Golang FlagSet.VisitAll方法代碼示例

// SetFlagsFromEnv parses all registered flags in the given flagset,
// and if they are not already set it attempts to set their values from
// environment variables. Environment variables take the name of the flag but
// are UPPERCASE, have the prefix "PREFIX_", and any dashes are replaced by
// underscores - for example: some-flag => PREFIX_SOME_FLAG
func SetFlagsFromEnv(fs *flag.FlagSet, prefix string) error {
	var err error
	alreadySet := make(map[string]bool)
	fs.Visit(func(f *flag.Flag) {
		alreadySet[f.Name] = true
	})

	if prefix == "" {
		prefix = "_"
	} else {
		prefix = strings.ToUpper(strings.Replace(prefix, "-", "_", -1))
	}

	fs.VisitAll(func(f *flag.Flag) {
		if !alreadySet[f.Name] {
			key := prefix + strings.ToUpper(strings.Replace(f.Name, "-", "_", -1))
			val := os.Getenv(key)
			if val != "" {
				if serr := fs.Set(f.Name, val); serr != nil {
					err = fmt.Errorf("invalid value %q for %s: %v", val, key, serr)
				}
			}
		}
	})
	return err
}

// SetFlagsFromYaml goes through all registered flags in the given flagset,
// and if they are not already set it attempts to set their values from
// the YAML config. It will use the key REPLACE(UPPERCASE(flagname), '-', '_')
func SetFlagsFromYaml(fs *flag.FlagSet, rawYaml []byte) (err error) {
	conf := make(map[string]string)
	if err = yaml.Unmarshal(rawYaml, conf); err != nil {
		return
	}
	alreadySet := map[string]struct{}{}
	fs.Visit(func(f *flag.Flag) {
		alreadySet[f.Name] = struct{}{}
	})

	errs := make([]error, 0)
	fs.VisitAll(func(f *flag.Flag) {
		if f.Name == "" {
			return
		}
		if _, ok := alreadySet[f.Name]; ok {
			return
		}
		tag := strings.Replace(strings.ToUpper(f.Name), "-", "_", -1)
		val, ok := conf[tag]
		if !ok {
			return
		}
		if serr := fs.Set(f.Name, val); serr != nil {
			errs = append(errs, fmt.Errorf("invalid value %q for %s: %v", val, tag, serr))
		}
	})
	if len(errs) != 0 {
		err = ErrorSlice(errs)
	}
	return
}

func usageFor(fs *flag.FlagSet, usage string, extra string) func() {
	return func() {
		var b bytes.Buffer
		b.WriteString("Usage:\n  " + usage + "\n")

		var options [][]string
		fs.VisitAll(func(f *flag.Flag) {
			var opt = "  -" + f.Name

			if f.DefValue == "[]" {
				f.DefValue = ""
			}
			if f.DefValue != "false" {
				opt += "=" + fmt.Sprintf(`"%s"`, f.DefValue)
			}
			options = append(options, []string{opt, f.Usage})
		})

		if len(options) > 0 {
			b.WriteString("\nOptions:\n")
			optionTable(&b, options)
		}

		fmt.Println(b.String())

		if len(extra) > 0 {
			fmt.Println(extra)
		}
	}
}

func getFlags(flagset *flag.FlagSet) (flags []*flag.Flag) {
	flags = make([]*flag.Flag, 0)
	flagset.VisitAll(func(f *flag.Flag) {
		flags = append(flags, f)
	})
	return
}

func hasFlags(flags *flag.FlagSet) bool {
	any := false
	flags.VisitAll(func(*flag.Flag) {
		any = true
	})
	return any
}

// Usage returns a usage documentation of a command.
func (c Command) Usage(flags *flag.FlagSet) string {
	usage := fmt.Sprintf("Usage: %s", c.Long)

	if flags == nil {
		return usage
	}

	var hasFlag bool
	flags.VisitAll(func(_ *flag.Flag) {
		hasFlag = true
	})

	if hasFlag == false {
		return usage
	}

	buf := bytes.NewBufferString(usage)
	buf.WriteString("\n\nOptions:\n")

	defer flags.SetOutput(nil)
	flags.SetOutput(buf)

	flags.PrintDefaults()

	return buf.String()
}

func usageFor(fs *flag.FlagSet, usage string) func() {
	return func() {
		var b bytes.Buffer
		b.WriteString(ansi.Bold("Usage:") + "\n  " + usage + "\n")

		var options [][]string
		fs.VisitAll(func(f *flag.Flag) {
			var opt = "  -" + f.Name

			if f.DefValue != "false" {
				opt += "=" + f.DefValue
			}

			options = append(options, []string{opt, f.Usage})
		})

		if len(options) > 0 {
			b.WriteString("\n" + ansi.Bold("Options:") + "\n")
			optionTable(&b, options)
		}

		fmt.Println(b.String())

	}
}

// checkCommandLine ensures all required positional and flag-like parameters
// are set. Returns true if they are, or false (and prints to stderr) if not.
func checkCommandLine(args []string, flags *flag.FlagSet, minPosCount, maxPosCount int) bool {
	// Check number of expected positional arguments.
	if maxPosCount == 0 && len(args) != 0 {
		log.Errorf("Unexpected arguments: %v", args)
		return false
	}
	if len(args) < minPosCount || len(args) > maxPosCount {
		log.Errorf("Expecting [%d, %d] arguments, got %d", minPosCount,
			maxPosCount, len(args))
		return false
	}
	// Check required unset flags.
	unset := []*flag.Flag{}
	flags.VisitAll(func(f *flag.Flag) {
		if strings.HasPrefix(f.DefValue, "<") && f.Value.String() == f.DefValue {
			unset = append(unset, f)
		}
	})
	if len(unset) != 0 {
		missing := []string{}
		for _, f := range unset {
			missing = append(missing, f.Name)
		}
		log.Errorf("Missing required flags: %v", missing)
		return false
	}
	return true
}

// ParseSet parses the given flagset. The specified prefix will be applied to
// the environment variable names.
func ParseSet(prefix string, set *flag.FlagSet) error {
	var explicit []*flag.Flag
	var all []*flag.Flag
	set.Visit(func(f *flag.Flag) {
		explicit = append(explicit, f)
	})

	var err error
	set.VisitAll(func(f *flag.Flag) {
		if err != nil {
			return
		}
		all = append(all, f)
		if !contains(explicit, f) {
			name := strings.Replace(f.Name, ".", "_", -1)
			name = strings.Replace(name, "-", "_", -1)
			if prefix != "" {
				name = prefix + name
			}
			name = strings.ToUpper(name)
			val := os.Getenv(name)
			if val != "" {
				if ferr := f.Value.Set(val); ferr != nil {
					err = fmt.Errorf("failed to set flag %q with value %q", f.Name, val)
				}
			}
		}
	})
	return err
}

func commandHelp(name string, cmd Command, f *flag.FlagSet) {
	type HasUsage interface {
		Usage() string
	}

	fmt.Fprintf(os.Stderr, "Usage: %s %s [OPTIONS]", os.Args[0], name)
	if u, ok := cmd.(HasUsage); ok {
		fmt.Fprintf(os.Stderr, " %s", u.Usage())
	}
	fmt.Fprintf(os.Stderr, "\n")

	type HasDescription interface {
		Description() string
	}

	if u, ok := cmd.(HasDescription); ok {
		fmt.Fprintf(os.Stderr, "%s\n", u.Description())
	}

	n := 0
	f.VisitAll(func(_ *flag.Flag) {
		n += 1
	})

	if n > 0 {
		fmt.Fprintf(os.Stderr, "\nOptions:\n")
		tw := tabwriter.NewWriter(os.Stderr, 2, 0, 2, ' ', 0)
		f.VisitAll(func(f *flag.Flag) {
			fmt.Fprintf(tw, "\t-%s=%s\t%s\n", f.Name, f.DefValue, f.Usage)
		})
		tw.Flush()
	}
}

// AddGoFlagSet will add the given *flag.FlagSet to the flag.FlagSet
func (f *FlagSet) AddGoFlagSet(newSet *goflag.FlagSet) {
	if newSet == nil {
		return
	}
	newSet.VisitAll(func(goflag *goflag.Flag) {
		f.AddGoFlag(goflag)
	})
}

// printCommandHelp is used by handlers to display command help.
func printCommandHelp(handler Handler, flags *flag.FlagSet) {
	fmt.Println("SYNTAX")
	fmt.Println("\t" + handler.Syntax())
	fmt.Println("")
	fmt.Println("OPTIONS:")
	flags.VisitAll(func(f *flag.Flag) {
		fmt.Printf("\t-%-10s%s\n", f.Name, f.Usage)
	})
}

func hasFlags(f flag.FlagSet) bool {
	nFlags := 0

	f.VisitAll(func(*flag.Flag) {
		nFlags++
	})
	if nFlags != 0 {
		return true
	}
	return false
}

// ParseSet parses the config file for the provided flag set.
// If the flags are already set, values are overwritten
// by the values in the config file. Defaults are not set
// if the flag is not in the file.
func (g *GlobalConf) ParseSet(flagSetName string, set *flag.FlagSet) {
	set.VisitAll(func(f *flag.Flag) {
		if val, ok := getEnv(g.EnvPrefix, flagSetName, f.Name); ok {
			set.Set(f.Name, val)
			return
		}

		val, found := g.dict.GetString(flagSetName, f.Name)
		if found {
			set.Set(f.Name, val)
		}
	})
}

func completeFlags(cl CommandLine, flags *flag.FlagSet) (completions []string, rest CommandLine) {
	if len(cl) == 0 {
		return nil, cl
	}
	var inFlag string
	for len(cl) > 1 {
		w := cl[0]
		if inFlag != "" {
			inFlag = ""
		} else if len(w) > 1 && w[0] == '-' && w != "--" {
			if !strings.Contains(w, "=") {
				var i int
				for i = 0; i < len(w) && w[i] == '-'; i++ {
				}
				inFlag = w[i:]
			}
			if flag := flags.Lookup(inFlag); flag != nil {
				if bf, ok := flag.Value.(boolFlag); ok && bf.IsBoolFlag() {
					inFlag = ""
				}
			}
		} else {
			if w == "--" {
				cl = cl[1:]
			}
			return nil, cl
		}
		cl = cl[1:]
	}

	if inFlag != "" {
		// Complete a flag value. No-op for now.
		return []string{}, nil
	} else if len(cl[0]) > 0 && cl[0][0] == '-' {
		// complete a flag name
		prefix := strings.TrimLeft(cl[0], "-")
		flags.VisitAll(func(f *flag.Flag) {
			if strings.HasPrefix(f.Name, prefix) {
				completions = append(completions, "-"+f.Name)
			}
		})
		return completions, nil
	}

	if cl[0] == "" {
		flags.VisitAll(func(f *flag.Flag) {
			completions = append(completions, "-"+f.Name)
		})
	}
	return completions, cl
}