introduce ParsePseudoNodeID

unused for now

A convenient place to document and deal with the ugliness.

render/id.go

@@ -23,6 +23,20 @@ func MakePseudoNodeID(parts ...string) string {
 	return strings.Join(append([]string{"pseudo"}, parts...), ":")
 }
 
+// ParsePseudoNodeID returns the joined id parts of a pseudonode
+// ID. If the ID is not recognisable as a pseudonode ID, it is
+// returned as is, with the returned bool set to false. That is
+// convenient because not all pseudonode IDs actually follow the
+// format produced by MakePseudoNodeID.
+func ParsePseudoNodeID(nodeID string) (string, bool) {
+	// Not using strings.SplitN() to avoid a heap allocation
+	pos := strings.Index(nodeID, ":")
+	if pos == -1 || nodeID[:pos] != "pseudo" {
+		return nodeID, false
+	}
+	return nodeID[pos+1:], true
+}
+
 // MakeGroupNodeTopology joins the parts of a group topology into the topology of a group node
 func MakeGroupNodeTopology(originalTopology, key string) string {
 	return strings.Join([]string{"group", originalTopology, key}, ":")