From f0af5ce7590463373ecee0e21dbfa2de228692c8 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Thu, 18 Nov 2021 18:13:17 +0300
Subject: [PATCH] [#356] refs: Add functions to work with zero subnet

Add helper functions which provide ease of use with subnet zero IDs.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 refs/types.go      | 10 ++++++++++
 refs/types_test.go | 20 ++++++++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 refs/types_test.go

diff --git a/refs/types.go b/refs/types.go
index f3ce1455..d8ff91a5 100644
--- a/refs/types.go
+++ b/refs/types.go
@@ -183,6 +183,16 @@ func (s *SubnetID) GetValue() uint32 {
 	return 0
 }
 
+// IsZeroSubnet returns true iff the SubnetID refers to zero subnet.
+func IsZeroSubnet(id *SubnetID) bool {
+	return id.GetValue() == 0
+}
+
+// MakeZeroSubnet makes the SubnetID to refer to zero subnet.
+func MakeZeroSubnet(id *SubnetID) {
+	id.SetValue(0)
+}
+
 func (v *Version) GetMajor() uint32 {
 	if v != nil {
 		return v.major
diff --git a/refs/types_test.go b/refs/types_test.go
new file mode 100644
index 00000000..a1c68cd0
--- /dev/null
+++ b/refs/types_test.go
@@ -0,0 +1,20 @@
+package refs_test
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/refs"
+	"github.com/stretchr/testify/require"
+)
+
+func TestZeroSubnet(t *testing.T) {
+	id := new(refs.SubnetID)
+
+	require.True(t, refs.IsZeroSubnet(id))
+
+	id.SetValue(1)
+	require.False(t, refs.IsZeroSubnet(id))
+
+	refs.MakeZeroSubnet(id)
+	require.True(t, refs.IsZeroSubnet(id))
+}