package main

import "golang.org/x/text/transform"

type Transformer struct {
	transform.NopResetter
}

func (t *Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	if !atEOF {
		err = transform.ErrShortSrc
	} else {
		n := copy(dst, src)
		nDst = n
		nSrc = n
		if n < len(src) {
			err = transform.ErrShortDst
		}
	}
	return
}

func main() {
	data := make([]byte, 4096+1)
	tr := transform.Chain(
		transform.Nop,
		&Transformer{},
	)
	_, _, err := transform.Bytes(tr, data)
	if err != nil {
		panic(err)
	}
}