low);
#if PY_MAJOR_VERSION < 3
    } else if (PyInt_Check(low)) {
      return PyInt_AsLong(low);
#endif
    } else {
      return 0;
    }
  }
  return low;
}

/* Return number of items in range/xrange (lo, hi, step).  step > 0
 * required.  Return a value < 0 if & only if the true value is too
 * large to fit in a signed long.
 */
static long get_len_of_range(long lo, long hi, long step) {
  /* -------------------------------------------------------------
     If lo >= hi, the range is empty.
     Else if n values are in the range, the last one is
     lo + (n-1)*step, which must be <= hi-1.  Rearranging,
     n <= (hi - lo - 1)/step + 1, so taking the floor of the RHS gives
     the proper value.  Since lo < hi in this case, hi-lo-1 >= 0, so
     the RHS is non-negative and so truncation is the same as the
     floor.  Letting M be the largest positive long, the worst case
     for the RHS numerator is hi=M, lo=-M-1, and then
     hi-lo-1 = M-(-M-1)-1 = 2*M.  Therefore unsigned long has enough
     precision to compute the RHS exactly.
     ---------------------------------------------------------------*/
  long n = 0;
  if (lo < hi) {
    unsigned long uhi = (unsigned long)hi;
    unsigned long ulo = (unsigned long)lo;
    unsigned long diff = uhi - ulo - 1;
    n = (long)(diff / (unsigned long)step + 1);
  }
  return n;
}

#if PY_MAJOR_VERSION >= 3
static PyStructSequence_Field pnull[] = {
    {"A1", NULL},  {"A2", NULL},  {"A3", NULL},  {"A4", NULL},  {"A5", NULL},
    {"A6", NULL},  {"A7", NULL},  {"A8", NULL},  {"A9", NULL},  {"A9", NULL},
    {"A10", NULL}, {"A11", NULL}, {"A12", NULL}, {"A13", NULL}, {"A14", NULL},
    {"A15", NULL}, {"A16", NULL}, {"A17", NULL}, {"A18", NULL}, {"A19", NULL},
    {"A19", NULL}, {"A20", NULL}, {"A21", NULL}, {"A22", NULL}, {"A23", NULL},
    {"A24", NULL}, {"A25", NULL}, {"A26", NULL}, {"A27", NULL}, {"A28", NULL},
    {"A29", NULL}, {"A29", NULL}, {"A30", NULL}, {"A31", NULL}, {"A32", NULL},
    {NULL, NULL}};

static PyObject *structseq_str(PyObject *iobj) {

/* buffer and type size were chosen well considered. */
#define REPR_BUFFER_SIZE 512
#define TYPE_MAXSIZE 100

  PyStructSequence *obj = (PyStructSequence *)iobj;
  PyTypeObject *typ = Py_TYPE(obj);
  bool removelast = false;
  Py_ssize_t len, i;
  char buf[REPR_BUFFER_SIZE];
  char *endofbuf, *pbuf = buf;
  /* pointer to end of writeable buffer; safes space for "...)\0" */
  endofbuf = &buf[REPR_BUFFER_SIZE - 5];

  /* "typename(", limited to  TYPE_MAXSIZE */
  len =
      strlen(typ->tp_name) > TYPE_MAXSIZE ? TYPE_MAXSIZE : strlen(typ->tp_name);
  strncpy(pbuf, typ->tp_name, len);
  pbuf += len;
  *pbuf++ = '(';

  for (i = 0; i < ((PyStructSequence *)obj)->ob_base.ob_size; i++) {
    PyObject *val, *repr;
    char *crepr;

    val = PyStructSequence_GET_ITEM(obj, i);
    repr = PyObject_Str(val);
    if (repr == NULL)
      return Py_None;
    crepr = PyUnicode_AsUTF8(repr);
    if (crepr == NULL) {
      Py_DECREF(repr);
      return Py_None;
    }

    /* + 3: keep space for ", " */
    len = strlen(crepr) + 2;
    if ((pbuf + len) <= endofbuf) {
      strcpy(pbuf, crepr);
      pbuf += strlen(crepr);
      *pbuf++ = ',';
      *pbuf++ = ' ';
      removelast = 1;
      Py_DECREF(repr);
    } else {
      strcpy(pbuf, "...");
      pbuf += 3;
      removelast = 0;
      Py_DECREF(repr);
      break;
    }
  }
  if (removelast) {
    /* overwrite last ", " */
    pbuf -= 2;
  }
  *pbuf++ = ')';
  *pbuf = '\0';

  return PyUnicode_FromString(buf);
}

static PyObject *structseq_repr(PyObject *iobj) {

/* buffer and type size were chosen well considered. */
#define REPR_BUFFER_SIZE 512
#define TYPE_MAXSIZE 100

  PyStructSequence *obj = (PyStructSequence *)iobj;
  PyTypeObject *typ = Py_TYPE(obj);
  bool removelast = false;
  Py_ssize_t len, i;
  char buf[REPR_BUFFER_SIZE];
  char *endofbuf, *pbuf = buf;
  /* pointer to end of writeable buffer; safes space for "...)\0" */
  endofbuf = &buf[REPR_BUFFER_SIZE - 5];

  /* "typename(", limited to  TYPE_MAXSIZE */
  len =
      strlen(typ->tp_name) > TYPE_MAXSIZE ? TYPE_MAXSIZE : strlen(typ->tp_name);
  strncpy(pbuf, typ->tp_name, len);
  pbuf += len;
  *pbuf++ = '(';

  for (i = 0; i < ((PyStructSequence *)obj)->ob_base.ob_size; i++) {
    PyObject *val, *repr;
    char *crepr;

    val = PyStructSequence_GET_ITEM(obj, i);
    repr = PyObject_Repr(val);
    if (repr == NULL)
      return NULL;
    crepr = PyUnicode_AsUTF8(repr);
    if (crepr == NULL) {
      Py_DECREF(repr);
      return NULL;
    }

    /* + 3: keep space for ", " */
    len = strlen(crepr) + 2;
    if ((pbuf + len) <= endofbuf) {
      strcpy(pbuf, crepr);
      pbuf += strlen(crepr);
      *pbuf++ = ',';
      *pbuf++ = ' ';
      removelast = 1;
      Py_DECREF(repr);
    } else {
      strcpy(pbuf, "...");
      pbuf += 3;
      removelast = 0;
      Py_DECREF(repr);
      break;
    }
  }
  if (removelast) {
    /* overwrite last ", " */
    pbuf -= 2;
  }
  *pbuf++ = ')';
  *pbuf = '\0';

  return PyUnicode_FromString(buf);
}
#endif

static bool
legal_symbol( const char *s)
{
    int ch;
    while(((ch = *s++) != '\0')) {
     if (isalnum(ch) || ch == '_')
         continue;
        return false;
    }
    return true;
}

PyObject *term_to_nametuple(const char *s, arity_t arity, PyObject *tuple) {
  PyObject *o, *d = NULL;
  if (legal_symbol(s)) {
      PyTypeObject *typp;
      PyObject *key = PyUnicode_FromString(s);
      if (Py_f2p && (d = PyList_GetItem(Py_f2p, arity)) &&
          PyDict_Contains(d, key)) {
          typp = (PyTypeObject *) PyDict_GetItem(d, key);
          Py_INCREF(typp);
      } else {
          typp = calloc(sizeof(PyTypeObject), 1);
          PyStructSequence_Desc *desc = calloc(sizeof(PyStructSequence_Desc), 1);
          desc->name = PyMem_Malloc(strlen(s) + 1);
          strcpy(desc->name, s);
          desc->doc = "YAPTerm";
          desc->fields = pnull;
          desc->n_in_sequence = arity;
          if (PyStructSequence_InitType2(typp, desc) < 0)
              return NULL;
          //    typp->tp_flags &= ~Py_TPFLAGS_HEAPTYPE;
          // typp->tp_flags &= ~Py_TPFLAGS_HAVE_GC;
          // typp->tp_str = structseq_str;
          typp->tp_repr = structseq_repr;
          //     typp = PyStructSequence_NewType(desc);
          // don't do this: we cannot add a type as an atribute.
          // PyModule_AddGObject(py_Main, s, (PyObject *)typp);
          if (d && !PyDict_Contains(d, key))
              PyDict_SetItem(d, key, (PyObject *) typp);
          Py_DECREF(key);
          Py_INCREF(typp);
      }
      o = PyStructSequence_New(typp);
      Py_INCREF(typp);
      arity_t i;
      for (i = 0; i < arity; i++) {
          PyObject *pArg = PyTuple_GET_ITEM(tuple, i);
          Py_INCREF(pArg);
          if (pArg)
              PyStructSequence_SET_ITEM(o, i, pArg);
          // PyObject_Print(pArg,stderr,0);fputc('\n',stderr);
      }
      //((PyStructSequence *)o)->ob_base.ob_size = arity;
      // PyObject_Print(o,stderr,0);fputc('\n',stderr);
      return o;
  } else {
      PyObject *o1;
      o1 = PyTuple_New(2);
      PyTuple_SET_ITEM(o1, 0, PyUnicode_FromString(s));
      PyTuple_SET_ITEM(o1, 1, tuple);
      return o1;
  }
}

static PyObject *bip_range(term_t t) {
  long ilow = 0, ihigh = 0, istep = 1;
  long bign;
  Py_ssize_t i, n;
  int arity;
  atom_t name;
  term_t arg = PL_new_term_ref();

  PyObject *v;

  if (!PL_get_name_arity(t, &name, &arity))
    return NULL;
  AOK(PL_get_arg(1, t, arg), NULL);
  ilow = get_int(arg, true);
  if (arity == 1) {
    ihigh = ilow;
    ilow = 0;
  } else {
    AOK(PL_get_arg(2, t, arg), NULL);
    ihigh = get_int(arg, true);
    if (arity == 3) {
      AOK(PL_get_arg(3, t, arg), NULL);
      istep = get_int(arg, true);
    }
  }
  if (istep == 0) {
    PyErr_SetString(PyExc_ValueError, "range() step argument must not be zero");
    return NULL;
  }
  if (istep > 0)
    bign = get_len_of_range(ilow, ihigh, istep);
  else
    bign = get_len_of_range(ihigh, ilow, -istep);
  n = (Py_ssize_t)bign;
  AOK(((bign >= 0 && (long)n == bign) || "range() result has too many items"),
      NULL);
  v = PyList_New(n);

  if (v == NULL)
    return Py_None;
  for (i = 0; i < n; i++) {
#if PY_MAJOR_VERSION < 3
    PyObject *w = PyInt_FromLong(ilow);
#else
    PyObject *w = PyLong_FromLong(ilow);
#endif
    if (w == NULL) {
      Py_DECREF(v);
      return NULL;
    }
    PyList_SET_ITEM(v, i, w);
    Py_INCREF(w);
    ilow += istep;
  }
  return v;
}

PyObject *compound_to_pytree(term_t t, PyObject *context, bool cvt) {
  PyObject *o = py_Main;
  functor_t fun;
  atom_t name;
  int arity;

  o = find_obj(context, t, false);
  AOK(PL_get_name_arity(t, &name, &arity), NULL);
  if (arity == 0)
    return term_to_python(t, false, o, false);
  AOK(PL_get_functor(t, &fun), NULL);
  if (!arity) {
    char *s = NULL;

    AOK(!PL_get_atom_chars(t, &s), NULL);
    // this should never happen
    return term_to_python(t, false, o, cvt);
  } else {
    const char *s;
    if (!(s = PL_atom_chars(name))) {
      return NULL;
    }
    term_t tleft;
    int i;

    PyObject *out = PyTuple_New(arity);
    DebugPrintf("Tuple %p\n", o);
    tleft = PL_new_term_ref();
    for (i = 0; i < arity; i++) {
      PyObject *pArg;
      AOK(PL_get_arg(i + 1, t, tleft), NULL);
      pArg = term_to_python(tleft, false, NULL, cvt);
      if (pArg) {
        /* pArg reference stolen here: */
        PyTuple_SET_ITEM(out, i, pArg);
        Py_INCREF(pArg);
      }
    }
    if (CHECKNULL(t, out) == NULL) {
      PyErr_Print();
      return NULL;
    }
    PyObject *c = lookupPySymbol(s, o, NULL);

    if (c && PyCallable_Check(c)) {
      PyObject *n = PyTuple_New(arity);
      PyTuple_SET_ITEM(n, 0, c);
      PyTuple_SET_ITEM(n, 1, out);
      return n;
    }
    return term_to_nametuple(s, arity, out);
  }
}

PyObject *compound_to_pyeval(term_t t, PyObject *context, bool cvt) {
  PyObject *o = NULL;
  atom_t name;
  int arity;
  functor_t fun;
  PyObject *d = NULL;

  o = find_obj(context, t, true);
  AOK(PL_get_name_arity(t, &name, &arity), NULL);
  if (arity == 0) {
    return term_to_python(t, true, o, cvt);
  }
  if (!PL_get_functor(t, &fun))
    return NULL;
  if (fun == FUNCTOR_abs1) {
    return bip_abs(t);
  } else if (fun == FUNCTOR_all1) {
    return bip_all(t);
  } else if (fun == FUNCTOR_any1) {
    return bip_any(t);
  } else if (fun == FUNCTOR_bin1) {
    return bip_bin(t);
  } else if (fun == FUNCTOR_ord1) {
    return bip_ord(t);
  } else if (fun == FUNCTOR_int1) {
    return bip_int(t);
  } else if (fun == FUNCTOR_long1) {
    return bip_long(t);
  } else if (fun == FUNCTOR_float1) {
    return bip_float(t, true);
  } else if (fun == FUNCTOR_iter1) {
    return bip_iter(t);
  } else if (fun == FUNCTOR_range1 || fun == FUNCTOR_range2 ||
             fun == FUNCTOR_range3) {
    return bip_range(t);
  } else if (fun == FUNCTOR_sum1) {
    return bip_sum(t);
  }
  if (fun == FUNCTOR_len1) {
    term_t targ = PL_new_term_ref();
    PyObject *ptr;

    AOK(PL_get_arg(1, t, targ), NULL);
    ptr = term_to_python(targ, true, NULL, true);
    return PyLong_FromLong(PyObject_Length(ptr));
  }

  if (fun == FUNCTOR_div2) {
    term_t targ = PL_new_term_ref();
    PyObject *lhs, *rhs;

    AOK(PL_get_arg(1, t, targ), NULL);
    lhs = term_to_python(targ, true, NULL, false);
    if (!PyNumber_Check(lhs))
      return NULL;
    AOK(PL_get_arg(2, t, targ), NULL);
    rhs = term_to_python(targ, true, NULL, false);
    if (!PyNumber_Check(rhs))
      return NULL;
#if PY_MAJOR_VERSION < 3
    return PyNumber_Divide(lhs, rhs);
#else
    return PyNumber_TrueDivide(lhs, rhs);
#endif
  }
  if (fun == FUNCTOR_dir1) {
    term_t targ = PL_new_term_ref();
    PyObject *ptr;

    AOK(PL_get_arg(1, t, targ), NULL);
    ptr = term_to_python(targ, true, NULL, true);
    return PyObject_Dir(ptr);

  }

  else if (fun == FUNCTOR_plus2) {
    term_t targ = PL_new_term_ref();
    PyObject *lhs, *rhs;

    if (!PL_get_arg(1, t, targ))
      return NULL;
    lhs = term_to_python(targ, true, NULL, true);
    AOK(PL_get_arg(2, t, targ), NULL);
    rhs = term_to_python(targ, true, NULL, true);
    if (PySequence_Check(lhs) && PySequence_Check(rhs)) {
      return PySequence_Concat(lhs, rhs);
    }
    if (!PyNumber_Check(lhs))
      return NULL;
    if (!PyNumber_Check(rhs))
      return NULL;
    return PyNumber_Add(lhs, rhs);
  } else if (fun == FUNCTOR_sub2) {
    term_t targ = PL_new_term_ref();
    PyObject *lhs, *rhs;

    if (!PL_get_arg(1, t, targ))
      return NULL;
    lhs = term_to_python(targ, true, NULL, true);
    if (!PyNumber_Check(lhs))
      return NULL;
    if (!PL_get_arg(2, t, targ))
      return NULL;
    rhs = term_to_python(targ, true, NULL, true);
    if (!PyNumber_Check(rhs))
      return NULL;
    return PyNumber_Subtract(lhs, rhs);
  } else if (fun == FUNCTOR_mul2) {
    term_t targ = PL_new_term_ref();
    PyObject *lhs, *rhs;

    AOK(PL_get_arg(1, t, targ), NULL);
    (lhs = term_to_python(targ, true, NULL, true));
    CHECKNULL(targ, lhs);
    AOK(PL_get_arg(2, t, targ), NULL);
    (rhs = term_to_python(targ, true, NULL, true));
    CHECKNULL(targ, rhs);
    if (PySequence_Check(lhs) && (
#if PY_MAJOR_VERSION < 3
                                     PyInt_Check(rhs) ||
#endif
                                     PyLong_Check(rhs))) {
      return PySequence_Repeat(lhs, get_p_int(rhs, 0));
    }
    if (!PyNumber_Check(lhs) + !PyNumber_Check(rhs))
      return NULL;
    return PyNumber_Multiply(lhs, rhs);
  }
  if (!arity) {
    char *s = NULL;
    PyObject *pValue;

    AOK(PL_get_atom_chars(t, &s), NULL);
    pValue = PyObject_GetAttrString(o, s);
    if (CHECKNULL(t, pValue) == NULL) {
      PyErr_Print();
      return NULL;
    }
    return pValue;
  } else {
    char *s = PL_atom_chars(name);
    PyObject *ys = lookupPySymbol(s, o, NULL);
    PyObject *pArgs = PyTuple_New(arity);
    DebugPrintf("Tuple %p\n", pArgs);
    int i;
    term_t tleft = PL_new_term_ref();
    for (i = 0; i < arity; i++) {
      PyObject *pArg;
      AOK(PL_get_arg(i + 1, t, tleft), NULL);
      /* ignore (_) */
      if (i == 0 && PL_is_variable(tleft)) {
        pArg = Py_None;
      } else {
        pArg = term_to_python(tleft, true, NULL, true);
        // PyObject_Print(pArg,fdopen(2,"w"),0);
        if (pArg == NULL) {
          pArg = Py_None;
        }
        /* pArg reference stolen here: */
        Py_INCREF(pArg);
      }

      PyTuple_SetItem(pArgs, i, pArg);
    }

        PyObject *rc;
    if (ys && PyCallable_Check(ys)) {

    // PyObject_Print(pArgs, stderr, 0);
    // PyObject_Print(o, stderr, 0);
    CHECK_CALL(rc, t, PyObject_CallObject(ys, pArgs));
    Py_DECREF(pArgs);
    Py_DECREF(ys);
    DebugPrintf("CallObject %p\n", rc);
    } else {
    rc = term_to_nametuple(s, arity, pArgs);
    }
  
    return rc;
  }
}