How to write an Scala parser for arithmetic operations including string?

Question

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

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~")"
    }

and this one for string:

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

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

blintend · Accepted Answer · 2015-06-10 07:03:54Z

1

I think you should add it to the factor alternatives:

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

answered Jun 10, 2015 at 7:03

blintend

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2 Comments

Mahsa Over a year ago

then can I extend "class Arith extends JavaTokenParsers with RegexParsers" ??? because ident extends RegexParsers and Arith class that I mentioned above extends JavaTokenParsers, to add ident I should extend the class that ident is there, like MyParsers

blintend Over a year ago

JavaTokenParsers already extends RegexParsers so you do not need to combine the two. Also, JavaTokenParsers already defines ident so you do not really need MyParsers at all.

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