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<?php
/**
OpenDb - Open Media Lending Database
Copyright (C) 2001,2002 by Jason Pell
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.
*/
/**
This function will return a complete sort function
to be used with usort and as a second argument to
create_argument (Ensure the first parameter to
create_function is '$a,$b':
usort($item_rs, create_function('$a,$b', get_usort_function('title ASC, owner_id ASC, s_item_type DESC')));
array(
array(title=>'Crow, The',owner_id=>'jpell',s_item_type=>'DVD'),
array(title=>'Rambo',owner_id=>'martin',s_item_type=>'DVD'),
array(title=>'Good Will Hunting',owner_id=>'lucy',s_item_type=>'VHS')
);
The call to get_usort_function('title ASC, owner_id ASC, s_item_type DESC'), results in the following
generated function:
$title=strcmp($a[title], $b[title]); if($title==0){$owner_id=strcmp($a[owner_id], $b[owner_id]); if($owner_id==0){return strcmp($b[s_item_type], $a[s_item_type]);}else{return $owner_id;}}else{return $title;}
The order_by_clause should look something like this:
'item_id ASC, owner_id DESC, title ASC'
*/
function get_usort_function($order_by_clause)
{
// We get the options in reverse order, so we can properly nest them.
$order_by_options_r = array_reverse(explode(",", $order_by_clause));
$first_element = TRUE;
while(list(,$order_by) = each($order_by_options_r))
{
if(strlen($retval)>0)
{
$inner_val = $retval;
}
$order_by = trim($order_by);
$indexOfSpace = strpos($order_by, ' ');
if($indexOfSpace !== FALSE)
{
$column = trim(substr($order_by,0,$indexOfSpace));
$sortorder = trim(substr($order_by,$indexOfSpace));
if(strcasecmp($sortorder,"DESC")===0)
$comp = 'strcmp($b[\''.$column.'\'], $a[\''.$column.'\'])';
else
$comp = 'strcmp($a[\''.$column.'\'], $b[\''.$column.'\'])';
if($first_element)
{
$retval = 'return '.$comp.';';
$first_element = FALSE;
}
else
{
$retval = '$'.$column.'='.$comp.'; if($'.$column.'==0){'.$inner_val.'}else{return $'.$column.';}';
}
}
}
return $retval;
}
?>
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