Performs the filter processing.
string $text: The text string to be filtered.
string $langcode: The language code of the text to be filtered.
bool $cache: A Boolean indicating whether the filtered text is going to be cached in {cache_filter}.
string $cache_id: The ID of the filtered text in {cache_filter}, if $cache is TRUE.
string The filtered text.
Overrides FilterInterface::process
public function process($text, $langcode, $cache, $cache_id) {
return php_eval($text);
}