Add some encoding methods (#378)

_Inspired by https://github.com/AxLabs/neofs-shared-lib project._

accounting/decimal.go

@@ -1,6 +1,8 @@
 package accounting
 
-import "github.com/nspcc-dev/neofs-api-go/v2/accounting"
+import (
+	"github.com/nspcc-dev/neofs-api-go/v2/accounting"
+)
 
 // Decimal represents decimal number for accounting operations.
 //
@@ -62,3 +64,30 @@ func (d Decimal) Precision() uint32 {
 func (d *Decimal) SetPrecision(p uint32) {
 	(*accounting.Decimal)(d).SetPrecision(p)
 }
+
+// Marshal encodes Decimal into a binary format of the NeoFS API protocol
+// (Protocol Buffers with direct field order).
+//
+// See also Unmarshal.
+func (d Decimal) Marshal() []byte {
+	var m accounting.Decimal
+	d.WriteToV2(&m)
+
+	return m.StableMarshal(nil)
+}
+
+// Unmarshal decodes NeoFS API protocol binary format into the Decimal
+// (Protocol Buffers with direct field order). Returns an error describing
+// a format violation.
+//
+// See also Marshal.
+func (d *Decimal) Unmarshal(data []byte) error {
+	var m accounting.Decimal
+
+	err := m.Unmarshal(data)
+	if err != nil {
+		return err
+	}
+
+	return d.ReadFromV2(m)
+}

accounting/decimal_test.go

@@ -5,6 +5,7 @@ import (
 
 	v2accounting "github.com/nspcc-dev/neofs-api-go/v2/accounting"
 	"github.com/nspcc-dev/neofs-sdk-go/accounting"
+	accountingtest "github.com/nspcc-dev/neofs-sdk-go/accounting/test"
 	"github.com/stretchr/testify/require"
 )
 
@@ -44,3 +45,12 @@ func TestDecimalMessageV2(t *testing.T) {
 	require.EqualValues(t, d.Value(), m2.GetValue())
 	require.EqualValues(t, d.Precision(), m2.GetPrecision())
 }
+
+func TestDecimal_Marshal(t *testing.T) {
+	d := *accountingtest.Decimal()
+
+	var d2 accounting.Decimal
+	require.NoError(t, d2.Unmarshal(d.Marshal()))
+
+	require.Equal(t, d, d2)
+}

netmap/network_info.go

@@ -112,6 +112,33 @@ func (x NetworkInfo) WriteToV2(m *netmap.NetworkInfo) {
 	*m = x.m
 }
 
+// Marshal encodes NetworkInfo into a binary format of the NeoFS API protocol
+// (Protocol Buffers with direct field order).
+//
+// See also Unmarshal.
+func (x NetworkInfo) Marshal() []byte {
+	var m netmap.NetworkInfo
+	x.WriteToV2(&m)
+
+	return m.StableMarshal(nil)
+}
+
+// Unmarshal decodes NeoFS API protocol binary format into the NetworkInfo
+// (Protocol Buffers with direct field order). Returns an error describing
+// a format violation.
+//
+// See also Marshal.
+func (x *NetworkInfo) Unmarshal(data []byte) error {
+	var m netmap.NetworkInfo
+
+	err := m.Unmarshal(data)
+	if err != nil {
+		return err
+	}
+
+	return x.readFromV2(m, false)
+}
+
 // CurrentEpoch returns epoch set using SetCurrentEpoch.
 //
 // Zero NetworkInfo has zero current epoch.

netmap/network_info_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/nspcc-dev/neofs-api-go/v2/netmap"
 	. "github.com/nspcc-dev/neofs-sdk-go/netmap"
+	netmaptest "github.com/nspcc-dev/neofs-sdk-go/netmap/test"
 	"github.com/stretchr/testify/require"
 )
 
@@ -251,3 +252,12 @@ func TestNetworkInfo_MaintenanceModeAllowed(t *testing.T) {
 		},
 	)
 }
+
+func TestNetworkInfo_Marshal(t *testing.T) {
+	v := netmaptest.NetworkInfo()
+
+	var v2 NetworkInfo
+	require.NoError(t, v2.Unmarshal(v.Marshal()))
+
+	require.Equal(t, v, v2)
+}

version/version.go

@@ -84,3 +84,29 @@ func (v Version) Equal(v2 Version) bool {
 	return v.Major() == v2.Major() &&
 		v.Minor() == v2.Minor()
 }
+
+// MarshalJSON encodes Version into a JSON format of the NeoFS API
+// protocol (Protocol Buffers JSON).
+//
+// See also UnmarshalJSON.
+func (v Version) MarshalJSON() ([]byte, error) {
+	var m refs.Version
+	v.WriteToV2(&m)
+
+	return m.MarshalJSON()
+}
+
+// UnmarshalJSON decodes NeoFS API protocol JSON format into the Version
+// (Protocol Buffers JSON). Returns an error describing a format violation.
+//
+// See also MarshalJSON.
+func (v *Version) UnmarshalJSON(data []byte) error {
+	var m refs.Version
+
+	err := m.UnmarshalJSON(data)
+	if err != nil {
+		return err
+	}
+
+	return v.ReadFromV2(m)
+}

version/version_test.go

@@ -1,6 +1,7 @@
 package version
 
 import (
+	"math/rand"
 	"testing"
 
 	"github.com/nspcc-dev/neofs-api-go/v2/refs"
@@ -48,3 +49,17 @@ func TestSDKVersion(t *testing.T) {
 	require.Equal(t, uint32(sdkMjr), v.Major())
 	require.Equal(t, uint32(sdkMnr), v.Minor())
 }
+
+func TestVersion_MarshalJSON(t *testing.T) {
+	var v Version
+	v.SetMajor(rand.Uint32())
+	v.SetMinor(rand.Uint32())
+
+	data, err := v.MarshalJSON()
+	require.NoError(t, err)
+
+	var v2 Version
+	require.NoError(t, v2.UnmarshalJSON(data))
+
+	require.Equal(t, v, v2)
+}