Index: Objects/abstract.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Objects/abstract.c,v
retrieving revision 2.135
diff -c -w -r2.135 abstract.c
*** Objects/abstract.c	18 Dec 2004 19:00:59 -0000	2.135
--- Objects/abstract.c	24 Jan 2005 11:05:42 -0000
***************
*** 106,111 ****
--- 106,126 ----
  			return type_error("sequence index must be integer");
  	}
  	
+ 	if (PyIter_Check(o)) {
+ 		return PyIter_GetItem(o, key);
+ 	}
+ 	
+ 	if (o->ob_type->tp_iter) {
+ 		PyObject *result = NULL;
+ 		PyObject *iterator = PyObject_GetIter(o);
+ 		if (iterator == NULL) {
+ 			return NULL;
+ 		}
+ 		result = PyIter_GetItem(o, key);
+ 		Py_DECREF(iterator);
+ 		return result;
+ 	}
+ 
  	return type_error("unsubscriptable object");
  }
  
***************
*** 2219,2221 ****
--- 2234,2298 ----
  		PyErr_Clear();
  	return result;
  }
+ 
+ /* Iterator slicing
+  * If an error occurs, return NULL.  PyErr_Occurred() will be true.
+  * For a simple index, consumes the iterator up to that point and
+  * returns the item at the supplied index. PyErr_Occurred() will be false.
+  * For a slice index, constructs an itertools.islice object based on the
+  * iterator and returns it. PyErr_Occurred() will be false.
+  */
+ PyObject *
+ PyIter_GetItem(PyObject *iter, PyObject *key)
+ {
+ 	assert(PyIter_Check(iter));
+ 	if (key == NULL) {
+ 		return null_error();
+ 	}
+ 	
+ 	if (PySlice_Check(key)) {
+ 		PyObject * itertools = NULL;
+ 		PySliceObject *slice = (PySliceObject *) key;
+ 		PyObject * iterslice = NULL;
+ 		
+ 		itertools = PyImport_ImportModule("itertools");
+ 		if (itertools) {
+ 			iterslice = PyObject_CallMethod(itertools, "islice", "OOOO",
+ 					     iter, slice->start, slice->stop, slice->step);
+ 			Py_DECREF(itertools);
+ 		}
+ 		return iterslice;
+ 	} else {
+ 		long current = 0;
+ 		long key_value = 0;
+ 		PyObject * item = NULL;
+ 		if (PyInt_Check(key)) {
+ 			key_value = PyInt_AsLong(key);
+ 		} else if (PyLong_Check(key)) {
+ 			key_value = PyLong_AsLong(key);
+ 			if (key_value == -1 && PyErr_Occurred()) {
+ 				return NULL;
+ 			}
+ 		} else {
+ 			return type_error("iterator index must be integer or slice");
+ 		}
+ 		if (key_value < 0) {
+ 			PyErr_SetString(PyExc_IndexError, "iterator requires non-negative index");
+ 			return NULL;
+ 		}
+ 		/* Retrieve items until we reach the desired index */
+ 		while ((item = PyIter_Next(iter)) && (current < key_value)) {
+ 			++current;
+ 			/* Note this decref does NOT fire for the item at the key index! */
+ 			Py_DECREF(item);
+ 		}
+ 		if (PyErr_Occurred()) {
+ 			return NULL;
+ 		}
+ 		if (current < key_value) {
+ 			PyErr_SetString(PyExc_IndexError, "iterator exhausted before reaching index");
+ 			return NULL;
+ 		}
+ 		return item;
+ 	}
+ }
Index: Include/abstract.h
===================================================================
RCS file: /cvsroot/python/python/dist/src/Include/abstract.h,v
retrieving revision 2.51
diff -c -w -r2.51 abstract.h
*** Include/abstract.h	12 Mar 2004 16:38:17 -0000	2.51
--- Include/abstract.h	24 Jan 2005 11:05:42 -0000
***************
*** 528,533 ****
--- 528,541 ----
  	this returns NULL without setting an exception.
  	NULL with an exception means an error occurred. */
  
+      PyAPI_FUNC(PyObject *) PyIter_GetItem(PyObject *o, PyObject *key);
+        /*
+ 	 Return the ith element of o, or NULL on failure. This is the
+ 	 equivalent of the Python expression: o[i].
+ 	 Negative indices are not allowed.
+ 	 Extended slicing is supported (positive steps only)
+        */
+ 
  /*  Number Protocol:*/
  
       PyAPI_FUNC(int) PyNumber_Check(PyObject *o);