vendor/github.com/urfave/cli/v2/app.go - cos/tools.git - Git at Google

 package cli

 import (
 	"context"
 	"flag"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"sort"
 	"time"
 )

 var (
 	changeLogURL            = "https://github.com/urfave/cli/blob/master/docs/CHANGELOG.md"
 	appActionDeprecationURL = fmt.Sprintf("%s#deprecated-cli-app-action-signature", changeLogURL)
 	contactSysadmin         = "This is an error in the application.  Please contact the distributor of this application if this is not you."
 	errInvalidActionType    = NewExitError("ERROR invalid Action type. "+
 		fmt.Sprintf("Must be `func(*Context`)` or `func(*Context) error).  %s", contactSysadmin)+
 		fmt.Sprintf("See %s", appActionDeprecationURL), 2)
 )

 // App is the main structure of a cli application. It is recommended that
 // an app be created with the cli.NewApp() function
 type App struct {
 	// The name of the program. Defaults to path.Base(os.Args[0])
 	Name string
 	// Full name of command for help, defaults to Name
 	HelpName string
 	// Description of the program.
 	Usage string
 	// Text to override the USAGE section of help
 	UsageText string
 	// Description of the program argument format.
 	ArgsUsage string
 	// Version of the program
 	Version string
 	// Description of the program
 	Description string
 	// List of commands to execute
 	Commands []*Command
 	// List of flags to parse
 	Flags []Flag
 	// Boolean to enable bash completion commands
 	EnableBashCompletion bool
 	// Boolean to hide built-in help command and help flag
 	HideHelp bool
 	// Boolean to hide built-in help command but keep help flag.
 	// Ignored if HideHelp is true.
 	HideHelpCommand bool
 	// Boolean to hide built-in version flag and the VERSION section of help
 	HideVersion bool
 	// categories contains the categorized commands and is populated on app startup
 	categories CommandCategories
 	// An action to execute when the shell completion flag is set
 	BashComplete BashCompleteFunc
 	// An action to execute before any subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no subcommands are run
 	Before BeforeFunc
 	// An action to execute after any subcommands are run, but after the subcommand has finished
 	// It is run even if Action() panics
 	After AfterFunc
 	// The action to execute when no subcommands are specified
 	Action ActionFunc
 	// Execute this function if the proper command cannot be found
 	CommandNotFound CommandNotFoundFunc
 	// Execute this function if an usage error occurs
 	OnUsageError OnUsageErrorFunc
 	// Compilation date
 	Compiled time.Time
 	// List of all authors who contributed
 	Authors []*Author
 	// Copyright of the binary if any
 	Copyright string
 	// Writer writer to write output to
 	Writer io.Writer
 	// ErrWriter writes error output
 	ErrWriter io.Writer
 	// Execute this function to handle ExitErrors. If not provided, HandleExitCoder is provided to
 	// function as a default, so this is optional.
 	ExitErrHandler ExitErrHandlerFunc
 	// Other custom info
 	Metadata map[string]interface{}
 	// Carries a function which returns app specific info.
 	ExtraInfo func() map[string]string
 	// CustomAppHelpTemplate the text template for app help topic.
 	// cli.go uses text/template to render templates. You can
 	// render custom help text by setting this variable.
 	CustomAppHelpTemplate string
 	// Boolean to enable short-option handling so user can combine several
 	// single-character bool arguments into one
 	// i.e. foobar -o -v -> foobar -ov
 	UseShortOptionHandling bool

 	didSetup bool
 }

 // Tries to find out when this binary was compiled.
 // Returns the current time if it fails to find it.
 func compileTime() time.Time {
 	info, err := os.Stat(os.Args[0])
 	if err != nil {
 		return time.Now()
 	}
 	return info.ModTime()
 }

 // NewApp creates a new cli Application with some reasonable defaults for Name,
 // Usage, Version and Action.
 func NewApp() *App {
 	return &App{
 		Name:         filepath.Base(os.Args[0]),
 		HelpName:     filepath.Base(os.Args[0]),
 		Usage:        "A new cli application",
 		UsageText:    "",
 		BashComplete: DefaultAppComplete,
 		Action:       helpCommand.Action,
 		Compiled:     compileTime(),
 		Writer:       os.Stdout,
 	}
 }

 // Setup runs initialization code to ensure all data structures are ready for
 // `Run` or inspection prior to `Run`.  It is internally called by `Run`, but
 // will return early if setup has already happened.
 func (a *App) Setup() {
 	if a.didSetup {
 		return
 	}

 	a.didSetup = true

 	if a.Name == "" {
 		a.Name = filepath.Base(os.Args[0])
 	}

 	if a.HelpName == "" {
 		a.HelpName = filepath.Base(os.Args[0])
 	}

 	if a.Usage == "" {
 		a.Usage = "A new cli application"
 	}

 	if a.Version == "" {
 		a.HideVersion = true
 	}

 	if a.BashComplete == nil {
 		a.BashComplete = DefaultAppComplete
 	}

 	if a.Action == nil {
 		a.Action = helpCommand.Action
 	}

 	if a.Compiled == (time.Time{}) {
 		a.Compiled = compileTime()
 	}

 	if a.Writer == nil {
 		a.Writer = os.Stdout
 	}

 	var newCommands []*Command

 	for _, c := range a.Commands {
 		if c.HelpName == "" {
 			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
 		}
 		newCommands = append(newCommands, c)
 	}
 	a.Commands = newCommands

 	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
 		if !a.HideHelpCommand {
 			a.appendCommand(helpCommand)
 		}

 		if HelpFlag != nil {
 			a.appendFlag(HelpFlag)
 		}
 	}

 	if !a.HideVersion {
 		a.appendFlag(VersionFlag)
 	}

 	a.categories = newCommandCategories()
 	for _, command := range a.Commands {
 		a.categories.AddCommand(command.Category, command)
 	}
 	sort.Sort(a.categories.(*commandCategories))

 	if a.Metadata == nil {
 		a.Metadata = make(map[string]interface{})
 	}

 	if a.Writer == nil {
 		a.Writer = os.Stdout
 	}
 }

 func (a *App) newFlagSet() (*flag.FlagSet, error) {
 	return flagSet(a.Name, a.Flags)
 }

 func (a *App) useShortOptionHandling() bool {
 	return a.UseShortOptionHandling
 }

 // Run is the entry point to the cli app. Parses the arguments slice and routes
 // to the proper flag/args combination
 func (a *App) Run(arguments []string) (err error) {
 	return a.RunContext(context.Background(), arguments)
 }

 // RunContext is like Run except it takes a Context that will be
 // passed to its commands and sub-commands. Through this, you can
 // propagate timeouts and cancellation requests
 func (a *App) RunContext(ctx context.Context, arguments []string) (err error) {
 	a.Setup()

 	// handle the completion flag separately from the flagset since
 	// completion could be attempted after a flag, but before its value was put
 	// on the command line. this causes the flagset to interpret the completion
 	// flag name as the value of the flag before it which is undesirable
 	// note that we can only do this because the shell autocomplete function
 	// always appends the completion flag at the end of the command
 	shellComplete, arguments := checkShellCompleteFlag(a, arguments)

 	set, err := a.newFlagSet()
 	if err != nil {
 		return err
 	}

 	err = parseIter(set, a, arguments[1:], shellComplete)
 	nerr := normalizeFlags(a.Flags, set)
 	context := NewContext(a, set, &Context{Context: ctx})
 	if nerr != nil {
 		_, _ = fmt.Fprintln(a.Writer, nerr)
 		_ = ShowAppHelp(context)
 		return nerr
 	}
 	context.shellComplete = shellComplete

 	if checkCompletions(context) {
 		return nil
 	}

 	if err != nil {
 		if a.OnUsageError != nil {
 			err := a.OnUsageError(context, err, false)
 			a.handleExitCoder(context, err)
 			return err
 		}
 		_, _ = fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
 		_ = ShowAppHelp(context)
 		return err
 	}

 	if !a.HideHelp && checkHelp(context) {
 		_ = ShowAppHelp(context)
 		return nil
 	}

 	if !a.HideVersion && checkVersion(context) {
 		ShowVersion(context)
 		return nil
 	}

 	cerr := checkRequiredFlags(a.Flags, context)
 	if cerr != nil {
 		_ = ShowAppHelp(context)
 		return cerr
 	}

 	if a.After != nil {
 		defer func() {
 			if afterErr := a.After(context); afterErr != nil {
 				if err != nil {
 					err = newMultiError(err, afterErr)
 				} else {
 					err = afterErr
 				}
 			}
 		}()
 	}

 	if a.Before != nil {
 		beforeErr := a.Before(context)
 		if beforeErr != nil {
 			_, _ = fmt.Fprintf(a.Writer, "%v\n\n", beforeErr)
 			_ = ShowAppHelp(context)
 			a.handleExitCoder(context, beforeErr)
 			err = beforeErr
 			return err
 		}
 	}

 	args := context.Args()
 	if args.Present() {
 		name := args.First()
 		c := a.Command(name)
 		if c != nil {
 			return c.Run(context)
 		}
 	}

 	if a.Action == nil {
 		a.Action = helpCommand.Action
 	}

 	// Run default Action
 	err = a.Action(context)

 	a.handleExitCoder(context, err)
 	return err
 }

 // RunAndExitOnError calls .Run() and exits non-zero if an error was returned
 //
 // Deprecated: instead you should return an error that fulfills cli.ExitCoder
 // to cli.App.Run. This will cause the application to exit with the given eror
 // code in the cli.ExitCoder
 func (a *App) RunAndExitOnError() {
 	if err := a.Run(os.Args); err != nil {
 		_, _ = fmt.Fprintln(a.errWriter(), err)
 		OsExiter(1)
 	}
 }

 // RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to
 // generate command-specific flags
 func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 	// Setup also handles HideHelp and HideHelpCommand
 	a.Setup()

 	var newCmds []*Command
 	for _, c := range a.Commands {
 		if c.HelpName == "" {
 			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
 		}
 		newCmds = append(newCmds, c)
 	}
 	a.Commands = newCmds

 	set, err := a.newFlagSet()
 	if err != nil {
 		return err
 	}

 	err = parseIter(set, a, ctx.Args().Tail(), ctx.shellComplete)
 	nerr := normalizeFlags(a.Flags, set)
 	context := NewContext(a, set, ctx)

 	if nerr != nil {
 		_, _ = fmt.Fprintln(a.Writer, nerr)
 		_, _ = fmt.Fprintln(a.Writer)
 		if len(a.Commands) > 0 {
 			_ = ShowSubcommandHelp(context)
 		} else {
 			_ = ShowCommandHelp(ctx, context.Args().First())
 		}
 		return nerr
 	}

 	if checkCompletions(context) {
 		return nil
 	}

 	if err != nil {
 		if a.OnUsageError != nil {
 			err = a.OnUsageError(context, err, true)
 			a.handleExitCoder(context, err)
 			return err
 		}
 		_, _ = fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
 		_ = ShowSubcommandHelp(context)
 		return err
 	}

 	if len(a.Commands) > 0 {
 		if checkSubcommandHelp(context) {
 			return nil
 		}
 	} else {
 		if checkCommandHelp(ctx, context.Args().First()) {
 			return nil
 		}
 	}

 	cerr := checkRequiredFlags(a.Flags, context)
 	if cerr != nil {
 		_ = ShowSubcommandHelp(context)
 		return cerr
 	}

 	if a.After != nil {
 		defer func() {
 			afterErr := a.After(context)
 			if afterErr != nil {
 				a.handleExitCoder(context, err)
 				if err != nil {
 					err = newMultiError(err, afterErr)
 				} else {
 					err = afterErr
 				}
 			}
 		}()
 	}

 	if a.Before != nil {
 		beforeErr := a.Before(context)
 		if beforeErr != nil {
 			a.handleExitCoder(context, beforeErr)
 			err = beforeErr
 			return err
 		}
 	}

 	args := context.Args()
 	if args.Present() {
 		name := args.First()
 		c := a.Command(name)
 		if c != nil {
 			return c.Run(context)
 		}
 	}

 	// Run default Action
 	err = a.Action(context)

 	a.handleExitCoder(context, err)
 	return err
 }

 // Command returns the named command on App. Returns nil if the command does not exist
 func (a *App) Command(name string) *Command {
 	for _, c := range a.Commands {
 		if c.HasName(name) {
 			return c
 		}
 	}

 	return nil
 }

 // VisibleCategories returns a slice of categories and commands that are
 // Hidden=false
 func (a *App) VisibleCategories() []CommandCategory {
 	ret := []CommandCategory{}
 	for _, category := range a.categories.Categories() {
 		if visible := func() CommandCategory {
 			if len(category.VisibleCommands()) > 0 {
 				return category
 			}
 			return nil
 		}(); visible != nil {
 			ret = append(ret, visible)
 		}
 	}
 	return ret
 }

 // VisibleCommands returns a slice of the Commands with Hidden=false
 func (a *App) VisibleCommands() []*Command {
 	var ret []*Command
 	for _, command := range a.Commands {
 		if !command.Hidden {
 			ret = append(ret, command)
 		}
 	}
 	return ret
 }

 // VisibleFlags returns a slice of the Flags with Hidden=false
 func (a *App) VisibleFlags() []Flag {
 	return visibleFlags(a.Flags)
 }

 func (a *App) errWriter() io.Writer {
 	// When the app ErrWriter is nil use the package level one.
 	if a.ErrWriter == nil {
 		return ErrWriter
 	}

 	return a.ErrWriter
 }

 func (a *App) appendFlag(fl Flag) {
 	if !hasFlag(a.Flags, fl) {
 		a.Flags = append(a.Flags, fl)
 	}
 }

 func (a *App) appendCommand(c *Command) {
 	if !hasCommand(a.Commands, c) {
 		a.Commands = append(a.Commands, c)
 	}
 }

 func (a *App) handleExitCoder(context *Context, err error) {
 	if a.ExitErrHandler != nil {
 		a.ExitErrHandler(context, err)
 	} else {
 		HandleExitCoder(err)
 	}
 }

 // Author represents someone who has contributed to a cli project.
 type Author struct {
 	Name  string // The Authors name
 	Email string // The Authors email
 }

 // String makes Author comply to the Stringer interface, to allow an easy print in the templating process
 func (a *Author) String() string {
 	e := ""
 	if a.Email != "" {
 		e = " <" + a.Email + ">"
 	}

 	return fmt.Sprintf("%v%v", a.Name, e)
 }

 // HandleAction attempts to figure out which Action signature was used.  If
 // it's an ActionFunc or a func with the legacy signature for Action, the func
 // is run!
 func HandleAction(action interface{}, context *Context) (err error) {
 	switch a := action.(type) {
 	case ActionFunc:
 		return a(context)
 	case func(*Context) error:
 		return a(context)
 	case func(*Context): // deprecated function signature
 		a(context)
 		return nil
 	}

 	return errInvalidActionType
 }
	package cli

	import (
	"context"
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"sort"
	"time"
	)

	var (
	changeLogURL = "https://github.com/urfave/cli/blob/master/docs/CHANGELOG.md"
	appActionDeprecationURL = fmt.Sprintf("%s#deprecated-cli-app-action-signature", changeLogURL)
	contactSysadmin = "This is an error in the application. Please contact the distributor of this application if this is not you."
	errInvalidActionType = NewExitError("ERROR invalid Action type. "+
	fmt.Sprintf("Must be `func(Context`)` or `func(Context) error). %s", contactSysadmin)+
	fmt.Sprintf("See %s", appActionDeprecationURL), 2)
	)

	// App is the main structure of a cli application. It is recommended that
	// an app be created with the cli.NewApp() function
	type App struct {
	// The name of the program. Defaults to path.Base(os.Args[0])
	Name string
	// Full name of command for help, defaults to Name
	HelpName string
	// Description of the program.
	Usage string
	// Text to override the USAGE section of help
	UsageText string
	// Description of the program argument format.
	ArgsUsage string
	// Version of the program
	Version string
	// Description of the program
	Description string
	// List of commands to execute
	Commands []*Command
	// List of flags to parse
	Flags []Flag
	// Boolean to enable bash completion commands
	EnableBashCompletion bool
	// Boolean to hide built-in help command and help flag
	HideHelp bool
	// Boolean to hide built-in help command but keep help flag.
	// Ignored if HideHelp is true.
	HideHelpCommand bool
	// Boolean to hide built-in version flag and the VERSION section of help
	HideVersion bool
	// categories contains the categorized commands and is populated on app startup
	categories CommandCategories
	// An action to execute when the shell completion flag is set
	BashComplete BashCompleteFunc
	// An action to execute before any subcommands are run, but after the context is ready
	// If a non-nil error is returned, no subcommands are run
	Before BeforeFunc
	// An action to execute after any subcommands are run, but after the subcommand has finished
	// It is run even if Action() panics
	After AfterFunc
	// The action to execute when no subcommands are specified
	Action ActionFunc
	// Execute this function if the proper command cannot be found
	CommandNotFound CommandNotFoundFunc
	// Execute this function if an usage error occurs
	OnUsageError OnUsageErrorFunc
	// Compilation date
	Compiled time.Time
	// List of all authors who contributed
	Authors []*Author
	// Copyright of the binary if any
	Copyright string
	// Writer writer to write output to
	Writer io.Writer
	// ErrWriter writes error output
	ErrWriter io.Writer
	// Execute this function to handle ExitErrors. If not provided, HandleExitCoder is provided to
	// function as a default, so this is optional.
	ExitErrHandler ExitErrHandlerFunc
	// Other custom info
	Metadata map[string]interface{}
	// Carries a function which returns app specific info.
	ExtraInfo func() map[string]string
	// CustomAppHelpTemplate the text template for app help topic.
	// cli.go uses text/template to render templates. You can
	// render custom help text by setting this variable.
	CustomAppHelpTemplate string
	// Boolean to enable short-option handling so user can combine several
	// single-character bool arguments into one
	// i.e. foobar -o -v -> foobar -ov
	UseShortOptionHandling bool

	didSetup bool
	}

	// Tries to find out when this binary was compiled.
	// Returns the current time if it fails to find it.
	func compileTime() time.Time {
	info, err := os.Stat(os.Args[0])
	if err != nil {
	return time.Now()
	}
	return info.ModTime()
	}

	// NewApp creates a new cli Application with some reasonable defaults for Name,
	// Usage, Version and Action.
	func NewApp() *App {
	return &App{
	Name: filepath.Base(os.Args[0]),
	HelpName: filepath.Base(os.Args[0]),
	Usage: "A new cli application",
	UsageText: "",
	BashComplete: DefaultAppComplete,
	Action: helpCommand.Action,
	Compiled: compileTime(),
	Writer: os.Stdout,
	}
	}

	// Setup runs initialization code to ensure all data structures are ready for
	// `Run` or inspection prior to `Run`. It is internally called by `Run`, but
	// will return early if setup has already happened.
	func (a *App) Setup() {
	if a.didSetup {
	return
	}

	a.didSetup = true

	if a.Name == "" {
	a.Name = filepath.Base(os.Args[0])
	}

	if a.HelpName == "" {
	a.HelpName = filepath.Base(os.Args[0])
	}

	if a.Usage == "" {
	a.Usage = "A new cli application"
	}

	if a.Version == "" {
	a.HideVersion = true
	}

	if a.BashComplete == nil {
	a.BashComplete = DefaultAppComplete
	}

	if a.Action == nil {
	a.Action = helpCommand.Action
	}

	if a.Compiled == (time.Time{}) {
	a.Compiled = compileTime()
	}

	if a.Writer == nil {
	a.Writer = os.Stdout
	}

	var newCommands []*Command

	for _, c := range a.Commands {
	if c.HelpName == "" {
	c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
	}
	newCommands = append(newCommands, c)
	}
	a.Commands = newCommands

	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
	if !a.HideHelpCommand {
	a.appendCommand(helpCommand)
	}

	if HelpFlag != nil {
	a.appendFlag(HelpFlag)
	}
	}

	if !a.HideVersion {
	a.appendFlag(VersionFlag)
	}

	a.categories = newCommandCategories()
	for _, command := range a.Commands {
	a.categories.AddCommand(command.Category, command)
	}
	sort.Sort(a.categories.(*commandCategories))

	if a.Metadata == nil {
	a.Metadata = make(map[string]interface{})
	}

	if a.Writer == nil {
	a.Writer = os.Stdout
	}
	}

	func (a App) newFlagSet() (flag.FlagSet, error) {
	return flagSet(a.Name, a.Flags)
	}

	func (a *App) useShortOptionHandling() bool {
	return a.UseShortOptionHandling
	}

	// Run is the entry point to the cli app. Parses the arguments slice and routes
	// to the proper flag/args combination
	func (a *App) Run(arguments []string) (err error) {
	return a.RunContext(context.Background(), arguments)
	}

	// RunContext is like Run except it takes a Context that will be
	// passed to its commands and sub-commands. Through this, you can
	// propagate timeouts and cancellation requests
	func (a *App) RunContext(ctx context.Context, arguments []string) (err error) {
	a.Setup()

	// handle the completion flag separately from the flagset since
	// completion could be attempted after a flag, but before its value was put
	// on the command line. this causes the flagset to interpret the completion
	// flag name as the value of the flag before it which is undesirable
	// note that we can only do this because the shell autocomplete function
	// always appends the completion flag at the end of the command
	shellComplete, arguments := checkShellCompleteFlag(a, arguments)

	set, err := a.newFlagSet()
	if err != nil {
	return err
	}

	err = parseIter(set, a, arguments[1:], shellComplete)
	nerr := normalizeFlags(a.Flags, set)
	context := NewContext(a, set, &Context{Context: ctx})
	if nerr != nil {
	_, _ = fmt.Fprintln(a.Writer, nerr)
	_ = ShowAppHelp(context)
	return nerr
	}
	context.shellComplete = shellComplete

	if checkCompletions(context) {
	return nil
	}

	if err != nil {
	if a.OnUsageError != nil {
	err := a.OnUsageError(context, err, false)
	a.handleExitCoder(context, err)
	return err
	}
	_, _ = fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
	_ = ShowAppHelp(context)
	return err
	}

	if !a.HideHelp && checkHelp(context) {
	_ = ShowAppHelp(context)
	return nil
	}

	if !a.HideVersion && checkVersion(context) {
	ShowVersion(context)
	return nil
	}

	cerr := checkRequiredFlags(a.Flags, context)
	if cerr != nil {
	_ = ShowAppHelp(context)
	return cerr
	}

	if a.After != nil {
	defer func() {
	if afterErr := a.After(context); afterErr != nil {
	if err != nil {
	err = newMultiError(err, afterErr)
	} else {
	err = afterErr
	}
	}
	}()
	}

	if a.Before != nil {
	beforeErr := a.Before(context)
	if beforeErr != nil {
	_, _ = fmt.Fprintf(a.Writer, "%v\n\n", beforeErr)
	_ = ShowAppHelp(context)
	a.handleExitCoder(context, beforeErr)
	err = beforeErr
	return err
	}
	}

	args := context.Args()
	if args.Present() {
	name := args.First()
	c := a.Command(name)
	if c != nil {
	return c.Run(context)
	}
	}

	if a.Action == nil {
	a.Action = helpCommand.Action
	}

	// Run default Action
	err = a.Action(context)

	a.handleExitCoder(context, err)
	return err
	}

	// RunAndExitOnError calls .Run() and exits non-zero if an error was returned
	//
	// Deprecated: instead you should return an error that fulfills cli.ExitCoder
	// to cli.App.Run. This will cause the application to exit with the given eror
	// code in the cli.ExitCoder
	func (a *App) RunAndExitOnError() {
	if err := a.Run(os.Args); err != nil {
	_, _ = fmt.Fprintln(a.errWriter(), err)
	OsExiter(1)
	}
	}

	// RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to
	// generate command-specific flags
	func (a App) RunAsSubcommand(ctx Context) (err error) {
	// Setup also handles HideHelp and HideHelpCommand
	a.Setup()

	var newCmds []*Command
	for _, c := range a.Commands {
	if c.HelpName == "" {
	c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
	}
	newCmds = append(newCmds, c)
	}
	a.Commands = newCmds

	set, err := a.newFlagSet()
	if err != nil {
	return err
	}

	err = parseIter(set, a, ctx.Args().Tail(), ctx.shellComplete)
	nerr := normalizeFlags(a.Flags, set)
	context := NewContext(a, set, ctx)

	if nerr != nil {
	_, _ = fmt.Fprintln(a.Writer, nerr)
	_, _ = fmt.Fprintln(a.Writer)
	if len(a.Commands) > 0 {
	_ = ShowSubcommandHelp(context)
	} else {
	_ = ShowCommandHelp(ctx, context.Args().First())
	}
	return nerr
	}

	if checkCompletions(context) {
	return nil
	}

	if err != nil {
	if a.OnUsageError != nil {
	err = a.OnUsageError(context, err, true)
	a.handleExitCoder(context, err)
	return err
	}
	_, _ = fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
	_ = ShowSubcommandHelp(context)
	return err
	}

	if len(a.Commands) > 0 {
	if checkSubcommandHelp(context) {
	return nil
	}
	} else {
	if checkCommandHelp(ctx, context.Args().First()) {
	return nil
	}
	}

	cerr := checkRequiredFlags(a.Flags, context)
	if cerr != nil {
	_ = ShowSubcommandHelp(context)
	return cerr
	}

	if a.After != nil {
	defer func() {
	afterErr := a.After(context)
	if afterErr != nil {
	a.handleExitCoder(context, err)
	if err != nil {
	err = newMultiError(err, afterErr)
	} else {
	err = afterErr
	}
	}
	}()
	}

	if a.Before != nil {
	beforeErr := a.Before(context)
	if beforeErr != nil {
	a.handleExitCoder(context, beforeErr)
	err = beforeErr
	return err
	}
	}

	args := context.Args()
	if args.Present() {
	name := args.First()
	c := a.Command(name)
	if c != nil {
	return c.Run(context)
	}
	}

	// Run default Action
	err = a.Action(context)

	a.handleExitCoder(context, err)
	return err
	}

	// Command returns the named command on App. Returns nil if the command does not exist
	func (a App) Command(name string) Command {
	for _, c := range a.Commands {
	if c.HasName(name) {
	return c
	}
	}

	return nil
	}

	// VisibleCategories returns a slice of categories and commands that are
	// Hidden=false
	func (a *App) VisibleCategories() []CommandCategory {
	ret := []CommandCategory{}
	for _, category := range a.categories.Categories() {
	if visible := func() CommandCategory {
	if len(category.VisibleCommands()) > 0 {
	return category
	}
	return nil
	}(); visible != nil {
	ret = append(ret, visible)
	}
	}
	return ret
	}

	// VisibleCommands returns a slice of the Commands with Hidden=false
	func (a App) VisibleCommands() []Command {
	var ret []*Command
	for _, command := range a.Commands {
	if !command.Hidden {
	ret = append(ret, command)
	}
	}
	return ret
	}

	// VisibleFlags returns a slice of the Flags with Hidden=false
	func (a *App) VisibleFlags() []Flag {
	return visibleFlags(a.Flags)
	}

	func (a *App) errWriter() io.Writer {
	// When the app ErrWriter is nil use the package level one.
	if a.ErrWriter == nil {
	return ErrWriter
	}

	return a.ErrWriter
	}

	func (a *App) appendFlag(fl Flag) {
	if !hasFlag(a.Flags, fl) {
	a.Flags = append(a.Flags, fl)
	}
	}

	func (a App) appendCommand(c Command) {
	if !hasCommand(a.Commands, c) {
	a.Commands = append(a.Commands, c)
	}
	}

	func (a App) handleExitCoder(context Context, err error) {
	if a.ExitErrHandler != nil {
	a.ExitErrHandler(context, err)
	} else {
	HandleExitCoder(err)
	}
	}

	// Author represents someone who has contributed to a cli project.
	type Author struct {
	Name string // The Authors name
	Email string // The Authors email
	}

	// String makes Author comply to the Stringer interface, to allow an easy print in the templating process
	func (a *Author) String() string {
	e := ""
	if a.Email != "" {
	e = " <" + a.Email + ">"
	}

	return fmt.Sprintf("%v%v", a.Name, e)
	}

	// HandleAction attempts to figure out which Action signature was used. If
	// it's an ActionFunc or a func with the legacy signature for Action, the func
	// is run!
	func HandleAction(action interface{}, context *Context) (err error) {
	switch a := action.(type) {
	case ActionFunc:
	return a(context)
	case func(*Context) error:
	return a(context)
	case func(*Context): // deprecated function signature
	a(context)
	return nil
	}

	return errInvalidActionType
	}