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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_FIELD_ITERATOR_H
#define DRIZZLED_FIELD_ITERATOR_H
#include <drizzled/memory/sql_alloc.h>
#include <drizzled/sql_list.h>
#include <drizzled/natural_join_column.h>
#include <drizzled/item/field.h>
namespace drizzled {
class Table;
class TableList;
/*
Iterator over the fields of a generic table reference.
*/
class Field_iterator: public memory::SqlAlloc
{
public:
Field_iterator() {} /* Remove gcc warning */
virtual ~Field_iterator() {}
virtual void set(TableList *)= 0;
virtual void next()= 0;
virtual bool end_of_fields()= 0; /* Return 1 at end of list */
virtual const char *name()= 0;
virtual Item *create_item(Session *)= 0;
virtual Field *field()= 0;
};
/*
Iterator over the fields of a base table, view with temporary
table, or subquery.
*/
class Field_iterator_table: public Field_iterator
{
Field **ptr;
public:
Field_iterator_table() :ptr(0) {}
void set(TableList *table);
void set_table(Table *table);
void next() { ptr++; }
bool end_of_fields() { return *ptr == 0; }
const char *name();
Item *create_item(Session *session);
Field *field() { return *ptr; }
};
/* Iterator over the fields of a merge view. */
/*
Field_iterator interface to the list of materialized fields of a
NATURAL/USING join.
*/
class Field_iterator_natural_join: public Field_iterator
{
List<Natural_join_column>::iterator column_ref_it;
Natural_join_column *cur_column_ref;
public:
Field_iterator_natural_join() :cur_column_ref(NULL) {}
~Field_iterator_natural_join() {}
void set(TableList *table);
void next();
bool end_of_fields() { return !cur_column_ref; }
const char *name() { return cur_column_ref->name(); }
Item *create_item(Session *session) { return cur_column_ref->create_item(session); }
Field *field() { return cur_column_ref->field(); }
Natural_join_column *column_ref() { return cur_column_ref; }
};
/*
Generic iterator over the fields of an arbitrary table reference.
DESCRIPTION
This class unifies the various ways of iterating over the columns
of a table reference depending on the type of SQL entity it
represents. If such an entity represents a nested table reference,
this iterator encapsulates the iteration over the columns of the
members of the table reference.
IMPLEMENTATION
The implementation assumes that all underlying NATURAL/USING table
references already contain their result columns and are linked into
the list TableList::next_name_resolution_table.
*/
class Field_iterator_table_ref: public Field_iterator
{
TableList *table_ref, *first_leaf, *last_leaf;
Field_iterator_table table_field_it;
Field_iterator_natural_join natural_join_it;
Field_iterator *field_it;
void set_field_iterator();
public:
Field_iterator_table_ref() :field_it(NULL) {}
void set(TableList *table);
void next();
bool end_of_fields()
{ return (table_ref == last_leaf && field_it->end_of_fields()); }
const char *name() { return field_it->name(); }
const char *table_name();
const char *db_name();
Item *create_item(Session *session) { return field_it->create_item(session); }
Field *field() { return field_it->field(); }
Natural_join_column *get_or_create_column_ref(TableList *parent_table_ref);
Natural_join_column *get_natural_column_ref();
};
} /* namespace drizzled */
#endif /* DRIZZLED_FIELD_ITERATOR_H */
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