mirror of
https://github.com/vbatts/tar-split.git
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347 lines
8.3 KiB
Go
347 lines
8.3 KiB
Go
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package cli
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import (
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"flag"
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"fmt"
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"io/ioutil"
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"reflect"
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"runtime"
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"strconv"
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"strings"
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"syscall"
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)
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const defaultPlaceholder = "value"
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// BashCompletionFlag enables bash-completion for all commands and subcommands
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var BashCompletionFlag Flag = BoolFlag{
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Name: "generate-bash-completion",
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Hidden: true,
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}
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// VersionFlag prints the version for the application
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var VersionFlag Flag = BoolFlag{
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Name: "version, v",
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Usage: "print the version",
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}
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// HelpFlag prints the help for all commands and subcommands
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// Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand
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// unless HideHelp is set to true)
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var HelpFlag Flag = BoolFlag{
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Name: "help, h",
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Usage: "show help",
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}
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// FlagStringer converts a flag definition to a string. This is used by help
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// to display a flag.
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var FlagStringer FlagStringFunc = stringifyFlag
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// FlagNamePrefixer converts a full flag name and its placeholder into the help
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// message flag prefix. This is used by the default FlagStringer.
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var FlagNamePrefixer FlagNamePrefixFunc = prefixedNames
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// FlagEnvHinter annotates flag help message with the environment variable
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// details. This is used by the default FlagStringer.
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var FlagEnvHinter FlagEnvHintFunc = withEnvHint
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// FlagFileHinter annotates flag help message with the environment variable
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// details. This is used by the default FlagStringer.
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var FlagFileHinter FlagFileHintFunc = withFileHint
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// FlagsByName is a slice of Flag.
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type FlagsByName []Flag
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func (f FlagsByName) Len() int {
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return len(f)
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}
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func (f FlagsByName) Less(i, j int) bool {
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return lexicographicLess(f[i].GetName(), f[j].GetName())
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}
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func (f FlagsByName) Swap(i, j int) {
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f[i], f[j] = f[j], f[i]
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}
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// Flag is a common interface related to parsing flags in cli.
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// For more advanced flag parsing techniques, it is recommended that
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// this interface be implemented.
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type Flag interface {
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fmt.Stringer
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// Apply Flag settings to the given flag set
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Apply(*flag.FlagSet)
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GetName() string
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}
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// RequiredFlag is an interface that allows us to mark flags as required
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// it allows flags required flags to be backwards compatible with the Flag interface
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type RequiredFlag interface {
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Flag
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IsRequired() bool
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}
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// DocGenerationFlag is an interface that allows documentation generation for the flag
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type DocGenerationFlag interface {
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Flag
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// TakesValue returns true if the flag takes a value, otherwise false
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TakesValue() bool
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// GetUsage returns the usage string for the flag
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GetUsage() string
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// GetValue returns the flags value as string representation and an empty
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// string if the flag takes no value at all.
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GetValue() string
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}
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// errorableFlag is an interface that allows us to return errors during apply
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// it allows flags defined in this library to return errors in a fashion backwards compatible
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// TODO remove in v2 and modify the existing Flag interface to return errors
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type errorableFlag interface {
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Flag
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ApplyWithError(*flag.FlagSet) error
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}
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func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
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set := flag.NewFlagSet(name, flag.ContinueOnError)
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for _, f := range flags {
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//TODO remove in v2 when errorableFlag is removed
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if ef, ok := f.(errorableFlag); ok {
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if err := ef.ApplyWithError(set); err != nil {
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return nil, err
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}
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} else {
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f.Apply(set)
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}
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}
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set.SetOutput(ioutil.Discard)
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return set, nil
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}
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func eachName(longName string, fn func(string)) {
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parts := strings.Split(longName, ",")
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for _, name := range parts {
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name = strings.Trim(name, " ")
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fn(name)
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}
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}
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func visibleFlags(fl []Flag) []Flag {
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var visible []Flag
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for _, f := range fl {
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field := flagValue(f).FieldByName("Hidden")
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if !field.IsValid() || !field.Bool() {
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visible = append(visible, f)
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}
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}
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return visible
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}
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func prefixFor(name string) (prefix string) {
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if len(name) == 1 {
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prefix = "-"
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} else {
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prefix = "--"
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}
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return
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}
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// Returns the placeholder, if any, and the unquoted usage string.
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func unquoteUsage(usage string) (string, string) {
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for i := 0; i < len(usage); i++ {
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if usage[i] == '`' {
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for j := i + 1; j < len(usage); j++ {
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if usage[j] == '`' {
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name := usage[i+1 : j]
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usage = usage[:i] + name + usage[j+1:]
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return name, usage
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}
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}
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break
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}
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}
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return "", usage
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}
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func prefixedNames(fullName, placeholder string) string {
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var prefixed string
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parts := strings.Split(fullName, ",")
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for i, name := range parts {
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name = strings.Trim(name, " ")
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prefixed += prefixFor(name) + name
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if placeholder != "" {
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prefixed += " " + placeholder
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}
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if i < len(parts)-1 {
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prefixed += ", "
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}
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}
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return prefixed
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}
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func withEnvHint(envVar, str string) string {
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envText := ""
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if envVar != "" {
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prefix := "$"
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suffix := ""
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sep := ", $"
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if runtime.GOOS == "windows" {
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prefix = "%"
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suffix = "%"
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sep = "%, %"
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}
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envText = " [" + prefix + strings.Join(strings.Split(envVar, ","), sep) + suffix + "]"
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}
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return str + envText
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}
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func withFileHint(filePath, str string) string {
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fileText := ""
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if filePath != "" {
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fileText = fmt.Sprintf(" [%s]", filePath)
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}
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return str + fileText
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}
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func flagValue(f Flag) reflect.Value {
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fv := reflect.ValueOf(f)
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for fv.Kind() == reflect.Ptr {
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fv = reflect.Indirect(fv)
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}
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return fv
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}
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func stringifyFlag(f Flag) string {
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fv := flagValue(f)
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switch f.(type) {
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case IntSliceFlag:
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return FlagFileHinter(
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fv.FieldByName("FilePath").String(),
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FlagEnvHinter(
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fv.FieldByName("EnvVar").String(),
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stringifyIntSliceFlag(f.(IntSliceFlag)),
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),
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)
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case Int64SliceFlag:
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return FlagFileHinter(
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fv.FieldByName("FilePath").String(),
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FlagEnvHinter(
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fv.FieldByName("EnvVar").String(),
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stringifyInt64SliceFlag(f.(Int64SliceFlag)),
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),
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)
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case StringSliceFlag:
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return FlagFileHinter(
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fv.FieldByName("FilePath").String(),
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FlagEnvHinter(
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fv.FieldByName("EnvVar").String(),
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stringifyStringSliceFlag(f.(StringSliceFlag)),
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),
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)
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}
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placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String())
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needsPlaceholder := false
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defaultValueString := ""
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if val := fv.FieldByName("Value"); val.IsValid() {
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needsPlaceholder = true
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defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface())
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if val.Kind() == reflect.String && val.String() != "" {
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defaultValueString = fmt.Sprintf(" (default: %q)", val.String())
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}
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}
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if defaultValueString == " (default: )" {
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defaultValueString = ""
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}
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if needsPlaceholder && placeholder == "" {
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placeholder = defaultPlaceholder
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}
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usageWithDefault := strings.TrimSpace(usage + defaultValueString)
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return FlagFileHinter(
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fv.FieldByName("FilePath").String(),
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FlagEnvHinter(
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fv.FieldByName("EnvVar").String(),
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FlagNamePrefixer(fv.FieldByName("Name").String(), placeholder)+"\t"+usageWithDefault,
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),
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)
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}
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func stringifyIntSliceFlag(f IntSliceFlag) string {
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var defaultVals []string
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if f.Value != nil && len(f.Value.Value()) > 0 {
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for _, i := range f.Value.Value() {
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defaultVals = append(defaultVals, strconv.Itoa(i))
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}
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}
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return stringifySliceFlag(f.Usage, f.Name, defaultVals)
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}
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func stringifyInt64SliceFlag(f Int64SliceFlag) string {
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var defaultVals []string
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if f.Value != nil && len(f.Value.Value()) > 0 {
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for _, i := range f.Value.Value() {
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defaultVals = append(defaultVals, strconv.FormatInt(i, 10))
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}
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}
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return stringifySliceFlag(f.Usage, f.Name, defaultVals)
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}
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func stringifyStringSliceFlag(f StringSliceFlag) string {
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var defaultVals []string
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if f.Value != nil && len(f.Value.Value()) > 0 {
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for _, s := range f.Value.Value() {
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if len(s) > 0 {
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defaultVals = append(defaultVals, strconv.Quote(s))
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}
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}
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}
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return stringifySliceFlag(f.Usage, f.Name, defaultVals)
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}
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func stringifySliceFlag(usage, name string, defaultVals []string) string {
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placeholder, usage := unquoteUsage(usage)
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if placeholder == "" {
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placeholder = defaultPlaceholder
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}
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defaultVal := ""
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if len(defaultVals) > 0 {
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defaultVal = fmt.Sprintf(" (default: %s)", strings.Join(defaultVals, ", "))
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}
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usageWithDefault := strings.TrimSpace(usage + defaultVal)
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return FlagNamePrefixer(name, placeholder) + "\t" + usageWithDefault
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}
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func flagFromFileEnv(filePath, envName string) (val string, ok bool) {
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for _, envVar := range strings.Split(envName, ",") {
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envVar = strings.TrimSpace(envVar)
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if envVal, ok := syscall.Getenv(envVar); ok {
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return envVal, true
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}
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}
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for _, fileVar := range strings.Split(filePath, ",") {
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if data, err := ioutil.ReadFile(fileVar); err == nil {
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return string(data), true
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}
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}
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return "", false
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}
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