Method DeleteNode

euler/parser/tree.h:214–220

  }

  void DeleteNode(TreeNode* t) {
    if (t->GetParent() != nullptr) {
      t->GetParent()->DeleteChild(t);
    } else {
      delete t;
    }
  }

  void PostTraversal(TreeNode* root,
                     std::vector<TreeNode*>* results) const {