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package cli
import (
"fmt"
"io"
"io/ioutil"
"os"
"path"
"time"
)
// 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
// 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
HideHelp bool
// Boolean to hide built-in version flag
HideVersion bool
// An action to execute when the bash-completion flag is set
BashComplete func(context *Context)
// 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 func(context *Context) error
// An action to execute after any subcommands are run, but after the subcommand has finished
// It is run even if Action() panics
After func(context *Context) error
// The action to execute when no subcommands are specified
Action func(context *Context)
// Execute this function if the proper command cannot be found
CommandNotFound func(context *Context, command string)
// Execute this function, if an usage error occurs. This is useful for displaying customized usage error messages.
// This function is able to replace the original error messages.
// If this function is not set, the "Incorrect usage" is displayed and the execution is interrupted.
OnUsageError func(context *Context, err error, isSubcommand bool) error
// Compilation date
Compiled time.Time
// List of all authors who contributed
Authors []Author
// Copyright of the binary if any
Copyright string
// Name of Author (Note: Use App.Authors, this is deprecated)
Author string
// Email of Author (Note: Use App.Authors, this is deprecated)
Email string
// Writer writer to write output to
Writer io.Writer
}
// 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()
}
// Creates a new cli Application with some reasonable defaults for Name, Usage, Version and Action.
func NewApp() *App {
return &App{
Name: path.Base(os.Args[0]),
HelpName: path.Base(os.Args[0]),
Usage: "A new cli application",
UsageText: "",
Version: "0.0.0",
BashComplete: DefaultAppComplete,
Action: helpCommand.Action,
Compiled: compileTime(),
Writer: os.Stdout,
}
}
// 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) {
if a.Author != "" || a.Email != "" {
a.Authors = append(a.Authors, Author{Name: a.Author, Email: a.Email})
}
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
// append help to commands
if a.Command(helpCommand.Name) == nil && !a.HideHelp {
a.Commands = append(a.Commands, helpCommand)
if (HelpFlag != BoolFlag{}) {
a.appendFlag(HelpFlag)
}
}
//append version/help flags
if a.EnableBashCompletion {
a.appendFlag(BashCompletionFlag)
}
if !a.HideVersion {
a.appendFlag(VersionFlag)
}
// parse flags
set := flagSet(a.Name, a.Flags)
set.SetOutput(ioutil.Discard)
err = set.Parse(arguments[1:])
nerr := normalizeFlags(a.Flags, set)
context := NewContext(a, set, nil)
if nerr != nil {
fmt.Fprintln(a.Writer, nerr)
ShowAppHelp(context)
return nerr
}
if checkCompletions(context) {
return nil
}
if err != nil {
if a.OnUsageError != nil {
err := a.OnUsageError(context, err, false)
return err
} else {
fmt.Fprintf(a.Writer, "%s\n\n", "Incorrect Usage.")
ShowAppHelp(context)
return err
}
}
if !a.HideHelp && checkHelp(context) {
ShowAppHelp(context)
return nil
}
if !a.HideVersion && checkVersion(context) {
ShowVersion(context)
return nil
}
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 {
err = a.Before(context)
if err != nil {
fmt.Fprintf(a.Writer, "%v\n\n", err)
ShowAppHelp(context)
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
a.Action(context)
return nil
}
// Another entry point to the cli app, takes care of passing arguments and error handling
func (a *App) RunAndExitOnError() {
if err := a.Run(os.Args); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
// Invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags
func (a *App) RunAsSubcommand(ctx *Context) (err error) {
// append help to commands
if len(a.Commands) > 0 {
if a.Command(helpCommand.Name) == nil && !a.HideHelp {
a.Commands = append(a.Commands, helpCommand)
if (HelpFlag != BoolFlag{}) {
a.appendFlag(HelpFlag)
}
}
}
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
// append flags
if a.EnableBashCompletion {
a.appendFlag(BashCompletionFlag)
}
// parse flags
set := flagSet(a.Name, a.Flags)
set.SetOutput(ioutil.Discard)
err = set.Parse(ctx.Args().Tail())
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)
return err
} else {
fmt.Fprintf(a.Writer, "%s\n\n", "Incorrect Usage.")
ShowSubcommandHelp(context)
return err
}
}
if len(a.Commands) > 0 {
if checkSubcommandHelp(context) {
return nil
}
} else {
if checkCommandHelp(ctx, context.Args().First()) {
return nil
}
}
if a.After != nil {
defer func() {
afterErr := a.After(context)
if afterErr != nil {
if err != nil {
err = NewMultiError(err, afterErr)
} else {
err = afterErr
}
}
}()
}
if a.Before != nil {
err := a.Before(context)
if err != nil {
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
a.Action(context)
return nil
}
// 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
}
func (a *App) hasFlag(flag Flag) bool {
for _, f := range a.Flags {
if flag == f {
return true
}
}
return false
}
func (a *App) appendFlag(flag Flag) {
if !a.hasFlag(flag) {
a.Flags = append(a.Flags, flag)
}
}
// 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)
}
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