Initial import

topic.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"strings"
+)
+
+const (
+	levelSep    = "/"
+	multiLevel  = "#"
+	singleLevel = "+"
+)
+
+// returns true if the MQTT topic filter matches the topic name
+func matchTopic(filter, name string) bool {
+	// split both strings into a root level and a remainder
+	f := strings.SplitN(filter, levelSep, 2)
+	n := strings.SplitN(name, levelSep, 2)
+
+	// check whether the root levels match
+	switch f[0] {
+	case multiLevel:
+		return true
+	case n[0], singleLevel:
+		// roots match, continue
+		break
+	default:
+		// roots do not match
+		return false
+	}
+
+	// check whether the filter or name consists of a single level
+	switch {
+	case len(f) == 1 && len(n) == 1:
+		return true
+	case len(f) == 1:
+		return false
+	case len(n) == 1:
+		if f[1] == multiLevel {
+			// special case is when filter has 1 extra level which is the '#' character
+			return true
+		}
+		return false
+
+	}
+	return matchTopic(f[1], n[1])
+}