~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

 */

#pragma once

#include <drizzled/item/ref.h>

#include <drizzled/item/direct_ref.h>

#include <drizzled/item/field.h>

/*

  Class for outer fields.

  An object of this class is created when the select where the outer field was

  resolved is a grouping one. After it has been fixed the ref field will point

  to either an Item_ref or an Item_direct_ref object which will be used to

  access the field.

  See also comments for the fix_inner_refs() and the

  Item_field::fix_outer_field() functions.

*/

namespace drizzled {

class Item_outer_ref : public Item_direct_ref

{

public:

  Item *outer_ref;

  /* The aggregate function under which this outer ref is used, if any. */

  Item_sum *in_sum_func;

  /*

    true <=> that the outer_ref is already present in the select list

    of the outer select.

  */

  bool found_in_select_list;

  Item_outer_ref(Name_resolution_context *context_arg,

                 Item_field *outer_field_arg)

    :Item_direct_ref(context_arg, 0, outer_field_arg->table_name,

                     outer_field_arg->field_name),

    outer_ref(outer_field_arg), in_sum_func(0),

    found_in_select_list(0)

  {

    ref= &outer_ref;

    set_properties();

    fixed= 0;

  }

  Item_outer_ref(Name_resolution_context *context_arg, Item **item,

                 const char *table_name_arg, const char *field_name_arg,

                 bool alias_name_used_arg)

    :Item_direct_ref(context_arg, item, table_name_arg, field_name_arg,

                     alias_name_used_arg),

    outer_ref(0), in_sum_func(0), found_in_select_list(1)

  {}

  void save_in_result_field(bool)

  {

    outer_ref->save_org_in_field(result_field);

  }

  bool fix_fields(Session *, Item **);

  void fix_after_pullout(Select_Lex *new_parent, Item **ref);

  table_map used_tables() const

  {

    return (*ref)->const_item() ? 0 : OUTER_REF_TABLE_BIT;

  }

  virtual Ref_Type ref_type() { return OUTER_REF; }

};

} /* namespace drizzled */