add method GetAndDelete

README.md

@@ -47,9 +47,11 @@ The API has changed in v0.4.2, 0.5.3, v0.6.3, v0.10.1, v0.11.0, v0.12.0, v0.12.6
     and/or writers.
 
   func (t *Table[V]) Insert(pfx netip.Prefix, val V)
+  func (t *Table[V]) Update(pfx netip.Prefix, cb func(val V, ok bool) V) (newVal V)
   func (t *Table[V]) Delete(pfx netip.Prefix)
+
   func (t *Table[V]) Get(pfx netip.Prefix) (val V, ok bool)
-  func (t *Table[V]) Update(pfx netip.Prefix, cb func(val V, ok bool) V) (newVal V)
+  func (t *Table[V]) GetAndDelete(pfx netip.Prefix) (val V, ok bool)
 
   func (t *Table[V]) Union(o *Table[V])
   func (t *Table[V]) Clone() *Table[V]

go.mod

@@ -2,4 +2,4 @@ module github.com/gaissmai/bart
 
 go 1.22.0
 
-require github.com/bits-and-blooms/bitset v1.14.2
+require github.com/bits-and-blooms/bitset v1.14.3

go.sum

@@ -1,2 +1,2 @@
-github.com/bits-and-blooms/bitset v1.14.2 h1:YXVoyPndbdvcEVcseEovVfp0qjJp7S+i5+xgp/Nfbdc=
-github.com/bits-and-blooms/bitset v1.14.2/go.mod h1:7hO7Gc7Pp1vODcmWvKMRA9BNmbv6a/7QIWpPxHddWR8=
+github.com/bits-and-blooms/bitset v1.14.3 h1:Gd2c8lSNf9pKXom5JtD7AaKO8o7fGQ2LtFj1436qilA=
+github.com/bits-and-blooms/bitset v1.14.3/go.mod h1:7hO7Gc7Pp1vODcmWvKMRA9BNmbv6a/7QIWpPxHddWR8=

node.go

@@ -98,17 +98,18 @@ func (n *node[V]) insertPrefix(idx uint, val V) (ok bool) {
 	return true
 }
 
-// deletePrefix removes the route octet/prefixLen.
-// Returns false if there was no prefix to delete.
-func (n *node[V]) deletePrefix(octet byte, prefixLen int) (ok bool) {
+// deletePrefix removes the route octet/prefixLen and returns the associated value and true
+// or false if there was no prefix to delete (and no value to return).
+func (n *node[V]) deletePrefix(octet byte, prefixLen int) (val V, ok bool) {
 	idx := pfxToIdx(octet, prefixLen)
 
 	// no route entry
 	if !n.prefixesBitset.Test(idx) {
-		return false
+		return val, false
 	}
 
 	rnk := n.prefixRank(idx)
+	val = n.prefixes[rnk]
 
 	// delete from slice
 	n.prefixes = slices.Delete(n.prefixes, rnk, rnk+1)
@@ -117,7 +118,7 @@ func (n *node[V]) deletePrefix(octet byte, prefixLen int) (ok bool) {
 	n.prefixesBitset.Clear(idx)
 	n.prefixesBitset.Compact()
 
-	return true
+	return val, true
 }
 
 // updatePrefix, update or set the value at prefix via callback. The new value returned

table.go

@@ -252,6 +252,16 @@ func (t *Table[V]) Get(pfx netip.Prefix) (val V, ok bool) {
 
 // Delete removes pfx from the tree, pfx does not have to be present.
 func (t *Table[V]) Delete(pfx netip.Prefix) {
+	_, _ = t.getAndDelete(pfx)
+}
+
+// GetAndDelete deletes the prefix and returns the associated payload for prefix and true,
+// or the zero vlaue and false if prefix is not set in the routing table.
+func (t *Table[V]) GetAndDelete(pfx netip.Prefix) (val V, ok bool) {
+	return t.getAndDelete(pfx)
+}
+
+func (t *Table[V]) getAndDelete(pfx netip.Prefix) (val V, ok bool) {
 	if !pfx.IsValid() || !t.isInit() {
 		return
 	}
@@ -305,8 +315,7 @@ func (t *Table[V]) Delete(pfx netip.Prefix) {
 	}
 
 	// try to delete prefix in trie node
-	if !n.deletePrefix(lastOctet, lastOctetBits) {
-		// nothing deleted
+	if val, ok = n.deletePrefix(lastOctet, lastOctetBits); !ok {
 		return
 	}
 
@@ -324,6 +333,8 @@ func (t *Table[V]) Delete(pfx netip.Prefix) {
 		i--
 		n = stack[i]
 	}
+
+	return val, ok
 }
 
 // Lookup does a route lookup (longest prefix match) for IP and

table_test.go

@@ -1049,6 +1049,44 @@ func TestDeleteIsReverseOfInsert(t *testing.T) {
 	}
 }
 
+func TestGetAndDelete(t *testing.T) {
+	t.Parallel()
+	// Insert N prefixes, then delete those same prefixes in shuffled
+	// order.
+	const N = 10_000
+
+	tbl := new(Table[int])
+	prefixes := randomPrefixes(N)
+
+	// insert the prefixes
+	for _, p := range prefixes {
+		tbl.Insert(p.pfx, p.val)
+	}
+
+	// shuffle the prefixes
+	rand.Shuffle(N, func(i, j int) {
+		prefixes[i], prefixes[j] = prefixes[j], prefixes[i]
+	})
+
+	for _, p := range prefixes {
+		want, _ := tbl.Get(p.pfx)
+		val, ok := tbl.GetAndDelete(p.pfx)
+
+		if !ok {
+			t.Errorf("GetAndDelete, expected true, got %v", ok)
+		}
+
+		if val != want {
+			t.Errorf("GetAndDelete, expected %v, got %v", want, val)
+		}
+
+		val, ok = tbl.GetAndDelete(p.pfx)
+		if ok {
+			t.Errorf("GetAndDelete, expected false, got (%v, %v)", val, ok)
+		}
+	}
+}
+
 func TestGet(t *testing.T) {
 	t.Parallel()