migrate go version to 1.17 (#203)

* migrate go version to 1.17

* update contributing

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

@@ -0,0 +1,242 @@
+package decoder
+
+import (
+	"fmt"
+	"reflect"
+	"unsafe"
+
+	"github.com/goccy/go-json/internal/errors"
+	"github.com/goccy/go-json/internal/runtime"
+)
+
+type intDecoder struct {
+	typ        *runtime.Type
+	kind       reflect.Kind
+	op         func(unsafe.Pointer, int64)
+	structName string
+	fieldName  string
+}
+
+func newIntDecoder(typ *runtime.Type, structName, fieldName string, op func(unsafe.Pointer, int64)) *intDecoder {
+	return &intDecoder{
+		typ:        typ,
+		kind:       typ.Kind(),
+		op:         op,
+		structName: structName,
+		fieldName:  fieldName,
+	}
+}
+
+func (d *intDecoder) typeError(buf []byte, offset int64) *errors.UnmarshalTypeError {
+	return &errors.UnmarshalTypeError{
+		Value:  fmt.Sprintf("number %s", string(buf)),
+		Type:   runtime.RType2Type(d.typ),
+		Struct: d.structName,
+		Field:  d.fieldName,
+		Offset: offset,
+	}
+}
+
+var (
+	pow10i64 = [...]int64{
+		1e00, 1e01, 1e02, 1e03, 1e04, 1e05, 1e06, 1e07, 1e08, 1e09,
+		1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18,
+	}
+	pow10i64Len = len(pow10i64)
+)
+
+func (d *intDecoder) parseInt(b []byte) (int64, error) {
+	isNegative := false
+	if b[0] == '-' {
+		b = b[1:]
+		isNegative = true
+	}
+	maxDigit := len(b)
+	if maxDigit > pow10i64Len {
+		return 0, fmt.Errorf("invalid length of number")
+	}
+	sum := int64(0)
+	for i := 0; i < maxDigit; i++ {
+		c := int64(b[i]) - 48
+		digitValue := pow10i64[maxDigit-i-1]
+		sum += c * digitValue
+	}
+	if isNegative {
+		return -1 * sum, nil
+	}
+	return sum, nil
+}
+
+var (
+	numTable = [256]bool{
+		'0': true,
+		'1': true,
+		'2': true,
+		'3': true,
+		'4': true,
+		'5': true,
+		'6': true,
+		'7': true,
+		'8': true,
+		'9': true,
+	}
+)
+
+var (
+	numZeroBuf = []byte{'0'}
+)
+
+func (d *intDecoder) decodeStreamByte(s *Stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '-':
+			start := s.cursor
+			for {
+				s.cursor++
+				if numTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						s.cursor-- // for retry current character
+						continue
+					}
+				}
+				break
+			}
+			num := s.buf[start:s.cursor]
+			if len(num) < 2 {
+				goto ERROR
+			}
+			return num, nil
+		case '0':
+			s.cursor++
+			return numZeroBuf, nil
+		case '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			start := s.cursor
+			for {
+				s.cursor++
+				if numTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						s.cursor-- // for retry current character
+						continue
+					}
+				}
+				break
+			}
+			num := s.buf[start:s.cursor]
+			return num, nil
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return nil, err
+			}
+			return nil, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		default:
+			return nil, d.typeError([]byte{s.char()}, s.totalOffset())
+		}
+	}
+ERROR:
+	return nil, errors.ErrUnexpectedEndOfJSON("number(integer)", s.totalOffset())
+}
+
+func (d *intDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
+	b := (*sliceHeader)(unsafe.Pointer(&buf)).data
+	for {
+		switch char(b, cursor) {
+		case ' ', '\n', '\t', '\r':
+			cursor++
+			continue
+		case '0':
+			cursor++
+			return numZeroBuf, cursor, nil
+		case '-', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			start := cursor
+			cursor++
+			for numTable[char(b, 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, d.typeError([]byte{char(b, cursor)}, cursor)
+		}
+	}
+}
+
+func (d *intDecoder) DecodeStream(s *Stream, depth int64, p unsafe.Pointer) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	if bytes == nil {
+		return nil
+	}
+	i64, err := d.parseInt(bytes)
+	if err != nil {
+		return d.typeError(bytes, s.totalOffset())
+	}
+	switch d.kind {
+	case reflect.Int8:
+		if i64 <= -1*(1<<7) || (1<<7) <= i64 {
+			return d.typeError(bytes, s.totalOffset())
+		}
+	case reflect.Int16:
+		if i64 <= -1*(1<<15) || (1<<15) <= i64 {
+			return d.typeError(bytes, s.totalOffset())
+		}
+	case reflect.Int32:
+		if i64 <= -1*(1<<31) || (1<<31) <= i64 {
+			return d.typeError(bytes, s.totalOffset())
+		}
+	}
+	d.op(p, i64)
+	s.reset()
+	return nil
+}
+
+func (d *intDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsafe.Pointer) (int64, error) {
+	bytes, c, err := d.decodeByte(ctx.Buf, cursor)
+	if err != nil {
+		return 0, err
+	}
+	if bytes == nil {
+		return c, nil
+	}
+	cursor = c
+
+	i64, err := d.parseInt(bytes)
+	if err != nil {
+		return 0, d.typeError(bytes, cursor)
+	}
+	switch d.kind {
+	case reflect.Int8:
+		if i64 <= -1*(1<<7) || (1<<7) <= i64 {
+			return 0, d.typeError(bytes, cursor)
+		}
+	case reflect.Int16:
+		if i64 <= -1*(1<<15) || (1<<15) <= i64 {
+			return 0, d.typeError(bytes, cursor)
+		}
+	case reflect.Int32:
+		if i64 <= -1*(1<<31) || (1<<31) <= i64 {
+			return 0, d.typeError(bytes, cursor)
+		}
+	}
+	d.op(p, i64)
+	return cursor, nil
+}