Golang encoding.DecodeIfNull函数代码示例

// decodeKeyVals decodes the values that are part of the key. ValTypes is a
// slice returned from makeKeyVals. The decoded values are stored in the vals
// parameter while the valTypes parameter is unmodified. Note that len(vals) >=
// len(valTypes). The types of the decoded values will match the corresponding
// entry in the valTypes parameter with the exception that a value might also
// be parser.DNull. The remaining bytes in the key after decoding the values
// are returned.
func decodeKeyVals(valTypes, vals []parser.Datum, key []byte) ([]byte, error) {
	for j := range valTypes {
		var isNull bool
		if key, isNull = encoding.DecodeIfNull(key); isNull {
			vals[j] = parser.DNull
			continue
		}

		switch valTypes[j].(type) {
		case parser.DInt:
			var i int64
			key, i = encoding.DecodeVarint(key)
			vals[j] = parser.DInt(i)
		case parser.DFloat:
			var f float64
			key, f = encoding.DecodeFloat(key, nil)
			vals[j] = parser.DFloat(f)
		case parser.DString:
			var r string
			key, r = encoding.DecodeString(key, nil)
			vals[j] = parser.DString(r)
		default:
			return nil, util.Errorf("TODO(pmattis): decoded index key: %s", valTypes[j].Type())
		}
	}

	return key, nil
}

func decodeTableKey(valType parser.Datum, key []byte) (parser.Datum, []byte, error) {
	var isNull bool
	if key, isNull = encoding.DecodeIfNull(key); isNull {
		return parser.DNull, key, nil
	}
	switch valType.(type) {
	case parser.DBool:
		rkey, i, err := encoding.DecodeVarint(key)
		return parser.DBool(i != 0), rkey, err
	case parser.DInt:
		rkey, i, err := encoding.DecodeVarint(key)
		return parser.DInt(i), rkey, err
	case parser.DFloat:
		rkey, f, err := encoding.DecodeFloat(key, nil)
		return parser.DFloat(f), rkey, err
	case parser.DString:
		rkey, r, err := encoding.DecodeString(key, nil)
		return parser.DString(r), rkey, err
	case parser.DBytes:
		rkey, r, err := encoding.DecodeString(key, nil)
		return parser.DBytes(r), rkey, err
	case parser.DDate:
		rkey, t, err := encoding.DecodeTime(key)
		return parser.DDate{Time: t}, rkey, err
	case parser.DTimestamp:
		rkey, t, err := encoding.DecodeTime(key)
		return parser.DTimestamp{Time: t}, rkey, err
	case parser.DInterval:
		rkey, d, err := encoding.DecodeVarint(key)
		return parser.DInterval{Duration: time.Duration(d)}, rkey, err
	default:
		return nil, nil, util.Errorf("TODO(pmattis): decoded index key: %s", valType.Type())
	}
}

func decodeTableKey(valType parser.Datum, key []byte) (parser.Datum, []byte, error) {
	var isNull bool
	if key, isNull = encoding.DecodeIfNull(key); isNull {
		return parser.DNull, key, nil
	}
	switch valType.(type) {
	case parser.DBool:
		var i int64
		key, i = encoding.DecodeVarint(key)
		return parser.DBool(i != 0), key, nil
	case parser.DInt:
		var i int64
		key, i = encoding.DecodeVarint(key)
		return parser.DInt(i), key, nil
	case parser.DFloat:
		var f float64
		key, f = encoding.DecodeFloat(key, nil)
		return parser.DFloat(f), key, nil
	case parser.DString:
		var r string
		key, r = encoding.DecodeString(key, nil)
		return parser.DString(r), key, nil
	default:
		return nil, nil, util.Errorf("TODO(pmattis): decoded index key: %s", valType.Type())
	}
}

func decodeKeyPrint(key roachpb.Key) string {
	var buf bytes.Buffer
	for k := 0; len(key) > 0; k++ {
		var err error
		switch encoding.PeekType(key) {
		case encoding.Null:
			key, _ = encoding.DecodeIfNull(key)
			fmt.Fprintf(&buf, "/NULL")
		case encoding.NotNull:
			key, _ = encoding.DecodeIfNotNull(key)
			fmt.Fprintf(&buf, "/#")
		case encoding.Int:
			var i int64
			key, i, err = encoding.DecodeVarintAscending(key)
			if err == nil {
				fmt.Fprintf(&buf, "/%d", i)
			}
		case encoding.Float:
			var f float64
			key, f, err = encoding.DecodeFloatAscending(key, nil)
			if err == nil {
				fmt.Fprintf(&buf, "/%f", f)
			}
		case encoding.Bytes:
			var s string
			key, s, err = encoding.DecodeStringAscending(key, nil)
			if err == nil {
				fmt.Fprintf(&buf, "/%q", s)
			}
		case encoding.BytesDesc:
			var s string
			key, s, err = encoding.DecodeStringDescending(key, nil)
			if err == nil {
				fmt.Fprintf(&buf, "/%q", s)
			}
		case encoding.Time:
			var t time.Time
			key, t, err = encoding.DecodeTimeAscending(key)
			if err == nil {
				fmt.Fprintf(&buf, "/%s", t.UTC().Format(time.UnixDate))
			}
		case encoding.TimeDesc:
			var t time.Time
			key, t, err = encoding.DecodeTimeDescending(key)
			if err == nil {
				fmt.Fprintf(&buf, "/%s", t.UTC().Format(time.UnixDate))
			}
		default:
			// This shouldn't ever happen, but if it does let the loop exit.
			fmt.Fprintf(&buf, "/%q", []byte(key))
			key = nil
		}

		if err != nil {
			fmt.Fprintf(&buf, "/<%v>", err)
			continue
		}
	}
	return buf.String()
}

// prettyKey pretty-prints the specified key, skipping over the first skip
// fields.
func prettyKey(key roachpb.Key, skip int) string {
	if !bytes.HasPrefix(key, keys.TableDataPrefix) {
		return fmt.Sprintf("index key missing table data prefix: %q vs %q",
			key, keys.TableDataPrefix)
	}
	key = key[len(keys.TableDataPrefix):]

	var buf bytes.Buffer
	for k := 0; len(key) > 0; k++ {
		var d interface{}
		var err error
		switch encoding.PeekType(key) {
		case encoding.Null:
			key, _ = encoding.DecodeIfNull(key)
			d = parser.DNull
		case encoding.NotNull:
			key, _ = encoding.DecodeIfNotNull(key)
			d = "#"
		case encoding.Int:
			var i int64
			key, i, err = encoding.DecodeVarint(key)
			d = parser.DInt(i)
		case encoding.Float:
			var f float64
			key, f, err = encoding.DecodeFloat(key, nil)
			d = parser.DFloat(f)
		case encoding.Bytes:
			var s string
			key, s, err = encoding.DecodeString(key, nil)
			d = parser.DString(s)
		case encoding.Time:
			var t time.Time
			key, t, err = encoding.DecodeTime(key)
			d = parser.DTimestamp{Time: t}
		default:
			// This shouldn't ever happen, but if it does let the loop exit.
			key = nil
			d = "unknown"
		}
		if skip > 0 {
			skip--
			continue
		}
		if err != nil {
			fmt.Fprintf(&buf, "/<%v>", err)
			continue
		}
		fmt.Fprintf(&buf, "/%s", d)
	}
	return buf.String()
}

// DecodeTableKey decodes a table key/value.
func DecodeTableKey(
	a *DatumAlloc, valType parser.Datum, key []byte, dir encoding.Direction,
) (parser.Datum, []byte, error) {
	if (dir != encoding.Ascending) && (dir != encoding.Descending) {
		return nil, nil, util.Errorf("invalid direction: %d", dir)
	}
	var isNull bool
	if key, isNull = encoding.DecodeIfNull(key); isNull {
		return parser.DNull, key, nil
	}
	var rkey []byte
	var err error
	switch valType.(type) {
	case *parser.DBool:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		// No need to chunk allocate DBool as MakeDBool returns either
		// parser.DBoolTrue or parser.DBoolFalse.
		return parser.MakeDBool(parser.DBool(i != 0)), rkey, err
	case *parser.DInt:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		return a.NewDInt(parser.DInt(i)), rkey, err
	case *parser.DFloat:
		var f float64
		if dir == encoding.Ascending {
			rkey, f, err = encoding.DecodeFloatAscending(key)
		} else {
			rkey, f, err = encoding.DecodeFloatDescending(key)
		}
		return a.NewDFloat(parser.DFloat(f)), rkey, err
	case *parser.DDecimal:
		var d *inf.Dec
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeDecimalAscending(key, nil)
		} else {
			rkey, d, err = encoding.DecodeDecimalDescending(key, nil)
		}
		dd := a.NewDDecimal(parser.DDecimal{})
		dd.Set(d)
		return dd, rkey, err
	case *parser.DString:
		var r string
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeUnsafeStringAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeUnsafeStringDescending(key, nil)
		}
		return a.NewDString(parser.DString(r)), rkey, err
	case *parser.DBytes:
		var r []byte
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeBytesAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeBytesDescending(key, nil)
		}
		return a.NewDBytes(parser.DBytes(r)), rkey, err
	case *parser.DDate:
		var t int64
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, t, err = encoding.DecodeVarintDescending(key)
		}
		return a.NewDDate(parser.DDate(t)), rkey, err
	case *parser.DTimestamp:
		var t time.Time
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeTimeAscending(key)
		} else {
			rkey, t, err = encoding.DecodeTimeDescending(key)
		}
		return a.NewDTimestamp(parser.DTimestamp{Time: t}), rkey, err
	case *parser.DTimestampTZ:
		var t time.Time
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeTimeAscending(key)
		} else {
			rkey, t, err = encoding.DecodeTimeDescending(key)
		}
		return a.NewDTimestampTZ(parser.DTimestampTZ{Time: t}), rkey, err
	case *parser.DInterval:
		var d duration.Duration
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeDurationAscending(key)
		} else {
			rkey, d, err = encoding.DecodeDurationDescending(key)
		}
		return a.NewDInterval(parser.DInterval{Duration: d}), rkey, err
	default:
		return nil, nil, util.Errorf("TODO(pmattis): decoded index key: %s", valType.Type())
//.........这里部分代码省略.........

func decodeTableKey(valType parser.Datum, key []byte, dir encoding.Direction) (
	parser.Datum, []byte, error) {
	if (dir != encoding.Ascending) && (dir != encoding.Descending) {
		return nil, nil, util.Errorf("invalid direction: %d", dir)
	}
	var isNull bool
	if key, isNull = encoding.DecodeIfNull(key); isNull {
		return parser.DNull, key, nil
	}
	var rkey []byte
	var err error
	switch valType.(type) {
	case parser.DBool:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		return parser.DBool(i != 0), rkey, err
	case parser.DInt:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		return parser.DInt(i), rkey, err
	case parser.DFloat:
		var f float64
		if dir == encoding.Ascending {
			rkey, f, err = encoding.DecodeFloatAscending(key, nil)
		} else {
			rkey, f, err = encoding.DecodeFloatDescending(key, nil)
		}
		return parser.DFloat(f), rkey, err
	case *parser.DDecimal:
		var d *inf.Dec
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeDecimalAscending(key, nil)
		} else {
			rkey, d, err = encoding.DecodeDecimalDescending(key, nil)
		}
		dd := &parser.DDecimal{}
		dd.Set(d)
		return dd, rkey, err
	case parser.DString:
		var r string
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeStringAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeStringDescending(key, nil)
		}
		return parser.DString(r), rkey, err
	case parser.DBytes:
		var r []byte
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeBytesAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeBytesDescending(key, nil)
		}
		return parser.DBytes(r), rkey, err
	case parser.DDate:
		var t int64
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, t, err = encoding.DecodeVarintDescending(key)
		}
		return parser.DDate(t), rkey, err
	case parser.DTimestamp:
		var t time.Time
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeTimeAscending(key)
		} else {
			rkey, t, err = encoding.DecodeTimeDescending(key)
		}
		return parser.DTimestamp{Time: t}, rkey, err
	case parser.DInterval:
		var d int64
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, d, err = encoding.DecodeVarintDescending(key)
		}
		return parser.DInterval{Duration: time.Duration(d)}, rkey, err
	default:
		return nil, nil, util.Errorf("TODO(pmattis): decoded index key: %s", valType.Type())
	}
}