func CharClass(negated bool, table *unicode.RangeTable) Matcher {
	var t unicode.RangeTable
	t.R16 = make([]unicode.Range16, len(table.R16))
	copy(t.R16, table.R16)
	t.R32 = make([]unicode.Range32, len(table.R32))
	copy(t.R32, table.R32)
	t.LatinOffset = table.LatinOffset
	return charClassMatcher{negated, t}
}
func OneOf(chars ...rune) Matcher {
	if len(chars) == 0 {
		return Fail()
	}
	var t unicode.RangeTable
	sort.Sort(utf8betical(chars))
	for _, ch := range chars {
		if ch >= 0x10000 {
			t.R32 = append(t.R32, unicode.Range32{Lo: uint32(ch), Hi: uint32(ch), Stride: 1})
		} else {
			t.R16 = append(t.R16, unicode.Range16{Lo: uint16(ch), Hi: uint16(ch), Stride: 1})
			if ch < 0x100 {
				t.LatinOffset += 1
			}
		}
	}
	return charClassMatcher{false, t}
}
func Range(lo, hi rune) Matcher {
	if lo > hi {
		return Fail()
	}
	var t unicode.RangeTable
	if lo >= 0x10000 {
		t.R32 = append(t.R32, unicode.Range32{Lo: uint32(lo), Hi: uint32(hi), Stride: 1})
	} else if hi < 0x10000 {
		t.R16 = append(t.R16, unicode.Range16{Lo: uint16(lo), Hi: uint16(hi), Stride: 1})
		if hi < 0x100 {
			t.LatinOffset = 1
		}
	} else {
		t.R16 = append(t.R16, unicode.Range16{Lo: uint16(lo), Hi: 0xffff, Stride: 1})
		t.R32 = append(t.R32, unicode.Range32{Lo: 0x10000, Hi: uint32(hi), Stride: 1})
	}
	return charClassMatcher{false, t}
}