// 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

// 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.
)

	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 {

	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 {

		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

func (s *Scanner) Init(src io.Reader) *Scanner {
	s.src = src

	// initialize source buffer
	// (the first call to next() will fill it by calling src.Read)
	s.srcBuf[0] = utf8.RuneSelf // sentinel
	s.srcPos = 0
	s.srcEnd = 0

	// initialize source position
	s.srcBufOffset = 0
	s.line = 1
	s.column = 0
	s.lastLineLen = 0
	s.lastCharLen = 0

	// initialize token text buffer

	// 0 < pos && pos <= len(i.str)
	if uint(pos-1) < uint(len(i.str)) {
		r1 = rune(i.str[pos-1])
		if r1 >= utf8.RuneSelf {
			r1, _ = utf8.DecodeLastRuneInString(i.str[:pos])
		}
	}
	// 0 <= pos && pos < len(i.str)
	if uint(pos) < uint(len(i.str)) {
		r2 = rune(i.str[pos])
		if r2 >= utf8.RuneSelf {
			r2, _ = utf8.DecodeRuneInString(i.str[pos:])
		}
	}
	return newLazyFlag(r1, r2)
}

		s.nextch()
	}

	// token start
	s.line, s.col = s.pos()
	s.blank = s.line > startLine || startCol == colbase
	s.start()
	if isLetter(s.ch) || s.ch >= utf8.RuneSelf && s.atIdentChar(true) {
		s.nextch()
		s.ident()
		return
	}

	switch s.ch {
	case -1:
		if nlsemi {
			s.lit = "EOF"
			s.tok = _Semi
			break
		}
		s.tok = _EOF

		nind.SetBounded(true)
		body = append(body, ir.NewAssignStmt(base.Pos, hv2, typecheck.Conv(nind, types.RuneType)))

		// if hv2 < utf8.RuneSelf
		nif := ir.NewIfStmt(base.Pos, nil, nil, nil)
		nif.Cond = ir.NewBinaryExpr(base.Pos, ir.OLT, hv2, ir.NewInt(base.Pos, utf8.RuneSelf))

		// hv1++
		nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, hv1, ir.NewBinaryExpr(base.Pos, ir.OADD, hv1, ir.NewInt(base.Pos, 1)))}

	return i + 1, int(n), err == nil
}

func isLetter(ch rune) bool {
	return 'a' <= lower(ch) && lower(ch) <= 'z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
}

func isDigit(ch rune) bool {
	return isDecimal(ch) || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
}

// scanIdentifier reads the string of valid identifier characters at s.offset.