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405613ebb5
The `Item` class methods `get_copy()`, `build_clone()`, and `clone_item()` face an issue where they may be defined in a descendant class (e.g., `Item_func`) but not in a further descendant (e.g., `Item_func_child`). This can lead to scenarios where `build_clone()`, when operating on an instance of `Item_func_child` with a pointer to the base class (`Item`), returns an instance of `Item_func` instead of `Item_func_child`. Since this limitation cannot be resolved at compile time, this commit introduces runtime type checks for the copy/clone operations. A debug assertion will now trigger in case of a type mismatch. `get_copy()`, `build_clone()`, and `clone_item()` are no more virtual, but virtual `do_get_copy()`, `do_build_clone()`, and `do_clone_item()` are added to the protected section of the class `Item`. Additionally, const qualifiers have been added to certain methods to enhance code reliability. Reviewer: Oleksandr Byelkin <sanja@mariadb.com>
87 lines
3 KiB
C++
87 lines
3 KiB
C++
/*
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Copyright (c) 2019, MariaDB Corporation
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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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#define MYSQL_SERVER
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#include <my_global.h>
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#include <sql_class.h>
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#include <mysql/plugin_function.h>
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class Item_func_sysconst_test :public Item_func_sysconst
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{
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public:
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Item_func_sysconst_test(THD *thd): Item_func_sysconst(thd) {}
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String *val_str(String *str) override
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{
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null_value= str->copy(STRING_WITH_LEN("sysconst_test"), system_charset_info);
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return null_value ? NULL : str;
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}
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bool fix_length_and_dec() override
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{
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max_length= MAX_FIELD_NAME * system_charset_info->mbmaxlen;
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maybe_null= true;
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return false;
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}
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const char *func_name() const override { return "sysconst_test"; }
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const char *fully_qualified_func_name() const override { return "sysconst_test()"; }
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Item *do_get_copy(THD *thd) const override
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{ return get_item_copy<Item_func_sysconst_test>(thd, this); }
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};
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class Create_func_sysconst_test : public Create_func_arg0
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{
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public:
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Item *create_builder(THD *thd) override;
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static Create_func_sysconst_test s_singleton;
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protected:
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Create_func_sysconst_test() {}
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};
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Create_func_sysconst_test Create_func_sysconst_test::s_singleton;
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Item* Create_func_sysconst_test::create_builder(THD *thd)
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{
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return new (thd->mem_root) Item_func_sysconst_test(thd);
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}
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#define BUILDER(F) & F::s_singleton
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static Plugin_function
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plugin_descriptor_function_sysconst_test(BUILDER(Create_func_sysconst_test));
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/*************************************************************************/
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maria_declare_plugin(type_test)
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{
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MariaDB_FUNCTION_PLUGIN, // the plugin type (see include/mysql/plugin.h)
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&plugin_descriptor_function_sysconst_test, // pointer to type-specific plugin descriptor
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"sysconst_test", // plugin name
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"MariaDB Corporation", // plugin author
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"Function SYSCONST_TEST()", // the plugin description
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PLUGIN_LICENSE_GPL, // the plugin license (see include/mysql/plugin.h)
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0, // Pointer to plugin initialization function
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0, // Pointer to plugin deinitialization function
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0x0100, // Numeric version 0xAABB means AA.BB version
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NULL, // Status variables
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NULL, // System variables
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"1.0", // String version representation
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MariaDB_PLUGIN_MATURITY_EXPERIMENTAL // Maturity(see include/mysql/plugin.h)*/
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}
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maria_declare_plugin_end;
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