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/* Copyright (C) 2000-2006 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Functions to create an item. Used by sql/sql_yacc.yy */
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#ifndef DRIZZLE_SERVER_ITEM_CREATE_H
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#define DRIZZLE_SERVER_ITEM_CREATE_H
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Public function builder interface.
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The parser (sql/sql_yacc.yy) uses a factory / builder pattern to
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construct an <code>Item</code> object for each function call.
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All the concrete function builders implements this interface,
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either directly or indirectly with some adapter helpers.
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Keeping the function creation separated from the bison grammar allows
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to simplify the parser, and avoid the need to introduce a new token
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for each function, which has undesirable side effects in the grammar.
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The builder create method.
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Given the function name and list or arguments, this method creates
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an <code>Item</code> that represents the function call.
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In case or errors, a NULL item is returned, and an error is reported.
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Note that the <code>thd</code> object may be modified by the builder.
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In particular, the following members/methods can be set/called,
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depending on the function called and the function possible side effects.
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<li><code>thd->lex->binlog_row_based_if_mixed</code></li>
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<li><code>thd->lex->current_context()</code></li>
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<li><code>thd->lex->safe_to_cache_query</code></li>
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<li><code>thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT)</code></li>
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<li><code>thd->lex->uncacheable(UNCACHEABLE_RAND)</code></li>
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<li><code>thd->lex->add_time_zone_tables_to_query_tables(thd)</code></li>
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@param thd The current thread
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@param name The function name
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@param item_list The list of arguments to the function, can be NULL
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@return An item representing the parsed function call, or NULL
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virtual Item *create(THD *thd, LEX_STRING name, List<Item> *item_list) = 0;
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virtual ~Create_func() {}
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Function builder for qualified functions.
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This builder is used with functions call using a qualified function name
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syntax, as in <code>db.func(expr, expr, ...)</code>.
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class Create_qfunc : public Create_func
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The builder create method, for unqualified functions.
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This builder will use the current database for the database name.
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@param thd The current thread
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@param name The function name
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@param item_list The list of arguments to the function, can be NULL
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@return An item representing the parsed function call
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virtual Item *create(THD *thd, LEX_STRING name, List<Item> *item_list);
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The builder create method, for qualified functions.
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@param thd The current thread
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@param db The database name
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@param name The function name
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@param use_explicit_name Should the function be represented as 'db.name'?
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@param item_list The list of arguments to the function, can be NULL
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@return An item representing the parsed function call
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virtual Item* create(THD *thd, LEX_STRING db, LEX_STRING name,
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bool use_explicit_name, List<Item> *item_list) = 0;
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virtual ~Create_qfunc() {}
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Find the native function builder associated with a given function name.
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@param thd The current thread
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@param name The native function name
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@return The native function builder associated with the name, or NULL
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extern Create_func * find_native_function_builder(THD *thd, LEX_STRING name);
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Find the function builder for qualified functions.
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@param thd The current thread
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@return A function builder for qualified functions
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extern Create_qfunc * find_qualified_function_builder(THD *thd);
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Function builder for User Defined Functions.
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class Create_udf_func : public Create_func
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virtual Item *create(THD *thd, LEX_STRING name, List<Item> *item_list);
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The builder create method, for User Defined Functions.
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@param thd The current thread
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@param fct The User Defined Function metadata
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@param item_list The list of arguments to the function, can be NULL
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@return An item representing the parsed function call
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Item *create(THD *thd, udf_func *fct, List<Item> *item_list);
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static Create_udf_func s_singleton;
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virtual ~Create_udf_func() {}
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create_func_char_cast(THD *thd, Item *a, int len, const CHARSET_INFO * const cs);
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Builder for cast expressions.
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@param thd The current thread
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@param a The item to cast
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@param cast_type the type casted into
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@param cs The character set
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create_func_cast(THD *thd, Item *a, Cast_target cast_type,
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const char *len, const char *dec,
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const CHARSET_INFO * const cs);
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int item_create_init();
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void item_create_cleanup();
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#endif /* DRIZZLE_SERVER_ITEM_CREATE_H */
added
removed
drizzled/item_create.h
