1 import scala.language.implicitConversions

     4 import scala.language.implicitConversions

     2 import scala.language.reflectiveCalls

     5 import scala.language.reflectiveCalls

     3 

     6 

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

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

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

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

   123    IdParser ==> Var || 

   126    IdParser ==> Var || 

   124    NumParser ==> Num)

   127    NumParser ==> Num)

   125 

   128 

   126 // boolean expressions

   129 // boolean expressions

   127 lazy val BExp: Parser[String, BExp] = 

   130 lazy val BExp: Parser[String, BExp] = 

   134    ("(" ~ BExp ~ ")") ==> { case ((x, y), z) => y})

   137    ("(" ~ BExp ~ ")") ==> { case ((x, y), z) => y})

   135 

   138 

   136 lazy val Stmt: Parser[String, Stmt] =

   139 lazy val Stmt: Parser[String, Stmt] =

   137   (("skip" ==> ((_) => Skip: Stmt)) ||

   140   (("skip" ==> ((_) => Skip: Stmt)) ||

   138    (IdParser ~ ":=" ~ AExp) ==> { case ((x, y), z) => Assign(x, z): Stmt } ||

   141    (IdParser ~ ":=" ~ AExp) ==> { case ((x, y), z) => Assign(x, z): Stmt } ||

   147 lazy val Block: Parser[String, Block] =

   150 lazy val Block: Parser[String, Block] =

   148   (("{" ~ Stmts ~ "}") ==> { case ((x, y), z) => y} || 

   151   (("{" ~ Stmts ~ "}") ==> { case ((x, y), z) => y} || 

   149    (Stmt ==> ((s) => List(s))))

   152    (Stmt ==> ((s) => List(s))))

   150 

   153 

   151 

   154 

   153 Block.parse_all("{x:=5;y:=8}")

   156 Block.parse_all("{x:=5;y:=8}")

   154 Block.parse_all("if(false)then{x:=5}else{x:=10}")

   157 Block.parse_all("if(false)then{x:=5}else{x:=10}")

   155 

   158 

   156 val fib = """{n:=10;minus1:=0;minus2:=1;temp:=0;while(n>0)do{temp:=minus2;minus2:=minus1+minus2;minus1:=temp;n:=n-1};result:=minus2}"""

   159 val fib = """{n:=10;minus1:=0;minus2:=1;temp:=0;while(n>0)do{temp:=minus2;minus2:=minus1+minus2;minus1:=temp;n:=n-1};result:=minus2}"""

   157 

   160 

   191   case s::bl => eval_bl(bl, eval_stmt(s, env))

   194   case s::bl => eval_bl(bl, eval_stmt(s, env))

   192 }

   195 }

   193 

   196 

   194 def eval(bl: Block) : Env = eval_bl(bl, Map())

   197 def eval(bl: Block) : Env = eval_bl(bl, Map())

   195 

   198