1 /* Copyright (c) 2000, 2010, Oracle and/or its affiliates.
2    Copyright (c) 2008-2011 Monty Program Ab
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 02110-1335  USA */
16 
17 /* Functions to create an item. Used by sql/sql_yacc.yy */
18 
19 #ifndef ITEM_CREATE_H
20 #define ITEM_CREATE_H
21 
22 #include "item_func.h" // Cast_target
23 
24 typedef struct st_udf_func udf_func;
25 
26 /**
27   Public function builder interface.
28   The parser (sql/sql_yacc.yy) uses a factory / builder pattern to
29   construct an <code>Item</code> object for each function call.
30   All the concrete function builders implements this interface,
31   either directly or indirectly with some adapter helpers.
32   Keeping the function creation separated from the bison grammar allows
33   to simplify the parser, and avoid the need to introduce a new token
34   for each function, which has undesirable side effects in the grammar.
35 */
36 
37 class Create_func
38 {
39 public:
40   /**
41     The builder create method.
42     Given the function name and list or arguments, this method creates
43     an <code>Item</code> that represents the function call.
44     In case or errors, a NULL item is returned, and an error is reported.
45     Note that the <code>thd</code> object may be modified by the builder.
46     In particular, the following members/methods can be set/called,
47     depending on the function called and the function possible side effects.
48     <ul>
49       <li><code>thd->lex->binlog_row_based_if_mixed</code></li>
50       <li><code>thd->lex->current_context()</code></li>
51       <li><code>thd->lex->safe_to_cache_query</code></li>
52       <li><code>thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT)</code></li>
53       <li><code>thd->lex->uncacheable(UNCACHEABLE_RAND)</code></li>
54       <li><code>thd->lex->add_time_zone_tables_to_query_tables(thd)</code></li>
55     </ul>
56     @param thd The current thread
57     @param name The function name
58     @param item_list The list of arguments to the function, can be NULL
59     @return An item representing the parsed function call, or NULL
60   */
61   virtual Item *create_func(THD *thd, LEX_CSTRING *name, List<Item> *item_list) = 0;
62 
63 protected:
64   /** Constructor */
Create_func()65   Create_func() {}
66   /** Destructor */
~Create_func()67   virtual ~Create_func() {}
68 };
69 
70 
71 /**
72   Adapter for native functions with a variable number of arguments.
73   The main use of this class is to discard the following calls:
74   <code>foo(expr1 AS name1, expr2 AS name2, ...)</code>
75   which are syntactically correct (the syntax can refer to a UDF),
76   but semantically invalid for native functions.
77 */
78 
79 class Create_native_func : public Create_func
80 {
81 public:
82   virtual Item *create_func(THD *thd, LEX_CSTRING *name,
83                             List<Item> *item_list);
84 
85   /**
86     Builder method, with no arguments.
87     @param thd The current thread
88     @param name The native function name
89     @param item_list The function parameters, none of which are named
90     @return An item representing the function call
91   */
92   virtual Item *create_native(THD *thd, LEX_CSTRING *name,
93                               List<Item> *item_list) = 0;
94 
95 protected:
96   /** Constructor. */
Create_native_func()97   Create_native_func() {}
98   /** Destructor. */
~Create_native_func()99   virtual ~Create_native_func() {}
100 };
101 
102 
103 /**
104   Function builder for qualified functions.
105   This builder is used with functions call using a qualified function name
106   syntax, as in <code>db.func(expr, expr, ...)</code>.
107 */
108 
109 class Create_qfunc : public Create_func
110 {
111 public:
112   /**
113     The builder create method, for unqualified functions.
114     This builder will use the current database for the database name.
115     @param thd The current thread
116     @param name The function name
117     @param item_list The list of arguments to the function, can be NULL
118     @return An item representing the parsed function call
119   */
120   virtual Item *create_func(THD *thd, LEX_CSTRING *name,
121                             List<Item> *item_list);
122 
123   /**
124     The builder create method, for qualified functions.
125     @param thd The current thread
126     @param db The database name
127     @param name The function name
128     @param use_explicit_name Should the function be represented as 'db.name'?
129     @param item_list The list of arguments to the function, can be NULL
130     @return An item representing the parsed function call
131   */
132   virtual Item *create_with_db(THD *thd, LEX_CSTRING *db, LEX_CSTRING *name,
133                                bool use_explicit_name,
134                                List<Item> *item_list) = 0;
135 
136 protected:
137   /** Constructor. */
Create_qfunc()138   Create_qfunc() {}
139   /** Destructor. */
~Create_qfunc()140   virtual ~Create_qfunc() {}
141 };
142 
143 
144 /**
145   Find the native function builder associated with a given function name.
146   @param thd The current thread
147   @param name The native function name
148   @return The native function builder associated with the name, or NULL
149 */
150 extern Create_func *find_native_function_builder(THD *thd,
151                                                  const LEX_CSTRING *name);
152 
153 
154 /**
155   Find the function builder for qualified functions.
156   @param thd The current thread
157   @return A function builder for qualified functions
158 */
159 extern Create_qfunc * find_qualified_function_builder(THD *thd);
160 
161 
162 #ifdef HAVE_DLOPEN
163 /**
164   Function builder for User Defined Functions.
165 */
166 
167 class Create_udf_func : public Create_func
168 {
169 public:
170   virtual Item *create_func(THD *thd, LEX_CSTRING *name,
171                             List<Item> *item_list);
172 
173   /**
174     The builder create method, for User Defined Functions.
175     @param thd The current thread
176     @param fct The User Defined Function metadata
177     @param item_list The list of arguments to the function, can be NULL
178     @return An item representing the parsed function call
179   */
180   Item *create(THD *thd, udf_func *fct, List<Item> *item_list);
181 
182   /** Singleton. */
183   static Create_udf_func s_singleton;
184 
185 protected:
186   /** Constructor. */
Create_udf_func()187   Create_udf_func() {}
188   /** Destructor. */
~Create_udf_func()189   virtual ~Create_udf_func() {}
190 };
191 #endif
192 
193 
194 struct Native_func_registry
195 {
196   LEX_CSTRING name;
197   Create_func *builder;
198 };
199 
200 int item_create_init();
201 int item_create_append(Native_func_registry array[]);
202 int item_create_remove(Native_func_registry array[]);
203 void item_create_cleanup();
204 
205 Item *create_func_dyncol_create(THD *thd, List<DYNCALL_CREATE_DEF> &list);
206 Item *create_func_dyncol_add(THD *thd, Item *str,
207                              List<DYNCALL_CREATE_DEF> &list);
208 Item *create_func_dyncol_delete(THD *thd, Item *str, List<Item> &nums);
209 Item *create_func_dyncol_get(THD *thd, Item *num, Item *str,
210                              const Type_handler *handler,
211                              const char *c_len, const char *c_dec,
212                              CHARSET_INFO *cs);
213 Item *create_func_dyncol_json(THD *thd, Item *str);
214 #endif
215 
216