package cli import ( "flag" "fmt" "os" "reflect" "runtime" "strconv" "strings" "time" ) const defaultPlaceholder = "value" // This flag enables bash-completion for all commands and subcommands var BashCompletionFlag = BoolFlag{ Name: "generate-bash-completion", Hidden: true, } // This flag prints the version for the application var VersionFlag = BoolFlag{ Name: "version, v", Usage: "print the version", } // This flag prints the help for all commands and subcommands // Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand // unless HideHelp is set to true) var HelpFlag = BoolFlag{ Name: "help, h", Usage: "show help", } var FlagStringer FlagStringFunc = stringifyFlag // 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) GetName() string } func flagSet(name string, flags []Flag) *flag.FlagSet { set := flag.NewFlagSet(name, flag.ContinueOnError) for _, f := range flags { f.Apply(set) } return set } func eachName(longName string, fn func(string)) { parts := strings.Split(longName, ",") for _, name := range parts { name = strings.Trim(name, " ") fn(name) } } // 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 Value Generic Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { val.Set(envVal) break } } } eachName(f.Name, func(name string) { set.Var(f.Value, name, f.Usage) }) } func (f GenericFlag) GetName() string { return f.Name } // StringSlice is an opaque type for []string to satisfy flag.Value type StringSlice []string // Set appends the string value to the list of values func (f *StringSlice) Set(value string) error { *f = append(*f, value) return nil } // String returns a readable representation of this value (for usage defaults) func (f *StringSlice) String() string { return fmt.Sprintf("%s", *f) } // Value returns the slice of strings set by this flag func (f *StringSlice) Value() []string { return *f } // StringSlice is a string flag that can be specified multiple times on the // command-line type StringSliceFlag struct { Name string Value *StringSlice Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { newVal := &StringSlice{} for _, s := range strings.Split(envVal, ",") { s = strings.TrimSpace(s) newVal.Set(s) } f.Value = newVal break } } } eachName(f.Name, func(name string) { if f.Value == nil { f.Value = &StringSlice{} } set.Var(f.Value, name, f.Usage) }) } func (f StringSliceFlag) GetName() string { return f.Name } // StringSlice is an opaque type for []int to satisfy flag.Value type IntSlice []int // Set parses the value into an integer and appends it to the list of values func (f *IntSlice) Set(value string) error { tmp, err := strconv.Atoi(value) if err != nil { return err } else { *f = append(*f, tmp) } return nil } // String returns a readable representation of this value (for usage defaults) func (f *IntSlice) String() string { return fmt.Sprintf("%d", *f) } // Value returns the slice of ints set by this flag func (f *IntSlice) Value() []int { return *f } // IntSliceFlag is an int flag that can be specified multiple times on the // command-line type IntSliceFlag struct { Name string Value *IntSlice Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { newVal := &IntSlice{} for _, s := range strings.Split(envVal, ",") { s = strings.TrimSpace(s) err := newVal.Set(s) if err != nil { fmt.Fprintf(os.Stderr, err.Error()) } } f.Value = newVal break } } } eachName(f.Name, func(name string) { if f.Value == nil { f.Value = &IntSlice{} } set.Var(f.Value, name, f.Usage) }) } func (f IntSliceFlag) GetName() string { return f.Name } // BoolFlag is a switch that defaults to false type BoolFlag struct { Name string Usage string EnvVar 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) { val := false if f.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { envValBool, err := strconv.ParseBool(envVal) if err == nil { val = envValBool } break } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.BoolVar(f.Destination, name, val, f.Usage) return } set.Bool(name, val, f.Usage) }) } func (f BoolFlag) GetName() string { return f.Name } // BoolTFlag this represents a boolean flag that is true by default, but can // still be set to false by --some-flag=false type BoolTFlag struct { Name string Usage string EnvVar string Destination *bool Hidden bool } // String returns a readable representation of this value (for usage defaults) func (f BoolTFlag) String() string { return FlagStringer(f) } // Apply populates the flag given the flag set and environment func (f BoolTFlag) Apply(set *flag.FlagSet) { val := true if f.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { envValBool, err := strconv.ParseBool(envVal) if err == nil { val = envValBool break } } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.BoolVar(f.Destination, name, val, f.Usage) return } set.Bool(name, val, f.Usage) }) } func (f BoolTFlag) GetName() string { return f.Name } // StringFlag represents a flag that takes as string value type StringFlag struct { Name string Value string Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { f.Value = envVal break } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.StringVar(f.Destination, name, f.Value, f.Usage) return } set.String(name, f.Value, f.Usage) }) } func (f StringFlag) GetName() string { return f.Name } // IntFlag is a flag that takes an integer // Errors if the value provided cannot be parsed type IntFlag struct { Name string Value int Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { envValInt, err := strconv.ParseInt(envVal, 0, 64) if err == nil { f.Value = int(envValInt) break } } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.IntVar(f.Destination, name, f.Value, f.Usage) return } set.Int(name, f.Value, f.Usage) }) } func (f IntFlag) GetName() string { return f.Name } // 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 Value time.Duration Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { envValDuration, err := time.ParseDuration(envVal) if err == nil { f.Value = envValDuration break } } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.DurationVar(f.Destination, name, f.Value, f.Usage) return } set.Duration(name, f.Value, f.Usage) }) } func (f DurationFlag) GetName() string { return f.Name } // Float64Flag is a flag that takes an float value // Errors if the value provided cannot be parsed type Float64Flag struct { Name string Value float64 Usage string EnvVar 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.EnvVar != "" { for _, envVar := range strings.Split(f.EnvVar, ",") { envVar = strings.TrimSpace(envVar) if envVal := os.Getenv(envVar); envVal != "" { envValFloat, err := strconv.ParseFloat(envVal, 10) if err == nil { f.Value = float64(envValFloat) } } } } eachName(f.Name, func(name string) { if f.Destination != nil { set.Float64Var(f.Destination, name, f.Value, f.Usage) return } set.Float64(name, f.Value, f.Usage) }) } func (f Float64Flag) GetName() string { return f.Name } 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(fullName, placeholder string) string { var prefixed string parts := strings.Split(fullName, ",") for i, name := range parts { name = strings.Trim(name, " ") prefixed += prefixFor(name) + name if placeholder != "" { prefixed += " " + placeholder } if i < len(parts)-1 { prefixed += ", " } } return prefixed } func withEnvHint(envVar, str string) string { envText := "" if envVar != "" { prefix := "$" suffix := "" sep := ", $" if runtime.GOOS == "windows" { prefix = "%" suffix = "%" sep = "%, %" } envText = fmt.Sprintf(" [%s%s%s]", prefix, strings.Join(strings.Split(envVar, ","), sep), suffix) } return str + envText } func stringifyFlag(f Flag) string { fv := reflect.ValueOf(f) switch f.(type) { case IntSliceFlag: return withEnvHint(fv.FieldByName("EnvVar").String(), stringifyIntSliceFlag(f.(IntSliceFlag))) case StringSliceFlag: return withEnvHint(fv.FieldByName("EnvVar").String(), stringifyStringSliceFlag(f.(StringSliceFlag))) } placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String()) needsPlaceholder := false defaultValueString := "" val := fv.FieldByName("Value") valString := "" if val.IsValid() { needsPlaceholder = true if val.Kind() == reflect.String && val.String() != "" { valString = fmt.Sprintf("%q", val.String()) } else { valString = fmt.Sprintf("%v", val.Interface()) } } if valString != "" { defaultValueString = valString } if needsPlaceholder && placeholder == "" { placeholder = defaultPlaceholder } formattedDefaultValueString := "" if defaultValueString != "" { formattedDefaultValueString = fmt.Sprintf(" (default: %v)", defaultValueString) } usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, formattedDefaultValueString)) return withEnvHint(fv.FieldByName("EnvVar").String(), fmt.Sprintf("%s\t%s", prefixedNames(fv.FieldByName("Name").String(), 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, f.Name, 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, f.Name, defaultVals) } func stringifySliceFlag(usage, name string, defaultVals []string) string { placeholder, usage := unquoteUsage(usage) if placeholder == "" { placeholder = defaultPlaceholder } nameParts := []string{} for _, part := range strings.Split(name, ",") { nameParts = append(nameParts, strings.TrimSpace(part)) } defaultVal := "" if len(defaultVals) > 0 { defaultVal = fmt.Sprintf(" (default: %s)", strings.Join(defaultVals, ", ")) } usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultVal)) if len(nameParts) < 2 { return fmt.Sprintf("%s%s %s\t%s", prefixFor(nameParts[0]), nameParts[0], placeholder, usageWithDefault) } return fmt.Sprintf("%s%s %s, %s%s %s\t%s", prefixFor(nameParts[0]), nameParts[0], placeholder, prefixFor(nameParts[1]), nameParts[1], placeholder, usageWithDefault) }