code: protected function addAttributeTokens()
      {
          $this->mapHandler('dq_attribute', 'acceptAttributeToken');
          $this->addEntryPattern('=\s*"', 'tag', 'dq_attribute');
          $this->addPattern('\\\\"', 'dq_attribute');
          $this->addExitPattern('"', 'dq_attribute');
          $this->mapHandler('sq_attribute', 'acceptAttributeToken');
          $this->addEntryPattern("=\s*'", 'tag', 'sq_attribute');
          $this->addPattern("\\\\'", 'sq_attribute');
          $this->addExitPattern("'", 'sq_attribute');
          $this->mapHandler('uq_attribute', 'acceptAttributeToken');
          $this->addSpecialPattern('=\s*[^>\s]*', 'tag', 'uq_attribute');
      }
docs: Matches attributes that are either single quoted, double quoted or unquoted.