Mondo changes to the iterator stuff, without changing how Python code

sees it (test_iter.py is unchanged).

- Added a tp_iternext slot, which calls the iterator's next() method;
  this is much faster for built-in iterators over built-in types
  such as lists and dicts, speeding up pybench's ForLoop with about
  25% compared to Python 2.1.  (Now there's a good argument for
  iterators. ;-)

- Renamed the built-in sequence iterator SeqIter, affecting the C API
  functions for it.  (This frees up the PyIter prefix for generic
  iterator operations.)

- Added PyIter_Check(obj), which checks that obj's type has a
  tp_iternext slot and that the proper feature flag is set.

- Added PyIter_Next(obj) which calls the tp_iternext slot.  It has a
  somewhat complex return condition due to the need for speed: when it
  returns NULL, it may not have set an exception condition, meaning
  the iterator is exhausted; when the exception StopIteration is set
  (or a derived exception class), it means the same thing; any other
  exception means some other error occurred.

3 files changed, 18 insertions, 3 deletions

diff --git a/Include/abstract.h b/Include/abstract.h
index c56c887..1dae5f1 100644
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -470,11 +470,24 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
 
        */
 
+/* Iterators */
+
      DL_IMPORT(PyObject *) PyObject_GetIter(PyObject *);
      /* Takes an object and returns an iterator for it.
         This is typically a new iterator but if the argument
 	is an iterator, this returns itself. */
 
+#define PyIter_Check(obj) \
+    (PyType_HasFeature((obj)->ob_type, Py_TPFLAGS_HAVE_ITER) && \
+     (obj)->ob_type->tp_iternext != NULL)
+
+     DL_IMPORT(PyObject *) PyIter_Next(PyObject *);
+     /* Takes an iterator object and calls its tp_iternext slot,
+	returning the next value.  If the iterator is exhausted,
+	this can return NULL without setting an exception, *or*
+	NULL with a StopIteration exception.
+	NULL with any other exception  means an error occurred. */
+
 /*  Number Protocol:*/
 
      DL_IMPORT(int) PyNumber_Check(PyObject *o);
diff --git a/Include/iterobject.h b/Include/iterobject.h
index 38454a4..bc18991 100644
--- a/Include/iterobject.h
+++ b/Include/iterobject.h
@@ -1,10 +1,10 @@
 /* Iterators (the basic kind, over a sequence) */
 
-extern DL_IMPORT(PyTypeObject) PyIter_Type;
+extern DL_IMPORT(PyTypeObject) PySeqIter_Type;
 
-#define PyIter_Check(op) ((op)->ob_type == &PyIter_Type)
+#define PySeqIter_Check(op) ((op)->ob_type == &PySeqIter_Type)
 
-extern DL_IMPORT(PyObject *) PyIter_New(PyObject *);
+extern DL_IMPORT(PyObject *) PySeqIter_New(PyObject *);
 
 extern DL_IMPORT(PyTypeObject) PyCallIter_Type;
 
diff --git a/Include/object.h b/Include/object.h
index 4a53835..0765748 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -201,6 +201,7 @@ typedef PyObject *(*reprfunc)(PyObject *);
 typedef long (*hashfunc)(PyObject *);
 typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
 typedef PyObject *(*getiterfunc) (PyObject *);
+typedef PyObject *(*iternextfunc) (PyObject *);
 
 typedef struct _typeobject {
 	PyObject_VAR_HEAD
@@ -252,6 +253,7 @@ typedef struct _typeobject {
 
 	/* Iterators */
 	getiterfunc tp_iter;
+	iternextfunc tp_iternext;
 
 #ifdef COUNT_ALLOCS
 	/* these must be last and never explicitly initialized */