implement UnionPersist

Author: gaissmai

README.md

@@ -93,8 +93,9 @@ See the `ExampleLite_concurrent` and `ExampleTable_concurrent` tests for concret
   func (t *Table[V]) GetAndDelete(pfx netip.Prefix) (val V, ok bool)
   func (t *Table[V]) GetAndDeletePersist(pfx netip.Prefix) (pt *Table[V], val V, ok bool)
 
-  func (t *Table[V]) Union(o *Table[V])
   func (t *Table[V]) Clone() *Table[V]
+  func (t *Table[V]) Union(o *Table[V])
+  func (t *Table[V]) UnionPersist(o *Table[V]) *Table[V]
 
   func (t *Table[V]) OverlapsPrefix(pfx netip.Prefix) bool
 
@@ -149,8 +150,9 @@ Some delegated methods are pointless without a payload.
    func (l *Lite) InsertPersist(pfx netip.Prefix) *Lite
    func (l *Lite) DeletePersist(pfx netip.Prefix) *Lite
 
-   func (l *Lite) Union(o *Lite)
    func (l *Lite) Clone() *Lite
+   func (l *Lite) Union(o *Lite)
+   func (l *Lite) UnionPersist(o *Lite) *Lite
 
    func (l *Lite) Overlaps(o *Lite) bool
    func (l *Lite) Overlaps4(o *Lite) bool

cloner.go

@@ -28,6 +28,11 @@ func cloneVal[V any](val V) V {
 	return any(val).(Cloner[V]).Clone()
 }
 
+// copyVal just copies the value.
+func copyVal[V any](val V) V {
+	return val
+}
+
 // cloneLeaf creates and returns a copy of the leafNode receiver.
 // If cloneFn is nil, the value is copied directly without modification.
 // Otherwise, cloneFn is applied to the value for deep cloning.

lite.go

@@ -71,6 +71,13 @@ func (l *Lite) Union(o *Lite) {
 	l.Table.Union(&o.Table)
 }
 
+// UnionPersist is an adapter for the underlying table.
+func (l *Lite) UnionPersist(o *Lite) *Lite {
+	tbl := l.Table.UnionPersist(&o.Table)
+	//nolint:govet // copy of *tbl is here by intention
+	return &Lite{*tbl}
+}
+
 // Overlaps4 is an adapter for the underlying table.
 func (l *Lite) Overlaps4(o *Lite) bool {
 	return l.Table.Overlaps4(&o.Table)

lite_test.go

@@ -676,6 +676,40 @@ func TestLiteUnion(t *testing.T) {
 	}
 }
 
+func TestLiteUnionPersist(t *testing.T) {
+	t.Parallel()
+
+	for range 10 {
+		t.Run("Union", func(t *testing.T) {
+			t.Parallel()
+			prng := rand.New(rand.NewPCG(42, 42))
+			pfx1 := randomRealWorldPrefixes(prng, 1_000)
+			pfx2 := randomRealWorldPrefixes(prng, 2_000)
+
+			golden := new(Lite)
+			for _, pfx := range append(pfx1, pfx2...) {
+				golden.Insert(pfx)
+			}
+
+			tbl1 := new(Lite)
+			for _, pfx := range pfx1 {
+				tbl1.Insert(pfx)
+			}
+
+			tbl2 := new(Lite)
+			for _, pfx := range pfx2 {
+				tbl2.Insert(pfx)
+			}
+
+			pTbl := tbl1.UnionPersist(tbl2)
+
+			if pTbl.dumpString() != golden.dumpString() {
+				t.Errorf("UnionPersist: got:\n%swant:\n%s", pTbl.dumpString(), golden.dumpString())
+			}
+		})
+	}
+}
+
 func TestLiteStringEmpty(t *testing.T) {
 	t.Parallel()
 	tbl := new(Lite)