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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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; either version 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* Buffers to save and compare item values */
#include "mysql_priv.h"
/*
** Create right type of item_buffer for an item
*/
Item_buff *new_Item_buff(THD *thd, Item *item)
{
if (item->type() == Item::FIELD_ITEM &&
!(((Item_field *) item)->field->flags & BLOB_FLAG))
return new Item_field_buff((Item_field *) item);
if (item->result_type() == STRING_RESULT)
return new Item_str_buff(thd, (Item_field *) item);
if (item->result_type() == INT_RESULT)
return new Item_int_buff((Item_field *) item);
return new Item_real_buff(item);
}
Item_buff::~Item_buff() {}
/*
** Compare with old value and replace value with new value
** Return true if values have changed
*/
Item_str_buff::Item_str_buff(THD *thd, Item *arg)
:item(arg), value(min(arg->max_length, thd->variables.max_sort_length))
{}
bool Item_str_buff::cmp(void)
{
String *res;
bool tmp;
if ((res=item->val_str(&tmp_value)))
res->length(min(res->length(), value.alloced_length()));
if (null_value != item->null_value)
{
if ((null_value= item->null_value))
return TRUE; // New value was null
tmp=TRUE;
}
else if (null_value)
return 0; // new and old value was null
else
tmp= sortcmp(&value,res,item->collation.collation) != 0;
if (tmp)
value.copy(*res); // Remember for next cmp
return tmp;
}
Item_str_buff::~Item_str_buff()
{
item=0; // Safety
}
bool Item_real_buff::cmp(void)
{
double nr=item->val();
if (null_value != item->null_value || nr != value)
{
null_value= item->null_value;
value=nr;
return TRUE;
}
return FALSE;
}
bool Item_int_buff::cmp(void)
{
longlong nr=item->val_int();
if (null_value != item->null_value || nr != value)
{
null_value= item->null_value;
value=nr;
return TRUE;
}
return FALSE;
}
bool Item_field_buff::cmp(void)
{
bool tmp= field->cmp(buff) != 0; // This is not a blob!
if (tmp)
field->get_image(buff,length,field->charset());
if (null_value != field->is_null())
{
null_value= !null_value;
tmp=TRUE;
}
return tmp;
}
/*****************************************************************************
** Instansiate templates
*****************************************************************************/
#ifdef __GNUC__
template class List<Item_buff>;
template class List_iterator<Item_buff>;
#endif
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