fork(3) download
copy 
  1. import scala.util.parsing.combinator._
  2. import scala.util.parsing.combinator.JavaTokenParsers
  3.  
  4. object Main extends App {
  5.   case class DataRecord(val doubleValue1 : Double,  val doubleValue2 : Double )
  6.  
  7.   type D = Double
  8.   type Extractor[Double] = DataRecord => Double
  9.  
  10.   object ArithParser extends JavaTokenParsers {
  11.     //arithmic expression
  12.     def arithmicExpr:       Parser[Extractor[D]] = plus
  13.     def plus:               Parser[Extractor[D]] = repsep(times, "+") ^^ { summands : List[Extractor[D]] =>
  14.       (in : DataRecord) => summands.map((e : Extractor[D]) => e(in)).foldLeft(0d)(_ + _)
  15.     }
  16.     def times:              Parser[Extractor[D]] = repsep(division, "*") ^^ { factors : List[Extractor[D]] =>
  17.       (in : DataRecord) => factors.map((e : Extractor[D]) => e(in)).foldLeft(1d)(_ * _)
  18.     }
  19.  
  20.     def division :           Parser[Extractor[D]] = rep1sep(number, "/") ^^ {divisons : List[Extractor[D]] =>
  21.       (in : DataRecord) => divisons.map((e : Extractor[D]) => e(in)).reduce(_ / _)
  22.     } | number
  23.     def number :            Parser[Extractor[D]] = fpn | intExtractor
  24.     def fpn:                Parser[Extractor[D]] = floatingPointNumber          ^^ (s => Function.const(s.toDouble)_)
  25.     def intExtractor:       Parser[Extractor[D]] = ("doubleValue1" | "doubleValue2")             ^^ {
  26.       case "doubleValue1" => _.doubleValue1
  27.       case "doubleValue2" => _.doubleValue2
  28.     }
  29.   }
  30.   val dataRecord = DataRecord(100, 75 )
  31.   val input = "doubleValue1 / 10 * 2 + doubleValue2"
  32.   println(ArithParser.parseAll(ArithParser.arithmicExpr, input).get(dataRecord)) // prints 95
  33.  
  34. }
Success #stdin #stdout 0.4s 382144KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
95.0
https://ideone.com/RzZLAA
language:
Scala (scala 2.12.8)
created:
11 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!