BUG-509: clean up comment

This cleans up a comment why subtracting 1 from nesting is safe. It also
adds a Preconditions.checkState() to explicitly guard on the
expectation.

Change-Id: Ia0b755d723d399b99fec98398afabba1222b97b3
Signed-off-by: Robert Varga <rovarga@cisco.com>

diff --git a/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/tree/TreeNodeUtils.java b/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/tree/TreeNodeUtils.java
index b2ec119ca942ac33ba2b7fbdecbaf26ee5831ceb..339d9cb44e2ed9515daa1eabbb8db2d913dab91a 100644 (file)
--- a/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/tree/TreeNodeUtils.java
+++ b/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/tree/TreeNodeUtils.java
@@ -80,11 +80,17 @@ public class TreeNodeUtils {
             final InstanceIdentifier currentPath = new InstanceIdentifier(path.getPath().subList(0, nesting));
             return new SimpleEntry<InstanceIdentifier,T>(currentPath,current.get());
         }
-        // Nesting minus one is safe, since current is allways present when nesting = 0
-        // so this prat of code is never triggered, in cases nesting == 0;
+
+        /*
+         * Subtracting 1 from nesting level at this point is safe, because we
+         * cannot reach here with nesting == 0: that would mean the above check
+         * for current.isPresent() failed, which it cannot, as current is always
+         * present. At any rate we check state just to be on the safe side.
+         */
+        Preconditions.checkState(nesting > 0);
         final InstanceIdentifier parentPath = new InstanceIdentifier(path.getPath().subList(0, nesting - 1));
-        return new SimpleEntry<InstanceIdentifier,T>(parentPath,parent.get());
 
+        return new SimpleEntry<InstanceIdentifier,T>(parentPath,parent.get());
     }
 
     public static <T extends StoreTreeNode<T>> Optional<T> getChild(final Optional<T> parent,final PathArgument child) {