Refactor and move parsing and stanza to a separate package

stanza/node.go

@@ -0,0 +1,51 @@
+package stanza
+
+import "encoding/xml"
+
+// ============================================================================
+// Generic / unknown content
+
+// Node is a generic structure to represent XML data. It is used to parse
+// unreferenced or custom stanza payload.
+type Node struct {
+	XMLName xml.Name
+	Attrs   []xml.Attr `xml:"-"`
+	Content string     `xml:",innerxml"`
+	Nodes   []Node     `xml:",any"`
+}
+
+func (n *Node) Namespace() string {
+	return n.XMLName.Space
+}
+
+// Attr represents generic XML attributes, as used on the generic XML Node
+// representation.
+type Attr struct {
+	K string
+	V string
+}
+
+// UnmarshalXML is a custom unmarshal function used by xml.Unmarshal to
+// transform generic XML content into hierarchical Node structure.
+func (n *Node) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	// Assign	"n.Attrs = start.Attr", without repeating xmlns in attributes:
+	for _, attr := range start.Attr {
+		// Do not repeat xmlns, it is already in XMLName
+		if attr.Name.Local != "xmlns" {
+			n.Attrs = append(n.Attrs, attr)
+		}
+	}
+	type node Node
+	return d.DecodeElement((*node)(n), &start)
+}
+
+// MarshalXML is a custom XML serializer used by xml.Marshal to serialize a
+// Node structure to XML.
+func (n Node) MarshalXML(e *xml.Encoder, start xml.StartElement) (err error) {
+	start.Attr = n.Attrs
+	start.Name = n.XMLName
+
+	err = e.EncodeToken(start)
+	e.EncodeElement(n.Nodes, xml.StartElement{Name: n.XMLName})
+	return e.EncodeToken(xml.EndElement{Name: start.Name})
+}