Drizzled Public API Documentation

counter.cc
00001 /* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
00002  *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
00003  *
00004  *  Copyright (C) 2010 Brian Aker
00005  *
00006  *  This program is free software; you can redistribute it and/or modify
00007  *  it under the terms of the GNU General Public License as published by
00008  *  the Free Software Foundation; either version 2 of the License, or
00009  *  (at your option) any later version.
00010  *
00011  *  This program is distributed in the hope that it will be useful,
00012  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  *  GNU General Public License for more details.
00015  *
00016  *  You should have received a copy of the GNU General Public License
00017  *  along with this program; if not, write to the Free Software
00018  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
00019  */
00020 
00021 #include <config.h>
00022 
00023 #include <plugin/utility_dictionary/dictionary.h>
00024 
00025 #include <drizzled/atomics.h>
00026 #include <drizzled/session.h>
00027 #include <drizzled/sql_lex.h>
00028 
00029 using namespace drizzled;
00030 using namespace std;
00031 
00032 drizzled::atomic<uint64_t> counter;
00033 
00034 utility_dictionary::Counter::Counter() :
00035   plugin::TableFunction("DATA_DICTIONARY", "COUNTER")
00036 {
00037   add_field("VALUE", plugin::TableFunction::NUMBER, 0, false);
00038 }
00039 
00040 bool utility_dictionary::Counter::Generator::populate()
00041 {
00042   if (lex().isSumExprUsed() && count > 0)
00043     return false;
00044 
00045   if (lex().current_select->group_list.elements && count > 0)
00046     return false;
00047 
00048   if (lex().current_select->explicit_limit or count == 0)
00049   {
00050     push(counter.increment());
00051   }
00052   else
00053   {
00054     return false;
00055   }
00056 
00057   count++;
00058 
00059   return true;
00060 }