Implements TagNode.__delitem__ and .__setitem__

They complement .__getitem__ for the same convenience.

_delb/nodes.py

@@ -1695,10 +1695,9 @@ class TagNode(_ElementWrappingNode, NodeBase):
     Attributes and nodes can be tested for membership in a node.
 
     >>> root = Document('<root ham="spam"><child/></root>').root
-    >>> child = root.first_child
     >>> "ham" in root
     True
-    >>> child in root
+    >>> root.first_child in root
     True
 
     Nodes can be copied. Note that this relies on :meth:`TagNode.clone`.
@@ -1718,7 +1717,8 @@ class TagNode(_ElementWrappingNode, NodeBase):
     >>> root[0] == root[2]
     False
 
-    Attribute values and child nodes can be obtained with the subscript notation.
+    Attribute values and child nodes can be obtained, set and deleted with the subscript
+    notation.
 
     >>> root = Document('<root x="y"><child_1/>child_2<child_3/></root>').root
     >>> print(root["x"])
@@ -1765,6 +1765,24 @@ def __contains__(self, item: AttributeAccessor | NodeBase) -> bool:
                 + ATTRIBUTE_ACCESSOR_MSG
             )
 
+    def __delitem__(self, item: AttributeAccessor | int):
+        if isinstance(item, (str, tuple)):
+            del self.attributes[item]
+        elif isinstance(item, int):
+            self[item].detach(retain_child_nodes=False)
+        elif isinstance(item, slice):
+            if isinstance(item.start, int) or isinstance(item.stop, int):
+                raise NotImplementedError(
+                    "This will be implemented in a later version."
+                )
+            else:
+                del self.attributes[(item.start, item.stop)]
+        else:
+            raise TypeError(
+                "Argument must be an integer or an attribute name. "
+                + ATTRIBUTE_ACCESSOR_MSG
+            )
+
     def __eq__(self, other: Any) -> bool:
         if not isinstance(other, TagNode):
             return False
@@ -1819,6 +1837,29 @@ def __repr__(self) -> str:
             f"{self.attributes}, {self.location_path}) [{hex(id(self))}]>"
         )
 
+    @overload
+    def __setitem__(self, item: int, value: NodeSource): ...
+
+    @overload
+    def __setitem__(self, item: AttributeAccessor, value: str | Attribute): ...
+
+    def __setitem__(self, item, value):
+        if isinstance(item, (slice, str, tuple)):
+            self.attributes[item] = value
+        elif isinstance(item, int):
+            children_size = len(self)
+            if not children_size and item == 0:
+                self.__add_first_child(value)
+            else:
+                if not 0 <= item < children_size:
+                    raise IndexError
+                self[item].replace_with(value)
+        else:
+            raise TypeError(
+                "Argument must be an integer or an attribute name. "
+                + ATTRIBUTE_ACCESSOR_MSG
+            )
+
     def __add_first_child(self, node: NodeBase):
         assert not len(self)
         if isinstance(node, _ElementWrappingNode):

tests/test_tag_node.py

@@ -123,6 +123,20 @@ def test_deepcopy():
     assert clone[0] is not node[0]
 
 
+def test_delitem():
+    namespace = "https://foo"
+    root = Document(f"<root xmlns='{namespace}' A='' B='' C=''><a/></root>").root
+    del root["A"]
+    del root[namespace:"B"]
+    del root[(namespace, "C")]
+    del root[0]
+    assert str(root) == f'<root xmlns="{namespace}"/>'
+    with pytest.raises(IndexError):
+        del root[0]
+    with pytest.raises(KeyError):
+        del root["A"]
+
+
 def test_depth():
     document = Document("<root><a><b/></a></root>")
 
@@ -267,10 +281,14 @@ def test_full_text():
 
 
 def test_getitem():
-    document = Document('<root ham="spam"><a/><b/><c/><d/></root>')
+    namespace = "http://foo"
+    document = Document(f'<root xmlns="{namespace}" ham="spam"><a/><b/><c/><d/></root>')
     root = document.root
 
     assert root["ham"] == "spam"
+    assert root[namespace:"ham"] == "spam"
+    assert root[(namespace, "ham")] == "spam"
+
     assert root["foo"] is None
 
     assert root[-1].local_name == "d"
@@ -281,6 +299,9 @@ def test_getitem():
 
     assert "".join(x.local_name for x in root[::-1]) == "dcba"
 
+    with pytest.raises(IndexError):
+        root[4]
+
 
 def test_id_property(files_path):
     document = Document(files_path / "marx_manifestws_1848.TEI-P5.xml")
@@ -646,6 +667,21 @@ def test_set_tag_components():
     assert str(root) == '<prfx:root xmlns:prfx="https://name.space"/>'
 
 
+def test_set_item():
+    namespace = "http://foo"
+    root = Document("<root/>").root
+    root[0] = tag("b")
+    root[0] = tag("a")
+    root["A"] = "1"
+    root[namespace:"B"] = "2"
+    root[(namespace, "C")] = "3"
+    assert str(root) == '<root xmlns:ns0="http://foo" A="1" ns0:B="2" ns0:C="3"/>'
+    with pytest.raises(IndexError):
+        root[-1] = "text"
+    with pytest.raises(IndexError):
+        root[1] = "text"
+
+
 def test_tag_definition_copies_attributes():
     root = Document('<root foo="bar"/>').root
     definition = tag("test", root.attributes)