Re-add 'advanced' xrange features, adding DeprecationWarnings as discussed

on python-dev. The features will still vanish, however, just one release
later.

Include/rangeobject.h

@@ -19,7 +19,7 @@ extern DL_IMPORT(PyTypeObject) PyRange_Type;
 
 #define PyRange_Check(op) ((op)->ob_type == &PyRange_Type)
 
-extern DL_IMPORT(PyObject *) PyRange_New(long, long, long);
+extern DL_IMPORT(PyObject *) PyRange_New(long, long, long, int);
 
 #ifdef __cplusplus
 }

Objects/rangeobject.c

@@ -5,40 +5,92 @@
 #include "structmember.h"
 #include <string.h>
 
+#define WARN(msg) if (PyErr_Warn(PyExc_DeprecationWarning, msg) < 0) \
+			return NULL;
+
 typedef struct {
 	PyObject_HEAD
 	long	start;
 	long	step;
 	long	len;
+	int	reps;
+	long	totlen;
 } rangeobject;
 
-PyObject *
-PyRange_New(long start, long len, long step)
+static int
+long_mul(long i, long j, long *kk)
 {
+	PyObject *a;
+	PyObject *b;
+	PyObject *c;
+	
+	if ((a = PyInt_FromLong(i)) == NULL)
+		return 0;
+	
+	if ((b = PyInt_FromLong(j)) == NULL)
+		return 0;
+	
+	c = PyNumber_Multiply(a, b);
+	
+	Py_DECREF(a);
+	Py_DECREF(b);
+	
+	if (c == NULL)
+		return 0;
+
+	*kk = PyInt_AS_LONG(c);
+	Py_DECREF(c);
+
+	if (*kk > INT_MAX) {
+		PyErr_SetString(PyExc_OverflowError,
+				"integer multiplication");
+		return 0;
+	}
+	else
+		return 1;
+}
+
+PyObject *
+PyRange_New(long start, long len, long step, int reps)
+{
+	long totlen = -1;
 	rangeobject *obj = PyObject_NEW(rangeobject, &PyRange_Type);
 
 	if (obj == NULL)
 		return NULL;
+		
+	if (reps != 1)
+		WARN("PyRange_New's 'repetitions' argument is deprecated");
 
-	if (len == 0) {
+	if (len == 0 || reps <= 0) {
 		start = 0;
 		len = 0;
 		step = 1;
+		reps = 1;
+		totlen = 0;
 	}
 	else {
 		long last = start + (len - 1) * step;
 		if ((step > 0) ?
-		    (last > (PyInt_GetMax() - step))
-		    :(last < (-1 - PyInt_GetMax() - step))) {
+		    (last > (PyInt_GetMax() - step)) : 
+		    (last < (-1 - PyInt_GetMax() - step))) {
 			PyErr_SetString(PyExc_OverflowError,
 					"integer addition");
 			return NULL;
+		}			
+		if (! long_mul(len, (long) reps, &totlen)) {
+			if(!PyErr_ExceptionMatches(PyExc_OverflowError))
+				return NULL;
+			PyErr_Clear();
+			totlen = -1;
 		}
 	}
 
 	obj->start = start;
 	obj->len   = len;
 	obj->step  = step;
+	obj->reps  = reps;
+	obj->totlen = totlen;
 
 	return (PyObject *) obj;
 }
@@ -52,11 +104,12 @@ range_dealloc(rangeobject *r)
 static PyObject *
 range_item(rangeobject *r, int i)
 {
-	if (i < 0 || i >= r->len) {
-		PyErr_SetString(PyExc_IndexError,
+	if (i < 0 || i >= r->totlen)
+		if (r->totlen!=-1) {
+			PyErr_SetString(PyExc_IndexError,
 				"xrange object index out of range");
-		return NULL;
-	}
+			return NULL;
+		}
 
 	return PyInt_FromLong(r->start + (i % r->len) * r->step);
 }
@@ -64,7 +117,10 @@ range_item(rangeobject *r, int i)
 static int
 range_length(rangeobject *r)
 {
-	return r->len;
+	if (r->totlen == -1)
+		PyErr_SetString(PyExc_OverflowError,
+				"xrange object has too many items");
+	return r->totlen;
 }
 
 static PyObject *
@@ -74,6 +130,7 @@ range_repr(rangeobject *r)
 	 * a bit of "(xrange(...) * ...)" text.
 	 */
 	char buf1[250];
+	char buf2[250];
 
 	if (r->start == 0 && r->step == 1)
 		sprintf(buf1, "xrange(%ld)", r->start + r->len * r->step);
@@ -89,18 +146,162 @@ range_repr(rangeobject *r)
 			r->start + r->len * r->step,
 			r->step);
 
-	return PyString_FromString(buf1);
+	if (r->reps != 1)
+		sprintf(buf2, "(%s * %d)", buf1, r->reps);
+
+	return PyString_FromString(r->reps == 1 ? buf1 : buf2);
+}
+
+static PyObject *
+range_repeat(rangeobject *r, int n)
+{
+	long lreps = 0;
+
+	WARN("xrange object multiplication is deprecated; "
+	     "convert to list instead");
+
+	if (n <= 0)
+		return (PyObject *) PyRange_New(0, 0, 1, 1);
+
+	else if (n == 1) {
+		Py_INCREF(r);
+		return (PyObject *) r;
+	}
+
+	else if (! long_mul((long) r->reps, (long) n, &lreps))
+		return NULL;
+	
+	else
+		return (PyObject *) PyRange_New(
+						r->start,
+						r->len,
+						r->step,
+						(int) lreps);
+}
+
+static int
+range_compare(rangeobject *r1, rangeobject *r2)
+{
+
+        if (PyErr_Warn(PyExc_DeprecationWarning,
+        	       "xrange object comparision is deprecated; "
+        	       "convert to list instead") < 0)
+        	return -1;
+
+	if (r1->start != r2->start)
+		return r1->start - r2->start;
+
+	else if (r1->step != r2->step)
+		return r1->step - r2->step;
+
+	else if (r1->len != r2->len)
+		return r1->len - r2->len;
+
+	else
+		return r1->reps - r2->reps;
+}
+
+static PyObject *
+range_slice(rangeobject *r, int low, int high)
+{
+	WARN("xrange object slicing is deprecated; "
+	     "convert to list instead");
+
+	if (r->reps != 1) {
+		PyErr_SetString(PyExc_TypeError,
+				"cannot slice a replicated xrange");
+		return NULL;
+	}
+	if (low < 0)
+		low = 0;
+	else if (low > r->len)
+		low = r->len;
+	if (high < 0)
+		high = 0;
+	if (high < low)
+		high = low;
+	else if (high > r->len)
+		high = r->len;
+
+	if (low == 0 && high == r->len) {
+		Py_INCREF(r);
+		return (PyObject *) r;
+	}
+
+	return (PyObject *) PyRange_New(
+				low * r->step + r->start,
+				high - low,
+				r->step,
+				1);
+}
+
+static PyObject *
+range_tolist(rangeobject *self, PyObject *args)
+{
+	PyObject *thelist;
+	int j;
+
+	WARN("xrange.tolist() is deprecated; use list(xrange) instead");
+
+	if (! PyArg_ParseTuple(args, ":tolist"))
+		return NULL;
+
+	if (self->totlen == -1)
+		return PyErr_NoMemory();
+
+	if ((thelist = PyList_New(self->totlen)) == NULL)
+		return NULL;
+
+	for (j = 0; j < self->totlen; ++j)
+		if ((PyList_SetItem(thelist, j, (PyObject *) PyInt_FromLong(
+			self->start + (j % self->len) * self->step))) < 0)
+			return NULL;
+
+	return thelist;
+}
+
+static PyObject *
+range_getattr(rangeobject *r, char *name)
+{
+	PyObject *result;
+
+	static PyMethodDef range_methods[] = {
+		{"tolist",	(PyCFunction)range_tolist, METH_VARARGS,
+                 "tolist() -> list\n"
+                 "Return a list object with the same values.\n"
+                 "(This method is deprecated; use list() instead.)"},
+		{NULL,		NULL}
+	};
+	static struct memberlist range_members[] = {
+		{"step",  T_LONG, offsetof(rangeobject, step), RO},
+		{"start", T_LONG, offsetof(rangeobject, start), RO},
+		{"stop",  T_LONG, 0, RO},
+		{NULL, 0, 0, 0}
+	};
+
+	result = Py_FindMethod(range_methods, (PyObject *) r, name);
+	if (result == NULL) {
+		PyErr_Clear();
+		if (strcmp("stop", name) == 0)
+			result = PyInt_FromLong(r->start + (r->len * r->step));
+		else
+			result = PyMember_Get((char *)r, range_members, name);
+		if (result)
+			WARN("xrange object's 'start', 'stop' and 'step' "
+			     "attributes are deprecated");
+	}
+	return result;
 }
 
 static PySequenceMethods range_as_sequence = {
 	(inquiry)range_length,	/*sq_length*/
 	0,			/*sq_concat*/
-	0,			/*sq_repeat*/
-	(intargfunc)range_item,	/*sq_item*/
-	0,			/*sq_slice*/
+	(intargfunc)range_repeat, /*sq_repeat*/
+	(intargfunc)range_item, /*sq_item*/
+	(intintargfunc)range_slice, /*sq_slice*/
 	0,			/*sq_ass_item*/
 	0,			/*sq_ass_slice*/
-	0,			/*sq_contains*/
+	0, 			/*sq_contains*/
 };
 
 PyTypeObject PyRange_Type = {
@@ -111,9 +312,9 @@ PyTypeObject PyRange_Type = {
 	0,			/* Item size for varobject */
 	(destructor)range_dealloc, /*tp_dealloc*/
 	0,			/*tp_print*/
-	0,			/*tp_getattr*/
+	(getattrfunc)range_getattr, /*tp_getattr*/
 	0,			/*tp_setattr*/
-	0,			/*tp_compare*/
+	(cmpfunc)range_compare, /*tp_compare*/
 	(reprfunc)range_repr,	/*tp_repr*/
 	0,			/*tp_as_number*/
 	&range_as_sequence,	/*tp_as_sequence*/
@@ -126,3 +327,5 @@ PyTypeObject PyRange_Type = {
 	0,			/*tp_as_buffer*/
 	Py_TPFLAGS_DEFAULT,	/*tp_flags*/
 };
+
+#undef WARN

Python/bltinmodule.c

@@ -1763,7 +1763,7 @@ builtin_xrange(PyObject *self, PyObject *args)
 				"xrange() result has too many items");
 		return NULL;
 	}
-	return PyRange_New(ilow, n, istep);
+	return PyRange_New(ilow, n, istep, 1);
 }
 
 static char xrange_doc[] =