vm: allow to convert stack to a slice

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/vm/stack.go

@@ -396,6 +396,15 @@ func (s *Stack) PopSigElements() ([][]byte, error) {
 	return elems, nil
 }
 
+// ToArray converts stack to an array of stackitems with top item being the last.
+func (s *Stack) ToArray() []stackitem.Item {
+	items := make([]stackitem.Item, 0, s.len)
+	s.IterBack(func(e *Element) {
+		items = append(items, e.Item())
+	})
+	return items
+}
+
 // ToContractParameters converts Stack to slice of smartcontract.Parameter.
 func (s *Stack) ToContractParameters() []smartcontract.Parameter {
 	items := make([]smartcontract.Parameter, 0, s.Len())

pkg/vm/stack_test.go

@@ -237,6 +237,22 @@ func TestPushVal(t *testing.T) {
 	assert.IsType(t, elem.value, &stackitem.Array{})
 }
 
+func TestStack_ToArray(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		s := NewStack("test")
+		items := s.ToArray()
+		require.Equal(t, 0, len(items))
+	})
+	t.Run("NonEmpty", func(t *testing.T) {
+		s := NewStack("test")
+		expected := []stackitem.Item{stackitem.Make(1), stackitem.Make(true)}
+		for i := range expected {
+			s.PushVal(expected[i])
+		}
+		require.Equal(t, expected, s.ToArray())
+	})
+}
+
 func TestSwapElemValues(t *testing.T) {
 	s := NewStack("test")