# 3A.3 语法解析

如果一个程序是良构的，那么代表该程序的 Token 序列就一定可以通过该程序的文法推导出来，并且只有一种推导方式，语法解析的核心逻辑就是还原该推导过程。如果将解析过程看着是构建一个解析树的过程，那么根据构建方式的不同，可以分为自顶向下与自底向上两种。接下来我们依次对其进行分析。


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