The notion of a visitor chain provides a very flexible framework with many options for how you structure and reuse the visitors on the tree.
访问者链接的概念为在树中构造和重用访问者提供了一种具有丰富选项的灵活框架。
EmptyVisitor just provides an empty implementation of all the various types of visitors, allowing you to subclass and override only the visitor methods of interest.
EmptyVisitor只是提供了所有不同种类的visitor的空的实现，允许您只对感兴趣的visitor方法建子类和重写。
The author comes up corresponding conclusion at the end and provides some beneficial Suggestions on visitor management of China's tourism attractions.
最后通过分析得出相应的结论，进而为我国景区的游客管理提供一些有益参考。
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