classを追加

gistfile1.php

<?php
add_filter ( 'wp_tag_cloud', 'tag_cloud_current_tag_highlight' );
function tag_cloud_current_tag_highlight( $return ) {
  $post_tags = array();
  if(is_single()) {
    global $post;
    $post_tags = get_the_terms($post->ID,'post_tag');
  }
  if(is_tag()) {
    $tags = explode( '+', get_query_var('tag') );
    foreach( $tags as $tag ) { $post_tags[] = get_term_by('slug',$tag,'post_tag'); }
  }
  if( $post_tags ) {
      foreach ($post_tags as $pt) {
      $tag = $pt->term_id;
        if(preg_match("#-link-" . $tag . "' #", $return)) {
        $return = str_replace("link-" . $tag . "' ", "link-" . $tag . " current-tag' ", $return);
        }
      }
    }
return $return;
}

//current-tagというclassが追加される
?>