Merge pull request #732 from ydb-platform/decimal

* Added `table/types.ToDecimal()` converter from `table/types.Value` …

Author: asmyasnikov

CHANGELOG.md

@@ -1,5 +1,7 @@
+* Added `table/types.ToDecimal()` converter from `table/types.Value` to `table/types.Decimal`
+
 ## v3.46.1
-* Implemented `xcontext.With{Cancel,Timeout}` with stack record and switched all usages from standard `context.With{Cancel,Timeout}`
+* Implemented `internal/xcontext.With{Cancel,Timeout}` with stack record and switched all usages from standard `context.With{Cancel,Timeout}`
 
 ## v3.46.0
 * Refactored package `log` for support typed fields in log messages

internal/value/value.go

@@ -410,11 +410,31 @@ func DatetimeValueFromTime(t time.Time) datetimeValue {
 	return datetimeValue(t.Unix())
 }
 
+var _ DecimalValuer = (*decimalValue)(nil)
+
 type decimalValue struct {
 	value     [16]byte
 	innerType *DecimalType
 }
 
+func (v *decimalValue) Value() [16]byte {
+	return v.value
+}
+
+func (v *decimalValue) Precision() uint32 {
+	return v.innerType.Precision
+}
+
+func (v *decimalValue) Scale() uint32 {
+	return v.innerType.Scale
+}
+
+type DecimalValuer interface {
+	Value() [16]byte
+	Precision() uint32
+	Scale() uint32
+}
+
 func (v *decimalValue) castTo(dst interface{}) error {
 	return xerrors.WithStackTrace(fmt.Errorf("cannot cast '%+v' to '%T' destination", v, dst))
 }

table/types/cast.go

@@ -18,6 +18,17 @@ func CastTo(v Value, dst interface{}) error {
 	return value.CastTo(v, dst)
 }
 
+func ToDecimal(v Value) (*Decimal, error) {
+	if valuer, isDecimalValuer := v.(value.DecimalValuer); isDecimalValuer {
+		return &Decimal{
+			Bytes:     valuer.Value(),
+			Precision: valuer.Precision(),
+			Scale:     valuer.Scale(),
+		}, nil
+	}
+	return nil, xerrors.WithStackTrace(fmt.Errorf("value type '%s' is not decimal type", v.Type().Yql()))
+}
+
 func TupleItems(v Value) ([]Value, error) {
 	if vv, has := v.(interface {
 		Items() []Value

table/types/cast_test.go

@@ -0,0 +1,54 @@
+package types
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestToDecimal(t *testing.T) {
+	for _, tt := range []struct {
+		v   Value
+		d   *Decimal
+		err bool
+	}{
+		{
+			v: DecimalValue(&Decimal{
+				Bytes:     [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5},
+				Precision: 22,
+				Scale:     9,
+			}),
+			d: &Decimal{
+				Bytes:     [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5},
+				Precision: 22,
+				Scale:     9,
+			},
+			err: false,
+		},
+		{
+			v: DecimalValueFromBigInt(big.NewInt(123456789), 22, 9),
+			d: &Decimal{
+				Bytes:     [16]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 91, 205, 21},
+				Precision: 22,
+				Scale:     9,
+			},
+			err: false,
+		},
+		{
+			v:   Uint64Value(0),
+			d:   nil,
+			err: true,
+		},
+	} {
+		t.Run("", func(t *testing.T) {
+			d, err := ToDecimal(tt.v)
+			if tt.err {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, tt.d, d)
+			}
+		})
+	}
+}