如何编写用于字符串等算术运算的Scala解析器? [英] How to write an Scala parser for arithmetic operations including string?

问题描述

我正在尝试使用 Scala组合器解析进行解析和算术运算其中至少一个变量是字符串.我是scala的初学者，我喜欢它的这一功能！ 例如，我想解析:
(数字+ 2)* 4

I am trying to use Scala Combinator-Parsing to parse and arithmetic operation in which at least one of the variables is string. I am a beginner in scala and I like this feature of it! For instance I wanna parse:
(number + 2) * 4

它是解析数字(带括号的浮点数和整数)的一个很好的例子，

It has a good example of parsing numbers (float and integer with parenthesis) like:

  class Arith extends JavaTokenParsers {  
      def expr: Parser[Any] = term~rep("+"~term | "-"~term)
      def term: Parser[Any] = factor~rep("*"~factor | "/"~factor)
      def factor: Parser[Any] = floatingPointNumber | "("~expr~")"
    } 

这是一个字符串:

       object MyParsers extends RegexParsers {
        val ident: Parser[String] = """[a-zA-Z_]\w*""".r
       }

如何更改第一部分以解析数字旁边的字符串?

how can I change the first part to parse string beside numbers?

推荐答案

我认为您应该将其添加到替代因子中:

I think you should add it to the factor alternatives:

def factor: Parser[Any] = ident | floatingPointNumber | "("~expr~")"

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