# Pastebin TrjoHYDe
diff -r 37a9de9e88b0 pypy/objspace/std/iterobject.py
--- a/pypy/objspace/std/iterobject.py	Sat Feb 16 14:52:38 2019 +0100
+++ b/pypy/objspace/std/iterobject.py	Sat Feb 16 22:37:02 2019 +0100
@@ -92,6 +92,33 @@
         return w_item
 
 
+class W_FastUnicodeIterObject(W_AbstractSeqIterObject):
+    """Sequence iterator specialized for unicode objects."""
+
+    def __init__(self, w_seq):
+        from pypy.objspace.std.unicodeobject import W_UnicodeObject
+        W_AbstractSeqIterObject.__init__(self, w_seq)
+        assert isinstance(w_seq, W_UnicodeObject)
+        self.byteindex = 0
+
+    def descr_next(self, space):
+        from pypy.objspace.std.unicodeobject import W_UnicodeObject
+        from rpython.rlib import rutf8
+        w_seq = self.w_seq
+        if w_seq is None:
+            raise OperationError(space.w_StopIteration, space.w_None)
+        assert isinstance(w_seq, W_UnicodeObject)
+        index = self.index
+        if index == w_seq._length:
+            self.w_seq = None
+            raise OperationError(space.w_StopIteration, space.w_None)
+        start = self.byteindex
+        end = rutf8.next_codepoint_pos(w_seq._utf8, start)
+        w_res = W_UnicodeObject(w_seq._utf8[start:end], 1)
+        self.byteindex = end
+        return w_res
+
+
 class W_FastTupleIterObject(W_AbstractSeqIterObject):
     """Sequence iterator specialized for tuples, accessing directly
     their RPython-level list of wrapped objects.
diff -r 37a9de9e88b0 pypy/objspace/std/test/test_unicodeobject.py
--- a/pypy/objspace/std/test/test_unicodeobject.py	Sat Feb 16 14:52:38 2019 +0100
+++ b/pypy/objspace/std/test/test_unicodeobject.py	Sat Feb 16 22:37:02 2019 +0100
@@ -41,6 +41,18 @@
                 space.w_unicode, "__new__", space.w_unicode, w_uni)
         assert w_new is w_uni
 
+    def test_fast_iter(self):
+        space = self.space
+        w_uni = space.newutf8(u"aä".encode("utf-8"), 2)
+        old_index_storage = w_uni._index_storage
+        w_iter = space.iter(w_uni)
+        w_char1 = w_iter.descr_next(space)
+        w_char2 = w_iter.descr_next(space)
+        assert w_uni._index_storage is old_index_storage
+        assert space.eq_w(w_char1, w_uni._getitem_result(space, 0))
+        assert space.eq_w(w_char2, w_uni._getitem_result(space, 1))
+
+
     if HAS_HYPOTHESIS:
         @given(strategies.text(), strategies.integers(min_value=0, max_value=10),
                                   strategies.integers(min_value=-1, max_value=10))
diff -r 37a9de9e88b0 pypy/objspace/std/unicodeobject.py
--- a/pypy/objspace/std/unicodeobject.py	Sat Feb 16 14:52:38 2019 +0100
+++ b/pypy/objspace/std/unicodeobject.py	Sat Feb 16 22:37:02 2019 +0100
@@ -224,6 +224,10 @@
     def descr_str(self, space):
         return encode_object(space, self, 'ascii', 'strict')
 
+    def descr_iter(self, space):
+        from pypy.objspace.std.iterobject import W_FastUnicodeIterObject
+        return W_FastUnicodeIterObject(self)
+
     def hash_w(self):
         # shortcut for UnicodeDictStrategy
         x = compute_hash(self._utf8)
@@ -1590,6 +1594,7 @@
                           doc=UnicodeDocstrings.__repr__.__doc__),
     __str__ = interp2app(W_UnicodeObject.descr_str,
                          doc=UnicodeDocstrings.__str__.__doc__),
+    __iter__ = interp2app(W_UnicodeObject.descr_iter),
     __hash__ = interp2app(W_UnicodeObject.descr_hash,
                           doc=UnicodeDocstrings.__hash__.__doc__),