Introduce noms struct name

cmd/noms/noms_struct.go

@@ -32,6 +32,10 @@ func nomsStruct(noms *kingpin.Application) (*kingpin.CmdClause, util.KingpinHand
 	delSpec := struktDel.Arg("spec", "value spec for the struct to edit").Required().String()
 	delFields := struktDel.Arg("fields", "fields to be removed").Strings()
 
+	struktName := strukt.Command("name", "updates the name of a struct")
+	nameSpec := struktName.Arg("spec", "value spec for the struct to edit").Required().String()
+	nameName := struktName.Arg("name", "new name for the struct").String()
+
 	return strukt, func(input string) int {
 		switch input {
 		case struktNew.FullCommand():
@@ -40,6 +44,8 @@ func nomsStruct(noms *kingpin.Application) (*kingpin.CmdClause, util.KingpinHand
 			return nomsStructSet(*setSpec, *setFields)
 		case struktDel.FullCommand():
 			return nomsStructDel(*delSpec, *delFields)
+		case struktName.FullCommand():
+			return nomsStructName(*nameSpec, *nameName)
 		}
 		d.Panic("notreached")
 		return 1
@@ -107,6 +113,26 @@ func nomsStructDel(specStr string, args []string) int {
 	}
 }
 
+func nomsStructName(specStr string, name string) int {
+	sp, err := spec.ForPath(specStr)
+	d.PanicIfError(err)
+	db := sp.GetDatabase()
+	val := sp.GetValue()
+	if st, ok := val.(types.Struct); ok {
+		sd := types.StructData{}
+		st.IterFields(func(name string, val types.Value) {
+			sd[name] = val
+		})
+		r := db.WriteValue(types.NewStruct(name, sd))
+		db.Flush()
+		fmt.Println(r.TargetHash().String())
+		return 0
+	} else {
+		d.CheckError(fmt.Errorf("Path does not resolve to a struct: %s", specStr))
+		return 1
+	}
+}
+
 func applyStructEdits(db datas.Database, st types.Struct, args []string) {
 	for i := 0; i < len(args); i += 2 {
 		if !types.IsValidStructFieldName(args[i]) {