package cli import ( "encoding/json" "flag" "fmt" "os" "reflect" "regexp" "runtime" "strconv" "strings" "time" ) const defaultPlaceholder = "value" var ( slPfx = fmt.Sprintf("sl:::%d:::", time.Now().UTC().UnixNano()) commaWhitespace = regexp.MustCompile("[, ]+.*") ) // BashCompletionFlag enables bash-completion for all commands and subcommands var BashCompletionFlag = BoolFlag{ Name: "generate-bash-completion", Hidden: true, } // VersionFlag prints the version for the application var VersionFlag = BoolFlag{ Name: "version", Aliases: []string{"v"}, Usage: "print the version", } // HelpFlag prints the help for all commands and subcommands. // Set to the zero value (BoolFlag{}) to disable the flag. The subcommand // will still be added unless HideHelp is set to true. var HelpFlag = BoolFlag{ Name: "help", Aliases: []string{"h"}, Usage: "show help", } // FlagStringer converts a flag definition to a string. This is used by help // to display a flag. var FlagStringer FlagStringFunc = stringifyFlag // Serializeder is used to circumvent the limitations of flag.FlagSet.Set type Serializeder interface { Serialized() string } // Flag is a common interface related to parsing flags in cli. // For more advanced flag parsing techniques, it is recommended that // this interface be implemented. type Flag interface { fmt.Stringer // Apply Flag settings to the given flag set Apply(*flag.FlagSet) Names() []string } func flagSet(name string, flags []Flag) *flag.FlagSet { set := flag.NewFlagSet(name, flag.ContinueOnError) for _, f := range flags { f.Apply(set) } return set } // Generic is a generic parseable type identified by a specific flag type Generic interface { Set(value string) error String() string } // GenericFlag is the flag type for types implementing Generic type GenericFlag struct { Name string Aliases []string Value Generic Usage string EnvVars []string Hidden bool } // String returns the string representation of the generic flag to display the // help text to the user (uses the String() method of the generic flag to show // the value) func (f GenericFlag) String() string { return FlagStringer(f) } // Apply takes the flagset and calls Set on the generic flag with the value // provided by the user for parsing by the flag func (f GenericFlag) Apply(set *flag.FlagSet) { val := f.Value if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { val.Set(envVal) break } } } for _, name := range f.Names() { set.Var(val, name, f.Usage) } } // Names returns the names of a flag. func (f GenericFlag) Names() []string { return flagNames(f) } // StringSlice wraps a []string to satisfy flag.Value type StringSlice struct { slice []string hasBeenSet bool } // NewStringSlice creates a *StringSlice with default values func NewStringSlice(defaults ...string) *StringSlice { return &StringSlice{slice: append([]string{}, defaults...)} } // Set appends the string value to the list of values func (f *StringSlice) Set(value string) error { if !f.hasBeenSet { f.slice = []string{} f.hasBeenSet = true } if strings.HasPrefix(value, slPfx) { // Deserializing assumes overwrite _ = json.Unmarshal([]byte(strings.Replace(value, slPfx, "", 1)), &f.slice) f.hasBeenSet = true return nil } f.slice = append(f.slice, value) return nil } // String returns a readable representation of this value (for usage defaults) func (f *StringSlice) String() string { return fmt.Sprintf("%s", f.slice) } // Serialized allows StringSlice to fulfill Serializeder func (f *StringSlice) Serialized() string { jsonBytes, _ := json.Marshal(f.slice) return fmt.Sprintf("%s%s", slPfx, string(jsonBytes)) } // Value returns the slice of strings set by this flag func (f *StringSlice) Value() []string { return f.slice } // StringSliceFlag is a string flag that can be specified multiple times on the // command-line type StringSliceFlag struct { Name string Aliases []string Value *StringSlice Usage string EnvVars []string Hidden bool } // String returns the usage func (f StringSliceFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f StringSliceFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { newVal := NewStringSlice() for _, s := range strings.Split(envVal, ",") { s = strings.TrimSpace(s) newVal.Set(s) } f.Value = newVal break } } } if f.Value == nil { f.Value = NewStringSlice() } for _, name := range f.Names() { set.Var(f.Value, name, f.Usage) } } // Names returns the name of a flag. func (f StringSliceFlag) Names() []string { return flagNames(f) } // IntSlice wraps an []int to satisfy flag.Value type IntSlice struct { slice []int hasBeenSet bool } // NewIntSlice makes an *IntSlice with default values func NewIntSlice(defaults ...int) *IntSlice { return &IntSlice{slice: append([]int{}, defaults...)} } // SetInt directly adds an integer to the list of values func (i *IntSlice) SetInt(value int) { if !i.hasBeenSet { i.slice = []int{} i.hasBeenSet = true } i.slice = append(i.slice, value) } // Set parses the value into an integer and appends it to the list of values func (i *IntSlice) Set(value string) error { if !i.hasBeenSet { i.slice = []int{} i.hasBeenSet = true } if strings.HasPrefix(value, slPfx) { // Deserializing assumes overwrite _ = json.Unmarshal([]byte(strings.Replace(value, slPfx, "", 1)), &i.slice) i.hasBeenSet = true return nil } tmp, err := strconv.Atoi(value) if err != nil { return err } i.slice = append(i.slice, tmp) return nil } // String returns a readable representation of this value (for usage defaults) func (i *IntSlice) String() string { return fmt.Sprintf("%v", i.slice) } // Serialized allows IntSlice to fulfill Serializeder func (i *IntSlice) Serialized() string { jsonBytes, _ := json.Marshal(i.slice) return fmt.Sprintf("%s%s", slPfx, string(jsonBytes)) } // Value returns the slice of ints set by this flag func (i *IntSlice) Value() []int { return i.slice } // IntSliceFlag is an int flag that can be specified multiple times on the // command-line type IntSliceFlag struct { Name string Aliases []string Value *IntSlice Usage string EnvVars []string Hidden bool } // String returns the usage func (f IntSliceFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f IntSliceFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { newVal := NewIntSlice() for _, s := range strings.Split(envVal, ",") { s = strings.TrimSpace(s) err := newVal.Set(s) if err != nil { fmt.Fprintf(ErrWriter, err.Error()) } } f.Value = newVal break } } } if f.Value == nil { f.Value = NewIntSlice() } for _, name := range f.Names() { set.Var(f.Value, name, f.Usage) } } // Names returns the name of the flag. func (f IntSliceFlag) Names() []string { return flagNames(f) } // BoolFlag is a switch that defaults to false type BoolFlag struct { Name string Aliases []string Value bool Usage string EnvVars []string Destination *bool Hidden bool } // String returns a readable representation of this value (for usage defaults) func (f BoolFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f BoolFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { envValBool, err := strconv.ParseBool(envVal) if err == nil { f.Value = envValBool } break } } } for _, name := range f.Names() { if f.Destination != nil { set.BoolVar(f.Destination, name, f.Value, f.Usage) continue } set.Bool(name, f.Value, f.Usage) } } // Names returns the name of the flag. func (f BoolFlag) Names() []string { return flagNames(f) } // StringFlag represents a flag that takes as string value type StringFlag struct { Name string Aliases []string Value string Usage string EnvVars []string Destination *string Hidden bool } // String returns the usage func (f StringFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f StringFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { f.Value = envVal break } } } for _, name := range f.Names() { if f.Destination != nil { set.StringVar(f.Destination, name, f.Value, f.Usage) continue } set.String(name, f.Value, f.Usage) } } // Names returns the name of the flag. func (f StringFlag) Names() []string { return flagNames(f) } // IntFlag is a flag that takes an integer // Errors if the value provided cannot be parsed type IntFlag struct { Name string Aliases []string Value int Usage string EnvVars []string Destination *int Hidden bool } // String returns the usage func (f IntFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f IntFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { envValInt, err := strconv.ParseInt(envVal, 0, 64) if err == nil { f.Value = int(envValInt) break } } } } for _, name := range f.Names() { if f.Destination != nil { set.IntVar(f.Destination, name, f.Value, f.Usage) continue } set.Int(name, f.Value, f.Usage) } } // Names returns the name of the flag. func (f IntFlag) Names() []string { return flagNames(f) } // DurationFlag is a flag that takes a duration specified in Go's duration // format: https://golang.org/pkg/time/#ParseDuration type DurationFlag struct { Name string Aliases []string Value time.Duration Usage string EnvVars []string Destination *time.Duration Hidden bool } // String returns a readable representation of this value (for usage defaults) func (f DurationFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f DurationFlag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { envValDuration, err := time.ParseDuration(envVal) if err == nil { f.Value = envValDuration break } } } } for _, name := range f.Names() { if f.Destination != nil { set.DurationVar(f.Destination, name, f.Value, f.Usage) continue } set.Duration(name, f.Value, f.Usage) } } // Names returns the name of the flag. func (f DurationFlag) Names() []string { return flagNames(f) } // Float64Flag is a flag that takes an float value // Errors if the value provided cannot be parsed type Float64Flag struct { Name string Aliases []string Value float64 Usage string EnvVars []string Destination *float64 Hidden bool } // String returns the usage func (f Float64Flag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f Float64Flag) Apply(set *flag.FlagSet) { if f.EnvVars != nil { for _, envVar := range f.EnvVars { if envVal := os.Getenv(envVar); envVal != "" { envValFloat, err := strconv.ParseFloat(envVal, 10) if err == nil { f.Value = float64(envValFloat) } } } } for _, name := range f.Names() { if f.Destination != nil { set.Float64Var(f.Destination, name, f.Value, f.Usage) continue } set.Float64(name, f.Value, f.Usage) } } // Names returns the name of the flag. func (f Float64Flag) Names() []string { return flagNames(f) } func visibleFlags(fl []Flag) []Flag { visible := []Flag{} for _, flag := range fl { if !reflect.ValueOf(flag).FieldByName("Hidden").Bool() { visible = append(visible, flag) } } return visible } func prefixFor(name string) (prefix string) { if len(name) == 1 { prefix = "-" } else { prefix = "--" } return } // Returns the placeholder, if any, and the unquoted usage string. func unquoteUsage(usage string) (string, string) { for i := 0; i < len(usage); i++ { if usage[i] == '`' { for j := i + 1; j < len(usage); j++ { if usage[j] == '`' { name := usage[i+1 : j] usage = usage[:i] + name + usage[j+1:] return name, usage } } break } } return "", usage } func prefixedNames(names []string, placeholder string) string { var prefixed string for i, name := range names { if name == "" { continue } prefixed += prefixFor(name) + name if placeholder != "" { prefixed += " " + placeholder } if i < len(names)-1 { prefixed += ", " } } return prefixed } func withEnvHint(envVars []string, str string) string { envText := "" if envVars != nil && len(envVars) > 0 { prefix := "$" suffix := "" sep := ", $" if runtime.GOOS == "windows" { prefix = "%" suffix = "%" sep = "%, %" } envText = fmt.Sprintf(" [%s%s%s]", prefix, strings.Join(envVars, sep), suffix) } return str + envText } func flagNames(f Flag) []string { ret := []string{} name := flagStringField(f, "Name") aliases := flagStringSliceField(f, "Aliases") for _, part := range append([]string{name}, aliases...) { // v1 -> v2 migration warning zone: // Strip off anything after the first found comma or space, which // *hopefully* makes it a tiny bit more obvious that unexpected behavior is // caused by using the v1 form of stringly typed "Name". ret = append(ret, commaWhitespace.ReplaceAllString(part, "")) } return ret } func flagStringSliceField(f Flag, name string) []string { fv := flagValue(f) field := fv.FieldByName(name) if field.IsValid() { return field.Interface().([]string) } return []string{} } func flagStringField(f Flag, name string) string { fv := flagValue(f) field := fv.FieldByName(name) if field.IsValid() { return field.String() } return "" } func flagValue(f Flag) reflect.Value { fv := reflect.ValueOf(f) for fv.Kind() == reflect.Ptr { fv = reflect.Indirect(fv) } return fv } func stringifyFlag(f Flag) string { fv := flagValue(f) switch f.(type) { case IntSliceFlag: return withEnvHint(flagStringSliceField(f, "EnvVars"), stringifyIntSliceFlag(f.(IntSliceFlag))) case StringSliceFlag: return withEnvHint(flagStringSliceField(f, "EnvVars"), stringifyStringSliceFlag(f.(StringSliceFlag))) } placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String()) needsPlaceholder := false defaultValueString := "" val := fv.FieldByName("Value") if val.IsValid() && val.Kind() != reflect.Bool { needsPlaceholder = true defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface()) if val.Kind() == reflect.String && val.String() != "" { defaultValueString = fmt.Sprintf(" (default: %q)", val.String()) } } if defaultValueString == " (default: )" { defaultValueString = "" } if needsPlaceholder && placeholder == "" { placeholder = defaultPlaceholder } usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultValueString)) return withEnvHint(flagStringSliceField(f, "EnvVars"), fmt.Sprintf("%s\t%s", prefixedNames(f.Names(), placeholder), usageWithDefault)) } func stringifyIntSliceFlag(f IntSliceFlag) string { defaultVals := []string{} if f.Value != nil && len(f.Value.Value()) > 0 { for _, i := range f.Value.Value() { defaultVals = append(defaultVals, fmt.Sprintf("%d", i)) } } return stringifySliceFlag(f.Usage, append([]string{f.Name}, f.Aliases...), defaultVals) } func stringifyStringSliceFlag(f StringSliceFlag) string { defaultVals := []string{} if f.Value != nil && len(f.Value.Value()) > 0 { for _, s := range f.Value.Value() { if len(s) > 0 { defaultVals = append(defaultVals, fmt.Sprintf("%q", s)) } } } return stringifySliceFlag(f.Usage, append([]string{f.Name}, f.Aliases...), defaultVals) } func stringifySliceFlag(usage string, names, defaultVals []string) string { placeholder, usage := unquoteUsage(usage) if placeholder == "" { placeholder = defaultPlaceholder } defaultVal := "" if len(defaultVals) > 0 { defaultVal = fmt.Sprintf(" (default: %s)", strings.Join(defaultVals, ", ")) } usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultVal)) return fmt.Sprintf("%s\t%s", prefixedNames(names, placeholder), usageWithDefault) }