Function PeekLength

pkg/util/encoding/encoding.go:1371–1421

PeekLength returns the length of the encoded value at the start of b. Note: if this function succeeds, it's not a guarantee that decoding the value will succeed. PeekLength is meant to be used on key encoded data only.

(b []byte)

// if this function succeeds, it's not a guarantee that decoding the value will
// succeed. PeekLength is meant to be used on key encoded data only.
func PeekLength(b []byte) (int, error) {
	if len(b) == 0 {
		return 0, errors.Errorf("empty slice")
	}
	m := b[0]
	switch m {
	case encodedNull, encodedNullDesc, encodedNotNull, encodedNotNullDesc,
		floatNaN, floatNaNDesc, floatZero, decimalZero, byte(True), byte(False):
		// interleavedSentinel also falls into this path. Since it
		// contains the same byte value as encodedNotNullDesc, it
		// cannot be included explicitly in the case statement.
		return 1, nil
	case bitArrayMarker, bitArrayDescMarker:
		terminator := byte(bitArrayDataTerminator)
		if m == bitArrayDescMarker {
			terminator = bitArrayDataDescTerminator
		}
		_, n, err := getBitArrayWordsLen(b[1:], terminator)
		if err != nil {
			return 1 + n, err
		}
		m, err := getVarintLen(b[n+2:])
		if err != nil {
			return 1 + n + m + 1, err
		}
		return 1 + n + m + 1, nil
	case bytesMarker:
		return getBytesLength(b, ascendingEscapes)
	case jsonInvertedIndex:
		return getJSONInvertedIndexKeyLength(b)
	case bytesDescMarker:
		return getBytesLength(b, descendingEscapes)
	case timeMarker, timeTZMarker:
		return GetMultiVarintLen(b, 2)
	case durationBigNegMarker, durationMarker, durationBigPosMarker:
		return GetMultiVarintLen(b, 3)
	case floatNeg, floatPos:
		// the marker is followed by 8 bytes
		if len(b) < 9 {
			return 0, errors.Errorf("slice too short for float (%d)", len(b))
		}
		return 9, nil
	}
	if m >= IntMin && m <= IntMax {
		return getVarintLen(b)
	}
	if m >= decimalNaN && m <= decimalNaNDesc {
		return getDecimalLen(b)
	}
	return 0, errors.Errorf("unknown tag %d", m)
}

// PrettyPrintValue returns the string representation of all contiguous
// decodable values in the provided byte slice, separated by a provided