src/TaggableBehavior.php
protected function parseTags($tags)
    {
        return array_unique(is_array($tags) ? array_filter($tags) : preg_split('/\s*,\s*/', $tags, -1, PREG_SPLIT_NO_EMPTY));
    }
protected function parseTags($tags)
    {
        return array_unique(is_array($tags) ? array_filter($tags) : preg_split('/\s*,\s*/', $tags, -1, PREG_SPLIT_NO_EMPTY));
    }
Parse tags list into array
@param string|string[] $tags list of tags. If specified as a string, the tags must be separated by commas
@return string[]