package flags import ( "bytes" "flag" "fmt" "io" "strings" text "github.com/tonnerre/golang-text" ) func Usage(txt string, flags *flag.FlagSet) string { u := &Usager{ Usage: txt, Flags: flags, } return u.String() } type Usager struct { Usage string Flags *flag.FlagSet } func (u *Usager) String() string { out := new(bytes.Buffer) out.WriteString(strings.TrimSpace(u.Usage)) out.WriteString("\n") out.WriteString("\n") if u.Flags != nil { f := &HTTPFlags{} clientFlags := f.ClientFlags() serverFlags := f.ServerFlags() var httpFlags, cmdFlags *flag.FlagSet u.Flags.VisitAll(func(f *flag.Flag) { if contains(clientFlags, f) || contains(serverFlags, f) { if httpFlags == nil { httpFlags = flag.NewFlagSet("", flag.ContinueOnError) } httpFlags.Var(f.Value, f.Name, f.Usage) } else { if cmdFlags == nil { cmdFlags = flag.NewFlagSet("", flag.ContinueOnError) } cmdFlags.Var(f.Value, f.Name, f.Usage) } }) if httpFlags != nil { printTitle(out, "HTTP API Options") httpFlags.VisitAll(func(f *flag.Flag) { printFlag(out, f) }) } if cmdFlags != nil { printTitle(out, "Command Options") cmdFlags.VisitAll(func(f *flag.Flag) { printFlag(out, f) }) } } return strings.TrimRight(out.String(), "\n") } // printTitle prints a consistently-formatted title to the given writer. func printTitle(w io.Writer, s string) { fmt.Fprintf(w, "%s\n\n", s) } // printFlag prints a single flag to the given writer. func printFlag(w io.Writer, f *flag.Flag) { example, _ := flag.UnquoteUsage(f) if example != "" { fmt.Fprintf(w, " -%s=<%s>\n", f.Name, example) } else { fmt.Fprintf(w, " -%s\n", f.Name) } indented := wrapAtLength(f.Usage, 5) fmt.Fprintf(w, "%s\n\n", indented) } // contains returns true if the given flag is contained in the given flag // set or false otherwise. func contains(fs *flag.FlagSet, f *flag.Flag) bool { if fs == nil { return false } var in bool fs.VisitAll(func(hf *flag.Flag) { in = in || f.Name == hf.Name }) return in } // maxLineLength is the maximum width of any line. const maxLineLength int = 72 // wrapAtLength wraps the given text at the maxLineLength, taking into account // any provided left padding. func wrapAtLength(s string, pad int) string { wrapped := text.Wrap(s, maxLineLength-pad) lines := strings.Split(wrapped, "\n") for i, line := range lines { lines[i] = strings.Repeat(" ", pad) + line } return strings.Join(lines, "\n") }