type streamSafe uint8

// first inserts the first rune of a segment. It is a faster version of next if
// it is known p represents the first rune in a segment.
func (ss *streamSafe) first(p Properties) {
	*ss = streamSafe(p.nTrailingNonStarters())
}

// insert returns a ssState value to indicate whether a rune represented by p
// can be inserted.
func (ss *streamSafe) next(p Properties) ssState {
	if *ss > maxNonStarters {

type streamSafe uint8

// first inserts the first rune of a segment. It is a faster version of next if
// it is known p represents the first rune in a segment.
func (ss *streamSafe) first(p Properties) {
	*ss = streamSafe(p.nTrailingNonStarters())
}

// insert returns a ssState value to indicate whether a rune represented by p
// can be inserted.
func (ss *streamSafe) next(p Properties) ssState {
	if *ss > maxNonStarters {

}

func (p Properties) multiSegment() bool {
	return p.index >= firstMulti && p.index < endMulti
}

func (p Properties) nLeadingNonStarters() uint8 {
	return p.nLead
}

func (p Properties) nTrailingNonStarters() uint8 {
	return uint8(p.flags & 0x03)
}

// Decomposition returns the decomposition for the underlying rune
// or nil if there is none.
func (p Properties) Decomposition() []byte {

}

func (p Properties) multiSegment() bool {
	return p.index >= firstMulti && p.index < endMulti
}

func (p Properties) nLeadingNonStarters() uint8 {
	return p.nLead
}

func (p Properties) nTrailingNonStarters() uint8 {
	return uint8(p.flags & 0x03)
}

// Decomposition returns the decomposition for the underlying rune
// or nil if there is none.
func (p Properties) Decomposition() []byte {