// r, or -1 if rune is not present in s.
// If r is utf8.RuneError, it returns the first instance of any
// invalid UTF-8 byte sequence.
func IndexRune(s string, r rune) int {
	switch {
	case 0 <= r && r < utf8.RuneSelf:
		return IndexByte(s, byte(r))
	case r == utf8.RuneError:
		for i, r := range s {
			if r == utf8.RuneError {
				return i
			}
		}
		return -1
	case !utf8.ValidRune(r):
		return -1

	if in.bytes == nil {
		return in.str[p]
	}
	return in.bytes[p]
}

func (in *input) skipASCII(p, max int) int {
	if in.bytes == nil {
		for ; p < max && in.str[p] < utf8.RuneSelf; p++ {
		}
	} else {
		for ; p < max && in.bytes[p] < utf8.RuneSelf; p++ {
		}
	}
	return p
}

func (in *input) skipContinuationBytes(p int) int {
	if in.bytes == nil {
		for ; p < len(in.str) && !utf8.RuneStart(in.str[p]); p++ {
		}

// Numbers fundamental to the encoding.
const (
	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
	MaxRune   = '\U0010FFFF' // Maximum valid Unicode code point.
	UTFMax    = 4            // maximum number of bytes of a UTF-8 encoded Unicode character.
)

	's':  true,
	't':  true,
	'u':  true,
	'v':  true,
	'w':  true,
	'x':  true,
	'y':  true,
	'z':  true,
	'|':  true,
	'~':  true,
}

func IsTokenRune(r rune) bool {
	return r < utf8.RuneSelf && isTokenTable[byte(r)]
}

// HeaderValuesContainsToken reports whether any string in values
// contains the provided token, ASCII case-insensitively.
func HeaderValuesContainsToken(values []string, token string) bool {

	return appendFoldedName(arr[:0], in)
}

func appendFoldedName(out, in []byte) []byte {
	for i := 0; i < len(in); {
		// Handle single-byte ASCII.
		if c := in[i]; c < utf8.RuneSelf {
			if 'a' <= c && c <= 'z' {
				c -= 'a' - 'A'
			}
			out = append(out, c)
			i++
			continue
		}
		// Handle multi-byte Unicode.
		r, n := utf8.DecodeRune(in[i:])

}

func hexEscapeNonASCII(s string) string {
	newLen := 0
	for i := 0; i < len(s); i++ {
		if s[i] >= utf8.RuneSelf {
			newLen += 3
		} else {
			newLen++
		}
	}
	if newLen == len(s) {
		return s
	}
	b := make([]byte, 0, newLen)
	var pos int
	for i := 0; i < len(s); i++ {
		if s[i] >= utf8.RuneSelf {
			if pos < i {
				b = append(b, s[pos:i]...)
			}
			b = append(b, '%')

	return i.next(i)
}

func nextASCIIBytes(i *Iter) []byte {
	p := i.p + 1
	if p >= i.rb.nsrc {
		p0 := i.p
		i.setDone()
		return i.rb.src.bytes[p0:p]
	}
	if i.rb.src.bytes[p] < utf8.RuneSelf {
		p0 := i.p
		i.p = p
		return i.rb.src.bytes[p0:p]
	}
	i.info = i.rb.f.info(i.rb.src, i.p)
	i.next = i.rb.f.nextMain
	return i.next(i)
}

func nextASCIIString(i *Iter) []byte {

func ToFold(s string) string {
	// Fast path: all ASCII, no upper case.
	// Most paths look like this already.
	for i := 0; i < len(s); i++ {
		c := s[i]
		if c >= utf8.RuneSelf || 'A' <= c && c <= 'Z' {
			goto Slow
		}
	}
	return s

Slow:
	var b strings.Builder
	for _, r := range s {
		// SimpleFold(x) cycles to the next equivalent rune > x

	char := func(b byte) { buf = append(buf, b) }
	str := func(s string) { buf = append(buf, s...) }

	start := 0
	for i := 0; i < len(s); {
		if b := s[i]; b < utf8.RuneSelf {
			if safeSet[b] {
				i++
				continue
			}
			if start < i {
				str(s[start:i])
			}
			char('\\')
			switch b {
			case '\\', '"':
				char(b)
			case '\n':
				char('n')

		nBuf := make([]byte, len(buf), len(buf)+1+len(s)+1)
		copy(nBuf, buf)
		buf = nBuf
	}
	buf = append(buf, quote)
	for width := 0; len(s) > 0; s = s[width:] {
		r := rune(s[0])
		width = 1
		if r >= utf8.RuneSelf {
			r, width = utf8.DecodeRuneInString(s)
		}
		if width == 1 && r == utf8.RuneError {
			buf = append(buf, `\x`...)
			buf = append(buf, lowerhex[s[0]>>4])
			buf = append(buf, lowerhex[s[0]&0xF])
			continue