[trac1067] The ZoneIterator interface

src/lib/datasrc/Makefile.am

@@ -21,7 +21,7 @@ libdatasrc_la_SOURCES += memory_datasrc.h memory_datasrc.cc
 libdatasrc_la_SOURCES += zone.h
 libdatasrc_la_SOURCES += result.h
 libdatasrc_la_SOURCES += logger.h logger.cc
-libdatasrc_la_SOURCES += client.h
+libdatasrc_la_SOURCES += client.h iterator.h
 libdatasrc_la_SOURCES += database.h database.cc
 libdatasrc_la_SOURCES += sqlite3_connection.h sqlite3_connection.cc
 nodist_libdatasrc_la_SOURCES = datasrc_messages.h datasrc_messages.cc

src/lib/datasrc/iterator.h

@@ -0,0 +1,60 @@
+// Copyright (C) 2011  Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+#include <dns/rrset.h>
+
+#include <boost/noncopyable.hpp>
+
+namespace isc {
+namespace datasrc {
+
+/**
+ * \brief Read-only iterator to a zone.
+ *
+ * You can get an instance of (descendand of) ZoneIterator from
+ * DataSourceClient::getIterator() method. The actual concrete implementation
+ * will be different depending on the actual data source used. This is the
+ * abstract interface.
+ *
+ * There's no way to start iterating from the beginning again or return.
+ */
+class ZoneIterator : public boost::noncopyable {
+public:
+    /**
+     * \brief Destructor
+     *
+     * Virtual destructor. It is empty, but ensures the right destructor from
+     * descendant is called.
+     */
+    virtual ~ ZoneIterator() { }
+    /**
+     * \brief Get next RRset from the zone.
+     *
+     * This returns the next RRset in the zone as a shared pointer. The
+     * shared pointer is used to allow both accessing in-memory data and
+     * automatic memory management.
+     *
+     * Any special order is not guaranteed.
+     *
+     * While this can potentially throw anything (including standard allocation
+     * errors), it should be rare.
+     *
+     * \return Pointer to the next RRset or NULL pointer when the iteration
+     *     gets to the end of the zone.
+     */
+    virtual isc::dns::ConstRRsetPtr getNextRRset() = 0;
+};
+
+}
+}