Add some support packages

cid/cid.go

@@ -0,0 +1,42 @@
+package cid
+
+type Map struct {
+	toCid  map[string]int
+	toName []string
+}
+
+func NewMap() *Map {
+	return &Map{
+		toCid: make(map[string]int),
+	}
+}
+
+func (m *Map) Get(name string) int {
+	cid, ok := m.toCid[name]
+	if ok {
+		return cid
+	}
+
+	// Find a free slot to get a new ID
+	for i, n := range m.toName {
+		if n == "" {
+			m.toName[i] = name
+			m.toCid[name] = i
+			return i
+		}
+	}
+
+	// Add it to the end since we didn't find a free slot
+	m.toName = append(m.toName, name)
+	cid = len(m.toName) - 1
+	m.toCid[name] = cid
+	return cid
+}
+
+func (m *Map) Clear(name string) {
+	cid, ok := m.toCid[name]
+	if ok {
+		m.toName[cid] = ""
+		delete(m.toCid, name)
+	}
+}