package options import ( "reflect" "restic/errors" "sort" "strconv" "strings" "time" ) // Options holds options in the form key=value. type Options map[string]string var opts []Help // Register allows registering options so that they can be listed with List. func Register(ns string, cfg interface{}) { opts = appendAllOptions(opts, ns, cfg) } // List returns a list of all registered options (using Register()). func List() (list []Help) { list = make([]Help, 0, len(opts)) for _, opt := range opts { list = append(list, opt) } return list } // appendAllOptions appends all options in cfg to opts, sorted by namespace. func appendAllOptions(opts []Help, ns string, cfg interface{}) []Help { for _, opt := range listOptions(cfg) { opt.Namespace = ns opts = append(opts, opt) } sort.Sort(helpList(opts)) return opts } // listOptions returns a list of options of cfg. func listOptions(cfg interface{}) (opts []Help) { // resolve indirection if cfg is a pointer v := reflect.Indirect(reflect.ValueOf(cfg)) for i := 0; i < v.NumField(); i++ { f := v.Type().Field(i) h := Help{ Name: f.Tag.Get("option"), Text: f.Tag.Get("help"), } if h.Name == "" { continue } opts = append(opts, h) } return opts } // Help contains information about an option. type Help struct { Namespace string Name string Text string } type helpList []Help // Len is the number of elements in the collection. func (h helpList) Len() int { return len(h) } // Less reports whether the element with // index i should sort before the element with index j. func (h helpList) Less(i, j int) bool { if h[i].Namespace == h[j].Namespace { return h[i].Name < h[j].Name } return h[i].Namespace < h[j].Namespace } // Swap swaps the elements with indexes i and j. func (h helpList) Swap(i, j int) { h[i], h[j] = h[j], h[i] } // splitKeyValue splits at the first equals (=) sign. func splitKeyValue(s string) (key string, value string) { data := strings.SplitN(s, "=", 2) key = strings.ToLower(strings.TrimSpace(data[0])) if len(data) == 1 { // no equals sign is treated as the empty value return key, "" } return key, strings.TrimSpace(data[1]) } // Parse takes a slice of key=value pairs and returns an Options type. // The key may include namespaces, separated by dots. Example: "foo.bar=value". // Keys are converted to lower-case. func Parse(in []string) (Options, error) { opts := make(Options, len(in)) for _, opt := range in { key, value := splitKeyValue(opt) if key == "" { return Options{}, errors.Fatalf("empty key is not a valid option") } if v, ok := opts[key]; ok && v != value { return Options{}, errors.Fatalf("key %q present more than once", key) } opts[key] = value } return opts, nil } // Extract returns an Options type with all keys in namespace ns, which is // also stripped from the keys. ns must end with a dot. func (o Options) Extract(ns string) Options { l := len(ns) if ns[l-1] != '.' { ns += "." l++ } opts := make(Options) for k, v := range o { if !strings.HasPrefix(k, ns) { continue } opts[k[l:]] = v } return opts } // Apply sets the options on dst via reflection, using the struct tag `option`. // The namespace argument (ns) is only used for error messages. func (o Options) Apply(ns string, dst interface{}) error { v := reflect.ValueOf(dst).Elem() fields := make(map[string]reflect.StructField) for i := 0; i < v.NumField(); i++ { f := v.Type().Field(i) tag := f.Tag.Get("option") if tag == "" { continue } if _, ok := fields[tag]; ok { panic("option tag " + tag + " is not unique in " + v.Type().Name()) } fields[tag] = f } for key, value := range o { field, ok := fields[key] if !ok { if ns != "" { key = ns + "." + key } return errors.Fatalf("option %v is not known", key) } i := field.Index[0] switch v.Type().Field(i).Type.Name() { case "string": v.Field(i).SetString(value) case "int": vi, err := strconv.ParseInt(value, 0, 32) if err != nil { return err } v.Field(i).SetInt(vi) case "uint": vi, err := strconv.ParseUint(value, 0, 32) if err != nil { return err } v.Field(i).SetUint(vi) case "Duration": d, err := time.ParseDuration(value) if err != nil { return err } v.Field(i).SetInt(int64(d)) default: panic("type " + v.Type().Field(i).Type.Name() + " not handled") } } return nil }