faker.go

package faker

// Faker is a simple fake data generator for your own struct.
// Save your time, and Fake your data for your testing now.
import (
	cryptorand "crypto/rand"
	"errors"
	"fmt"
	mathrand "math/rand"
	"reflect"
	"regexp"
	"strconv"
	"strings"
	"sync"
	"time"

	fakerErrors "github.com/go-faker/faker/v4/pkg/errors"
	"github.com/go-faker/faker/v4/pkg/interfaces"
	"github.com/go-faker/faker/v4/pkg/options"
	"github.com/go-faker/faker/v4/pkg/slice"
)

var (
	// Unique values are kept in memory so the generator retries if the value already exists
	uniqueValues = &sync.Map{}
)

// Supported tags
const (
	letterIdxBits             = 6                    // 6 bits to represent a letter index
	letterIdxMask             = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax              = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
	maxRetry                  = 10000                // max number of retry for unique values
	keep                      = "keep"
	unique                    = "unique"
	ID                        = "uuid_digit"
	HyphenatedID              = "uuid_hyphenated"
	EmailTag                  = "email"
	MacAddressTag             = "mac_address"
	DomainNameTag             = "domain_name"
	UserNameTag               = "username"
	URLTag                    = "url"
	IPV4Tag                   = "ipv4"
	IPV6Tag                   = "ipv6"
	PASSWORD                  = "password"
	JWT                       = "jwt"
	LATITUDE                  = "lat"
	LONGITUDE                 = "long"
	RealAddressTag            = "real_address"
	CreditCardNumber          = "cc_number"
	CreditCardType            = "cc_type"
	PhoneNumber               = "phone_number"
	TollFreeNumber            = "toll_free_number"
	E164PhoneNumberTag        = "e_164_phone_number"
	TitleMaleTag              = "title_male"
	TitleFemaleTag            = "title_female"
	FirstNameTag              = "first_name"
	FirstNameMaleTag          = "first_name_male"
	FirstNameFemaleTag        = "first_name_female"
	LastNameTag               = "last_name"
	NAME                      = "name"
	ChineseFirstNameTag       = "chinese_first_name"
	ChineseLastNameTag        = "chinese_last_name"
	ChineseNameTag            = "chinese_name"
	GENDER                    = "gender"
	UnixTimeTag               = "unix_time"
	DATE                      = "date"
	TIME                      = "time"
	MonthNameTag              = "month_name"
	YEAR                      = "year"
	DayOfWeekTag              = "day_of_week"
	DayOfMonthTag             = "day_of_month"
	TIMESTAMP                 = "timestamp"
	CENTURY                   = "century"
	TIMEZONE                  = "timezone"
	TimePeriodTag             = "time_period"
	WORD                      = "word"
	SENTENCE                  = "sentence"
	PARAGRAPH                 = "paragraph"
	CurrencyTag               = "currency"
	AmountTag                 = "amount"
	AmountWithCurrencyTag     = "amount_with_currency"
	SKIP                      = "-"
	Length                    = "len"
	SliceLength               = "slice_len"
	Language                  = "lang"
	BoundaryStart             = "boundary_start"
	BoundaryEnd               = "boundary_end"
	Equals                    = "="
	comma                     = ","
	colon                     = ":"
	ONEOF                     = "oneof"
	RussianFirstNameMaleTag   = "russian_first_name_male"
	RussianLastNameMaleTag    = "russian_last_name_male"
	RussianFirstNameFemaleTag = "russian_first_name_female"
	RussianLastNameFemaleTag  = "russian_last_name_female"
	BloodTypeTag              = "blood_type"
	CountryInfoTag            = "country_info"
	UserAgentTag              = "user_agent"
)

// PriorityTags define the priority order of the tag
var PriorityTags = []string{ID, HyphenatedID, EmailTag, MacAddressTag, DomainNameTag, UserNameTag, URLTag, IPV4Tag,
	IPV6Tag, PASSWORD, JWT, CountryInfoTag, LATITUDE, LONGITUDE, CreditCardNumber, CreditCardType, PhoneNumber, TollFreeNumber,
	E164PhoneNumberTag, TitleMaleTag, TitleFemaleTag, FirstNameTag, FirstNameMaleTag, FirstNameFemaleTag, LastNameTag,
	NAME, ChineseFirstNameTag, ChineseLastNameTag, ChineseNameTag, GENDER, UnixTimeTag, DATE, TIME, MonthNameTag,
	YEAR, DayOfWeekTag, DayOfMonthTag, TIMESTAMP, CENTURY, TIMEZONE, TimePeriodTag, WORD, SENTENCE, PARAGRAPH,
	CurrencyTag, AmountTag, AmountWithCurrencyTag, SKIP, Length, SliceLength, Language, BoundaryStart, BoundaryEnd, ONEOF, BloodTypeTag,
	UserAgentTag,
}

type mapperTagCustom struct {
	sync.Map
}

func (m *mapperTagCustom) Load(key string) (interfaces.TaggedFunction, bool) {
	mappedTagFunc, ok := m.Map.Load(key)
	if !ok {
		return nil, ok
	}
	tagFunc, ok := mappedTagFunc.(interfaces.TaggedFunction)
	if ok {
		return tagFunc, ok
	}
	tagPureFunc, ok := mappedTagFunc.(func(v reflect.Value) (interface{}, error))
	if ok {
		return tagPureFunc, ok
	}
	return nil, false
}

func (m *mapperTagCustom) Store(key string, taggedFunc interfaces.TaggedFunction) {
	m.Map.Store(key, taggedFunc)
}

var defaultTag = sync.Map{}

func initDefaultTag() {
	defaultTag.Store(BloodTypeTag, BloodTypeTag)
	defaultTag.Store(EmailTag, EmailTag)
	defaultTag.Store(MacAddressTag, MacAddressTag)
	defaultTag.Store(DomainNameTag, DomainNameTag)
	defaultTag.Store(URLTag, URLTag)
	defaultTag.Store(UserNameTag, UserNameTag)
	defaultTag.Store(IPV4Tag, IPV4Tag)
	defaultTag.Store(IPV6Tag, IPV6Tag)
	defaultTag.Store(PASSWORD, PASSWORD)
	defaultTag.Store(JWT, JWT)
	defaultTag.Store(CreditCardType, CreditCardType)
	defaultTag.Store(CreditCardNumber, CreditCardNumber)
	defaultTag.Store(CountryInfoTag, CountryInfoTag)
	defaultTag.Store(LATITUDE, LATITUDE)
	defaultTag.Store(LONGITUDE, LONGITUDE)
	defaultTag.Store(RealAddressTag, RealAddressTag)
	defaultTag.Store(PhoneNumber, PhoneNumber)
	defaultTag.Store(TollFreeNumber, TollFreeNumber)
	defaultTag.Store(E164PhoneNumberTag, E164PhoneNumberTag)
	defaultTag.Store(TitleMaleTag, TitleMaleTag)
	defaultTag.Store(TitleFemaleTag, TitleFemaleTag)
	defaultTag.Store(FirstNameTag, FirstNameTag)
	defaultTag.Store(FirstNameMaleTag, FirstNameMaleTag)
	defaultTag.Store(FirstNameFemaleTag, FirstNameFemaleTag)
	defaultTag.Store(LastNameTag, LastNameTag)
	defaultTag.Store(NAME, NAME)
	defaultTag.Store(ChineseFirstNameTag, ChineseFirstNameTag)
	defaultTag.Store(ChineseLastNameTag, ChineseLastNameTag)
	defaultTag.Store(ChineseNameTag, ChineseNameTag)
	defaultTag.Store(GENDER, GENDER)
	defaultTag.Store(UnixTimeTag, UnixTimeTag)
	defaultTag.Store(DATE, DATE)
	defaultTag.Store(TIME, TimeFormat)
	defaultTag.Store(MonthNameTag, MonthNameTag)
	defaultTag.Store(YEAR, YearFormat)
	defaultTag.Store(DayOfWeekTag, DayOfWeekTag)
	defaultTag.Store(DayOfMonthTag, DayOfMonthFormat)
	defaultTag.Store(TIMESTAMP, TIMESTAMP)
	defaultTag.Store(CENTURY, CENTURY)
	defaultTag.Store(TIMEZONE, TIMEZONE)
	defaultTag.Store(TimePeriodTag, TimePeriodFormat)
	defaultTag.Store(WORD, WORD)
	defaultTag.Store(SENTENCE, SENTENCE)
	defaultTag.Store(PARAGRAPH, PARAGRAPH)
	defaultTag.Store(CurrencyTag, CurrencyTag)
	defaultTag.Store(AmountTag, AmountTag)
	defaultTag.Store(AmountWithCurrencyTag, AmountWithCurrencyTag)
	defaultTag.Store(ID, ID)
	defaultTag.Store(HyphenatedID, HyphenatedID)
	defaultTag.Store(RussianFirstNameMaleTag, RussianFirstNameMaleTag)
	defaultTag.Store(RussianLastNameMaleTag, RussianLastNameMaleTag)
	defaultTag.Store(RussianFirstNameFemaleTag, RussianFirstNameFemaleTag)
	defaultTag.Store(RussianLastNameFemaleTag, RussianLastNameFemaleTag)
	defaultTag.Store(UserAgentTag, UserAgentTag)
}

var mapperTag = mapperTagCustom{}

func initMapperTagDefault() {
	mapperTag.Store(CreditCardType, GetPayment().CreditCardType)
	mapperTag.Store(CreditCardNumber, GetPayment().CreditCardNumber)
	mapperTag.Store(CountryInfoTag, GetAddress().CountryInfo)
	mapperTag.Store(LATITUDE, GetAddress().Latitude)
	mapperTag.Store(LONGITUDE, GetAddress().Longitude)
	mapperTag.Store(RealAddressTag, GetAddress().RealWorld)
	mapperTag.Store(PhoneNumber, GetPhoner().PhoneNumber)
	mapperTag.Store(TollFreeNumber, GetPhoner().TollFreePhoneNumber)
	mapperTag.Store(E164PhoneNumberTag, GetPhoner().E164PhoneNumber)
	mapperTag.Store(TitleMaleTag, GetPerson().TitleMale)
	mapperTag.Store(TitleFemaleTag, GetPerson().TitleFeMale)
	mapperTag.Store(FirstNameTag, GetPerson().FirstName)
	mapperTag.Store(FirstNameMaleTag, GetPerson().FirstNameMale)
	mapperTag.Store(FirstNameFemaleTag, GetPerson().FirstNameFemale)
	mapperTag.Store(LastNameTag, GetPerson().LastName)
	mapperTag.Store(NAME, GetPerson().Name)
	mapperTag.Store(ChineseFirstNameTag, GetPerson().ChineseFirstName)
	mapperTag.Store(ChineseLastNameTag, GetPerson().ChineseLastName)
	mapperTag.Store(ChineseNameTag, GetPerson().ChineseName)
	mapperTag.Store(GENDER, GetPerson().Gender)
	mapperTag.Store(UnixTimeTag, GetDateTimer().UnixTime)
	mapperTag.Store(DATE, GetDateTimer().Date)
	mapperTag.Store(TIME, GetDateTimer().Time)
	mapperTag.Store(MonthNameTag, GetDateTimer().MonthName)
	mapperTag.Store(YEAR, GetDateTimer().Year)
	mapperTag.Store(DayOfWeekTag, GetDateTimer().DayOfWeek)
	mapperTag.Store(DayOfMonthTag, GetDateTimer().DayOfMonth)
	mapperTag.Store(TIMESTAMP, GetDateTimer().Timestamp)
	mapperTag.Store(CENTURY, GetDateTimer().Century)
	mapperTag.Store(TIMEZONE, GetDateTimer().TimeZone)
	mapperTag.Store(TimePeriodTag, GetDateTimer().TimePeriod)
	mapperTag.Store(WORD, GetLorem().Word)
	mapperTag.Store(SENTENCE, GetLorem().Sentence)
	mapperTag.Store(PARAGRAPH, GetLorem().Paragraph)
	mapperTag.Store(CurrencyTag, GetPrice().Currency)
	mapperTag.Store(AmountTag, GetPrice().Amount)
	mapperTag.Store(AmountWithCurrencyTag, GetPrice().AmountWithCurrency)
	mapperTag.Store(ID, GetIdentifier().Digit)
	mapperTag.Store(HyphenatedID, GetIdentifier().Hyphenated)
	mapperTag.Store(RussianFirstNameMaleTag, GetPerson().RussianFirstNameMale)
	mapperTag.Store(RussianFirstNameFemaleTag, GetPerson().RussianFirstNameFemale)
	mapperTag.Store(RussianLastNameMaleTag, GetPerson().RussianLastNameMale)
	mapperTag.Store(RussianLastNameFemaleTag, GetPerson().RussianLastNameFemale)
	mapperTag.Store(BloodTypeTag, GetBlood().BloodGroup)
	mapperTag.Store(UserAgentTag, GetUserAgent().UserAgent)
}

// Compiled regexp
var (
	findLangReg     *regexp.Regexp
	findLenReg      *regexp.Regexp
	findSliceLenReg *regexp.Regexp
)

func init() {
	rand = mathrand.New(NewSafeSource(mathrand.NewSource(time.Now().UnixNano())))
	crypto = cryptorand.Reader
}

func init() {
	findLangReg, _ = regexp.Compile("lang=[a-z]{3}")
	findLenReg, _ = regexp.Compile(`len=\d+`)
	findSliceLenReg, _ = regexp.Compile(`slice_len=\d+`)

	randNameFlag = rand.Intn(100) // for person
}

func init() {
	initDefaultTag()
	initMapperTagDefault()
}

// ResetUnique is used to forget generated unique values.
// Call this when you're done generating a dataset.
func ResetUnique() {
	uniqueValues = &sync.Map{}
}

var (
	SetGenerateUniqueValues     = options.SetGenerateUniqueValues
	SetIgnoreInterface          = options.SetIgnoreInterface
	SetRandomStringLength       = options.SetRandomStringLength
	SetStringLang               = options.SetStringLang
	SetRandomMapAndSliceSize    = options.SetRandomMapAndSliceSize
	SetRandomMapAndSliceMaxSize = options.SetRandomMapAndSliceMaxSize
	SetRandomMapAndSliceMinSize = options.SetRandomMapAndSliceMinSize
	SetRandomNumberBoundaries   = options.SetRandomNumberBoundaries
)

func initMapperTagWithOption(opts ...options.OptionFunc) {
	mapperTag.Store(EmailTag, GetNetworker(opts...).Email)
	mapperTag.Store(MacAddressTag, GetNetworker(opts...).MacAddress)
	mapperTag.Store(DomainNameTag, GetNetworker(opts...).DomainName)
	mapperTag.Store(URLTag, GetNetworker(opts...).URL)
	mapperTag.Store(UserNameTag, GetNetworker(opts...).UserName)
	mapperTag.Store(IPV4Tag, GetNetworker(opts...).IPv4)
	mapperTag.Store(IPV6Tag, GetNetworker(opts...).IPv6)
	mapperTag.Store(PASSWORD, GetNetworker(opts...).Password)
	mapperTag.Store(JWT, GetNetworker(opts...).Jwt)
}

func initOption(opt ...options.OptionFunc) *options.Options {
	opts := options.BuildOptions(opt)
	initMapperTagWithOption(opt...)
	return opts
}

// FakeData is the main function. Will generate a fake data based on your struct.  You can use this for automation testing, or anything that need automated data.
// You don't need to Create your own data for your testing.
func FakeData(a interface{}, opt ...options.OptionFunc) error {
	opts := initOption(opt...)
	reflectType := reflect.TypeOf(a)

	if reflectType.Kind() != reflect.Ptr {
		return errors.New(fakerErrors.ErrValueNotPtr)
	}

	if reflect.ValueOf(a).IsNil() {
		return fmt.Errorf(fakerErrors.ErrNotSupportedPointer, reflectType.Elem().String())
	}

	rval := reflect.ValueOf(a)
	finalValue, err := getFakedValue(a, opts)
	if err != nil {
		return err
	}

	if rval.Elem().CanSet() && rval.Elem().
		CanConvert(reflectType.Elem()) {
		rval.Elem().Set(finalValue.Elem().
			Convert(reflectType.Elem()))
	}
	return nil
}

// AddProvider extend faker with tag to generate fake data with specified custom algorithm
// Example:
//
//	type Gondoruwo struct {
//		Name       string
//		Locatadata int
//	}
//
//	type Sample struct {
//		ID                 int64     `faker:"customIdFaker"`
//		Gondoruwo          Gondoruwo `faker:"gondoruwo"`
//		Danger             string    `faker:"danger"`
//	}
//
//	func CustomGenerator() {
//		// explicit
//		faker.AddProvider("customIdFaker", func(v reflect.Value) (interface{}, error) {
//		 	return int64(43), nil
//		})
//		// functional
//		faker.AddProvider("danger", func() faker.TaggedFunction {
//			return func(v reflect.Value) (interface{}, error) {
//				return "danger-ranger", nil
//			}
//		}())
//		faker.AddProvider("gondoruwo", func(v reflect.Value) (interface{}, error) {
//			obj := Gondoruwo{
//				Name:       "Power",
//				Locatadata: 324,
//			}
//			return obj, nil
//		})
//	}
//
//	func main() {
//		CustomGenerator()
//		var sample Sample
//		faker.FakeData(&sample)
//		fmt.Printf("%+v", sample)
//	}
//
// Will print
//
//	{ID:43 Gondoruwo:{Name:Power Locatadata:324} Danger:danger-ranger}
//
// Notes: when using a custom provider make sure to return the same type as the field
func AddProvider(tag string, provider interfaces.TaggedFunction) error {
	if _, ok := mapperTag.Load(tag); ok {
		return errors.New(fakerErrors.ErrTagAlreadyExists)
	}
	PriorityTags = append(PriorityTags, tag)
	mapperTag.Store(tag, provider)

	return nil
}

// RemoveProvider removes existing customization added with AddProvider
func RemoveProvider(tag string) error {
	if _, ok := mapperTag.Load(tag); !ok {
		return errors.New(fakerErrors.ErrTagDoesNotExist)
	}
	mapperTag.Delete(tag)
	return nil
}

func getFakedValue(item interface{}, opts *options.Options) (reflect.Value, error) {
	t := reflect.TypeOf(item)
	if t == nil {
		if opts.IgnoreInterface {
			return reflect.ValueOf(nil), nil
		}
		return reflect.Value{}, fmt.Errorf("interface{} not allowed")
	}
	if opts.MaxDepthOption.RecursionOutOfLimit(t) {
		return reflect.Zero(t), nil
	}
	opts.MaxDepthOption.RememberType(t)
	defer func() {
		opts.MaxDepthOption.ForgetType(t)
	}()
	k := t.Kind()
	switch k {
	case reflect.Ptr:
		v := reflect.New(t.Elem())
		var val reflect.Value
		var err error
		if item != reflect.Zero(reflect.TypeOf(item)).Interface() {
			val, err = getFakedValue(reflect.ValueOf(item).Elem().Interface(), opts)

		} else {
			val, err = getFakedValue(v.Elem().Interface(), opts)
		}
		if err != nil {
			return reflect.Value{}, err
		}

		if reflect.ValueOf(val).IsZero() {
			return v, nil
		}

		if v.Elem().CanSet() && v.Elem().CanConvert(t.Elem()) {
			v.Elem().Set(val.Convert(t.Elem()))
		}
		return v, nil
	case reflect.Struct:
		switch t.String() {
		case "time.Time":
			ft := time.Now().Add(time.Duration(rand.Int63()))
			return reflect.ValueOf(ft), nil
		default:
			originalDataVal := reflect.ValueOf(item)
			v := reflect.New(t).Elem()
			retry := 0 // error if cannot generate unique value after maxRetry tries
			for i := 0; i < v.NumField(); i++ {
				if !v.Field(i).CanSet() {
					continue // to avoid panic to set on unexported field in struct
				}

				if _, ok := opts.IgnoreFields[t.Field(i).Name]; ok {
					continue
				}

				if p, ok := opts.FieldProviders[t.Field(i).Name]; ok {
					val, err := p()
					if err != nil {
						return reflect.Value{}, fmt.Errorf("custom provider for field %s: %w", t.Field(i).Name, err)
					}
					v.Field(i).Set(reflect.ValueOf(val))
					continue
				}

				tags := decodeTags(t, i, opts.TagName)
				switch {
				case tags.keepOriginal:
					zero, err := isZero(reflect.ValueOf(item).Field(i))
					if err != nil {
						return reflect.Value{}, err
					}
					if zero {
						err := setDataWithTag(v.Field(i).Addr(), tags.fieldType, *opts)
						if err != nil {
							return reflect.Value{}, err
						}
						continue
					}
					v.Field(i).Set(reflect.ValueOf(item).Field(i))
				case tags.fieldType == "":
					val, err := getFakedValue(v.Field(i).Interface(), opts)
					if err != nil {
						return reflect.Value{}, err
					}

					if v.Field(i).CanSet() {
						if !reflect.ValueOf(val).IsZero() && val.CanConvert(v.Field(i).Type()) {
							val = val.Convert(v.Field(i).Type())
							v.Field(i).Set(val)
						}

					}
				case tags.fieldType == SKIP:
					data := originalDataVal.Field(i).Interface()
					if v.CanSet() && data != nil {
						v.Field(i).Set(reflect.ValueOf(data))
					}
				default:
					err := setDataWithTag(v.Field(i).Addr(), tags.fieldType, *opts)
					if err != nil {
						return reflect.Value{}, err
					}
				}

				if tags.unique {
					if retry >= maxRetry {
						return reflect.Value{}, fmt.Errorf(fakerErrors.ErrUniqueFailure, reflect.TypeOf(item).Field(i).Name)
					}
					value := v.Field(i).Interface()
					uniqueVal, _ := uniqueValues.Load(tags.fieldType)
					uniqueValArr, _ := uniqueVal.([]interface{})
					if slice.ContainsValue(uniqueValArr, value) { // Retry if unique value already found
						i--
						retry++
						continue
					}
					retry = 0
					uniqueValues.Store(tags.fieldType, append(uniqueValArr, value))
				} else {
					retry = 0
				}

			}
			return v, nil
		}

	case reflect.String:
		res, err := randomString(opts.RandomStringLength, *opts)
		return reflect.ValueOf(res), err
	case reflect.Slice:

		length := randomSliceAndMapSize(*opts)
		if opts.SetSliceMapNilIfLenZero && length == 0 {
			return reflect.Zero(t), nil
		}
		v := reflect.MakeSlice(t, length, length)
		for i := 0; i < length; i++ {
			val, err := getFakedValue(v.Index(i).Interface(), opts)
			if err != nil {
				return reflect.Value{}, err
			}
			// if the value generated is NIL/Zero
			// it will kept it as nil
			if reflect.ValueOf(val).IsZero() {
				continue
			}
			if val.CanConvert(v.Index(i).Type()) {
				val = val.Convert(v.Index(i).Type())
				v.Index(i).Set(val)
			}
		}
		return v, nil
	case reflect.Array:
		v := reflect.New(t).Elem()
		for i := 0; i < v.Len(); i++ {
			val, err := getFakedValue(v.Index(i).Interface(), opts)
			if err != nil {
				return reflect.Value{}, err
			}
			if reflect.ValueOf(val).IsZero() {
				continue
			}
			if val.CanConvert(v.Index(i).Type()) {
				val = val.Convert(v.Index(i).Type())
			}
			v.Index(i).Set(val)
		}
		return v, nil
	case reflect.Int:
		return reflect.ValueOf(randomInteger(opts)), nil
	case reflect.Int8:
		return reflect.ValueOf(int8(randomInteger(opts))), nil
	case reflect.Int16:
		return reflect.ValueOf(int16(randomInteger(opts))), nil
	case reflect.Int32:
		return reflect.ValueOf(int32(randomInteger(opts))), nil
	case reflect.Int64:
		return reflect.ValueOf(int64(randomInteger(opts))), nil
	case reflect.Float32:
		return reflect.ValueOf(float32(randomFloat(opts))), nil
	case reflect.Float64:
		return reflect.ValueOf(randomFloat(opts)), nil
	case reflect.Bool:
		val := rand.Intn(2) > 0
		return reflect.ValueOf(val), nil

	case reflect.Uint:
		return reflect.ValueOf(uint(randomInteger(opts))), nil

	case reflect.Uint8:
		return reflect.ValueOf(uint8(randomInteger(opts))), nil

	case reflect.Uint16:
		return reflect.ValueOf(uint16(randomInteger(opts))), nil

	case reflect.Uint32:
		return reflect.ValueOf(uint32(randomInteger(opts))), nil

	case reflect.Uint64:
		return reflect.ValueOf(uint64(randomInteger(opts))), nil

	case reflect.Map:
		length := randomSliceAndMapSize(*opts)
		if opts.SetSliceMapNilIfLenZero && length == 0 {
			return reflect.Zero(t), nil
		}
		v := reflect.MakeMap(t)
		for i := 0; i < length; i++ {
			keyInstance := reflect.New(t.Key()).Elem().Interface()
			key, err := getFakedValue(keyInstance, opts)
			if err != nil {
				return reflect.Value{}, err
			}

			valueInstance := reflect.New(t.Elem()).Elem().Interface()
			val, err := getFakedValue(valueInstance, opts)
			if err != nil {
				return reflect.Value{}, err
			}

			keyIsZero := reflect.ValueOf(key).IsZero()
			valIsZero := reflect.ValueOf(val).IsZero()

			if keyIsZero || valIsZero {
				continue
			}
			key = key.Convert(t.Key())
			val = val.Convert(v.Type().Elem())
			v.SetMapIndex(key, val)
		}
		return v, nil
	default:
		err := fmt.Errorf("no support for kind %+v", t)
		return reflect.Value{}, err
	}

}

func isZero(field reflect.Value) (bool, error) {
	if field.Kind() == reflect.Map {
		return field.Len() == 0, nil
	}

	for _, kind := range []reflect.Kind{reflect.Struct, reflect.Slice, reflect.Array} {
		if kind == field.Kind() {
			return false, fmt.Errorf("keep not allowed on struct")
		}
	}
	return reflect.Zero(field.Type()).Interface() == field.Interface(), nil
}

func decodeTags(typ reflect.Type, i int, tagName string) structTag {
	tagField := typ.Field(i).Tag.Get(tagName)
	tags := strings.Split(tagField, ",")

	keepOriginal := false
	uni := false
	res := make([]string, 0)
	pMap := make(map[string]string)
	for _, tag := range tags {
		if tag == keep {
			keepOriginal = true
			continue
		} else if tag == unique {
			uni = true
			continue
		}
		// res = append(res, tag)
		ptag := strings.ToLower(strings.Trim(strings.Split(tag, "=")[0], " "))
		pMap[ptag] = tag
		ptag = strings.ToLower(strings.Trim(strings.Split(tag, ":")[0], " "))
		pMap[ptag] = tag
	}
	// Priority
	for _, ptag := range PriorityTags {
		if tag, ok := pMap[ptag]; ok {
			if ptag == ONEOF {
				res = append(res, tags...)
			} else {
				res = append(res, tag)
			}
			delete(pMap, ptag)
		}
	}
	// custom,keep,unique
	if len(res) < 1 {
		if !keepOriginal && !uni {
			res = append(res, tags...)
		}
	}

	return structTag{
		fieldType:    strings.Join(res, ","),
		unique:       uni,
		keepOriginal: keepOriginal,
	}
}

type structTag struct {
	fieldType    string
	unique       bool
	keepOriginal bool
}

func setDataWithTag(v reflect.Value, tag string, opt options.Options) error {
	if v.Kind() != reflect.Ptr {
		return errors.New(fakerErrors.ErrValueNotPtr)
	}
	v = reflect.Indirect(v)
	switch v.Kind() {
	case reflect.Ptr:
		if _, exist := mapperTag.Load(tag); !exist {
			newv := reflect.New(v.Type().Elem())
			if err := setDataWithTag(newv, tag, opt); err != nil {
				return err
			}
			v.Set(newv)
			return nil
		}
		if _, def := defaultTag.Load(tag); !def {
			tagFunc, ok := mapperTag.Load(tag)
			if !ok {
				return fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
			}
			res, err := tagFunc(v)
			if err != nil {
				return err
			}
			v.Set(reflect.ValueOf(res))
			return nil
		}

		t := v.Type()
		newv := reflect.New(t.Elem())
		tagFunc, ok := mapperTag.Load(tag)
		if !ok {
			return fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
		}
		res, err := tagFunc(newv.Elem())
		if err != nil {
			return err
		}
		rval := reflect.ValueOf(res)
		newv.Elem().Set(rval)
		v.Set(newv)
		return nil
	case reflect.String:
		return userDefinedString(v, tag, opt)
	case reflect.Int, reflect.Int32, reflect.Int64, reflect.Int8, reflect.Int16, reflect.Uint, reflect.Uint8,
		reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64:
		return userDefinedNumber(v, tag)
	case reflect.Slice, reflect.Array:
		return userDefinedArray(v, tag, opt)
	case reflect.Map:
		return userDefinedMap(v, tag, opt)
	default:
		tagFunc, ok := mapperTag.Load(tag)
		if !ok {
			return fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
		}
		res, err := tagFunc(v)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(res))
	}
	return nil
}

func userDefinedMap(v reflect.Value, tag string, opt options.Options) error {
	if tagFunc, ok := mapperTag.Load(tag); ok {
		res, err := tagFunc(v)
		if err != nil {
			return err
		}

		v.Set(reflect.ValueOf(res))
		return nil
	}

	length := randomSliceAndMapSize(opt)
	if opt.SetSliceMapNilIfLenZero && length == 0 {
		v.Set(reflect.Zero(v.Type()))
		return nil
	}
	definedMap := reflect.MakeMap(v.Type())
	for i := 0; i < length; i++ {
		key, err := getValueWithTag(v.Type().Key(), tag, opt)
		if err != nil {
			return err
		}
		val, err := getValueWithTag(v.Type().Elem(), tag, opt)
		if err != nil {
			return err
		}
		definedMap.SetMapIndex(reflect.ValueOf(key), reflect.ValueOf(val))
	}
	v.Set(definedMap)
	return nil
}

func getValueWithTag(t reflect.Type, tag string, opt options.Options) (interface{}, error) {
	switch t.Kind() {
	case reflect.Int, reflect.Int32, reflect.Int64, reflect.Int8, reflect.Int16, reflect.Uint, reflect.Uint8,
		reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64:
		res, err := extractNumberFromTag(tag, t)
		if err != nil {
			return nil, err
		}
		return res, nil
	case reflect.String:
		res, err := extractStringFromTag(tag, opt)
		if err != nil {
			return nil, err
		}
		return res, nil
	default:
		return 0, errors.New(fakerErrors.ErrUnknownType)
	}
}

func getNumberWithBoundary(t reflect.Type, boundary interfaces.RandomIntegerBoundary) (interface{}, error) {
	switch t.Kind() {
	case reflect.Uint:
		return uint(randomIntegerWithBoundary(boundary)), nil
	case reflect.Uint8:
		return uint8(randomIntegerWithBoundary(boundary)), nil
	case reflect.Uint16:
		return uint16(randomIntegerWithBoundary(boundary)), nil
	case reflect.Uint32:
		return uint32(randomIntegerWithBoundary(boundary)), nil
	case reflect.Uint64:
		return uint64(randomIntegerWithBoundary(boundary)), nil
	case reflect.Int:
		return randomIntegerWithBoundary(boundary), nil
	case reflect.Int8:
		return int8(randomIntegerWithBoundary(boundary)), nil
	case reflect.Int16:
		return int16(randomIntegerWithBoundary(boundary)), nil
	case reflect.Int32:
		return int32(randomIntegerWithBoundary(boundary)), nil
	case reflect.Int64:
		return int64(randomIntegerWithBoundary(boundary)), nil
	default:
		return nil, errors.New(fakerErrors.ErrNotSupportedTypeForTag)
	}
}

func getValueWithNoTag(t reflect.Type, opt options.Options) (interface{}, error) {
	switch t.Kind() {
	case reflect.Int, reflect.Int32, reflect.Int64, reflect.Int8, reflect.Int16, reflect.Uint, reflect.Uint8,
		reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64:
		boundary := interfaces.RandomIntegerBoundary{
			Start: opt.RandomIntegerBoundary.Start,
			End:   opt.RandomIntegerBoundary.End}
		res, err := getNumberWithBoundary(t, boundary)
		if err != nil {
			return nil, err
		}
		return res, nil
	case reflect.String:
		res, err := randomString(opt.RandomStringLength, opt)
		if err != nil {
			return nil, err
		}
		return res, nil
	default:
		return 0, errors.New(fakerErrors.ErrUnknownType)
	}
}

func userDefinedArray(v reflect.Value, tag string, opt options.Options) error {
	tagFunc, tagExists := mapperTag.Load(tag)
	if tagExists {
		res, err := tagFunc(v)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(res))
		return nil
	}
	sliceLen, err := extractSliceLengthFromTag(tag, opt)
	if err != nil {
		return err
	}

	if opt.SetSliceMapNilIfLenZero && sliceLen == 0 {
		v.Set(reflect.Zero(v.Type()))
		return nil
	}
	//remove slice_len from tag string to avoid extra logic in downstream function
	tag = findSliceLenReg.ReplaceAllString(tag, "")
	array := reflect.MakeSlice(v.Type(), sliceLen, sliceLen)
	for i := 0; i < array.Len(); i++ {
		k := v.Type().Elem().Kind()
		if k == reflect.Pointer || k == reflect.Struct {
			res, err := getFakedValue(array.Index(i).Interface(), &opt)
			if err != nil {
				return err
			}
			if res.Kind() == reflect.Invalid {
				return fmt.Errorf("got invalid reflect value")
			}
			array.Index(i).Set(res)
			continue
		}
		if tag == "" {
			res, err := getValueWithNoTag(v.Type().Elem(), opt)
			if err != nil {
				return err
			}
			array.Index(i).Set(reflect.ValueOf(res))
			continue
		}

		res, err := getValueWithTag(v.Type().Elem(), tag, opt)
		if err != nil {
			return err
		}
		array.Index(i).Set(reflect.ValueOf(res))
	}
	v.Set(array)
	return nil
}

func userDefinedString(v reflect.Value, tag string, opt options.Options) error {
	var res interface{}
	var err error

	if tagFunc, ok := mapperTag.Load(tag); ok {
		res, err = tagFunc(v)
		if err != nil {
			return err
		}
	} else {
		res, err = extractStringFromTag(tag, opt)
		if err != nil {
			return err
		}
	}
	if res == nil {
		return fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
	}
	val, _ := res.(string)
	v.SetString(val)
	return nil
}

func userDefinedNumber(v reflect.Value, tag string) error {
	var res interface{}
	var err error

	if tagFunc, ok := mapperTag.Load(tag); ok {
		res, err = tagFunc(v)
		if err != nil {
			return err
		}
	} else {
		res, err = extractNumberFromTag(tag, v.Type())
		if err != nil {
			return err
		}
	}
	if res == nil {
		return fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
	}

	if v.CanSet() && v.CanConvert(v.Type()) {
		v.Set(reflect.ValueOf(res).Convert(v.Type()))
	}
	return nil
}

// extractSliceLengthFromTag checks if the sliceLength tag 'slice_len' is set, if so, returns its value, else return a random length
func extractSliceLengthFromTag(tag string, opt options.Options) (int, error) {
	if strings.Contains(tag, SliceLength) {
		lenParts := strings.SplitN(findSliceLenReg.FindString(tag), Equals, -1)
		if len(lenParts) != 2 {
			return 0, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, tag)
		}
		sliceLen, err := strconv.Atoi(lenParts[1])
		if err != nil {
			return 0, fmt.Errorf("the given sliceLength has to be numeric, tag: %s", tag)
		}
		if sliceLen < 0 {
			return 0, fmt.Errorf("slice length can not be negative, tag: %s", tag)
		}
		return sliceLen, nil
	}

	return randomSliceAndMapSize(opt), nil //Returns random slice length if the sliceLength tag isn't set
}

func extractStringFromTag(tag string, opts options.Options) (interface{}, error) {
	var err error
	strlen := opts.RandomStringLength
	strlng := opts.StringLanguage
	isOneOfTag := strings.Contains(tag, ONEOF)
	if !strings.Contains(tag, Length) && !strings.Contains(tag, Language) && !isOneOfTag {
		return nil, fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
	}
	if strings.Contains(tag, Length) {
		lenParts := strings.SplitN(findLenReg.FindString(tag), Equals, -1)
		if len(lenParts) != 2 {
			return nil, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, tag)
		}
		strlen, _ = strconv.Atoi(lenParts[1])
	}
	if strings.Contains(tag, Language) {
		strlng, err = extractLangFromTag(tag)
		if err != nil {
			return nil, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, tag)
		}
	}
	if isOneOfTag {
		var args []string
		args, err = fetchOneOfArgsFromTag(tag)
		if err != nil {
			return nil, err
		}
		toRet := args[rand.Intn(len(args))]
		return strings.TrimSpace(toRet), nil
	}

	copyOption := opts
	copyOption.StringLanguage = strlng
	res, err := randomString(strlen, copyOption)
	return res, err
}

func extractLangFromTag(tag string) (*interfaces.LangRuneBoundary, error) {
	text := findLangReg.FindString(tag)
	texts := strings.SplitN(text, Equals, -1)
	if len(texts) != 2 {
		return nil, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, text)
	}
	switch strings.ToLower(texts[1]) {
	case "eng":
		return &interfaces.LangENG, nil
	case "rus":
		return &interfaces.LangRUS, nil
	case "chi":
		return &interfaces.LangCHI, nil
	case "jpn":
		return &interfaces.LangJPN, nil
	case "kor":
		return &interfaces.LangKOR, nil
	case "emj":
		return &interfaces.EmotEMJ, nil
	default:
		return &interfaces.LangENG, nil
	}
}

func extractNumberFromTag(tag string, t reflect.Type) (interface{}, error) {
	hasOneOf := strings.Contains(tag, ONEOF)
	hasBoundaryStart := strings.Contains(tag, BoundaryStart)
	hasBoundaryEnd := strings.Contains(tag, BoundaryEnd)
	usingOneOfTag := hasOneOf && (!hasBoundaryStart && !hasBoundaryEnd)
	usingBoundariesTags := !hasOneOf && (hasBoundaryStart && hasBoundaryEnd)
	if !usingOneOfTag && !usingBoundariesTags {
		return nil, fmt.Errorf(fakerErrors.ErrTagNotSupported, tag)
	}

	// handling oneof tag
	if usingOneOfTag {
		args, err := fetchOneOfArgsFromTag(tag)
		if err != nil {
			return nil, err
		}
		switch t.Kind() {
		case reflect.Float64:
			{
				toRet, err := extractFloat64FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(float64), nil
			}
		case reflect.Float32:
			{
				toRet, err := extractFloat32FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(float32), nil
			}
		case reflect.Int64:
			{
				toRet, err := extractInt64FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(int64), nil
			}
		case reflect.Int32:
			{
				toRet, err := extractInt32FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(int32), nil
			}
		case reflect.Int16:
			{
				toRet, err := extractInt16FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(int16), nil
			}
		case reflect.Int8:
			{
				toRet, err := extractInt8FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(int8), nil
			}
		case reflect.Int:
			{
				toRet, err := extractIntFromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(int), nil
			}
		case reflect.Uint64:
			{
				toRet, err := extractUint64FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(uint64), nil
			}
		case reflect.Uint32:
			{
				toRet, err := extractUint32FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(uint32), nil
			}
		case reflect.Uint16:
			{
				toRet, err := extractUint16FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(uint16), nil
			}
		case reflect.Uint8:
			{
				toRet, err := extractUint8FromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(uint8), nil
			}
		case reflect.Uint:
			{
				toRet, err := extractUintFromTagArgs(args)
				if err != nil {
					return nil, err
				}
				return toRet.(uint), nil
			}
		default:
			{
				return nil, fmt.Errorf(fakerErrors.ErrUnsupportedNumberType)
			}
		}
	}

	// handling boundary tags
	valuesStr := strings.SplitN(tag, comma, -1)
	if len(valuesStr) != 2 {
		return nil, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, tag)
	}

	// TODO(Xaspy): When Golang provides generics, we will be able to make this method simpler and more beautiful.
	if t.Kind() == reflect.Float64 || t.Kind() == reflect.Float32 {
		startBoundary, err := extractFloatFromText(valuesStr[0])
		if err != nil {
			return nil, err
		}
		endBoundary, err := extractFloatFromText(valuesStr[1])
		if err != nil {
			return nil, err
		}
		boundary := interfaces.RandomFloatBoundary{Start: startBoundary, End: endBoundary}
		switch t.Kind() {
		case reflect.Float32:
			return float32(randomFloatWithBoundary(boundary)), nil
		case reflect.Float64:
			return randomFloatWithBoundary(boundary), nil
		}
	}

	startBoundary, err := extractIntFromText(valuesStr[0])
	if err != nil {
		return nil, err
	}
	endBoundary, err := extractIntFromText(valuesStr[1])
	if err != nil {
		return nil, err
	}
	boundary := interfaces.RandomIntegerBoundary{Start: startBoundary, End: endBoundary}
	return getNumberWithBoundary(t, boundary)
}

func extractIntFromText(text string) (int, error) {
	text = strings.TrimSpace(text)
	texts := strings.SplitN(text, Equals, -1)
	if len(texts) != 2 {
		return 0, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, text)
	}
	return strconv.Atoi(texts[1])
}

func extractFloatFromText(text string) (float64, error) {
	text = strings.TrimSpace(text)
	texts := strings.SplitN(text, Equals, -1)
	if len(texts) != 2 {
		return 0, fmt.Errorf(fakerErrors.ErrWrongFormattedTag, text)
	}
	return strconv.ParseFloat(texts[1], 64)
}

func fetchOneOfArgsFromTag(tag string) ([]string, error) {
	items := strings.Split(tag, colon)
	argsList := items[1:]
	if len(argsList) != 1 {
		return nil, fmt.Errorf(fakerErrors.ErrUnsupportedTagArguments)
	}
	if strings.Contains(argsList[0], ",,") {
		return nil, fmt.Errorf(fakerErrors.ErrDuplicateSeparator)
	}
	if argsList[0] == "" {
		return nil, fmt.Errorf(fakerErrors.ErrNotEnoughTagArguments)
	}
	args := strings.Split(argsList[0], comma)
	if len(args) < 1 {
		return nil, fmt.Errorf(fakerErrors.ErrNotEnoughTagArguments)
	}
	return args, nil
}

func randomString(n int, fakerOpt options.Options) (string, error) {
	b := make([]rune, 0)
	set := make(map[rune]struct{})
	if fakerOpt.StringLanguage.Exclude != nil {
		for _, s := range fakerOpt.StringLanguage.Exclude {
			set[s] = struct{}{}
		}
	}

	counter := 0
	for i := 0; i < n; {
		randRune := rune(rand.Intn(int(fakerOpt.StringLanguage.End-fakerOpt.StringLanguage.Start)) + int(fakerOpt.StringLanguage.Start))
		for slice.ContainsRune(set, randRune) {
			if counter++; counter >= fakerOpt.MaxGenerateStringRetries {
				return "", errors.New("Max number of string generation retries exhausted")
			}
			randRune = rune(rand.Intn(int(fakerOpt.StringLanguage.End-fakerOpt.StringLanguage.Start)) + int(fakerOpt.StringLanguage.Start))
			_, ok := set[randRune]
			if !ok {
				break
			}
		}
		b = append(b, randRune)
		i++
	}

	k := string(b)
	return k, nil
}

// randomIntegerWithBoundary returns a random integer between input start and end boundary. [start, end)
func randomIntegerWithBoundary(boundary interfaces.RandomIntegerBoundary) int {
	span := boundary.End - boundary.Start
	if span <= 0 {
		return boundary.Start
	}
	return rand.Intn(span) + boundary.Start
}

// randomFloatWithBoundary returns a random float between input start and end boundary. [start, end)
func randomFloatWithBoundary(boundary interfaces.RandomFloatBoundary) float64 {
	span := boundary.End - boundary.Start
	if span <= 0 {
		return boundary.Start
	}
	return boundary.Start + rand.Float64()*span
}

// randomInteger returns a random integer between start and end boundary. [start, end)
func randomInteger(opt *options.Options) int {
	if opt == nil {
		opt = options.DefaultOption()
	}

	return randomIntegerWithBoundary(*opt.RandomIntegerBoundary)
}

// randomFloat returns a random float between start and end boundary. [start, end)
func randomFloat(opt *options.Options) float64 {
	if opt == nil {
		opt = options.DefaultOption()
	}

	return randomFloatWithBoundary(*opt.RandomFloatBoundary)
}

// randomSliceAndMapSize returns a random integer between [0,randomSliceAndMapSize). If the testRandZero is set, returns 0
// Written for test purposes for shouldSetNil
func randomSliceAndMapSize(opt options.Options) int {
	if opt.SetSliceMapRandomToZero {
		return 0
	}
	r := opt.RandomMaxSliceSize - opt.RandomMinSliceSize
	if r < 1 {
		r = 1
	}
	return opt.RandomMinSliceSize + rand.Intn(r)
}

func randomElementFromSliceString(s []string) string {
	return s[rand.Int()%len(s)]
}
func randomStringNumber(n int) string {
	b := make([]byte, n)
	for i, cache, remain := n-1, rand.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = rand.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(numberBytes) {
			b[i] = numberBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return string(b)
}

// RandomInt Get three parameters , only first mandatory and the rest are optional
// (minimum_int, maximum_int, count)
//
//	If only set one parameter :  An integer greater than minimum_int will be returned
//	If only set two parameters : All integers between minimum_int and maximum_int will be returned, in a random order.
//	If three parameters: `count` integers between minimum_int and maximum_int will be returned.
func RandomInt(parameters ...int) (p []int, err error) {
	switch len(parameters) {
	case 1:
		minInt := parameters[0]
		p = rand.Perm(minInt)
		for i := range p {
			p[i] += minInt
		}
	case 2:
		minInt, maxInt := parameters[0], parameters[1]
		p = rand.Perm(maxInt - minInt + 1)

		for i := range p {
			p[i] += minInt
		}
	case 3:
		minInt, maxInt := parameters[0], parameters[1]
		count := parameters[2]
		p = rand.Perm(maxInt - minInt + 1)

		for i := range p {
			p[i] += minInt
		}
		if len(p) > count {
			p = p[0:count]
		}
	default:
		err = fmt.Errorf(fakerErrors.ErrMoreArguments, len(parameters))
	}
	return p, err
}

func generateUnique(dataType string, fn func() interface{}) (interface{}, error) {
	for i := 0; i < maxRetry; i++ {
		value := fn()
		uniqueVal, _ := uniqueValues.Load(dataType)
		uniqueValArr, _ := uniqueVal.([]interface{})
		if !slice.ContainsValue(uniqueValArr, value) { // Retry if unique value already found
			uniqueValues.Store(dataType, append(uniqueValArr, value))
			return value, nil
		}
	}
	return reflect.Value{}, fmt.Errorf(fakerErrors.ErrUniqueFailure, dataType)
}

func singleFakeData(dataType string, fn func() interface{}, opts ...options.OptionFunc) interface{} {
	ops := initOption(opts...)
	if ops.GenerateUniqueValues {
		v, err := generateUnique(dataType, fn)
		if err != nil {
			panic(err)
		}
		return v
	}
	return fn()
}