decode.go

		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
			n, err := strconv.ParseUint(string(item), 10, 64)
			if err != nil || v.OverflowUint(n) {
				d.saveError(&UnmarshalTypeError{Value: "number " + string(item), Type: v.Type(), Offset: int64(d.readIndex())})
				break
			}
			v.SetUint(n)

		case reflect.Float32, reflect.Float64:
			n, err := strconv.ParseFloat(string(item), v.Type().Bits())
			if err != nil || v.OverflowFloat(n) {
				d.saveError(&UnmarshalTypeError{Value: "number " + string(item), Type: v.Type(), Offset: int64(d.readIndex())})
				break
			}
			v.SetFloat(n)
		}
	}
	return nil
}

// The xxxInterface routines build up a value to be stored
// in an empty interface. They are not strictly necessary,
// but they avoid the weight of reflection in this common case.

// valueInterface is like value but returns any.
func (d *decodeState) valueInterface() (val any) {
	switch d.opcode {
	default:
		panic(phasePanicMsg)
	case scanBeginArray:
		val = d.arrayInterface()
		d.scanNext()
	case scanBeginObject:
		val = d.objectInterface()
		d.scanNext()
	case scanBeginLiteral:
		val = d.literalInterface()
	}
	return
}

// arrayInterface is like array but returns []any.
func (d *decodeState) arrayInterface() []any {
	var v = make([]any, 0)
	for {
		// Look ahead for ] - can only happen on first iteration.
		d.scanWhile(scanSkipSpace)
		if d.opcode == scanEndArray {
			break
		}

		v = append(v, d.valueInterface())

		// Next token must be , or ].
		if d.opcode == scanSkipSpace {
			d.scanWhile(scanSkipSpace)
		}
		if d.opcode == scanEndArray {
			break
		}
		if d.opcode != scanArrayValue {
			panic(phasePanicMsg)
		}
	}
	return v
}

// objectInterface is like object but returns map[string]any.
func (d *decodeState) objectInterface() map[string]any {
	m := make(map[string]any)
	for {
		// Read opening " of string key or closing }.
		d.scanWhile(scanSkipSpace)
		if d.opcode == scanEndObject {
			// closing } - can only happen on first iteration.
			break
		}
		if d.opcode != scanBeginLiteral {
			panic(phasePanicMsg)
		}

		// Read string key.
		start := d.readIndex()
		d.rescanLiteral()
		item := d.data[start:d.readIndex()]
		key, ok := unquote(item)
		if !ok {
			panic(phasePanicMsg)
		}

		// Read : before value.
		if d.opcode == scanSkipSpace {
			d.scanWhile(scanSkipSpace)
		}
		if d.opcode != scanObjectKey {
			panic(phasePanicMsg)
		}
		d.scanWhile(scanSkipSpace)

		// Read value.
		m[key] = d.valueInterface()

		// Next token must be , or }.
		if d.opcode == scanSkipSpace {
			d.scanWhile(scanSkipSpace)
		}
		if d.opcode == scanEndObject {
			break
		}
		if d.opcode != scanObjectValue {
			panic(phasePanicMsg)
		}
	}
	return m
}

// literalInterface consumes and returns a literal from d.data[d.off-1:] and
// it reads the following byte ahead. The first byte of the literal has been
// read already (that's how the caller knows it's a literal).
func (d *decodeState) literalInterface() any {
	// All bytes inside literal return scanContinue op code.
	start := d.readIndex()
	d.rescanLiteral()

	item := d.data[start:d.readIndex()]

	switch c := item[0]; c {
	case 'n': // null
		return nil

	case 't', 'f': // true, false
		return c == 't'

	case '"': // string
		s, ok := unquote(item)
		if !ok {
			panic(phasePanicMsg)
		}
		return s

	default: // number
		if c != '-' && (c < '0' || c > '9') {
			panic(phasePanicMsg)
		}
		n, err := d.convertNumber(string(item))
		if err != nil {
			d.saveError(err)
		}
		return n
	}
}

// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
// or it returns -1.
func getu4(s []byte) rune {
	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
		return -1
	}
	var r rune
	for _, c := range s[2:6] {
		switch {
		case '0' <= c && c <= '9':
			c = c - '0'
		case 'a' <= c && c <= 'f':
			c = c - 'a' + 10
		case 'A' <= c && c <= 'F':
			c = c - 'A' + 10
		default:
			return -1
		}
		r = r*16 + rune(c)
	}
	return r
}

// unquote converts a quoted JSON string literal s into an actual string t.
// The rules are different than for Go, so cannot use strconv.Unquote.
func unquote(s []byte) (t string, ok bool) {
	s, ok = unquoteBytes(s)
	t = string(s)
	return
}

// unquoteBytes should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - github.com/bytedance/sonic
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname unquoteBytes
func unquoteBytes(s []byte) (t []byte, ok bool) {
	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
		return
	}
	s = s[1 : len(s)-1]

	// Check for unusual characters. If there are none,
	// then no unquoting is needed, so return a slice of the
	// original bytes.
	r := 0
	for r < len(s) {
		c := s[r]
		if c == '\\' || c == '"' || c < ' ' {
			break
		}
		if c < utf8.RuneSelf {
			r++
			continue
		}
		rr, size := utf8.DecodeRune(s[r:])
		if rr == utf8.RuneError && size == 1 {
			break
		}
		r += size
	}
	if r == len(s) {
		return s, true
	}

	b := make([]byte, len(s)+2*utf8.UTFMax)
	w := copy(b, s[0:r])
	for r < len(s) {
		// Out of room? Can only happen if s is full of
		// malformed UTF-8 and we're replacing each
		// byte with RuneError.
		if w >= len(b)-2*utf8.UTFMax {
			nb := make([]byte, (len(b)+utf8.UTFMax)*2)
			copy(nb, b[0:w])
			b = nb
		}
		switch c := s[r]; {
		case c == '\\':
			r++
			if r >= len(s) {
				return
			}
			switch s[r] {
			default:
				return
			case '"', '\\', '/', '\'':
				b[w] = s[r]
				r++
				w++
			case 'b':
				b[w] = '\b'
				r++
				w++
			case 'f':
				b[w] = '\f'
				r++
				w++
			case 'n':
				b[w] = '\n'
				r++
				w++
			case 'r':
				b[w] = '\r'
				r++
				w++
			case 't':
				b[w] = '\t'
				r++
				w++
			case 'u':
				r--
				rr := getu4(s[r:])
				if rr < 0 {
					return
				}
				r += 6
				if utf16.IsSurrogate(rr) {
					rr1 := getu4(s[r:])
					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
						// A valid pair; consume.
						r += 6
						w += utf8.EncodeRune(b[w:], dec)
						break
					}
					// Invalid surrogate; fall back to replacement rune.
					rr = unicode.ReplacementChar
				}
				w += utf8.EncodeRune(b[w:], rr)
			}

		// Quote, control characters are invalid.
		case c == '"', c < ' ':
			return

		// ASCII
		case c < utf8.RuneSelf:
			b[w] = c
			r++
			w++

		// Coerce to well-formed UTF-8.
		default:
			rr, size := utf8.DecodeRune(s[r:])
			r += size
			w += utf8.EncodeRune(b[w:], rr)
		}
	}
	return b[0:w], true
}