2	rune1 "a" -> 3
  3	alt -> 2, 4
  4	cap 3 -> 5
  5	cap 4 -> 6
  6	rune1 "b" -> 7
  7	alt -> 6, 8
  8	cap 5 -> 9
  9	match
`},
	{"a+|b+", `  0	fail
  1	rune1 "a" -> 2
  2	alt -> 1, 6
  3	rune1 "b" -> 4
  4	alt -> 3, 6
  5*	alt -> 1, 3
  6	match
`},
	{"A[Aa]", `  0	fail
  1*	rune1 "A" -> 2
  2	rune "A"/i -> 3
  3	match
`},
	{"(?:(?:^).)", `  0	fail
  1*	empty 4 -> 2
  2	anynotnl -> 3
  3	match

	case InstNop:
		bw(b, "nop -> ", u32(i.Out))
	case InstRune:
		if i.Rune == nil {
			// shouldn't happen
			bw(b, "rune <nil>")
		}
		bw(b, "rune ", strconv.QuoteToASCII(string(i.Rune)))
		if Flags(i.Arg)&FoldCase != 0 {
			bw(b, "/i")
		}
		bw(b, " -> ", u32(i.Out))
	case InstRune1:
		bw(b, "rune1 ", strconv.QuoteToASCII(string(i.Rune)), " -> ", u32(i.Out))
	case InstRuneAny:
		bw(b, "any -> ", u32(i.Out))

//	2..0  case mode
//
// For the non-exceptional cases, a rune must be either uncased, lowercase or
// uppercase. If the rune is cased, the XOR pattern maps either a lowercase
// rune to uppercase or an uppercase rune to lowercase (applied to the 10
// least-significant bits of the rune).
//
// See the definitions below for a more detailed description of the various
// bits.
type info uint16

		[]rune{69, 74},
		[]rune{65, 69},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// overlap from above
		[]rune{69, 74},
		[]rune{71, 74},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// overlap from below
		[]rune{69, 74},
		[]rune{65, 71},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// out of order []rune
		[]rune{69, 74, 60, 65},

		}
		// Handle multi-byte Unicode.
		r, n := utf8.DecodeRune(in[i:])
		out = utf8.AppendRune(out, foldRune(r))
		i += n
	}
	return out
}

// foldRune is returns the smallest rune for all runes in the same fold set.
func foldRune(r rune) rune {
	for {
		r2 := unicode.SimpleFold(r)
		if r2 <= r {
			return r2
		}
		r = r2
	}

		fmt.Fprintf(&buf, "\t%#04x,\n", r-0x10000)
	}
	fmt.Fprintf(&buf, "}\n\n")

	// The list of graphic but not "printable" runes is short. Just make one easy table.
	fmt.Fprintf(&buf, "// isGraphic lists the graphic runes not matched by IsPrint.\n")
	fmt.Fprintf(&buf, "var isGraphic = []uint16{\n")
	for r := rune(0); r <= unicode.MaxRune; r++ {
		if unicode.IsPrint(r) != unicode.IsGraphic(r) {
			// Sanity check.

func decodeWTF16(s []uint16, buf []byte) []byte {
	for i := 0; i < len(s); i++ {
		var ar rune
		switch r := s[i]; {
		case r < surr1, surr3 <= r:
			// normal rune
			ar = rune(r)
		case surr1 <= r && r < surr2 && i+1 < len(s) &&
			surr2 <= s[i+1] && s[i+1] < surr3:
			// valid surrogate sequence
			ar = utf16.DecodeRune(rune(r), rune(s[i+1]))
			i++
		default:
			// WTF-8 fallback.

func (p Properties) CCC() uint8 {
	if p.index >= firstCCCZeroExcept {
		return 0
	}
	return ccc[p.ccc]
}

// LeadCCC returns the CCC of the first rune in the decomposition.
// If there is no decomposition, LeadCCC equals CCC.
func (p Properties) LeadCCC() uint8 {
	return ccc[p.ccc]
}

// TrailCCC returns the CCC of the last rune in the decomposition.

func (p Properties) CCC() uint8 {
	if p.index >= firstCCCZeroExcept {
		return 0
	}
	return ccc[p.ccc]
}

// LeadCCC returns the CCC of the first rune in the decomposition.
// If there is no decomposition, LeadCCC equals CCC.
func (p Properties) LeadCCC() uint8 {
	return ccc[p.ccc]
}

// TrailCCC returns the CCC of the last rune in the decomposition.

func Decode(s []uint16) []rune {
	// Preallocate capacity to hold up to 64 runes.
	// Decode inlines, so the allocation can live on the stack.
	buf := make([]rune, 0, 64)
	return decode(s, buf)
}

// decode appends to buf the Unicode code point sequence represented
// by the UTF-16 encoding s and return the extended buffer.
func decode(s []uint16, buf []rune) []rune {
	for i := 0; i < len(s); i++ {