func (d *Decoder) Pos() int { return int(d.pos) }

// Err returns the most recent decoder error if any, or nil
func (d *Decoder) Err() error { return d.err }

// MaxDepth will set the maximum recursion depth.
// If the maximum depth is exceeded, ErrMaxDepth is returned.
// Less than or 0 means no limit (default).
func (d *Decoder) MaxDepth(n int) *Decoder {
	d.maxDepth = n
	return d
}

func (filter FilterRule) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	if filter.isEmpty() {
		return nil
	}
	type filterRuleWrapper FilterRule
	return e.EncodeElement(filterRuleWrapper(filter), start)
}

// UnmarshalXML - decodes XML data.
func (filter *FilterRule) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	// Make subtype to avoid recursive UnmarshalXML().

		body    = `[{"bio":"bada bing bada boom","id":1,"name":"Charles","falseVal":false}]`
	)

	decoder := NewDecoder(mkReader(body), 1)

	for mv = range decoder.Stream() {
		counter++
		t.Logf("depth=%d offset=%d len=%d (%v)", mv.Depth, mv.Offset, mv.Length, mv.Value)
	}

	if err := decoder.Err(); err != nil {
		t.Fatalf("decoder error: %s", err)
	}
}

func TestDecoderNested(t *testing.T) {
	var (
		counter int

func (n NoncurrentVersionExpiration) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	if n.IsNull() {
		return nil
	}
	type noncurrentVersionExpirationWrapper NoncurrentVersionExpiration
	return e.EncodeElement(noncurrentVersionExpirationWrapper(n), start)
}

// UnmarshalXML decodes NoncurrentVersionExpiration
func (n *NoncurrentVersionExpiration) UnmarshalXML(d *xml.Decoder, startElement xml.StartElement) error {

	raw, err := store.GetRaw(key)
	if err != nil {
		return nil, err
	}

	decoder := jsoniter.ConfigCompatibleWithStandardLibrary.NewDecoder(bytes.NewReader(raw))
	for decoder.More() {
		var item I
		if err := decoder.Decode(&item); err != nil {
			return nil, err
		}
		items = append(items, item)
	}

	return items, err
}

// Reader - JSON record reader for S3Select.
type Reader struct {
	args       *ReaderArgs
	decoder    *jstream.Decoder
	valueCh    chan *jstream.MetaValue
	readCloser io.ReadCloser
}

// Read - reads single record.
func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
	v, ok := <-r.valueCh
	if !ok {
		if err := r.decoder.Err(); err != nil {
			return nil, errJSONParsingError(err)
		}
		return nil, io.EOF
	}

		case []byte:
			bytesValue = v
		default:
			return fmt.Errorf("failed to unmarshal gob value: %#v", dbValue)
		}
		if len(bytesValue) > 0 {
			decoder := gob.NewDecoder(bytes.NewBuffer(bytesValue))
			err = decoder.Decode(fieldValue.Interface())
		}
	}
	field.ReflectValueOf(ctx, dst).Set(fieldValue.Elem())
	return
}

// Value implements serializer interface

we can choose to extract and act only the objects within the top-level array:
```go
f, _ := os.Open("input.json")
decoder := jstream.NewDecoder(f, 1) // extract JSON values at a depth level of 1
for mv := range decoder.Stream() {
  fmt.Printf("%v\n ", mv.Value)
}
```

output:
```
map[desc:RGB colors:[red green blue]]
map[desc:CMYK colors:[cyan magenta yellow black]]
```

          // otherwise try to presize a StringBuilder
          // it is kind of lame that we need to construct a decoder to access this value.
          // if this is a concern we could add special cases for some known charsets (like utf8)
          // or we could avoid inputstreamreader and use the decoder api directly
          // TODO(lukes): in a real implementation we would need to handle overflow conditions

// MarshalXML encodes delete marker boolean into an XML form.
func (b Boolean) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if !b.set {
		return nil
	}
	return e.EncodeElement(b.val, startElement)
}

// UnmarshalXML decodes delete marker boolean from the XML form.
func (b *Boolean) UnmarshalXML(d *xml.Decoder, startElement xml.StartElement) error {
	var exp bool
	err := d.DecodeElement(&exp, &startElement)