path: root/Godeps/_workspace/src/gopkg.in/urfave/cli.v1/flag.go

package cli

import (
    "flag"
    "fmt"
    "os"
    "reflect"
    "runtime"
    "strconv"
    "strings"
    "time"
)

const defaultPlaceholder = "value"

// 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, v",
    Usage: "print the version",
}

// HelpFlag 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",
}

// FlagStringer converts a flag definition to a string. This is used by help
// to display a flag.
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)
    })
}

// GetName returns the name of a flag.
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
}

// StringSliceFlag 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)
    })
}

// GetName returns the name of a flag.
func (f StringSliceFlag) GetName() string {
    return f.Name
}

// IntSlice 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
    }
    *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(ErrWriter, 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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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)
    })
}

// GetName returns the name of the flag.
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")

    if val.IsValid() {
        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(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
    }

    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(name, placeholder), usageWithDefault)
}