migrate go version to 1.17 (#203)

* migrate go version to 1.17

* update contributing

vendor/github.com/goccy/go-json/internal/decoder/float.go

@@ -0,0 +1,158 @@
+package decoder
+
+import (
+	"strconv"
+	"unsafe"
+
+	"github.com/goccy/go-json/internal/errors"
+)
+
+type floatDecoder struct {
+	op         func(unsafe.Pointer, float64)
+	structName string
+	fieldName  string
+}
+
+func newFloatDecoder(structName, fieldName string, op func(unsafe.Pointer, float64)) *floatDecoder {
+	return &floatDecoder{op: op, structName: structName, fieldName: fieldName}
+}
+
+var (
+	floatTable = [256]bool{
+		'0': true,
+		'1': true,
+		'2': true,
+		'3': true,
+		'4': true,
+		'5': true,
+		'6': true,
+		'7': true,
+		'8': true,
+		'9': true,
+		'.': true,
+		'e': true,
+		'E': true,
+		'+': true,
+		'-': true,
+	}
+
+	validEndNumberChar = [256]bool{
+		nul:  true,
+		' ':  true,
+		'\t': true,
+		'\r': true,
+		'\n': true,
+		',':  true,
+		':':  true,
+		'}':  true,
+		']':  true,
+	}
+)
+
+func floatBytes(s *Stream) []byte {
+	start := s.cursor
+	for {
+		s.cursor++
+		if floatTable[s.char()] {
+			continue
+		} else if s.char() == nul {
+			if s.read() {
+				s.cursor-- // for retry current character
+				continue
+			}
+		}
+		break
+	}
+	return s.buf[start:s.cursor]
+}
+
+func (d *floatDecoder) decodeStreamByte(s *Stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			return floatBytes(s), nil
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return nil, err
+			}
+			return nil, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		default:
+			goto ERROR
+		}
+	}
+ERROR:
+	return nil, errors.ErrUnexpectedEndOfJSON("float", s.totalOffset())
+}
+
+func (d *floatDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
+	for {
+		switch buf[cursor] {
+		case ' ', '\n', '\t', '\r':
+			cursor++
+			continue
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			start := cursor
+			cursor++
+			for floatTable[buf[cursor]] {
+				cursor++
+			}
+			num := buf[start:cursor]
+			return num, cursor, nil
+		case 'n':
+			if err := validateNull(buf, cursor); err != nil {
+				return nil, 0, err
+			}
+			cursor += 4
+			return nil, cursor, nil
+		default:
+			return nil, 0, errors.ErrUnexpectedEndOfJSON("float", cursor)
+		}
+	}
+}
+
+func (d *floatDecoder) DecodeStream(s *Stream, depth int64, p unsafe.Pointer) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	if bytes == nil {
+		return nil
+	}
+	str := *(*string)(unsafe.Pointer(&bytes))
+	f64, err := strconv.ParseFloat(str, 64)
+	if err != nil {
+		return errors.ErrSyntax(err.Error(), s.totalOffset())
+	}
+	d.op(p, f64)
+	return nil
+}
+
+func (d *floatDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsafe.Pointer) (int64, error) {
+	buf := ctx.Buf
+	bytes, c, err := d.decodeByte(buf, cursor)
+	if err != nil {
+		return 0, err
+	}
+	if bytes == nil {
+		return c, nil
+	}
+	cursor = c
+	if !validEndNumberChar[buf[cursor]] {
+		return 0, errors.ErrUnexpectedEndOfJSON("float", cursor)
+	}
+	s := *(*string)(unsafe.Pointer(&bytes))
+	f64, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return 0, errors.ErrSyntax(err.Error(), cursor)
+	}
+	d.op(p, f64)
+	return cursor, nil
+}