[#164] sdk/object: Define filters to search root objects

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/object/search.go

@@ -98,3 +98,15 @@ func (f SearchFilters) ToV2() []*v2object.SearchFilter {
 
 	return result
 }
+
+func (f *SearchFilters) addRootFilter(val string) {
+	f.AddFilter(KeyRoot, val, MatchStringEqual)
+}
+
+func (f *SearchFilters) AddRootFilter() {
+	f.addRootFilter(ValRoot)
+}
+
+func (f *SearchFilters) AddNonRootFilter() {
+	f.addRootFilter(ValNonRoot)
+}

pkg/object/search_test.go

@@ -51,3 +51,31 @@ func TestFilter(t *testing.T) {
 	newFilters := object.NewSearchFiltersFromV2(v2)
 	require.Equal(t, filters, newFilters)
 }
+
+func TestSearchFilters_AddRootFilter(t *testing.T) {
+	fs := new(object.SearchFilters)
+
+	fs.AddRootFilter()
+
+	require.Len(t, *fs, 1)
+
+	f := (*fs)[0]
+
+	require.Equal(t, object.MatchStringEqual, f.Operation())
+	require.Equal(t, object.KeyRoot, f.Header())
+	require.Equal(t, object.ValRoot, f.Value())
+}
+
+func TestSearchFilters_AddNonRootFilter(t *testing.T) {
+	fs := new(object.SearchFilters)
+
+	fs.AddNonRootFilter()
+
+	require.Len(t, *fs, 1)
+
+	f := (*fs)[0]
+
+	require.Equal(t, object.MatchStringEqual, f.Operation())
+	require.Equal(t, object.KeyRoot, f.Header())
+	require.Equal(t, object.ValNonRoot, f.Value())
+}

pkg/object/wellknown_filters.go

@@ -0,0 +1,20 @@
+package object
+
+const (
+	valFalse = "false"
+	valTrue  = "true"
+)
+
+// ReservedFilterPrefix is a reserved prefix for system search filter keys.
+const ReservedFilterPrefix = "$Object:"
+
+const (
+	// KeyRoot is a reserved search filter key to source objects.
+	KeyRoot = ReservedFilterPrefix + "ROOT"
+
+	// ValRoot is a value of root object filter.
+	ValRoot = valTrue
+
+	// ValNonRoot is a value of non-root object filter.
+	ValNonRoot = valFalse
+)