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flag.go
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flag.go
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package fcli
import (
"errors"
"flag"
"fmt"
"math"
"reflect"
"github.com/berquerant/fcli/internal/logger"
)
// Flag is a command-line flag.
type Flag interface {
// Name is the flag name.
Name() string
// AddFlag defines the flag in the flag set.
AddFlag(flagSet *flag.FlagSet)
// Unwrap returns the flag value.
// Default value is the zero value.
Unwrap() (any, error)
// ReflectValue returns the flag value for reflection.
// Default value is the zero value.
ReflectValue() (reflect.Value, error)
}
type baseFlag struct {
name string
}
func (s *baseFlag) Name() string { return s.name }
func newBaseFlag(name string) *baseFlag {
return &baseFlag{
name: name,
}
}
// IntFlag is a flag for int.
type IntFlag struct {
*baseFlag
value *int
}
func NewIntFlag(name string) Flag {
return &IntFlag{
baseFlag: newBaseFlag(name),
}
}
func (s *IntFlag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Int(s.name, 0, "") }
func (s *IntFlag) Value() (int, error) { return *s.value, nil }
func (s *IntFlag) Unwrap() (any, error) { return s.Value() }
func (s *IntFlag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
var (
// ErrValueOutOfRange is the error returned if the parsed value from the command-line arguments
// is the out of the range.
ErrValueOutOfRange = errors.New("value out of range")
)
type sizedIntFlag struct {
*IntFlag
min, max int
}
func newSizedIntFlag(name string, min, max int) *sizedIntFlag {
return &sizedIntFlag{
IntFlag: &IntFlag{
baseFlag: newBaseFlag(name),
},
min: min,
max: max,
}
}
func (s *sizedIntFlag) Value() (int, error) {
v := *s.value
if v < s.min || v > s.max {
return 0, ErrValueOutOfRange
}
return v, nil
}
func (s *sizedIntFlag) Unwrap() (any, error) { return s.Value() }
// Int8Flag is the flag for int8.
type Int8Flag struct {
*sizedIntFlag
}
func NewInt8Flag(name string) Flag {
return &Int8Flag{
sizedIntFlag: newSizedIntFlag(name, math.MinInt8, math.MaxInt8),
}
}
func (s *Int8Flag) Unwrap() (any, error) { return s.Value() }
func (s *Int8Flag) Value() (int8, error) {
v, err := s.sizedIntFlag.Value()
if err != nil {
return 0, err
}
return int8(v), nil
}
func (s *Int8Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Int16Flag is the flag for int16.
type Int16Flag struct {
*sizedIntFlag
}
func NewInt16Flag(name string) Flag {
return &Int16Flag{
sizedIntFlag: newSizedIntFlag(name, math.MinInt16, math.MaxInt16),
}
}
func (s *Int16Flag) Unwrap() (any, error) { return s.Value() }
func (s *Int16Flag) Value() (int16, error) {
v, err := s.sizedIntFlag.Value()
if err != nil {
return 0, err
}
return int16(v), nil
}
func (s *Int16Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Int32Flag is the flag for int32.
type Int32Flag struct {
*sizedIntFlag
}
func NewInt32Flag(name string) Flag {
return &Int32Flag{
sizedIntFlag: newSizedIntFlag(name, math.MinInt32, math.MaxInt32),
}
}
func (s *Int32Flag) Unwrap() (any, error) { return s.Value() }
func (s *Int32Flag) Value() (int32, error) {
v, err := s.sizedIntFlag.Value()
if err != nil {
return 0, err
}
return int32(v), nil
}
func (s *Int32Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Int64Flag is the flag for int64.
type Int64Flag struct {
*baseFlag
value *int64
}
func NewInt64Flag(name string) Flag {
return &Int64Flag{
baseFlag: newBaseFlag(name),
}
}
func (s *Int64Flag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Int64(s.name, 0, "") }
func (s *Int64Flag) Value() (int64, error) { return *s.value, nil }
func (s *Int64Flag) Unwrap() (any, error) { return s.Value() }
func (s *Int64Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// UintFlag is the flag for uint.
type UintFlag struct {
*baseFlag
value *uint
}
func NewUintFlag(name string) Flag {
return &UintFlag{
baseFlag: newBaseFlag(name),
}
}
func (s *UintFlag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Uint(s.name, 0, "") }
func (s *UintFlag) Value() (uint, error) { return *s.value, nil }
func (s *UintFlag) Unwrap() (any, error) { return s.Value() }
func (s *UintFlag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
type sizedUintFlag struct {
*UintFlag
max uint
}
func newSizedUintFlag(name string, max uint) *sizedUintFlag {
return &sizedUintFlag{
UintFlag: &UintFlag{
baseFlag: newBaseFlag(name),
},
max: max,
}
}
func (s *sizedUintFlag) Value() (uint, error) {
v := *s.value
if v > s.max {
return 0, ErrValueOutOfRange
}
return v, nil
}
func (s *sizedUintFlag) Unwrap() (any, error) { return s.Value() }
// Uint8Flag is the flag for uint8.
type Uint8Flag struct {
*sizedUintFlag
}
func NewUint8Flag(name string) Flag {
return &Uint8Flag{
sizedUintFlag: newSizedUintFlag(name, math.MaxUint8),
}
}
func (s *Uint8Flag) Unwrap() (any, error) { return s.Value() }
func (s *Uint8Flag) Value() (uint8, error) {
v, err := s.sizedUintFlag.Value()
if err != nil {
return 0, err
}
return uint8(v), nil
}
func (s *Uint8Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Uint16Flag is the flag for uint16.
type Uint16Flag struct {
*sizedUintFlag
}
func NewUint16Flag(name string) Flag {
return &Uint16Flag{
sizedUintFlag: newSizedUintFlag(name, math.MaxUint16),
}
}
func (s *Uint16Flag) Unwrap() (any, error) { return s.Value() }
func (s *Uint16Flag) Value() (uint16, error) {
v, err := s.sizedUintFlag.Value()
if err != nil {
return 0, err
}
return uint16(v), nil
}
func (s *Uint16Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Uint32Flag is the flag for uint32.
type Uint32Flag struct {
*sizedUintFlag
}
func NewUint32Flag(name string) Flag {
return &Uint32Flag{
sizedUintFlag: newSizedUintFlag(name, math.MaxUint32),
}
}
func (s *Uint32Flag) Unwrap() (any, error) { return s.Value() }
func (s *Uint32Flag) Value() (uint32, error) {
v, err := s.sizedUintFlag.Value()
if err != nil {
return 0, err
}
return uint32(v), nil
}
func (s *Uint32Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Uint64Flag is the flag for uint64.
type Uint64Flag struct {
*baseFlag
value *uint64
}
func NewUint64Flag(name string) Flag {
return &Uint64Flag{
baseFlag: newBaseFlag(name),
}
}
func (s *Uint64Flag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Uint64(s.name, 0, "") }
func (s *Uint64Flag) Value() (uint64, error) { return *s.value, nil }
func (s *Uint64Flag) Unwrap() (any, error) { return s.Value() }
func (s *Uint64Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// BoolFlag is the flag for bool.
type BoolFlag struct {
*baseFlag
value *bool
}
func NewBoolFlag(name string) Flag {
return &BoolFlag{
baseFlag: newBaseFlag(name),
}
}
func (s *BoolFlag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Bool(s.name, false, "") }
func (s *BoolFlag) Value() (bool, error) { return *s.value, nil }
func (s *BoolFlag) Unwrap() (any, error) { return s.Value() }
func (s *BoolFlag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Float64Flag is the flag for float64.
type Float64Flag struct {
*baseFlag
value *float64
}
func NewFloat64Flag(name string) Flag {
return &Float64Flag{
baseFlag: newBaseFlag(name),
}
}
func (s *Float64Flag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.Float64(s.name, 0, "") }
func (s *Float64Flag) Value() (float64, error) { return *s.value, nil }
func (s *Float64Flag) Unwrap() (any, error) { return s.Value() }
func (s *Float64Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
// Float32Flag is the flag for float32.
type Float32Flag struct {
*Float64Flag
}
func NewFloat32Flag(name string) Flag {
return &Float32Flag{
Float64Flag: &Float64Flag{
baseFlag: newBaseFlag(name),
},
}
}
func (s *Float32Flag) Value() (float32, error) {
v, err := s.Float64Flag.Value()
if err != nil {
return 0, err
}
if v < -math.MaxFloat32 || v > math.MaxFloat32 {
return 0, ErrValueOutOfRange
}
return float32(v), nil
}
func (s *Float32Flag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
func (s *Float32Flag) Unwrap() (any, error) { return s.Value() }
// StringFlag is the flag for string.
type StringFlag struct {
*baseFlag
value *string
}
func NewStringFlag(name string) Flag {
return &StringFlag{
baseFlag: newBaseFlag(name),
}
}
func (s *StringFlag) AddFlag(flagSet *flag.FlagSet) { s.value = flagSet.String(s.name, "", "") }
func (s *StringFlag) Value() (string, error) { return *s.value, nil }
func (s *StringFlag) Unwrap() (any, error) { return s.Value() }
func (s *StringFlag) ReflectValue() (reflect.Value, error) {
v, err := s.Value()
return reflect.ValueOf(v), err
}
var (
// ErrInvalidCustomFlag is the error returned if failed to parse the value of the custom flag.
ErrCannotUnmarshalCustomFlag = errors.New("cannot unmarshal custom flag")
// ErrInvalidCustomFlag is the error returned if the type of the flag is not proper.
ErrInvalidCustomFlag = errors.New("invalid custom flag")
)
// CustomFlagUnmarshaller should be implemented by the type for CustomFlag.
type CustomFlagUnmarshaller interface {
// UnmarshalFlag converts string into the value.
// The value must be the implementing type.
UnmarshalFlag(string) (CustomFlagUnmarshaller, error)
}
// CustomFlagZeroer provides zero value.
type CustomFlagZeroer interface {
FlagZero() CustomFlagUnmarshaller
}
// CustomFlag is the flag for types that implement CustomFlagUnmarshaller.
type CustomFlag struct {
*baseFlag
typ reflect.Type
value any
}
// NewCustomFlag returns the new CustomFlag.
// typ is the type that implements CustomFlagUnmarshaller.
// struct should be passed as pointer.
// If typ implements CustomFlagZeroer, use it as the default value of the flag.
func NewCustomFlag(name string, typ reflect.Type) (Flag, error) {
v := reflect.Zero(typ).Interface()
if _, ok := v.(CustomFlagUnmarshaller); ok {
f := &CustomFlag{
baseFlag: newBaseFlag(name),
typ: typ,
}
if x, ok := v.(CustomFlagZeroer); ok {
f.value = x.FlagZero()
}
return f, nil
}
return nil, fmt.Errorf("%w %s", ErrInvalidCustomFlag, name)
}
func (s *CustomFlag) AddFlag(flagSet *flag.FlagSet) {
flagSet.Func(s.name, "", s.parse)
}
func (s *CustomFlag) parse(v string) error {
z := reflect.Zero(s.typ).Interface()
m, ok := z.(CustomFlagUnmarshaller)
if !ok {
return fmt.Errorf("%w type assertion %#v %s %s", ErrCannotUnmarshalCustomFlag, z, s.name, v)
}
p, err := m.UnmarshalFlag(v)
if err != nil {
return fmt.Errorf("%w UnmarshalFlag() %s %s %v", ErrCannotUnmarshalCustomFlag, s.name, v, err)
}
logger.Trace("CustomFlag %s parse %s into %#v", s.Name(), v, p)
s.value = p
return nil
}
func (s *CustomFlag) Unwrap() (any, error) { return s.value, nil }
func (s *CustomFlag) ReflectValue() (reflect.Value, error) { return reflect.ValueOf(s.value), nil }
type FlagFactory func(name string) Flag
// NewFlagFactory returns the proper flag for the v.
func NewFlagFactory(v any) (FlagFactory, bool) {
newCustomFlag := func(typ reflect.Type) (FlagFactory, bool) {
if _, err := NewCustomFlag("", typ); err != nil {
return nil, false
}
return func(name string) Flag {
f, _ := NewCustomFlag(name, typ)
return f
}, true
}
t := func() reflect.Type {
if rt, ok := v.(reflect.Type); ok {
return rt
}
return reflect.TypeOf(v)
}()
logger.Trace("NewFlagFactory %v %#v", t.Kind(), v)
if f, ok := newCustomFlag(t); ok {
return f, true
}
switch t.Kind() {
case reflect.Bool:
return NewBoolFlag, true
case reflect.Int:
return NewIntFlag, true
case reflect.Int8:
return NewInt8Flag, true
case reflect.Int16:
return NewInt16Flag, true
case reflect.Int32:
return NewInt32Flag, true
case reflect.Int64:
return NewInt64Flag, true
case reflect.Uint:
return NewUintFlag, true
case reflect.Uint8:
return NewUint8Flag, true
case reflect.Uint16:
return NewUint16Flag, true
case reflect.Uint32:
return NewUint32Flag, true
case reflect.Uint64:
return NewUint64Flag, true
case reflect.Float32:
return NewFloat32Flag, true
case reflect.Float64:
return NewFloat64Flag, true
case reflect.String:
return NewStringFlag, true
default:
return nil, false
}
}