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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008 Sun Microsystems, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef DRIZZLED_NAME_RESOLUTION_CONTEXT_H
#define DRIZZLED_NAME_RESOLUTION_CONTEXT_H
#include <drizzled/item.h>
namespace drizzled
{
class TableList;
class SecurityContext;
class Session;
class Select_Lex;
/**
* Instances of Name_resolution_context store the information necesary for
* name resolution of Items and other context analysis of a query made in
* fix_fields().
*
* This structure is a part of Select_Lex, a pointer to this structure is
* assigned when an item is created (which happens mostly during parsing
* (sql_yacc.yy)), but the structure itself will be initialized after parsing
* is complete
*
* @todo
*
* Move subquery of INSERT ... SELECT and CREATE ... SELECT to
* separate Select_Lex which allow to remove tricks of changing this
* structure before and after INSERT/CREATE and its SELECT to make correct
* field name resolution.
*/
class Name_resolution_context: public memory::SqlAlloc
{
public:
/**
* The name resolution context to search in when an Item cannot be
* resolved in this context (the context of an outer select)
*/
Name_resolution_context *outer_context;
/**
* List of tables used to resolve the items of this context. Usually these
* are tables from the FROM clause of SELECT statement. The exceptions are
* INSERT ... SELECT and CREATE ... SELECT statements, where SELECT
* subquery is not moved to a separate Select_Lex. For these types of
* statements we have to change this member dynamically to ensure correct
* name resolution of different parts of the statement.
*/
TableList *table_list;
/**
* In most cases the two table references below replace 'table_list' above
* for the purpose of name resolution. The first and last name resolution
* table references allow us to search only in a sub-tree of the nested
* join tree in a FROM clause. This is needed for NATURAL JOIN, JOIN ... USING
* and JOIN ... ON.
*/
TableList *first_name_resolution_table;
/**
* Last table to search in the list of leaf table references that begins
* with first_name_resolution_table.
*/
TableList *last_name_resolution_table;
/**
* Select_Lex item belong to, in case of merged VIEW it can differ from
* Select_Lex where item was created, so we can't use table_list/field_list
* from there
*/
Select_Lex *select_lex;
/**
* Processor of errors caused during Item name resolving, now used only to
* hide underlying tables in errors about views (i.e. it substitute some
* errors for views)
*/
void (*error_processor)(Session *, void *);
void *error_processor_data;
/**
* When true items are resolved in this context both against the
* SELECT list and this->table_list. If false, items are resolved
* only against this->table_list.
*/
bool resolve_in_select_list;
/**
* Security context of this name resolution context. It's used for views
* and is non-zero only if the view is defined with SQL SECURITY DEFINER.
*/
SecurityContext *security_ctx;
Name_resolution_context()
:
outer_context(0),
table_list(0),
select_lex(0),
error_processor_data(0),
security_ctx(0)
{}
inline void init()
{
resolve_in_select_list= false;
error_processor= &dummy_error_processor;
first_name_resolution_table= NULL;
last_name_resolution_table= NULL;
}
inline void resolve_in_table_list_only(TableList *tables)
{
table_list= first_name_resolution_table= tables;
resolve_in_select_list= false;
}
inline void process_error(Session *session)
{
(*error_processor)(session, error_processor_data);
}
};
} /* namespace drizzled */
#endif /* DRIZZLED_NAME_RESOLUTION_CONTEXT_H */
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