language-agnostic - 将EBNF转换为BNF

Question

从我的计算机语言类(class)开始已经过去了几年，所以我忘记了BNF和EBNF的优缺点，而且我旁边没有教科书。具体来说，我忘记了如何将EBNF转换为BNF。
从我所记得的很少，我知道要点之一就是

{ term }

进入

<term> | <many-terms>

但我不记得其他规则。我试图在网上查找此内容，但只能找到指向家庭作业问题的链接，或者有关用花括号转换术语的小注释。我找不到定义翻译的详尽规则列表。

Answer 1

参见this page。 🕗它包含需要转换的每个产品的说明:

From EBNF to BNF

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For building parsers (especially bottom-up) a BNF grammar is often better, than EBNF. But it's easy to convert an EBNF Grammar to BNF:

• Convert every repetition { E } to a fresh non-terminal X and add

  X = ε | X E.
  

• Convert every option [ E ] to a fresh non-terminal X and add

  X = ε | E.
  

  (We can convert X = A [ E ] B. to X = A E B | A B.)

• Convert every group ( E ) to a fresh non-terminal X and add

  X = E.
  

• We can even do away with alternatives by having several productions with the same non-terminal.

  X = E | E'. becomes X = E. X = E'.