BIND 10 #1062: add a base for DatabaseZoneHandle::find()

[BIND 10 Development]

#1062: add a base for DatabaseZoneHandle::find()
-------------------------------------+-------------------------------------
                   Reporter:         |                 Owner:  UnAssigned
  jinmei                             |                Status:  reviewing
                       Type:  task   |             Milestone:
                   Priority:  major  |  Sprint-20110816
                  Component:  data   |            Resolution:
  source                             |             Sensitive:  0
                   Keywords:         |           Sub-Project:  DNS
            Defect Severity:  N/A    |  Estimated Difficulty:  5.0
Feature Depending on Ticket:         |           Total Hours:  0
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
-------------------------------------+-------------------------------------
Changes (by jelte):

 * owner:  jelte => UnAssigned
 * status:  assigned => reviewing


Comment:

 Ready for review.

 Some notes;

 I added a method typeCovered() to the (further incomplete) type
 dns/rdata/generic/rrsig_46.

 The interface for getNextRecord is slightly different; the original was
 const, this one is not (it modifies internal state, as does
 searchForRecords btw), and it does not return void but bool (true if there
 was a next row, false if there was not).

 As for Finder::find(), for the direct (full) match and CNAME, it also
 support RRSIGS (but doesn't do NSEC for NXDOMAIN/NXRRSET yet). I added a
 class RRsigStore in local namespace for that (to keep track of the rrsigs
 it encounters while walking through the data, see the inline comments on
 why). If we want to move this to util and add some tests for it, I'm not
 opposed, though if we only need it here I think this way is quite ok.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1062#comment:4>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development