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package kingpin
import (
"fmt"
"io"
"os"
"regexp"
"strings"
)
var (
ErrCommandNotSpecified = fmt.Errorf("command not specified")
)
var (
envarTransformRegexp = regexp.MustCompile(`[^a-zA-Z0-9_]+`)
)
type ApplicationValidator func(*Application) error
// An Application contains the definitions of flags, arguments and commands
// for an application.
type Application struct {
cmdMixin
initialized bool
Name string
Help string
author string
version string
errorWriter io.Writer // Destination for errors.
usageWriter io.Writer // Destination for usage
usageTemplate string
validator ApplicationValidator
terminate func(status int) // See Terminate()
noInterspersed bool // can flags be interspersed with args (or must they come first)
defaultEnvars bool
completion bool
// Help flag. Exposed for user customisation.
HelpFlag *FlagClause
// Help command. Exposed for user customisation. May be nil.
HelpCommand *CmdClause
// Version flag. Exposed for user customisation. May be nil.
VersionFlag *FlagClause
}
// New creates a new Kingpin application instance.
func New(name, help string) *Application {
a := &Application{
Name: name,
Help: help,
errorWriter: os.Stderr, // Left for backwards compatibility purposes.
usageWriter: os.Stderr,
usageTemplate: DefaultUsageTemplate,
terminate: os.Exit,
}
a.flagGroup = newFlagGroup()
a.argGroup = newArgGroup()
a.cmdGroup = newCmdGroup(a)
a.HelpFlag = a.Flag("help", "Show context-sensitive help (also try --help-long and --help-man).")
a.HelpFlag.Bool()
a.Flag("help-long", "Generate long help.").Hidden().PreAction(a.generateLongHelp).Bool()
a.Flag("help-man", "Generate a man page.").Hidden().PreAction(a.generateManPage).Bool()
a.Flag("completion-bash", "Output possible completions for the given args.").Hidden().BoolVar(&a.completion)
a.Flag("completion-script-bash", "Generate completion script for bash.").Hidden().PreAction(a.generateBashCompletionScript).Bool()
a.Flag("completion-script-zsh", "Generate completion script for ZSH.").Hidden().PreAction(a.generateZSHCompletionScript).Bool()
return a
}
func (a *Application) generateLongHelp(c *ParseContext) error {
a.Writer(os.Stdout)
if err := a.UsageForContextWithTemplate(c, 2, LongHelpTemplate); err != nil {
return err
}
a.terminate(0)
return nil
}
func (a *Application) generateManPage(c *ParseContext) error {
a.Writer(os.Stdout)
if err := a.UsageForContextWithTemplate(c, 2, ManPageTemplate); err != nil {
return err
}
a.terminate(0)
return nil
}
func (a *Application) generateBashCompletionScript(c *ParseContext) error {
a.Writer(os.Stdout)
if err := a.UsageForContextWithTemplate(c, 2, BashCompletionTemplate); err != nil {
return err
}
a.terminate(0)
return nil
}
func (a *Application) generateZSHCompletionScript(c *ParseContext) error {
a.Writer(os.Stdout)
if err := a.UsageForContextWithTemplate(c, 2, ZshCompletionTemplate); err != nil {
return err
}
a.terminate(0)
return nil
}
// DefaultEnvars configures all flags (that do not already have an associated
// envar) to use a default environment variable in the form "<app>_<flag>".
//
// For example, if the application is named "foo" and a flag is named "bar-
// waz" the environment variable: "FOO_BAR_WAZ".
func (a *Application) DefaultEnvars() *Application {
a.defaultEnvars = true
return a
}
// Terminate specifies the termination handler. Defaults to os.Exit(status).
// If nil is passed, a no-op function will be used.
func (a *Application) Terminate(terminate func(int)) *Application {
if terminate == nil {
terminate = func(int) {}
}
a.terminate = terminate
return a
}
// Writer specifies the writer to use for usage and errors. Defaults to os.Stderr.
// DEPRECATED: See ErrorWriter and UsageWriter.
func (a *Application) Writer(w io.Writer) *Application {
a.errorWriter = w
a.usageWriter = w
return a
}
// ErrorWriter sets the io.Writer to use for errors.
func (a *Application) ErrorWriter(w io.Writer) *Application {
a.errorWriter = w
return a
}
// UsageWriter sets the io.Writer to use for errors.
func (a *Application) UsageWriter(w io.Writer) *Application {
a.usageWriter = w
return a
}
// UsageTemplate specifies the text template to use when displaying usage
// information. The default is UsageTemplate.
func (a *Application) UsageTemplate(template string) *Application {
a.usageTemplate = template
return a
}
// Validate sets a validation function to run when parsing.
func (a *Application) Validate(validator ApplicationValidator) *Application {
a.validator = validator
return a
}
// ParseContext parses the given command line and returns the fully populated
// ParseContext.
func (a *Application) ParseContext(args []string) (*ParseContext, error) {
return a.parseContext(false, args)
}
func (a *Application) parseContext(ignoreDefault bool, args []string) (*ParseContext, error) {
if err := a.init(); err != nil {
return nil, err
}
context := tokenize(args, ignoreDefault)
err := parse(context, a)
return context, err
}
// Parse parses command-line arguments. It returns the selected command and an
// error. The selected command will be a space separated subcommand, if
// subcommands have been configured.
//
// This will populate all flag and argument values, call all callbacks, and so
// on.
func (a *Application) Parse(args []string) (command string, err error) {
context, parseErr := a.ParseContext(args)
selected := []string{}
var setValuesErr error
if context == nil {
// Since we do not throw error immediately, there could be a case
// where a context returns nil. Protect against that.
return "", parseErr
}
if err = a.setDefaults(context); err != nil {
return "", err
}
selected, setValuesErr = a.setValues(context)
if err = a.applyPreActions(context, !a.completion); err != nil {
return "", err
}
if a.completion {
a.generateBashCompletion(context)
a.terminate(0)
} else {
if parseErr != nil {
return "", parseErr
}
a.maybeHelp(context)
if !context.EOL() {
return "", fmt.Errorf("unexpected argument '%s'", context.Peek())
}
if setValuesErr != nil {
return "", setValuesErr
}
command, err = a.execute(context, selected)
if err == ErrCommandNotSpecified {
a.writeUsage(context, nil)
}
}
return command, err
}
func (a *Application) writeUsage(context *ParseContext, err error) {
if err != nil {
a.Errorf("%s", err)
}
if err := a.UsageForContext(context); err != nil {
panic(err)
}
if err != nil {
a.terminate(1)
} else {
a.terminate(0)
}
}
func (a *Application) maybeHelp(context *ParseContext) {
for _, element := range context.Elements {
if flag, ok := element.Clause.(*FlagClause); ok && flag == a.HelpFlag {
// Re-parse the command-line ignoring defaults, so that help works correctly.
context, _ = a.parseContext(true, context.rawArgs)
a.writeUsage(context, nil)
}
}
}
// Version adds a --version flag for displaying the application version.
func (a *Application) Version(version string) *Application {
a.version = version
a.VersionFlag = a.Flag("version", "Show application version.").PreAction(func(*ParseContext) error {
fmt.Fprintln(a.usageWriter, version)
a.terminate(0)
return nil
})
a.VersionFlag.Bool()
return a
}
// Author sets the author output by some help templates.
func (a *Application) Author(author string) *Application {
a.author = author
return a
}
// Action callback to call when all values are populated and parsing is
// complete, but before any command, flag or argument actions.
//
// All Action() callbacks are called in the order they are encountered on the
// command line.
func (a *Application) Action(action Action) *Application {
a.addAction(action)
return a
}
// Action called after parsing completes but before validation and execution.
func (a *Application) PreAction(action Action) *Application {
a.addPreAction(action)
return a
}
// Command adds a new top-level command.
func (a *Application) Command(name, help string) *CmdClause {
return a.addCommand(name, help)
}
// Interspersed control if flags can be interspersed with positional arguments
//
// true (the default) means that they can, false means that all the flags must appear before the first positional arguments.
func (a *Application) Interspersed(interspersed bool) *Application {
a.noInterspersed = !interspersed
return a
}
func (a *Application) defaultEnvarPrefix() string {
if a.defaultEnvars {
return a.Name
}
return ""
}
func (a *Application) init() error {
if a.initialized {
return nil
}
if a.cmdGroup.have() && a.argGroup.have() {
return fmt.Errorf("can't mix top-level Arg()s with Command()s")
}
// If we have subcommands, add a help command at the top-level.
if a.cmdGroup.have() {
var command []string
a.HelpCommand = a.Command("help", "Show help.").PreAction(func(context *ParseContext) error {
a.Usage(command)
a.terminate(0)
return nil
})
a.HelpCommand.Arg("command", "Show help on command.").StringsVar(&command)
// Make help first command.
l := len(a.commandOrder)
a.commandOrder = append(a.commandOrder[l-1:l], a.commandOrder[:l-1]...)
}
if err := a.flagGroup.init(a.defaultEnvarPrefix()); err != nil {
return err
}
if err := a.cmdGroup.init(); err != nil {
return err
}
if err := a.argGroup.init(); err != nil {
return err
}
for _, cmd := range a.commands {
if err := cmd.init(); err != nil {
return err
}
}
flagGroups := []*flagGroup{a.flagGroup}
for _, cmd := range a.commandOrder {
if err := checkDuplicateFlags(cmd, flagGroups); err != nil {
return err
}
}
a.initialized = true
return nil
}
// Recursively check commands for duplicate flags.
func checkDuplicateFlags(current *CmdClause, flagGroups []*flagGroup) error {
// Check for duplicates.
for _, flags := range flagGroups {
for _, flag := range current.flagOrder {
if flag.shorthand != 0 {
if _, ok := flags.short[string(flag.shorthand)]; ok {
return fmt.Errorf("duplicate short flag -%c", flag.shorthand)
}
}
if _, ok := flags.long[flag.name]; ok {
return fmt.Errorf("duplicate long flag --%s", flag.name)
}
}
}
flagGroups = append(flagGroups, current.flagGroup)
// Check subcommands.
for _, subcmd := range current.commandOrder {
if err := checkDuplicateFlags(subcmd, flagGroups); err != nil {
return err
}
}
return nil
}
func (a *Application) execute(context *ParseContext, selected []string) (string, error) {
var err error
if err = a.validateRequired(context); err != nil {
return "", err
}
if err = a.applyValidators(context); err != nil {
return "", err
}
if err = a.applyActions(context); err != nil {
return "", err
}
command := strings.Join(selected, " ")
if command == "" && a.cmdGroup.have() {
return "", ErrCommandNotSpecified
}
return command, err
}
func (a *Application) setDefaults(context *ParseContext) error {
flagElements := map[string]*ParseElement{}
for _, element := range context.Elements {
if flag, ok := element.Clause.(*FlagClause); ok {
if flag.name == "help" {
return nil
}
flagElements[flag.name] = element
}
}
argElements := map[string]*ParseElement{}
for _, element := range context.Elements {
if arg, ok := element.Clause.(*ArgClause); ok {
argElements[arg.name] = element
}
}
// Check required flags and set defaults.
for _, flag := range context.flags.long {
if flagElements[flag.name] == nil {
if err := flag.setDefault(); err != nil {
return err
}
}
}
for _, arg := range context.arguments.args {
if argElements[arg.name] == nil {
if err := arg.setDefault(); err != nil {
return err
}
}
}
return nil
}
func (a *Application) validateRequired(context *ParseContext) error {
flagElements := map[string]*ParseElement{}
for _, element := range context.Elements {
if flag, ok := element.Clause.(*FlagClause); ok {
flagElements[flag.name] = element
}
}
argElements := map[string]*ParseElement{}
for _, element := range context.Elements {
if arg, ok := element.Clause.(*ArgClause); ok {
argElements[arg.name] = element
}
}
// Check required flags and set defaults.
for _, flag := range context.flags.long {
if flagElements[flag.name] == nil {
// Check required flags were provided.
if flag.needsValue() {
return fmt.Errorf("required flag --%s not provided", flag.name)
}
}
}
for _, arg := range context.arguments.args {
if argElements[arg.name] == nil {
if arg.needsValue() {
return fmt.Errorf("required argument '%s' not provided", arg.name)
}
}
}
return nil
}
func (a *Application) setValues(context *ParseContext) (selected []string, err error) {
// Set all arg and flag values.
var (
lastCmd *CmdClause
flagSet = map[string]struct{}{}
)
for _, element := range context.Elements {
switch clause := element.Clause.(type) {
case *FlagClause:
if _, ok := flagSet[clause.name]; ok {
if v, ok := clause.value.(repeatableFlag); !ok || !v.IsCumulative() {
return nil, fmt.Errorf("flag '%s' cannot be repeated", clause.name)
}
}
if err = clause.value.Set(*element.Value); err != nil {
return
}
flagSet[clause.name] = struct{}{}
case *ArgClause:
if err = clause.value.Set(*element.Value); err != nil {
return
}
case *CmdClause:
if clause.validator != nil {
if err = clause.validator(clause); err != nil {
return
}
}
selected = append(selected, clause.name)
lastCmd = clause
}
}
if lastCmd != nil && len(lastCmd.commands) > 0 {
return nil, fmt.Errorf("must select a subcommand of '%s'", lastCmd.FullCommand())
}
return
}
func (a *Application) applyValidators(context *ParseContext) (err error) {
// Call command validation functions.
for _, element := range context.Elements {
if cmd, ok := element.Clause.(*CmdClause); ok && cmd.validator != nil {
if err = cmd.validator(cmd); err != nil {
return err
}
}
}
if a.validator != nil {
err = a.validator(a)
}
return err
}
func (a *Application) applyPreActions(context *ParseContext, dispatch bool) error {
if err := a.actionMixin.applyPreActions(context); err != nil {
return err
}
// Dispatch to actions.
if dispatch {
for _, element := range context.Elements {
if applier, ok := element.Clause.(actionApplier); ok {
if err := applier.applyPreActions(context); err != nil {
return err
}
}
}
}
return nil
}
func (a *Application) applyActions(context *ParseContext) error {
if err := a.actionMixin.applyActions(context); err != nil {
return err
}
// Dispatch to actions.
for _, element := range context.Elements {
if applier, ok := element.Clause.(actionApplier); ok {
if err := applier.applyActions(context); err != nil {
return err
}
}
}
return nil
}
// Errorf prints an error message to w in the format "<appname>: error: <message>".
func (a *Application) Errorf(format string, args ...interface{}) {
fmt.Fprintf(a.errorWriter, a.Name+": error: "+format+"\n", args...)
}
// Fatalf writes a formatted error to w then terminates with exit status 1.
func (a *Application) Fatalf(format string, args ...interface{}) {
a.Errorf(format, args...)
a.terminate(1)
}
// FatalUsage prints an error message followed by usage information, then
// exits with a non-zero status.
func (a *Application) FatalUsage(format string, args ...interface{}) {
a.Errorf(format, args...)
// Force usage to go to error output.
a.usageWriter = a.errorWriter
a.Usage([]string{})
a.terminate(1)
}
// FatalUsageContext writes a printf formatted error message to w, then usage
// information for the given ParseContext, before exiting.
func (a *Application) FatalUsageContext(context *ParseContext, format string, args ...interface{}) {
a.Errorf(format, args...)
if err := a.UsageForContext(context); err != nil {
panic(err)
}
a.terminate(1)
}
// FatalIfError prints an error and exits if err is not nil. The error is printed
// with the given formatted string, if any.
func (a *Application) FatalIfError(err error, format string, args ...interface{}) {
if err != nil {
prefix := ""
if format != "" {
prefix = fmt.Sprintf(format, args...) + ": "
}
a.Errorf(prefix+"%s", err)
a.terminate(1)
}
}
func (a *Application) completionOptions(context *ParseContext) []string {
args := context.rawArgs
var (
currArg string
prevArg string
target cmdMixin
)
numArgs := len(args)
if numArgs > 1 {
args = args[1:]
currArg = args[len(args)-1]
}
if numArgs > 2 {
prevArg = args[len(args)-2]
}
target = a.cmdMixin
if context.SelectedCommand != nil {
// A subcommand was in use. We will use it as the target
target = context.SelectedCommand.cmdMixin
}
if (currArg != "" && strings.HasPrefix(currArg, "--")) || strings.HasPrefix(prevArg, "--") {
// Perform completion for A flag. The last/current argument started with "-"
var (
flagName string // The name of a flag if given (could be half complete)
flagValue string // The value assigned to a flag (if given) (could be half complete)
)
if strings.HasPrefix(prevArg, "--") && !strings.HasPrefix(currArg, "--") {
// Matches: ./myApp --flag value
// Wont Match: ./myApp --flag --
flagName = prevArg[2:] // Strip the "--"
flagValue = currArg
} else if strings.HasPrefix(currArg, "--") {
// Matches: ./myApp --flag --
// Matches: ./myApp --flag somevalue --
// Matches: ./myApp --
flagName = currArg[2:] // Strip the "--"
}
options, flagMatched, valueMatched := target.FlagCompletion(flagName, flagValue)
if valueMatched {
// Value Matched. Show cmdCompletions
return target.CmdCompletion(context)
}
// Add top level flags if we're not at the top level and no match was found.
if context.SelectedCommand != nil && !flagMatched {
topOptions, topFlagMatched, topValueMatched := a.FlagCompletion(flagName, flagValue)
if topValueMatched {
// Value Matched. Back to cmdCompletions
return target.CmdCompletion(context)
}
if topFlagMatched {
// Top level had a flag which matched the input. Return it's options.
options = topOptions
} else {
// Add top level flags
options = append(options, topOptions...)
}
}
return options
}
// Perform completion for sub commands and arguments.
return target.CmdCompletion(context)
}
func (a *Application) generateBashCompletion(context *ParseContext) {
options := a.completionOptions(context)
fmt.Printf("%s", strings.Join(options, "\n"))
}
func envarTransform(name string) string {
return strings.ToUpper(envarTransformRegexp.ReplaceAllString(name, "_"))
}
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