BIND 10 #1803: update the RBTreeNodeChain class to identify the "previous" node

[BIND 10 Development]

#1803: update the RBTreeNodeChain class to identify the "previous" node
-------------------------------------+-------------------------------------
                   Reporter:         |                 Owner:  muks
  jinmei                             |                Status:  reviewing
                       Type:  task   |             Milestone:
                   Priority:         |  Sprint-20120515
  medium                             |            Resolution:
                  Component:  data   |             Sensitive:  0
  source                             |           Sub-Project:  DNS
                   Keywords:         |  Estimated Difficulty:  7
            Defect Severity:  N/A    |           Total Hours:  0
Feature Depending on Ticket:  in-    |
  memory NSEC                        |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 lcov indicates that these parts of the code aren't tested:
 {{{#!cpp
                         // A small trick. The current may be NULLNODE, but
                         // such node has the right_ pointer and it is
 equal
                         // to NULLNODE.
                         current = current->right_;
 }}}

 and

 {{{#!cpp
         // We got past the first one. So, we're returning NULL from
         // now on.
         return (NULL);
 }}}

 If these are not false positives, please make sure these cases are
 covered by tests.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1803#comment:6>
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