~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_ITEM_REF_H

#define DRIZZLED_ITEM_REF_H

#include "drizzled/item/ident.h"

namespace drizzled

{

class Item_ref :public Item_ident

{

protected:

  void set_properties();

public:

  enum Ref_Type { REF, DIRECT_REF, OUTER_REF };

  Field *result_field;			 /* Save result here */

  Item **ref;

  Item_ref(Name_resolution_context *context_arg,

           const char *db_arg, const char *table_name_arg,

           const char *field_name_arg)

    :Item_ident(context_arg, db_arg, table_name_arg, field_name_arg),

     result_field(0), ref(0) {}

  /*

    This constructor is used in two scenarios:

    A) *item = NULL

      No initialization is performed, fix_fields() call will be necessary.

    B) *item points to an Item this Item_ref will refer to. This is

      used for GROUP BY. fix_fields() will not be called in this case,

      so we call set_properties to make this item "fixed". set_properties

      performs a subset of action Item_ref::fix_fields does, and this subset

      is enough for Item_ref's used in GROUP BY.

    TODO we probably fix a superset of problems like in BUG#6658. Check this

         with Bar, and if we have a more broader set of problems like this.

  */

  Item_ref(Name_resolution_context *context_arg, Item **item,

           const char *table_name_arg, const char *field_name_arg,

           bool alias_name_used_arg= false);

  /* Constructor need to process subselect with temporary tables (see Item) */

  Item_ref(Session *session, Item_ref *item)

    :Item_ident(session, item), result_field(item->result_field), ref(item->ref) {}

  enum Type type() const		{ return REF_ITEM; }

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

  {

    const Item *it= item->real_item();

    return ref && (*ref)->eq(it, binary_cmp);

  }

  double val_real();

  int64_t val_int();

  type::Decimal *val_decimal(type::Decimal *);

  bool val_bool();

  String *val_str(String* tmp);

  bool is_null();

  bool get_date(type::Time &ltime,uint32_t fuzzydate);

  double val_result();

  int64_t val_int_result();

  String *str_result(String* tmp);

  type::Decimal *val_decimal_result(type::Decimal *);

  bool val_bool_result();

  bool send(plugin::Client *client, String *tmp);

  void make_field(SendField *field);

  bool fix_fields(Session *, Item **);

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

  int save_in_field(Field *field, bool no_conversions);

  void save_org_in_field(Field *field);

  enum Item_result result_type () const { return (*ref)->result_type(); }

  enum_field_types field_type() const   { return (*ref)->field_type(); }

  Field *get_tmp_table_field()

  { return result_field ? result_field : (*ref)->get_tmp_table_field(); }

  Item *get_tmp_table_item(Session *session);

  table_map used_tables() const

  {

    return depended_from ? OUTER_REF_TABLE_BIT : (*ref)->used_tables();

  }

  void update_used_tables()

  {

    if (!depended_from)

      (*ref)->update_used_tables();

  }

  table_map not_null_tables() const { return (*ref)->not_null_tables(); }

  void set_result_field(Field *field)	{ result_field= field; }

  bool is_result_field() { return 1; }

  void save_in_result_field(bool no_conversions)

  {

    (*ref)->save_in_field(result_field, no_conversions);

  }

  Item *real_item(void)

  {

    return ref ? (*ref)->real_item() : this;

  }

  const Item *real_item(void) const

  {

    return ref ? (*ref)->real_item() : this;

  }

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

  { return (*ref)->walk(processor, walk_subquery, arg); }

  virtual void print(String *str, enum_query_type query_type);

  bool result_as_int64_t()

  {

    return (*ref)->result_as_int64_t();

  }

  void cleanup();

  virtual Ref_Type ref_type() { return REF; }

  // Row emulation: forwarding of ROW-related calls to ref

  uint32_t cols()

  {

    return ref && result_type() == ROW_RESULT ? (*ref)->cols() : 1;

  }

  Item* element_index(uint32_t i)

  {

    return ref && result_type() == ROW_RESULT ? (*ref)->element_index(i) : this;

  }

  Item** addr(uint32_t i)

  {

    return ref && result_type() == ROW_RESULT ? (*ref)->addr(i) : 0;

  }

  bool check_cols(uint32_t c)

  {

    return ref && result_type() == ROW_RESULT ? (*ref)->check_cols(c)

                                              : Item::check_cols(c);

  }

  bool null_inside()

  {

    return ref && result_type() == ROW_RESULT ? (*ref)->null_inside() : 0;

  }

  void bring_value()

  {

    if (ref && result_type() == ROW_RESULT)

      (*ref)->bring_value();

  }

  bool basic_const_item() const

  {

    return (*ref)->basic_const_item();

  }

};

} /* namespace drizzled */

#endif /* DRIZZLED_ITEM_REF_H */