将语法转换为 LL1 语法
我明天要复习考试，复习前几年的考试。
测试的是语法。
Expression -> Foo "+" Bar "end"
Foo -> [a-z0-9]+ | Expression
Bar -> Expression Foo | a*b*c+
我已经尝试并花了几个小时研究如何做到这一点，但无法弄清楚。
我已经考虑过用 epsilon 替换一些东西，但没有信心。
我认为我需要创建一个 Foo' 和一个 Bar'，然后添加 epsilon 规则，但我不确定。
有人可以告诉我（简单地）_如何将其更改为 LL(1) 能力的语法
提前致谢
I am revising for an exam tomorrow, and going over a previous years one.
In the test was the grammar.
Expression -> Foo "+" Bar "end"
Foo -> [a-z0-9]+ | Expression
Bar -> Expression Foo | a*b*c+
I have tried and spent hours researching on how to do it, but can't figure it out.
I have had a look at replacing things with epsilion and that, but don't feel confident.
I think that I need to create a Foo' and a Bar' and then just add in the epsilon rules, but I am not sure.
Could somebody please show me (simply)_how to change it to an LL(1) capable grammar
Thanks in advance
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我记得 LL-1 语法以 1 个符号向前看。您的目标是消除歧义和左递归。您所需要的一切 - 使用左分解。首先看一下这个。
As i remember LL-1 grammar look ahead in 1 symbol. Your goal to eliminate ambiguity and left recursion. All that you need - use left factorization. Take a look this first.