56    *   group => (none|firstauthor|entrytype|$field)
87    *                       - group => (none|year|firstauthor|entrytype|$field)
101       'group' => 'year',
181     if ( preg_match('/@\{group@/s', $template) + preg_match('/@\}group@/s', $template) < 2 ) {
182       $groupingDisabled = $this->options['group'];
183       $this->options['group'] = 'none';
187     if ( $this->options['group'] === 'none' ) {
188       $template = preg_replace(array('/@\{group@/s', '/@\}group@/s'), '', $template);
200     $data   = $this->group($data);
207       $this->options['group'] = $groupingDisabled;
218    * language file are put into a distinct group.
274   private function group(&$data) {  function in BibtexConverter
277     if ( $this->options['group'] !== 'none' ) {
279 …      if ( !empty($entry[$this->options['group']]) || $this->options['group'] === 'firstauthor' ) {
280           if ( $this->options['group'] === 'firstauthor' ) {
283           elseif ( $this->options['group'] === 'author' ) {
287             $target =  $entry[$this->options['group']];
309    * This function sorts the passed group of entries and the individual
318     if ( $this->options['group'] !== 'none' ) {
323     foreach ( $data as &$group ) {
324       uasort($group, array($this->helper, 'entry_cmp'));
347     if ( $this->options['group'] !== 'none' ) {
348       $pattern = '/@\{group@(.*?)@\}group@/s';
350       // Extract group templates
354       // For all occurrences of an group template
359         foreach ( $data as $groupkey => $group ) {
360           $groups .= $this->translate_group($groupkey, $id++, $group, $group_tpl[1]);
371       foreach ( $data as $groupkey => $group ) { // loop will only be run once
372         $groups .= $this->translate_group($groupkey, 0, $group, $template);
379    * This function translates one entry group
382    * @param string key The rendered group's key
383    * @param int id A unique ID for this group
384    * @param array data Array of entries in this group
385    * @param string template The group part of the template
386    * @return string String representing the passed group wrt template
391     // Replace group values
392     if ( $this->options['group'] === 'entrytype' ) {
464      * Group 1  field             field            \w+
465      * Group 2  then              operator         .*?  /  <=|>=|==|!=|~
466      * Group 3  [else]            value            .*?
467      * Group 4   ---              then             .*?
468      * Group 5   ---              [else]           .*?