function get_select_from_sort($sort_sql)
{
$sort_clauses = preg_split('/\\s?,\\s?/', $sort_sql);
if (count($sort_clauses) === 1) {
return str_replace(AMP_SORT_DESC, '', $sort_sql);
}
$previous_sort_segment = false;
$delimiter = "''";
foreach ($sort_clauses as $sort_segment) {
if ($previous_sort_segment) {
$delimiter = 'if ( isnull( ' . $previous_sort_segment . '), \'\', \', \')';
}
$index_segment = str_replace(AMP_SORT_DESC, '', $sort_segment);
$local_method = 'make_readable_select_for_' . AMP_from_camelcase($index_segment);
if (method_exists($this, $local_method)) {
$index_segment = $this->{$local_method}();
}
$index_sort[] = '( if( isnull( ' . $index_segment . '), \'\', Concat( ' . $delimiter . ',' . $index_segment . ')))';
//after first time through loop all segments need leading punctuation
$previous_sort_segment = $index_segment;
}
return "Concat( " . join(',', $index_sort) . " ) as index_field";
}
function AMP_underscore($value)
{
$start = AMP_from_camelcase($value);
return strtolower(preg_replace('/_+/', '_', preg_replace('/[^A-z0-9]/', '_', $value)));
}
function cache_key($type, $instance_var = null)
{
$lookup_cache_key = AMP_CACHE_TOKEN_LOOKUP . AMP_from_camelcase($type);
if (defined('AMP_SYSTEM_USER_ID')) {
$lookup_cache_key = AMP_System_Cache::identify($lookup_cache_key, AMP_SYSTEM_USER_ID);
}
if (!isset($instance_var)) {
return $lookup_cache_key;
}
//instanced lookup
return AMP_System_Cache::identify($lookup_cache_key . 'K', $instance_var);
}