编译原理-笔记

概述

阅读一下龙书🐲。

罗马数字的 BNF 语法：

<roman> ::= <thousands> <hundreds> <tens> <ones>
<thousands> ::= "" | "M" | "MM" | "MMM"
<hundreds> ::= "" | "C" | "CC" | "CCC" | "CD" | "D" | "DC" | "DCC" | "DCCC" | "CM"
<tens> ::= "" | "X" | "XX" | "XXX" | "XL" | "L" | "LX" | "LXX" | "LXXX" | "XC"
<ones> ::= "" | "I" | "II" | "III" | "IV" | "V" | "VI" | "VII" | "VIII" | "IX"
<ones> ::= <one_to_three> | <four> | <five_to_eight> | <nine>
<one_to_three> ::= "I" | "II" | "III"
<four> ::= "IV"
<five_to_eight> ::= "V" | "VI" | "VII" | "VIII"
<nine> ::= "IX"