dev(hansbug): update __iter__ and __reversed__

docs/source/api_doc/tree/tree.rst

@@ -9,7 +9,7 @@ TreeValue
 ---------------
 
 .. autoclass:: TreeValue
-    :members: __init__, __getattribute__, __setattr__, __delattr__, __contains__, __repr__, __iter__, __hash__, __eq__, _attr_extern, __len__, __bool__, __str__, __getstate__, __setstate__, get, pop, keys, values, items, __getitem__, __setitem__, __delitem__, _getitem_extern, _setitem_extern, _delitem_extern, popitem, clear, update, setdefault
+    :members: __init__, __getattribute__, __setattr__, __delattr__, __contains__, __repr__, __iter__, __hash__, __eq__, _attr_extern, __len__, __bool__, __str__, __getstate__, __setstate__, get, pop, keys, values, items, __getitem__, __setitem__, __delitem__, _getitem_extern, _setitem_extern, _delitem_extern, popitem, clear, update, setdefault, __reversed__
 
 
 .. _apidoc_tree_tree_delayed:

test/tree/tree/test_tree.py

@@ -252,12 +252,19 @@ def test_tree_value_repr(self):
     def test_tree_value_iter(self):
         # Attention: dict(tv1) is not supported in python 3.7+
         tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})
-        assert sorted(list(tv1)) == [
-            ('a', 1),
-            ('b', 2),
-            ('c', TreeValue({'x': 2, 'y': 3}))
-        ]
-        assert sorted(list(tv1.c)) == [('x', 2), ('y', 3)]
+        assert sorted(list(tv1)) == ['a', 'b', 'c']
+        assert sorted(list(tv1.c)) == ['x', 'y']
+
+    def test_tree_value_reversed(self):
+        tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})
+        if _reversible:
+            assert list(reversed(tv1)) == list(iter(tv1))[::-1]
+            assert list(reversed(tv1.c)) == list(iter(tv1.c))[::-1]
+        else:
+            with pytest.raises(TypeError):
+                reversed(tv1)
+            with pytest.raises(TypeError):
+                reversed(tv1.c)
 
     def test_tree_value_len(self):
         tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})

treevalue/tree/tree/graph.py

@@ -185,7 +185,7 @@ def _node_tag(current, parent, current_path, parent_path, is_node):
         graph_title=title or "<untitled>",
         graph_cfg=cfg or {},
         repr_gen=repr_gen or (lambda x: nohtml(repr(x))),
-        iter_gen=lambda n: iter(n) if isinstance(n, TreeValue) else None,
+        iter_gen=lambda n: iter(n.items()) if isinstance(n, TreeValue) else None,
         node_cfg_gen=_dict_call_merge(lambda n, p, np, pp, is_node, is_root, root: {
             'fillcolor': _shape_color(root[2]),
             'color': _border_color(root[2], is_node),

treevalue/tree/tree/tree.pyx

@@ -15,6 +15,13 @@ from ...utils import format_tree
 cdef class _CObject:
     pass
 
+try:
+    reversed({'a': 1}.keys())
+except TypeError:
+    _reversible = False
+else:
+    _reversible = True
+
 cdef inline object _item_unwrap(object v):
     if isinstance(v, list) and len(v) == 1:
         return v[0]
@@ -529,24 +536,49 @@ cdef class TreeValue:
         Overview:
             Get iterator of this tree value.
 
-        Returns:
-            - iter (:obj:`iter`): Iterator for keys and values.
+        :return: An iterator for the keys.
 
-        Example:
+        Examples:
+            >>> from treevalue import TreeValue
+            >>>
             >>> t = TreeValue({'a': 1, 'b': 2, 'x': 3})
-            >>> for key, value in t:
-            >>>     print(key, value)
+            >>> for key in t:
+            ...     print(key)
+            a
+            b
+            x
 
-            The output will be:
+        .. note::
+            The method :meth:`__iter__`'s bahaviour should be similar to \
+            `dict.__iter__ <https://docs.python.org/3/library/stdtypes.html#dict.update>`_.
+        """
+        yield from self._st.iter_keys()
 
-            >>> a 1
-            >>> b 2
-            >>> x 3
+    @cython.binding(True)
+    def __reversed__(self):
         """
-        cdef str k
-        cdef object v
-        for k, v in self._st.iter_items():
-            yield k, self._unraw(v)
+        Overview:
+            Get the reversed iterator of tree value.
+
+        :return: A reversed iterator for the keys.
+
+        Examples:
+            >>> from treevalue import TreeValue
+            >>>
+            >>> t = TreeValue({'a': 1, 'b': 2, 'x': 3})
+            >>> for key in reversed(t):
+            ...     print(key)
+            x
+            b
+            a
+
+        .. note::
+            Only available in python 3.8 or higher version.
+        """
+        if _reversible:
+            return self._st.iter_rev_keys()
+        else:
+            raise TypeError(f'{self._type.__name__!r} object is not reversible')
 
     @cython.binding(True)
     def __len__(self):
@@ -810,13 +842,6 @@ cdef object _build_tree(TreeStorage st, object type_, str prefix, dict id_pool,
     self_repr = _prefix_fix(self_repr, prefix)
     return self_repr, children
 
-try:
-    reversed({'a': 1}.keys())
-except TypeError:
-    _reversible = False
-else:
-    _reversible = True
-
 # noinspection PyPep8Naming
 cdef class treevalue_keys(_CObject, Sized, Container, Reversible):
     def __cinit__(self, TreeStorage storage, type _type):