// Package utf16 implements encoding and decoding of UTF-16 sequences.
package utf16

// The conditions replacementChar==unicode.ReplacementChar and
// maxRune==unicode.MaxRune are verified in the tests.
// Defining them locally avoids this package depending on package unicode.

const (
	replacementChar = '\uFFFD'     // Unicode replacement character
	maxRune         = '\U0010FFFF' // Maximum valid Unicode code point.
)

package utf16

// Extra names for constants so we can validate them during testing.
const (
	Surr1           = surr1
	Surr3           = surr3
	SurrSelf        = surrSelf
	MaxRune         = maxRune
	ReplacementChar = replacementChar

func TestConstants(t *testing.T) {
	if MaxRune != unicode.MaxRune {
		t.Errorf("utf16.maxRune is wrong: %x should be %x", MaxRune, unicode.MaxRune)
	}
	if ReplacementChar != unicode.ReplacementChar {
		t.Errorf("utf16.replacementChar is wrong: %x should be %x", ReplacementChar, unicode.ReplacementChar)
	}
}

func TestRuneLen(t *testing.T) {
	for _, tt := range []struct {
		r      rune
		length int
	}{
		{0, 1},
		{Surr1 - 1, 1},

// Package unicode provides data and functions to test some properties of
// Unicode code points.
package unicode

const (
	MaxRune         = '\U0010FFFF' // Maximum valid Unicode code point.
	ReplacementChar = '\uFFFD'     // Represents invalid code points.
	MaxASCII        = '\u007F'     // maximum ASCII value.
	MaxLatin1       = '\u00FF'     // maximum Latin-1 value.
)

			t.Errorf("unmarshaled %v (bits 0x%x)", x2, u2)
		}
	})
}

func FuzzRuneRoundTrip(f *testing.F) {
	f.Add(rune(-1))
	f.Add(rune(0xd800))
	f.Add(rune(0xdfff))
	f.Add(rune(unicode.ReplacementChar))
	f.Add(rune(unicode.MaxASCII))
	f.Add(rune(unicode.MaxLatin1))
	f.Add(rune(unicode.MaxRune))
	f.Add(rune(unicode.MaxRune + 1))
	f.Add(rune(-0x80000000))
	f.Add(rune(0x7fffffff))

		switch t, _ := under(T).(*Basic); {
		case t == nil:
			// nothing to do
		case representableConst(x.val, check, t, val):
			return true
		case isInteger(x.typ) && isString(t):
			codepoint := unicode.ReplacementChar
			if i, ok := constant.Uint64Val(x.val); ok && i <= unicode.MaxRune {
				codepoint = rune(i)
			}
			if val != nil {
				*val = constant.MakeString(string(codepoint))
			}
			return true
		}

		for _, c := range content {
			buf.WriteRune(rune(c))
		}
	case strings.EqualFold("us-ascii", charset):
		for _, c := range content {
			if c >= utf8.RuneSelf {
				buf.WriteRune(unicode.ReplacementChar)
			} else {
				buf.WriteByte(c)
			}
		}
	default:
		if d.CharsetReader == nil {
			return fmt.Errorf("mime: unhandled charset %q", charset)
		}

		switch t, _ := under(T).(*Basic); {
		case t == nil:
			// nothing to do
		case representableConst(x.val, check, t, val):
			return true
		case isInteger(x.typ) && isString(t):
			codepoint := unicode.ReplacementChar
			if i, ok := constant.Uint64Val(x.val); ok && i <= unicode.MaxRune {
				codepoint = rune(i)
			}
			if val != nil {
				*val = constant.MakeString(string(codepoint))
			}
			return true
		}

		}
	}

	// Prevent follow-on errors.
	return constant.MakeUnknown()
}

func tostr(v constant.Value) constant.Value {
	if v.Kind() == constant.Int {
		r := unicode.ReplacementChar
		if x, ok := constant.Uint64Val(v); ok && x <= unicode.MaxRune {
			r = rune(x)
		}
		v = constant.MakeString(string(r))
	}
	return v
}

func makeFloat64(f float64) constant.Value {

			}
			if j-i < 1 || j-i > 7 || j >= len(s) || s[j] != ';' {
				return nil, 0, 0, false
			}
			r, _ = strconv.Atoi(s[i:j])
			end = j + 1
		}
		if r > unicode.MaxRune || r == 0 {
			r = unicode.ReplacementChar
		}
		return &Plain{string(rune(r))}, start, end, true
	}

	// Max name in list is 32 bytes. Try for 64 for good measure.
	for j := i + 1; j < len(s) && j-i < 64; j++ {