~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/field.h>

namespace drizzled {

/*

  Item_insert_value -- an implementation of VALUES() function.

  You can use the VALUES(col_name) function in the UPDATE clause

  to refer to column values from the INSERT portion of the INSERT

  ... UPDATE statement. In other words, VALUES(col_name) in the

  UPDATE clause refers to the value of col_name that would be

  inserted, had no duplicate-key conflict occurred.

  In all other places this function returns NULL.

*/

class Item_insert_value : public Item_field

{

public: 

  Item *arg;

  Item_insert_value(Name_resolution_context *context_arg, Item *a)

    : Item_field(context_arg, NULL, NULL, NULL),

     arg(a) {}

  bool eq(const Item *item, bool binary_cmp) const;

  bool fix_fields(Session *, Item **);

  virtual void print(String *str);

  int save_in_field(Field *field_arg, bool no_conversions)

  {

    return Item_field::save_in_field(field_arg, no_conversions);

  }

  /*

   We use RAND_TABLE_BIT to prevent Item_insert_value from

   being treated as a constant and precalculated before execution

  */

  table_map used_tables() const { return RAND_TABLE_BIT; }

  bool walk(Item_processor processor, bool walk_subquery, unsigned char *args)

  {

    return arg->walk(processor, walk_subquery, args) || (this->*processor)(args);

  }

};

} /* namespace drizzled */