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 'a' <= r && r <= 'z' ||
		'A' <= r && r <= 'Z' ||
		'0' <= r && r <= '9' ||
		r == '-' ||
		r == '_' ||
		// Non-ASCII cases below.
		0x80 <= r && r <= 0xd7ff ||
		0xe000 <= r && r <= 0xfffd ||
		0x10000 <= r && r <= 0x10ffff
}

// decodeCSS decodes CSS3 escapes given a sequence of stringchars.
// If there is no change, it returns the input, otherwise it returns a slice
// backed by a new array.

	{'a', `'a'`, `'a'`, `'a'`},
	{'\a', `'\a'`, `'\a'`, `'\a'`},
	{'\\', `'\\'`, `'\\'`, `'\\'`},
	{0xFF, `'ÿ'`, `'\u00ff'`, `'ÿ'`},
	{0x263a, `'☺'`, `'\u263a'`, `'☺'`},
	{0xdead, `'�'`, `'\ufffd'`, `'�'`},
	{0xfffd, `'�'`, `'\ufffd'`, `'�'`},
	{0x0010ffff, `'\U0010ffff'`, `'\U0010ffff'`, `'\U0010ffff'`},
	{0x0010ffff + 1, `'�'`, `'\ufffd'`, `'�'`},
	{0x04, `'\x04'`, `'\x04'`, `'\x04'`},

byte('\x00')
byte('\'')
math.Float64frombits(0x7ff8000000000002)
math.Float32frombits(0x7fc00001)`,
		},
		{
			desc: "rune validation",
			in: `go test fuzz v1
rune(0)
rune(0x41)
rune(-1)
rune(0xfffd)
rune(0xd800)
rune(0x10ffff)
rune(0x110000)
`,
			want: `go test fuzz v1
rune('\x00')
rune('A')
int32(-1)
rune('�')
int32(55296)
rune('\U0010ffff')
int32(1114112)`,
		},
		{

	0xd7b0, 0xd7c6,
	0xd7cb, 0xd7fb,
	0xf900, 0xfa6d,
	0xfa70, 0xfad9,
	0xfb00, 0xfb06,
	0xfb13, 0xfb17,
	0xfb1d, 0xfbc2,
	0xfbd3, 0xfd8f,
	0xfd92, 0xfdc7,
	0xfdcf, 0xfdcf,
	0xfdf0, 0xfe19,
	0xfe20, 0xfe6b,
	0xfe70, 0xfefc,
	0xff01, 0xffbe,
	0xffc2, 0xffc7,
	0xffca, 0xffcf,
	0xffd2, 0xffd7,
	0xffda, 0xffdc,
	0xffe0, 0xffee,
	0xfffc, 0xfffd,
}

var isNotPrint16 = []uint16{

	0xedd,
	0x1000,
	0x1200,
	0x1312,
	0x1401,
	0x2c00,
	0xa800,
	0xf900,
	0xfa30,
	0xffda,
	0xffdc,
	0x10000,
	0x10300,
	0x10400,
	0x20000,
	0x2f800,
	0x2fa1d,
}

var notletterTest = []rune{
	0x20,
	0x35,
	0x375,
	0x619,
	0x700,
	0x1885,
	0xfffe,
	0x1ffff,
	0x10ffff,
}

// Contains all the special cased Latin-1 chars.
var spaceTest = []rune{
	0x09,

		{0x11F9, 0x11F9, 1},
		{0x1E00, 0x1E9B, 1},
		{0x1EA0, 0x1EF9, 1},
		{0x1F00, 0x1F15, 1},
		{0x1F18, 0x1F1D, 1},
		{0x1F20, 0x1F45, 1},
		{0x1F48, 0x1F4D, 1},
		{0x1F50, 0x1F57, 1},
		{0x1F59, 0x1F5B, 0x1F5B - 0x1F59},
		{0x1F5D, 0x1F5D, 1},
		{0x1F5F, 0x1F7D, 1},
		{0x1F80, 0x1FB4, 1},
		{0x1FB6, 0x1FBC, 1},
		{0x1FBE, 0x1FBE, 1},
		{0x1FC2, 0x1FC4, 1},
		{0x1FC6, 0x1FCC, 1},

	SOCK_SEQPACKET                = 0x6
	SOCK_STREAM                   = 0x2
	SOCK_TYPE_MASK                = 0xffff
	SOL_FILTER                    = 0xfffc
	SOL_PACKET                    = 0xfffd
	SOL_ROUTE                     = 0xfffe
	SOL_SOCKET                    = 0xffff
	SOMAXCONN                     = 0x80
	SO_ACCEPTCONN                 = 0x2
	SO_ALL                        = 0x3f

	{0xfffe, "\xef\xbf\xbe"},
	{0xffff, "\xef\xbf\xbf"},
	{0x10000, "\xf0\x90\x80\x80"},
	{0x10001, "\xf0\x90\x80\x81"},
	{0x40000, "\xf1\x80\x80\x80"},
	{0x10fffe, "\xf4\x8f\xbf\xbe"},
	{0x10ffff, "\xf4\x8f\xbf\xbf"},
	{0xFFFD, "\xef\xbf\xbd"},
}

var surrogateMap = []Utf8Map{
	{0xd800, "\xed\xa0\x80"}, // surrogate min decodes to (RuneError, 1)

	default:
		switch {
		case r < ' ' || r == 0x7f:
			buf = append(buf, `\x`...)
			buf = append(buf, lowerhex[byte(r)>>4])
			buf = append(buf, lowerhex[byte(r)&0xF])
		case !utf8.ValidRune(r):
			r = 0xFFFD
			fallthrough
		case r < 0x10000:
			buf = append(buf, `\u`...)
			for s := 12; s >= 0; s -= 4 {
				buf = append(buf, lowerhex[r>>uint(s)&0xF])
			}
		default:
			buf = append(buf, `\U`...)