private function constDeclaration() {
    $node = new ConstantDeclarationNode();
    $name_node = new NameNode();
    $this->mustMatch(T_STRING, $name_node, NULL, TRUE);
    $node->addChild($name_node, 'name');
    if ($this->mustMatch('=', $node)) {
      $node->addChild($this->staticScalar(), 'value');
    }
    return $node;
  }