Add operator[] for xml_node, ensure child, more convinently for config updating

src/pugixml.cpp

@@ -5482,6 +5482,14 @@ namespace pugi
 		return (_root && _root->value) ? _root->value + 0 : PUGIXML_TEXT("");
 	}
 
+    PUGI__FN xml_node xml_node::operator[](const char_t* name)
+    {
+        if (!_root) return xml_node();
+        auto node = this->child(name);
+        if (node) return node;
+        return this->append_child(name);
+    }
+
 	PUGI__FN xml_node xml_node::child(const char_t* name_) const
 	{
 		if (!_root) return xml_node();

src/pugixml.hpp

@@ -510,6 +510,9 @@ namespace pugi
 		// Get text object for the current node
 		xml_text text() const;
 
+        // Ensure child, more convinently for config updating
+        xml_node operator[](const char_t* name);
+
 		// Get child, attribute or next/previous sibling with the specified name
 		xml_node child(const char_t* name) const;
 		xml_attribute attribute(const char_t* name) const;