/
struct.go
63 lines (58 loc) · 1.33 KB
/
struct.go
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package command
import (
"errors"
"fmt"
"reflect"
"unicode"
"unicode/utf8"
)
var (
errNoPointer = errors.New("not a pointer")
errNoStruct = errors.New("not a struct")
)
func defaultFieldName(name string) string {
var runes []rune
for ii := 0; ii < len(name); {
c, s := utf8.DecodeRuneInString(name[ii:])
ii += s
if unicode.IsUpper(c) {
if len(runes) > 0 {
runes = append(runes, '-')
}
c = unicode.ToLower(c)
}
runes = append(runes, c)
}
return string(runes)
}
type structVisitor func(name string, help string, field *reflect.StructField, val reflect.Value, ptr interface{}) error
func visitStruct(val reflect.Value, visitor structVisitor) error {
if val.Kind() != reflect.Ptr {
return errNoPointer
}
val = reflect.Indirect(val)
if val.Kind() != reflect.Struct {
return errNoStruct
}
typ := val.Type()
for ii := 0; ii < typ.NumField(); ii++ {
field := typ.Field(ii)
fieldVal := val.Field(ii)
ptr := fieldVal.Addr().Interface()
name := defaultFieldName(field.Name)
var help string
if n := field.Tag.Get("name"); n != "" {
name = n
}
if h := field.Tag.Get("help"); h != "" {
help = h
}
if name == "" {
return fmt.Errorf("no name provided for field %s in type %s", field.Name, typ)
}
if err := visitor(name, help, &field, fieldVal, ptr); err != nil {
return err
}
}
return nil
}