/tutorial/xml/dom/my_validating_tree.e

 1class MY_VALIDATING_TREE
 2--
 3-- Just to show how to simply have some home-crafted validation.
 4-- The principle is to redefine the `new_node' factory.
 5--
 6
 7inherit
 8	XML_TREE
 9		redefine
10			new_node
11		end
12
13create {EXAMPLE2}
14	with_error_handler
15
16feature {}
17	Tree_tag: STRING is "tree"
18	Node_tag: STRING is "node"
19	Leaf_tag: STRING is "leaf"
20
21	new_node (node_name: STRING; line, column: INTEGER): XML_NODE is
22		do
23			inspect node_name
24			when "tree" then
25				if current_node /= Void then
26					parse_error(line, column, once "unexpected tree without a parent node")
27				else
28					create Result.make(Tree_tag, line, column)
29				end
30			when "node" then
31				if current_node = Void or else current_node = Leaf_tag then
32					parse_error(line, column, once "unexpected node without parent node or with parent node being a leaf")
33				else
34					create Result.make(Node_tag, line, column)
35				end
36			when "leaf" then
37				if current_node = Void then
38					parse_error(line, column, once "unexpected leaf without parent node")
39				else
40					create Result.make(Leaf_tag, line, column)
41				end
42			end
43		end
44
45end