migrate go version to 1.17 (#203)

* migrate go version to 1.17

* update contributing

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

@@ -0,0 +1,186 @@
+package decoder
+
+import (
+	"reflect"
+	"unsafe"
+
+	"github.com/goccy/go-json/internal/errors"
+	"github.com/goccy/go-json/internal/runtime"
+)
+
+type mapDecoder struct {
+	mapType                 *runtime.Type
+	keyType                 *runtime.Type
+	valueType               *runtime.Type
+	canUseAssignFaststrType bool
+	keyDecoder              Decoder
+	valueDecoder            Decoder
+	structName              string
+	fieldName               string
+}
+
+func newMapDecoder(mapType *runtime.Type, keyType *runtime.Type, keyDec Decoder, valueType *runtime.Type, valueDec Decoder, structName, fieldName string) *mapDecoder {
+	return &mapDecoder{
+		mapType:                 mapType,
+		keyDecoder:              keyDec,
+		keyType:                 keyType,
+		canUseAssignFaststrType: canUseAssignFaststrType(keyType, valueType),
+		valueType:               valueType,
+		valueDecoder:            valueDec,
+		structName:              structName,
+		fieldName:               fieldName,
+	}
+}
+
+const (
+	mapMaxElemSize = 128
+)
+
+// See detail: https://github.com/goccy/go-json/pull/283
+func canUseAssignFaststrType(key *runtime.Type, value *runtime.Type) bool {
+	indirectElem := value.Size() > mapMaxElemSize
+	if indirectElem {
+		return false
+	}
+	return key.Kind() == reflect.String
+}
+
+//go:linkname makemap reflect.makemap
+func makemap(*runtime.Type, int) unsafe.Pointer
+
+//nolint:golint
+//go:linkname mapassign_faststr runtime.mapassign_faststr
+//go:noescape
+func mapassign_faststr(t *runtime.Type, m unsafe.Pointer, s string) unsafe.Pointer
+
+//go:linkname mapassign reflect.mapassign
+//go:noescape
+func mapassign(t *runtime.Type, m unsafe.Pointer, k, v unsafe.Pointer)
+
+func (d *mapDecoder) mapassign(t *runtime.Type, m, k, v unsafe.Pointer) {
+	if d.canUseAssignFaststrType {
+		mapV := mapassign_faststr(t, m, *(*string)(k))
+		typedmemmove(d.valueType, mapV, v)
+	} else {
+		mapassign(t, m, k, v)
+	}
+}
+
+func (d *mapDecoder) DecodeStream(s *Stream, depth int64, p unsafe.Pointer) error {
+	depth++
+	if depth > maxDecodeNestingDepth {
+		return errors.ErrExceededMaxDepth(s.char(), s.cursor)
+	}
+
+	switch s.skipWhiteSpace() {
+	case 'n':
+		if err := nullBytes(s); err != nil {
+			return err
+		}
+		**(**unsafe.Pointer)(unsafe.Pointer(&p)) = nil
+		return nil
+	case '{':
+	default:
+		return errors.ErrExpected("{ character for map value", s.totalOffset())
+	}
+	mapValue := *(*unsafe.Pointer)(p)
+	if mapValue == nil {
+		mapValue = makemap(d.mapType, 0)
+	}
+	if s.buf[s.cursor+1] == '}' {
+		*(*unsafe.Pointer)(p) = mapValue
+		s.cursor += 2
+		return nil
+	}
+	for {
+		s.cursor++
+		k := unsafe_New(d.keyType)
+		if err := d.keyDecoder.DecodeStream(s, depth, k); err != nil {
+			return err
+		}
+		s.skipWhiteSpace()
+		if !s.equalChar(':') {
+			return errors.ErrExpected("colon after object key", s.totalOffset())
+		}
+		s.cursor++
+		v := unsafe_New(d.valueType)
+		if err := d.valueDecoder.DecodeStream(s, depth, v); err != nil {
+			return err
+		}
+		d.mapassign(d.mapType, mapValue, k, v)
+		s.skipWhiteSpace()
+		if s.equalChar('}') {
+			**(**unsafe.Pointer)(unsafe.Pointer(&p)) = mapValue
+			s.cursor++
+			return nil
+		}
+		if !s.equalChar(',') {
+			return errors.ErrExpected("comma after object value", s.totalOffset())
+		}
+	}
+}
+
+func (d *mapDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsafe.Pointer) (int64, error) {
+	buf := ctx.Buf
+	depth++
+	if depth > maxDecodeNestingDepth {
+		return 0, errors.ErrExceededMaxDepth(buf[cursor], cursor)
+	}
+
+	cursor = skipWhiteSpace(buf, cursor)
+	buflen := int64(len(buf))
+	if buflen < 2 {
+		return 0, errors.ErrExpected("{} for map", cursor)
+	}
+	switch buf[cursor] {
+	case 'n':
+		if err := validateNull(buf, cursor); err != nil {
+			return 0, err
+		}
+		cursor += 4
+		**(**unsafe.Pointer)(unsafe.Pointer(&p)) = nil
+		return cursor, nil
+	case '{':
+	default:
+		return 0, errors.ErrExpected("{ character for map value", cursor)
+	}
+	cursor++
+	cursor = skipWhiteSpace(buf, cursor)
+	mapValue := *(*unsafe.Pointer)(p)
+	if mapValue == nil {
+		mapValue = makemap(d.mapType, 0)
+	}
+	if buf[cursor] == '}' {
+		**(**unsafe.Pointer)(unsafe.Pointer(&p)) = mapValue
+		cursor++
+		return cursor, nil
+	}
+	for {
+		k := unsafe_New(d.keyType)
+		keyCursor, err := d.keyDecoder.Decode(ctx, cursor, depth, k)
+		if err != nil {
+			return 0, err
+		}
+		cursor = skipWhiteSpace(buf, keyCursor)
+		if buf[cursor] != ':' {
+			return 0, errors.ErrExpected("colon after object key", cursor)
+		}
+		cursor++
+		v := unsafe_New(d.valueType)
+		valueCursor, err := d.valueDecoder.Decode(ctx, cursor, depth, v)
+		if err != nil {
+			return 0, err
+		}
+		d.mapassign(d.mapType, mapValue, k, v)
+		cursor = skipWhiteSpace(buf, valueCursor)
+		if buf[cursor] == '}' {
+			**(**unsafe.Pointer)(unsafe.Pointer(&p)) = mapValue
+			cursor++
+			return cursor, nil
+		}
+		if buf[cursor] != ',' {
+			return 0, errors.ErrExpected("comma after object value", cursor)
+		}
+		cursor++
+	}
+}