1/*
2 Copyright (c) 2000, 2010, Oracle and/or its affiliates.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; version 2 of the License.
7
8 This program is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 GNU General Public License for more details.
12
13 You should have received a copy of the GNU General Public License
14 along with this program; if not, write to the Free Software
15 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
16
17
18/**
19 @file
20
21 @brief
22 Buffers to save and compare item values
23*/
24
25#include "mariadb.h"
26#include "sql_priv.h"
27/*
28 It is necessary to include set_var.h instead of item.h because there
29 are dependencies on include order for set_var.h and item.h. This
30 will be resolved later.
31*/
32#include "sql_class.h" // THD
33#include "set_var.h" // Cached_item, Cached_item_field, ...
34
35/**
36 Create right type of Cached_item for an item.
37*/
38
39Cached_item *new_Cached_item(THD *thd, Item *item, bool pass_through_ref)
40{
41 if (pass_through_ref && item->real_item()->type() == Item::FIELD_ITEM &&
42 !(((Item_field *) (item->real_item()))->field->flags & BLOB_FLAG))
43 {
44 Item_field *real_item= (Item_field *) item->real_item();
45 Field *cached_field= real_item->field;
46 return new (thd->mem_root) Cached_item_field(thd, cached_field);
47 }
48 switch (item->result_type()) {
49 case STRING_RESULT:
50 return new Cached_item_str(thd, (Item_field *) item);
51 case INT_RESULT:
52 return new Cached_item_int((Item_field *) item);
53 case REAL_RESULT:
54 return new Cached_item_real(item);
55 case DECIMAL_RESULT:
56 return new Cached_item_decimal(item);
57 case ROW_RESULT:
58 default:
59 DBUG_ASSERT(0);
60 return 0;
61 }
62}
63
64Cached_item::~Cached_item() {}
65
66/**
67 Compare with old value and replace value with new value.
68
69 @return
70 Return true if values have changed
71*/
72
73Cached_item_str::Cached_item_str(THD *thd, Item *arg)
74 :Cached_item_item(arg),
75 value_max_length(MY_MIN(arg->max_length, thd->variables.max_sort_length)),
76 value(value_max_length)
77{}
78
79bool Cached_item_str::cmp(void)
80{
81 String *res;
82 bool tmp;
83
84 if ((res=item->val_str(&tmp_value)))
85 res->length(MY_MIN(res->length(), value_max_length));
86 if (null_value != item->null_value)
87 {
88 if ((null_value= item->null_value))
89 return TRUE; // New value was null
90 tmp=TRUE;
91 }
92 else if (null_value)
93 return 0; // new and old value was null
94 else
95 tmp= sortcmp(&value,res,item->collation.collation) != 0;
96 if (tmp)
97 value.copy(*res); // Remember for next cmp
98 return tmp;
99}
100
101
102int Cached_item_str::cmp_read_only()
103{
104 String *res= item->val_str(&tmp_value);
105
106 if (null_value)
107 {
108 if (item->null_value)
109 return 0;
110 else
111 return -1;
112 }
113 if (item->null_value)
114 return 1;
115
116 return sortcmp(&value, res, item->collation.collation);
117}
118
119
120Cached_item_str::~Cached_item_str()
121{
122 item=0; // Safety
123}
124
125bool Cached_item_real::cmp(void)
126{
127 double nr= item->val_real();
128 if (null_value != item->null_value || nr != value)
129 {
130 null_value= item->null_value;
131 value=nr;
132 return TRUE;
133 }
134 return FALSE;
135}
136
137
138int Cached_item_real::cmp_read_only()
139{
140 double nr= item->val_real();
141 if (null_value)
142 {
143 if (item->null_value)
144 return 0;
145 else
146 return -1;
147 }
148 if (item->null_value)
149 return 1;
150 return (nr == value)? 0 : ((nr < value)? 1: -1);
151}
152
153
154bool Cached_item_int::cmp(void)
155{
156 longlong nr=item->val_int();
157 if (null_value != item->null_value || nr != value)
158 {
159 null_value= item->null_value;
160 value=nr;
161 return TRUE;
162 }
163 return FALSE;
164}
165
166
167int Cached_item_int::cmp_read_only()
168{
169 longlong nr= item->val_int();
170 if (null_value)
171 {
172 if (item->null_value)
173 return 0;
174 else
175 return -1;
176 }
177 if (item->null_value)
178 return 1;
179 return (nr == value)? 0 : ((nr < value)? 1: -1);
180}
181
182
183bool Cached_item_field::cmp(void)
184{
185 bool tmp= FALSE; // Value is identical
186 /* Note that field can't be a blob here ! */
187 if (null_value != field->is_null())
188 {
189 null_value= !null_value;
190 tmp= TRUE; // Value has changed
191 }
192
193 /*
194 If value is not null and value changed (from null to not null or
195 becasue of value change), then copy the new value to buffer.
196 */
197 if (! null_value && (tmp || (tmp= (field->cmp(buff) != 0))))
198 field->get_image(buff,length,field->charset());
199 return tmp;
200}
201
202
203int Cached_item_field::cmp_read_only()
204{
205 if (null_value)
206 {
207 if (field->is_null())
208 return 0;
209 else
210 return -1;
211 }
212 if (field->is_null())
213 return 1;
214
215 return field->cmp(buff);
216}
217
218
219Cached_item_decimal::Cached_item_decimal(Item *it)
220 :Cached_item_item(it)
221{
222 my_decimal_set_zero(&value);
223}
224
225
226bool Cached_item_decimal::cmp()
227{
228 my_decimal tmp;
229 my_decimal *ptmp= item->val_decimal(&tmp);
230 if (null_value != item->null_value ||
231 (!item->null_value && my_decimal_cmp(&value, ptmp)))
232 {
233 null_value= item->null_value;
234 /* Save only not null values */
235 if (!null_value)
236 {
237 my_decimal2decimal(ptmp, &value);
238 return TRUE;
239 }
240 return FALSE;
241 }
242 return FALSE;
243}
244
245
246int Cached_item_decimal::cmp_read_only()
247{
248 my_decimal tmp;
249 my_decimal *ptmp= item->val_decimal(&tmp);
250 if (null_value)
251 {
252 if (item->null_value)
253 return 0;
254 else
255 return -1;
256 }
257 if (item->null_value)
258 return 1;
259 return my_decimal_cmp(&value, ptmp);
260}
261
262