Add ScanPeers() to iterate peers with zero allocations

firefly/net.go

@@ -108,6 +108,11 @@ func (peers Peers) Iter() iter.Seq[Peer] {
 	}
 }
 
+// Get a scanner of the peers, allowing iterating over them without any allocations.
+func (peers Peers) Scanner() PeerScanner {
+	return PeerScanner{peers: peers}
+}
+
 // Check if the given [Peer] is online.
 func (peers Peers) Contains(peer Peer) bool {
 	return peers.p>>peer.raw&1 != 0
@@ -134,6 +139,32 @@ func GetPeers() Peers {
 	return Peers{getPeers()}
 }
 
+// Scanner used to iterate a list of peers without any allocations.
+//
+// Can be obtained using [Peers.NewScanner].
+type PeerScanner struct {
+	peers  Peers
+	nextID uint8
+}
+
+// Find the next peer. Use [PeerScanner.Peer] to get the current value.
+func (s *PeerScanner) Scan() bool {
+	for s.nextID < 32 {
+		if s.peers.Contains(Peer{s.nextID}) {
+			s.nextID++
+			return true
+		}
+		s.nextID++
+	}
+	return false
+}
+
+// Current scanned peer. Calling this function before [PeerScanner.Scan]
+// is considered undefined behavior.
+func (s *PeerScanner) Peer() Peer {
+	return Peer{s.nextID - 1}
+}
+
 // Save the given [Stash].
 //
 // When called, the stash for the given peer will be stored in RAM.

firefly/net_example_test.go

@@ -0,0 +1,11 @@
+package firefly_test
+
+import "github.com/firefly-zero/firefly-go/firefly"
+
+func ExamplePeers_Scanner() {
+	scanner := firefly.GetPeers().Scanner()
+	for scanner.Scan() {
+		peer := scanner.Peer()
+		_ = peer
+	}
+}