Drizzled Public API Documentation

outer_ref.h
1 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
2  * vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
3  *
4  * Copyright (C) 2008 Sun Microsystems, Inc.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; version 2 of the License.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18  */
19 
20 #pragma once
21 
22 #include <drizzled/item/ref.h>
23 #include <drizzled/item/direct_ref.h>
24 #include <drizzled/item/field.h>
25 
26 /*
27  Class for outer fields.
28  An object of this class is created when the select where the outer field was
29  resolved is a grouping one. After it has been fixed the ref field will point
30  to either an Item_ref or an Item_direct_ref object which will be used to
31  access the field.
32  See also comments for the fix_inner_refs() and the
33  Item_field::fix_outer_field() functions.
34 */
35 
36 namespace drizzled {
37 
39 {
40 public:
41  Item *outer_ref;
42  /* The aggregate function under which this outer ref is used, if any. */
43  Item_sum *in_sum_func;
44  /*
45  true <=> that the outer_ref is already present in the select list
46  of the outer select.
47  */
48  bool found_in_select_list;
50  Item_field *outer_field_arg)
51  :Item_direct_ref(context_arg, 0, outer_field_arg->table_name,
52  outer_field_arg->field_name),
53  outer_ref(outer_field_arg), in_sum_func(0),
54  found_in_select_list(0)
55  {
56  ref= &outer_ref;
57  set_properties();
58  fixed= 0;
59  }
60  Item_outer_ref(Name_resolution_context *context_arg, Item **item,
61  const char *table_name_arg, const char *field_name_arg,
62  bool alias_name_used_arg)
63  :Item_direct_ref(context_arg, item, table_name_arg, field_name_arg,
64  alias_name_used_arg),
65  outer_ref(0), in_sum_func(0), found_in_select_list(1)
66  {}
67  void save_in_result_field(bool)
68  {
69  outer_ref->save_org_in_field(result_field);
70  }
71  bool fix_fields(Session *, Item **);
72  void fix_after_pullout(Select_Lex *new_parent, Item **ref);
73  table_map used_tables() const
74  {
75  return (*ref)->const_item() ? 0 : OUTER_REF_TABLE_BIT;
76  }
77  virtual Ref_Type ref_type() { return OUTER_REF; }
78 };
79 
80 } /* namespace drizzled */
81