1 // A parser and evaluator for the while language

     1 // A parser and evaluator for the while language

     2 // 

     2 // 

     3 

     3 

     4 import scala.language.implicitConversions

     4 import scala.language.implicitConversions

     5 import scala.language.reflectiveCalls

     5 import scala.language.reflectiveCalls

     6 

     7 

     7 abstract class Parser[I <% Seq[_], T] {

     8 abstract class Parser[I <% Seq[_], T] {

     8   def parse(ts: I): Set[(T, I)]

     9   def parse(ts: I): Set[(T, I)]

     9 

    10 

    10   def parse_all(ts: I) : Set[T] =

    11   def parse_all(ts: I) : Set[T] =

    68 lazy val T: Parser[String, Int] = 

    69 lazy val T: Parser[String, Int] = 

    69   (F ~ "*" ~ T) ==> { case ((x, y), z) => x * z} || F

    70   (F ~ "*" ~ T) ==> { case ((x, y), z) => x * z} || F

    70 lazy val F: Parser[String, Int] = 

    71 lazy val F: Parser[String, Int] = 

    71   ("(" ~ E ~ ")") ==> { case ((x, y), z) => y} || NumParser

    72   ("(" ~ E ~ ")") ==> { case ((x, y), z) => y} || NumParser

    72 

    73 

    73 println(E.parse_all("1*2+3"))

    75 println(E.parse_all("1*2+3"))

    74 println(E.parse_all("1+2*3"))

    76 println(E.parse_all("1+2*3"))

    75 println(E.parse_all("1+2+3"))

    77 println(E.parse_all("1+2+3"))

    76 println(E.parse_all("1+2+3"))

    78 println(E.parse_all("1+2+3"))

    77 println(E.parse_all("1+2*3+1"))

    79 println(E.parse_all("1+2*3+1"))