~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems, Inc.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; version 2 of the License.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#ifndef DRIZZLED_NESTED_JOIN_H

#define DRIZZLED_NESTED_JOIN_H

#include <drizzled/item.h>

#include <drizzled/lex_string.h>

#include <drizzled/sql_list.h>

#include <bitset>

namespace drizzled

{

class TableList;

class JoinTable;

class NestedJoin

{

public:

  /* list of elements in the nested join */

  List<TableList> join_list;

  /* bitmap of tables in the nested join */

  table_map used_tables;

  /* tables that rejects nulls           */

  table_map not_null_tables;

  /* the first nested table in the plan  */

  JoinTable *first_nested;

  /*

    Used to count tables in the nested join in 2 isolated places:

    1. In make_outerjoin_info().

    2. check_interleaving_with_nj/restore_prev_nj_state (these are called

    by the join optimizer.

    Before each use the counters are zeroed by reset_nj_counters.

  */

  uint32_t counter_;

  /* Bit used to identify this nested join*/

  std::bitset<64> nj_map;

  /*

    (Valid only for semi-join nests) Bitmap of tables outside the semi-join

    that are used within the semi-join's ON condition.

  */

  table_map sj_depends_on;

  /* Outer non-trivially correlated tables */

  table_map sj_corr_tables;

  List<Item> sj_outer_expr_list;

  /**

     True if this join nest node is completely covered by the query execution

     plan. This means two things.

     1. All tables on its @c join_list are covered by the plan.

     2. All child join nest nodes are fully covered.

   */

  bool is_fully_covered() const { return join_list.elements == counter_; }

};

} /* namespace drizzled */

#endif /* DRIZZLED_NESTED_JOIN_H */