Goでstructのフィールドを[][]interface{}に変換

inspector.go

package main

import (
	"fmt"
	"reflect"
	"time"
	"unsafe"
)

var timeType = reflect.TypeOf(time.Time{})

func Inspect(items interface{}) ([]reflect.StructField, [][]interface{}) {
	v := reflect.ValueOf(items)
	if v.Len() == 0 {
		return nil, nil
	}

	vs := make([]reflect.Value, v.Len())
	for i := 0; i < v.Len(); i++ {
		vs[i] = v.Index(i)
	}
	t := vs[0].Type()

	fields := make([]reflect.StructField, t.NumField())
	for i := 0; i < t.NumField(); i++ {
		fields[i] = t.Field(i)
	}

	xs := make([][]interface{}, v.Len())
	for i, x := range vs {
		values := make([]interface{}, len(fields))
		for j, f := range fields {
			v := x.FieldByName(f.Name)
			var r interface{}
			switch v.Kind() {
			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
				r = v.Int()
			case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
				r = v.Uint()
			case reflect.Float32, reflect.Float64:
				r = v.Float()
			case reflect.String:
				r = v.String()
			case reflect.Bool:
				r = v.Bool()
			case reflect.Slice:
				r = v.Bytes()
			default:
				if v.Type().ConvertibleTo(timeType) {
					tt := (*time.Time)(unsafe.Pointer(v.Addr().Pointer()))
					r = *tt
				}
			}
			values[j] = r
		}
		xs[i] = values
	}
	return fields, xs
}

func main() {
	xs := []struct {
		id        int
		name      string
		age       uint8
		superuser bool
		b         []byte
		bb        [1]byte
		birthday  time.Time
	}{
		{1, "imagawa", 13, false, []byte("imgw"), [1]byte{}, time.Now()},
		{2, "yoshimot", 20, true, nil, [1]byte{}, time.Time{}},
		{3, "moyomot", 35, false, nil, [1]byte{1}, time.Now()},
	}
	fields, items := Inspect(xs)
	fmt.Println(fields)
	for _, x := range items {
		fmt.Println(x)
	}
}