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kube-arangodb/deps/github.com/voxelbrain/goptions/flag.go
2018-03-12 16:18:23 +01:00

90 lines
2.1 KiB
Go

package goptions
import (
"fmt"
"reflect"
"strings"
)
// Flag represents a single flag of a FlagSet.
type Flag struct {
Short string
Long string
MutexGroups []string
Description string
Obligatory bool
WasSpecified bool
value reflect.Value
optionMeta map[string]interface{}
DefaultValue interface{}
}
// Return the name of the flag preceding the right amount of dashes.
// The long name is preferred. If no name has been specified, "<unspecified>"
// will be returned.
func (f *Flag) Name() string {
if len(f.Long) > 0 {
return "--" + f.Long
}
if len(f.Short) > 0 {
return "-" + f.Short
}
return "<unspecified>"
}
// NeedsExtraValue returns true if the flag expects a separate value.
func (f *Flag) NeedsExtraValue() bool {
// Explicit over implicit
if f.value.Type() == reflect.TypeOf(new([]bool)).Elem() ||
f.value.Type() == reflect.TypeOf(new(bool)).Elem() {
return false
}
if _, ok := f.value.Interface().(Help); ok {
return false
}
return true
}
// IsMulti returns true if the flag can be specified multiple times.
func (f *Flag) IsMulti() bool {
if f.value.Kind() == reflect.Slice {
return true
}
return false
}
func isShort(arg string) bool {
return strings.HasPrefix(arg, "-") && !strings.HasPrefix(arg, "--") && len(arg) >= 2
}
func isLong(arg string) bool {
return strings.HasPrefix(arg, "--") && len(arg) >= 3
}
func (f *Flag) Handles(arg string) bool {
return (isShort(arg) && arg[1:2] == f.Short) ||
(isLong(arg) && arg[2:] == f.Long)
}
func (f *Flag) Parse(args []string) ([]string, error) {
param, value := args[0], ""
if f.NeedsExtraValue() &&
(len(args) < 2 || (isShort(param) && len(param) > 2)) {
return args, fmt.Errorf("Flag %s needs an argument", f.Name())
}
if f.WasSpecified && !f.IsMulti() {
return args, fmt.Errorf("Flag %s can only be specified once", f.Name())
}
if isShort(param) && len(param) > 2 {
// Short flag cluster
args[0] = "-" + param[2:]
} else if f.NeedsExtraValue() {
value = args[1]
args = args[2:]
} else {
args = args[1:]
}
f.WasSpecified = true
return args, f.setValue(value)
}