go-json/decode_array.go

package json

import "unsafe"

type arrayDecoder struct {
	elemType     *rtype
	size         uintptr
	valueDecoder decoder
	alen         int
}

func newArrayDecoder(dec decoder, elemType *rtype, alen int) *arrayDecoder {
	return &arrayDecoder{
		valueDecoder: dec,
		elemType:     elemType,
		size:         elemType.Size(),
		alen:         alen,
	}
}

func (d *arrayDecoder) decodeStream(s *stream, p unsafe.Pointer) error {
	for {
		switch s.char() {
		case ' ', '\n', '\t', '\r':
		case 'n':
			if err := nullBytes(s); err != nil {
				return err
			}
			return nil
		case '[':
			idx := 0
			for {
				s.cursor++
				addr := uintptr(p) + uintptr(idx)*d.size
				if err := d.valueDecoder.decodeStream(s, *(*unsafe.Pointer)(unsafe.Pointer(&addr))); err != nil {
					return err
				}
				s.skipWhiteSpace()
				switch s.char() {
				case ']':
					s.cursor++
					return nil
				case ',':
					idx++
				case nul:
					if s.read() {
						continue
					}
					goto ERROR
				default:
					goto ERROR
				}
			}
		case nul:
			if s.read() {
				continue
			}
			goto ERROR
		default:
			goto ERROR
		}
		s.cursor++
	}
ERROR:
	return errUnexpectedEndOfJSON("array", s.totalOffset())
}

func (d *arrayDecoder) decode(buf []byte, cursor int64, p unsafe.Pointer) (int64, error) {
	buflen := int64(len(buf))
	for ; cursor < buflen; cursor++ {
		switch buf[cursor] {
		case ' ', '\n', '\t', '\r':
			continue
		case 'n':
			buflen := int64(len(buf))
			if cursor+3 >= buflen {
				return 0, errUnexpectedEndOfJSON("null", cursor)
			}
			if buf[cursor+1] != 'u' {
				return 0, errInvalidCharacter(buf[cursor+1], "null", cursor)
			}
			if buf[cursor+2] != 'l' {
				return 0, errInvalidCharacter(buf[cursor+2], "null", cursor)
			}
			if buf[cursor+3] != 'l' {
				return 0, errInvalidCharacter(buf[cursor+3], "null", cursor)
			}
			cursor += 4
			return cursor, nil
		case '[':
			idx := 0
			for {
				cursor++
				addr := uintptr(p) + uintptr(idx)*d.size
				c, err := d.valueDecoder.decode(buf, cursor, *(*unsafe.Pointer)(unsafe.Pointer(&addr)))
				if err != nil {
					return 0, err
				}
				cursor = c
				cursor = skipWhiteSpace(buf, cursor)
				switch buf[cursor] {
				case ']':
					cursor++
					return cursor, nil
				case ',':
					idx++
					continue
				default:
					return 0, errInvalidCharacter(buf[cursor], "array", cursor)
				}
			}
		}
	}
	return 0, errUnexpectedEndOfJSON("array", cursor)
}