Improved logic of PortRangeIterator. Now calculate only once instead of

twice the next port.

1 files changed, 8 insertions, 12 deletions

diff --git a/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java b/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
index 82c3971..e67b362 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/PortRangeIterator.java
@@ -9,30 +9,26 @@ import static com.it_jaros.jns.scan.domain.PortRange.MIN_PORT;
 
 public class PortRangeIterator implements Iterator<Integer> {
 
-    private int currentPortCursor;
-    private int done = 0;
+    private int nextPort; // cached next-set-bit, only ever advances
     private final BitSet availablePorts = new BitSet(MAX_PORT);
 
     public PortRangeIterator(BitSet specifiedPorts) {
         availablePorts.or(specifiedPorts);
-        currentPortCursor = availablePorts.nextSetBit(MIN_PORT);
+        nextPort = availablePorts.nextSetBit(MIN_PORT);
     }
 
     @Override
     public Integer next() {
-        int p = availablePorts.nextSetBit(currentPortCursor);
-        if (p > 0) {
-            availablePorts.clear(p);
-            currentPortCursor = p + 1;
-            done++;
-            return p;
+        final int port = nextPort;
+        if (port <= 0) {
+            throw new NoSuchElementException("Reached end of port range");
         }
-
-        throw new NoSuchElementException("Reached end of port range");
+        nextPort = availablePorts.nextSetBit(port + 1);
+        return port;
     }
 
     @Override
     public boolean hasNext() {
-        return availablePorts.nextSetBit(currentPortCursor) > 0;
+        return nextPort > 0;
     }
 }