//
// For each rune, it takes the indexes into the original string, the class the
// bracket type (in pairTypes) and the bracket identifier (pairValues). It also
// takes the direction type for the start-of-sentence and the embedding level.
//
// The identifiers for bracket types are the rune of the canonicalized opening
// bracket for brackets (open or close) or 0 for runes that are not brackets.

}

// next returns the next rune in the input.
func (l *lexer) next() rune {
	if int(l.pos) >= len(l.input) {
		l.atEOF = true
		return eof
	}
	r, w := utf8.DecodeRuneInString(l.input[l.pos:])
	l.pos += Pos(w)
	if r == '\n' {
		l.line++
	}
	return r
}

// peek returns but does not consume the next rune in the input.
func (l *lexer) peek() rune {
	r := l.next()
	l.backup()

type Reader struct {
	// Comma is the field delimiter.
	// It is set to comma (',') by NewReader.
	// Comma must be a valid rune and must not be \r, \n,
	// or the Unicode replacement character (0xFFFD).
	Comma rune

	// Comment, if not 0, is the comment character. Lines beginning with the
	// Comment character without preceding whitespace are ignored.

	return s
}

// replace replaces each rune r of s with replacementTable[r], provided that
// r < len(replacementTable). If replacementTable[r] is the empty string then
// no replacement is made.
// It also replaces runes U+2028 and U+2029 with the raw strings `\u2028` and
// `\u2029`.
func replace(s string, replacementTable []string) string {
	var b strings.Builder
	r, w, written := rune(0), 0, 0
	for i := 0; i < len(s); i += w {

}

func digitVal(ch rune) int {
	switch {
	case '0' <= ch && ch <= '9':
		return int(ch - '0')
	case 'a' <= lower(ch) && lower(ch) <= 'f':
		return int(lower(ch) - 'a' + 10)
	}
	return 16 // larger than any legal digit val
}

func lower(ch rune) rune     { return ('a' - 'A') | ch } // returns lower-case ch iff ch is ASCII letter
func isDecimal(ch rune) bool { return '0' <= ch && ch <= '9' }

package norm

import (
	"fmt"
	"unicode/utf8"
)

// MaxSegmentSize is the maximum size of a byte buffer needed to consider any
// sequence of starter and non-starter runes for the purpose of normalization.
const MaxSegmentSize = maxByteBufferSize

// An Iter iterates over a string or byte slice, while normalizing it
// to a given Form.
type Iter struct {
	rb     reorderBuffer

// It records the pair of relevant runes and does not
// determine the implied flags until absolutely necessary
// (most of the time, that means never).
type lazyFlag uint64

func newLazyFlag(r1, r2 rune) lazyFlag {
	return lazyFlag(uint64(r1)<<32 | uint64(uint32(r2)))
}

func (f lazyFlag) match(op syntax.EmptyOp) bool {
	if op == 0 {
		return true
	}
	r1 := rune(f >> 32)
	if op&syntax.EmptyBeginLine != 0 {

	// So limit the buffer to 16000 characters. This number was
	// discovered by experimenting with syscall.WriteConsole.
	const maxWrite = 16000
	for len(runes) > 0 {
		m := len(runes)
		if m > maxWrite {
			m = maxWrite
		}
		chunk := runes[:m]
		runes = runes[m:]
		uint16s := utf16.Encode(chunk)
		for len(uint16s) > 0 {
			var written uint32

func (e labelError) Error() string {
	return fmt.Sprintf("idna: invalid label %q", e.label)
}

type runeError rune

func (e runeError) code() string { return "P1" }
func (e runeError) Error() string {
	return fmt.Sprintf("idna: disallowed rune %U", e)
}

// process implements the algorithm described in section 4 of UTS #46,
// see https://www.unicode.org/reports/tr46.

	// the closure once per rune.
	prev := ' '
	return Map(
		func(r rune) rune {
			if isSeparator(prev) {
				prev = r
				return unicode.ToTitle(r)
			}
			prev = r
			return r
		},
		s)
}

// TrimLeftFunc returns a slice of the string s with all leading
// Unicode code points c satisfying f(c) removed.
func TrimLeftFunc(s string, f func(rune) bool) string {
	i := indexFunc(s, f, false)