package msgpack import ( "fmt" "strconv" "strings" "github.com/vmihailenco/msgpack/codes" ) type queryResult struct { query string key string hasAsterisk bool values []interface{} } func (q *queryResult) nextKey() { ind := strings.IndexByte(q.query, '.') if ind == -1 { q.key = q.query q.query = "" return } q.key = q.query[:ind] q.query = q.query[ind+1:] } // Query extracts data specified by the query from the msgpack stream skipping // any other data. Query consists of map keys and array indexes separated with dot, // e.g. key1.0.key2. func (d *Decoder) Query(query string) ([]interface{}, error) { res := queryResult{ query: query, } if err := d.query(&res); err != nil { return nil, err } return res.values, nil } func (d *Decoder) query(q *queryResult) error { q.nextKey() if q.key == "" { v, err := d.decodeInterface() if err != nil { return err } q.values = append(q.values, v) return nil } code, err := d.PeekCode() if err != nil { return err } switch { case code == codes.Map16 || code == codes.Map32 || codes.IsFixedMap(code): err = d.queryMapKey(q) case code == codes.Array16 || code == codes.Array32 || codes.IsFixedArray(code): err = d.queryArrayIndex(q) default: err = fmt.Errorf("msgpack: unsupported code=%x decoding key=%q", code, q.key) } return err } func (d *Decoder) queryMapKey(q *queryResult) error { n, err := d.DecodeMapLen() if err != nil { return err } if n == -1 { return nil } for i := 0; i < n; i++ { k, err := d.bytesNoCopy() if err != nil { return err } if string(k) == q.key { if err := d.query(q); err != nil { return err } if q.hasAsterisk { return d.skipNext((n - i - 1) * 2) } return nil } if err := d.Skip(); err != nil { return err } } return nil } func (d *Decoder) queryArrayIndex(q *queryResult) error { n, err := d.DecodeArrayLen() if err != nil { return err } if n == -1 { return nil } if q.key == "*" { q.hasAsterisk = true query := q.query for i := 0; i < n; i++ { q.query = query if err := d.query(q); err != nil { return err } } q.hasAsterisk = false return nil } ind, err := strconv.Atoi(q.key) if err != nil { return err } for i := 0; i < n; i++ { if i == ind { if err := d.query(q); err != nil { return err } if q.hasAsterisk { return d.skipNext(n - i - 1) } return nil } if err := d.Skip(); err != nil { return err } } return nil } func (d *Decoder) skipNext(n int) error { for i := 0; i < n; i++ { if err := d.Skip(); err != nil { return err } } return nil }