protected function writePreprocessorDefinitions(DOMElement $parent, Configuration $configuration)
 {
     $definitions = array_merge($this->project->getDefinitions(), $configuration->getDefinitions());
     if ($configuration->getDebug()) {
         $definitions[] = '_DEBUG';
     } else {
         $definitions[] = 'NDEBUG';
     }
     $definitions[] = '%(PreprocessorDefinitions)';
     $uniqueDefinitions = array_unique($definitions);
     XmlDom::createElement($parent, 'PreprocessorDefinitions', implode(';', $uniqueDefinitions));
 }