// Read implements the [io.Reader] interface.
func (r *Reader) Read(b []byte) (n int, err error) {
	if r.i >= int64(len(r.s)) {
		return 0, io.EOF
	}
	r.prevRune = -1
	n = copy(b, r.s[r.i:])
	r.i += int64(n)
	return
}

// ReadAt implements the [io.ReaderAt] interface.
func (r *Reader) ReadAt(b []byte, off int64) (n int, err error) {
	// cannot modify state - see io.ReaderAt
	if off < 0 {

func NewParquetReader(rsc io.ReadSeekCloser, _ *ReaderArgs) (r *Reader, err error) {
	fr, err := parquetgo.NewFileReader(rsc)
	if err != nil {
		return nil, errParquetParsingError(err)
	}

	return &Reader{Closer: rsc, r: fr}, nil
}

func (pr *Reader) Read(dst sql.Record) (rec sql.Record, rerr error) {
	nextRow, err := pr.r.NextRow()
	if err != nil {
		if err == io.EOF {
			return nil, err
		}

	var tmpObj simdjson.Object
	for {
		var in simdjson.Stream
		select {
		case in = <-r.input:
		case <-r.exitReader:
			return
		}
		if in.Error != nil && in.Error != io.EOF {
			r.err = &in.Error
			return
		}
		if in.Value == nil {
			if in.Error == io.EOF {
				return
			}
			continue
		}
		i := in.Value.Iter()
	readloop:
		for {
			var next simdjson.Iter

	blk  block      // Buffer to use as temporary local storage

	// err is a persistent error.
	// It is only the responsibility of every exported method of Reader to
	// ensure that this error is sticky.
	err error
}

type fileReader interface {
	io.Reader
	fileState

	WriteTo(io.Writer) (int64, error)
}

// NewReader creates a new [Reader] reading from r.
func NewReader(r io.Reader) *Reader {

func (r *Reader) ETag() ETag {
	sum := r.md5.Sum(nil)
	return ETag(sum)
}

// VerifyError is an error signaling that a
// computed ETag does not match an expected
// ETag.
type VerifyError struct {
	Expected ETag
	Computed ETag
}

func (v VerifyError) Error() string {
	return fmt.Sprintf("etag: expected ETag %q does not match computed ETag %q", v.Expected, v.Computed)
}

	f     *File
	desr  io.Reader // if non-nil, where to read the data descriptor
	err   error     // sticky error
}

func (r *checksumReader) Stat() (fs.FileInfo, error) {
	return headerFileInfo{&r.f.FileHeader}, nil
}

func (r *checksumReader) Read(b []byte) (n int, err error) {
	if r.err != nil {
		return 0, r.err
	}
	n, err = r.rc.Read(b)
	r.hash.Write(b[:n])

	dst   chan [][]string // result of block decode
	err   error           // any error encountered will be set here
}

// Read - reads single record.
// Once Read is called the previous record should no longer be referenced.
func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
	// If we have have any records left, return these before any error.
	for len(r.current) <= r.recordsRead {
		if r.err != nil {

	return newReader(ctx, src, size, md5Hex, sha256Hex, actualSize, false, nil)
}

func newReader(ctx context.Context, src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64, disableMD5 bool, forceMD5 []byte) (*Reader, error) {
	MD5, err := hex.DecodeString(md5Hex)
	if err != nil {

// MonitoredReader represents a throttled reader subject to bandwidth monitoring
type MonitoredReader struct {
	r        io.Reader
	throttle *bucketThrottle
	ctx      context.Context // request context
	lastErr  error           // last error reported, if this non-nil all reads will fail.
	m        *Monitor
	opts     *MonitorReaderOptions
}

// BucketOptions represents the bucket and optionally its replication target pair.