// A Small Compiler for a Simple Functional Language

// (includes an external lexer and parser)

//

// call with 

//

//     scala fun.scala fact

//

//     scala fun.scala defs

//

// this will generate a .j file and run the jasmin

// assembler (installed at jvm/jasmin-2.4/jasmin.jar)

// it runs the resulting JVM file twice for timing 

// purposes.

object Compiler {

import java.io._  

import scala.util._

import scala.sys.process._

// Abstract syntax trees for the Fun language

abstract class Exp extends Serializable 

abstract class BExp extends Serializable 

abstract class Decl extends Serializable 

case class Def(name: String, args: List[String], body: Exp) extends Decl

case class Main(e: Exp) extends Decl

case class Call(name: String, args: List[Exp]) extends Exp

case class If(a: BExp, e1: Exp, e2: Exp) extends Exp

case class Write(e: Exp) extends Exp

case class Var(s: String) extends Exp

case class Num(i: Int) extends Exp

case class Aop(o: String, a1: Exp, a2: Exp) extends Exp

case class Sequence(e1: Exp, e2: Exp) extends Exp

case class Bop(o: String, a1: Exp, a2: Exp) extends BExp

// compiler - built-in functions 

// copied from http://www.ceng.metu.edu.tr/courses/ceng444/link/jvm-cpm.html

//

// for generating new labels

var counter = -1

def Fresh(x: String) = {

  counter += 1

  x ++ "_" ++ counter.toString()

}

// Abstract syntax trees for the Fun language

abstract class KExp

}

  override def toString = s"let $x = $e1 in \n$e2" 

}

    }

  }

val e = Aop("*", Aop("+", Num(1), Call("foo", List(Var("a"), Num(3)))), Num(4))

// convenient string interpolations 

// for instructions, labels and methods

import scala.language.implicitConversions

import scala.language.reflectiveCalls

implicit def sring_inters(sc: StringContext) = new {

    def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"

    def l(args: Any*): String = sc.s(args:_*) ++ ":\n"

    def m(args: Any*): String = sc.s(args:_*) ++ "\n"

}

// compile K expressions

def compile_exp(a: KExp) : String = a match {

    val if_br = Fresh("if_br")

    val else_br = Fresh("else_br")

    i"br i1 %$x, label %$if_br, label %$else_br" ++

    l"\n$if_br" ++

    l"\n$else_br" ++ 

  }

    compile_exp(a1, env) ++

    i"dup" ++

    i"invokestatic XXX/XXX/write(I)V"

  }

// compile function for declarations and main

def compile_decl(d: Decl) : String = d match {

  case Def(name, args, body) => { 

    m"define i32 @$name (${args.mkString("i32 %", ", i32 %", "")}) {" ++

    m"}\n"

  }

  case Main(body) => {

    m"define i32 @main() {" ++

    m"}\n"

  }

}

// main compiler functions

def time_needed[T](i: Int, code: => T) = {

  val start = System.nanoTime()

  for (j <- 1 to i) code

  val end = System.nanoTime()

  (end - start)/(i * 1.0e9)

}

def deserialise[T](fname: String) : Try[T] = {

  import scala.util.Using

  Using(new ObjectInputStream(new FileInputStream(fname))) {

    in => in.readObject.asInstanceOf[T]

  }

}

def compile(class_name: String) : String = {

  val ast = deserialise[List[Decl]](class_name ++ ".prs").getOrElse(Nil) 

}

/*

def compile_to_file(class_name: String) = {

  val output = compile(class_name)

  scala.tools.nsc.io.File(s"${class_name}.j").writeAll(output)

}

def compile_and_run(class_name: String) : Unit = {

  compile_to_file(class_name)

  (s"java -jar jvm/jasmin-2.4/jasmin.jar ${class_name}.j").!!

  println("Time: " + time_needed(2, (s"java ${class_name}/${class_name}").!))

}

*/

// some examples of .fun files

//compile_to_file("fact")

//compile_and_run("fact")

//compile_and_run("defs")

def main(args: Array[String]) : Unit = 

   println(compile(args(0)))

}