prometheus/vendor/gopkg.in/alecthomas/kingpin.v2/flags.go
2017-07-27 13:08:20 +02:00

309 lines
7.2 KiB
Go

package kingpin
import (
"fmt"
"strings"
)
type flagGroup struct {
short map[string]*FlagClause
long map[string]*FlagClause
flagOrder []*FlagClause
}
func newFlagGroup() *flagGroup {
return &flagGroup{
short: map[string]*FlagClause{},
long: map[string]*FlagClause{},
}
}
// GetFlag gets a flag definition.
//
// This allows existing flags to be modified after definition but before parsing. Useful for
// modular applications.
func (f *flagGroup) GetFlag(name string) *FlagClause {
return f.long[name]
}
// Flag defines a new flag with the given long name and help.
func (f *flagGroup) Flag(name, help string) *FlagClause {
flag := newFlag(name, help)
f.long[name] = flag
f.flagOrder = append(f.flagOrder, flag)
return flag
}
func (f *flagGroup) init(defaultEnvarPrefix string) error {
if err := f.checkDuplicates(); err != nil {
return err
}
for _, flag := range f.long {
if defaultEnvarPrefix != "" && !flag.noEnvar && flag.envar == "" {
flag.envar = envarTransform(defaultEnvarPrefix + "_" + flag.name)
}
if err := flag.init(); err != nil {
return err
}
if flag.shorthand != 0 {
f.short[string(flag.shorthand)] = flag
}
}
return nil
}
func (f *flagGroup) checkDuplicates() error {
seenShort := map[rune]bool{}
seenLong := map[string]bool{}
for _, flag := range f.flagOrder {
if flag.shorthand != 0 {
if _, ok := seenShort[flag.shorthand]; ok {
return fmt.Errorf("duplicate short flag -%c", flag.shorthand)
}
seenShort[flag.shorthand] = true
}
if _, ok := seenLong[flag.name]; ok {
return fmt.Errorf("duplicate long flag --%s", flag.name)
}
seenLong[flag.name] = true
}
return nil
}
func (f *flagGroup) parse(context *ParseContext) (*FlagClause, error) {
var token *Token
loop:
for {
token = context.Peek()
switch token.Type {
case TokenEOL:
break loop
case TokenLong, TokenShort:
flagToken := token
defaultValue := ""
var flag *FlagClause
var ok bool
invert := false
name := token.Value
if token.Type == TokenLong {
flag, ok = f.long[name]
if !ok {
if strings.HasPrefix(name, "no-") {
name = name[3:]
invert = true
}
flag, ok = f.long[name]
}
if !ok {
return nil, fmt.Errorf("unknown long flag '%s'", flagToken)
}
} else {
flag, ok = f.short[name]
if !ok {
return nil, fmt.Errorf("unknown short flag '%s'", flagToken)
}
}
context.Next()
fb, ok := flag.value.(boolFlag)
if ok && fb.IsBoolFlag() {
if invert {
defaultValue = "false"
} else {
defaultValue = "true"
}
} else {
if invert {
context.Push(token)
return nil, fmt.Errorf("unknown long flag '%s'", flagToken)
}
token = context.Peek()
if token.Type != TokenArg {
context.Push(token)
return nil, fmt.Errorf("expected argument for flag '%s'", flagToken)
}
context.Next()
defaultValue = token.Value
}
context.matchedFlag(flag, defaultValue)
return flag, nil
default:
break loop
}
}
return nil, nil
}
// FlagClause is a fluid interface used to build flags.
type FlagClause struct {
parserMixin
actionMixin
completionsMixin
envarMixin
name string
shorthand rune
help string
defaultValues []string
placeholder string
hidden bool
}
func newFlag(name, help string) *FlagClause {
f := &FlagClause{
name: name,
help: help,
}
return f
}
func (f *FlagClause) setDefault() error {
if f.HasEnvarValue() {
if v, ok := f.value.(repeatableFlag); !ok || !v.IsCumulative() {
// Use the value as-is
return f.value.Set(f.GetEnvarValue())
} else {
for _, value := range f.GetSplitEnvarValue() {
if err := f.value.Set(value); err != nil {
return err
}
}
return nil
}
}
if len(f.defaultValues) > 0 {
for _, defaultValue := range f.defaultValues {
if err := f.value.Set(defaultValue); err != nil {
return err
}
}
return nil
}
return nil
}
func (f *FlagClause) needsValue() bool {
haveDefault := len(f.defaultValues) > 0
return f.required && !(haveDefault || f.HasEnvarValue())
}
func (f *FlagClause) init() error {
if f.required && len(f.defaultValues) > 0 {
return fmt.Errorf("required flag '--%s' with default value that will never be used", f.name)
}
if f.value == nil {
return fmt.Errorf("no type defined for --%s (eg. .String())", f.name)
}
if v, ok := f.value.(repeatableFlag); (!ok || !v.IsCumulative()) && len(f.defaultValues) > 1 {
return fmt.Errorf("invalid default for '--%s', expecting single value", f.name)
}
return nil
}
// Dispatch to the given function after the flag is parsed and validated.
func (f *FlagClause) Action(action Action) *FlagClause {
f.addAction(action)
return f
}
func (f *FlagClause) PreAction(action Action) *FlagClause {
f.addPreAction(action)
return f
}
// HintAction registers a HintAction (function) for the flag to provide completions
func (a *FlagClause) HintAction(action HintAction) *FlagClause {
a.addHintAction(action)
return a
}
// HintOptions registers any number of options for the flag to provide completions
func (a *FlagClause) HintOptions(options ...string) *FlagClause {
a.addHintAction(func() []string {
return options
})
return a
}
func (a *FlagClause) EnumVar(target *string, options ...string) {
a.parserMixin.EnumVar(target, options...)
a.addHintActionBuiltin(func() []string {
return options
})
}
func (a *FlagClause) Enum(options ...string) (target *string) {
a.addHintActionBuiltin(func() []string {
return options
})
return a.parserMixin.Enum(options...)
}
// Default values for this flag. They *must* be parseable by the value of the flag.
func (f *FlagClause) Default(values ...string) *FlagClause {
f.defaultValues = values
return f
}
// DEPRECATED: Use Envar(name) instead.
func (f *FlagClause) OverrideDefaultFromEnvar(envar string) *FlagClause {
return f.Envar(envar)
}
// Envar overrides the default value(s) for a flag from an environment variable,
// if it is set. Several default values can be provided by using new lines to
// separate them.
func (f *FlagClause) Envar(name string) *FlagClause {
f.envar = name
f.noEnvar = false
return f
}
// NoEnvar forces environment variable defaults to be disabled for this flag.
// Most useful in conjunction with app.DefaultEnvars().
func (f *FlagClause) NoEnvar() *FlagClause {
f.envar = ""
f.noEnvar = true
return f
}
// PlaceHolder sets the place-holder string used for flag values in the help. The
// default behaviour is to use the value provided by Default() if provided,
// then fall back on the capitalized flag name.
func (f *FlagClause) PlaceHolder(placeholder string) *FlagClause {
f.placeholder = placeholder
return f
}
// Hidden hides a flag from usage but still allows it to be used.
func (f *FlagClause) Hidden() *FlagClause {
f.hidden = true
return f
}
// Required makes the flag required. You can not provide a Default() value to a Required() flag.
func (f *FlagClause) Required() *FlagClause {
f.required = true
return f
}
// Short sets the short flag name.
func (f *FlagClause) Short(name rune) *FlagClause {
f.shorthand = name
return f
}
// Bool makes this flag a boolean flag.
func (f *FlagClause) Bool() (target *bool) {
target = new(bool)
f.SetValue(newBoolValue(target))
return
}