遵循一套语法

Question

我正在尝试计算以下语法的 FOLLOW 集：

E -> TX
T -> int Y | ( E )
X -> + E | ε
Y -> * T | ε

到目前为止，我已经计算出以下 FOLLOW 集：

follow (E) = {$} U {)}
follow (Y) = follow (T)
follow (T) = follow (Y)
follow (X) = follow (E) = {$, )}
follow (E) = first ()) = {)}

我知道 follow (T) / follow (Y) 包含 {+,$,)} 但我正在努力达到这一点。

在此处解释该方法的任何帮助都会非常有帮助。

注意：我已遵守这些规则

1)  If A is the start symbol put $ in Follow (A)
2)  If there is a production B -> αAb, then Follow (A) = First (b) 
3)  If there is a production B -> aA or B -> αAb where First (b) is ε, add Follow (A) = Follow (B)

Answer 1

我已经想通了（并度过了下午的大部分时间）！

因此，对于发现此问题的任何人，我都遵循的规则是：

follow(E) = follow(T)
follow(E) = first ())
follow(X) = follow(E)
follow(Y) = follow(T)
**follow(T) = first(X)** //the important one!

按照这些规则，您可以构建集合：

follow(E) = {$, )}
follow(T) = {$, ), +}
follow(X) = {$, )}
follow(Y) = {$, ), +}

以下是语法的总结！