Golang DDecimal.Set方法代碼示例

// Arg implements the parser.Args interface.
// TODO: This does not support arguments of the SQL 'Date' type, as there is not
// an equivalent type in Go's standard library. It's not currently needed by any
// of our internal tables.
func (gp golangParameters) Arg(name string) (parser.Datum, bool) {
	i, err := processPositionalArgument(name)
	if err != nil {
		return nil, false
	}
	if i < 1 || int(i) > len(gp) {
		return nil, false
	}
	arg := gp[i-1]
	if arg == nil {
		return parser.DNull, true
	}

	// A type switch to handle a few explicit types with special semantics.
	switch t := arg.(type) {
	// Datums are passed along as is.
	case parser.Datum:
		return t, true
	// Time datatypes get special representation in the database.
	case time.Time:
		return parser.DTimestamp{Time: t}, true
	case time.Duration:
		return parser.DInterval{Duration: t}, true
	case *inf.Dec:
		dd := parser.DDecimal{}
		dd.Set(t)
		return dd, true
	}

	// Handle all types which have an underlying type that can be stored in the
	// database.
	// Note: if this reflection becomes a performance concern in the future,
	// commonly used types could be added explicitly into the type switch above
	// for a performance gain.
	val := reflect.ValueOf(arg)
	switch val.Kind() {
	case reflect.Bool:
		return parser.DBool(val.Bool()), true
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return parser.DInt(val.Int()), true
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return parser.DInt(val.Uint()), true
	case reflect.Float32, reflect.Float64:
		return parser.DFloat(val.Float()), true
	case reflect.String:
		return parser.DString(val.String()), true
	case reflect.Slice:
		// Handle byte slices.
		if val.Type().Elem().Kind() == reflect.Uint8 {
			return parser.DBytes(val.Bytes()), true
		}
	}

	panic(fmt.Sprintf("unexpected type %T", arg))
}

func (a *sumAggregate) result() (parser.Datum, error) {
	if a.sum == nil {
		return parser.DNull, nil
	}
	switch t := a.sum.(type) {
	case parser.DDecimal:
		dd := parser.DDecimal{}
		dd.Set(&t.Dec)
		return dd, nil
	default:
		return a.sum, nil
	}
}

func (a *sumAggregate) add(datum parser.Datum) error {
	if datum == parser.DNull {
		return nil
	}
	if a.sum == nil {
		switch t := datum.(type) {
		case parser.DDecimal:
			// Make copy of decimal to allow for modification later.
			dd := parser.DDecimal{}
			dd.Set(&t.Dec)
			datum = dd
		}
		a.sum = datum
		return nil
	}

	switch t := datum.(type) {
	case parser.DInt:
		if v, ok := a.sum.(parser.DInt); ok {
			a.sum = v + t
			return nil
		}

	case parser.DFloat:
		if v, ok := a.sum.(parser.DFloat); ok {
			a.sum = v + t
			return nil
		}

	case parser.DDecimal:
		if v, ok := a.sum.(parser.DDecimal); ok {
			v.Add(&v.Dec, &t.Dec)
			a.sum = v
			return nil
		}
	}

	return util.Errorf("unexpected SUM argument type: %s", datum.Type())
}

// unmarshalColumnValue decodes the value from a key-value pair using the type
// expected by the column. An error is returned if the value's type does not
// match the column's type.
func unmarshalColumnValue(kind ColumnType_Kind, value *roachpb.Value) (parser.Datum, *roachpb.Error) {
	if value == nil {
		return parser.DNull, nil
	}

	switch kind {
	case ColumnType_BOOL:
		v, err := value.GetInt()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DBool(v != 0), nil
	case ColumnType_INT:
		v, err := value.GetInt()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DInt(v), nil
	case ColumnType_FLOAT:
		v, err := value.GetFloat()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DFloat(v), nil
	case ColumnType_DECIMAL:
		v, err := value.GetDecimal()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		dd := parser.DDecimal{}
		dd.Set(v)
		return dd, nil
	case ColumnType_STRING:
		v, err := value.GetBytes()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DString(v), nil
	case ColumnType_BYTES:
		v, err := value.GetBytes()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DBytes(v), nil
	case ColumnType_DATE:
		v, err := value.GetInt()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DDate(v), nil
	case ColumnType_TIMESTAMP:
		v, err := value.GetTime()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DTimestamp{Time: v}, nil
	case ColumnType_INTERVAL:
		v, err := value.GetInt()
		if err != nil {
			return nil, roachpb.NewError(err)
		}
		return parser.DInterval{Duration: time.Duration(v)}, nil
	default:
		return nil, roachpb.NewErrorf("unsupported column type: %s", kind)
	}
}

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())
	}
}