import scala.language.implicitConversions    

import scala.language.reflectiveCalls 

import scala.util._

import scala.annotation.tailrec

import scala.sys.process._

def fromFile(name: String) : String = 

  io.Source.fromFile(name).mkString

abstract class Rexp 

case object NULL extends Rexp

case object EMPTY extends Rexp

case class CHAR(c: Char) extends Rexp

case class ALT(r1: Rexp, r2: Rexp) extends Rexp 

case class RANGE(cs: List[Char]) extends Rexp 

case class SEQ(r1: Rexp, r2: Rexp) extends Rexp 

case class PLUS(r: Rexp) extends Rexp 

case class STAR(r: Rexp) extends Rexp 

case class NTIMES(r: Rexp, n: Int) extends Rexp 

case class NUPTOM(r: Rexp, n: Int, m: Int) extends Rexp

object RANGE {

  def apply(s: String) : RANGE = RANGE(s.toList)

}

def NMTIMES(r: Rexp, n: Int, m: Int) = {

  if (m < n) throw new IllegalArgumentException("the number m cannot be smaller than n.")

  else NUPTOM(r, n, m - n)

}

case class NOT(r: Rexp) extends Rexp 

case class OPT(r: Rexp) extends Rexp 

// some convenience for typing in regular expressions

def charlist2rexp(s : List[Char]) : Rexp = s match {

  case Nil => EMPTY

  case c::Nil => CHAR(c)

  case c::s => SEQ(CHAR(c), charlist2rexp(s))

}

implicit def string2rexp(s : String) : Rexp = charlist2rexp(s.toList)

implicit def RexpOps (r: Rexp) = new {

  def | (s: Rexp) = ALT(r, s)

  def % = STAR(r)

  def ~ (s: Rexp) = SEQ(r, s)

}

implicit def stringOps (s: String) = new {

  def | (r: Rexp) = ALT(s, r)

  def | (r: String) = ALT(s, r)

  def % = STAR(s)

  def ~ (r: Rexp) = SEQ(s, r)

  def ~ (r: String) = SEQ(s, r)

}

// nullable function: tests whether the regular 

// expression can recognise the empty string

def nullable (r: Rexp) : Boolean = r match {

  case NULL => false

  case EMPTY => true

  case CHAR(_) => false

  case ALT(r1, r2) => nullable(r1) || nullable(r2)

  case SEQ(r1, r2) => nullable(r1) && nullable(r2)

  case STAR(_) => true

  case PLUS(r) => nullable(r)

  case NTIMES(r, i) => if (i == 0) true else nullable(r)

  case NUPTOM(r, i, j) => if (i == 0) true else nullable(r)

  case RANGE(_) => false

  case NOT(r) => !(nullable(r))

  case OPT(_) => true

}

// derivative of a regular expression w.r.t. a character

def der (c: Char, r: Rexp) : Rexp = r match {

  case NULL => NULL

  case EMPTY => NULL

  case CHAR(d) => if (c == d) EMPTY else NULL

  case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))

  case SEQ(r1, r2) => 

    if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))

    else SEQ(der(c, r1), r2)

  case STAR(r) => SEQ(der(c, r), STAR(r))

  case PLUS(r) => SEQ(der(c, r), STAR(r))

  case NTIMES(r, i) => 

    if (i == 0) NULL else der(c, SEQ(r, NTIMES(r, i - 1)))

  case NUPTOM(r, i, j) =>

    if (i == 0 && j == 0) NULL else 

    if (i == 0) ALT(der(c, NTIMES(r, j)), der(c, NUPTOM(r, 0, j - 1)))

    else der(c, SEQ(r, NUPTOM(r, i - 1, j)))

  case RANGE(cs) => if (cs contains c) EMPTY else NULL

  case NOT(r) => NOT(der (c, r))

  case OPT(r) => der(c, r)

}

def zeroable (r: Rexp) : Boolean = r match {

  case NULL => true

  case EMPTY => false

  case CHAR(_) => false

  case ALT(r1, r2) => zeroable(r1) && zeroable(r2)

  case SEQ(r1, r2) => zeroable(r1) || zeroable(r2)

  case STAR(_) => false

  case PLUS(r) => zeroable(r)

  case NTIMES(r, i) => if (i == 0) false else zeroable(r)

  case NUPTOM(r, i, j) => if (i == 0) false else zeroable(r)

  case RANGE(_) => false

  case NOT(r) => !(zeroable(r))     // bug: incorrect definition for NOT

  case OPT(_) => false

}

// derivative w.r.t. a string (iterates der)

def ders (s: List[Char], r: Rexp) : Rexp = s match {

  case Nil => r

  case c::s => ders(s, der(c, r))

}

// regular expressions for the While language

val SYM = RANGE("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_".toList)

val DIGIT = RANGE("0123456789".toList)

val ID = SYM ~ (SYM | DIGIT).% 

val NUM = PLUS(DIGIT)

val KEYWORD : Rexp = "if" | "then" | "else" | "write" | "def"

val SEMI: Rexp = ";"

val COMMA: Rexp = ","

val OP: Rexp = ":=" | "==" | "-" | "+" | "*" | "!=" | "<=" | "=>" | "<" | ">" | "%" | "=" | "/"

val WHITESPACE = PLUS(" " | "\n" | "\t")

val RPAREN: Rexp = ")"

val LPAREN: Rexp = "("

val ALL = SYM | DIGIT | OP | " " | ":" | ";" | "\"" | "=" | "," | "(" | ")"

val ALL2 = ALL | "\n"

//val COMMENT2 = ("/*" ~ NOT(ALL.% ~ "*/" ~ ALL.%) ~ "*/")

val COMMENT = ("/*" ~ ALL2.% ~ "*/") | ("//" ~ ALL.% ~ "\n")

// token for While language

abstract class Token

case object T_WHITESPACE extends Token

case object T_SEMI extends Token

case object T_COMMA extends Token

case object T_LPAREN extends Token

case object T_RPAREN extends Token

case object T_COMMENT extends Token

case class T_ID(s: String) extends Token

case class T_OP(s: String) extends Token

case class T_NUM(s: String) extends Token

case class T_KWD(s: String) extends Token

case class T_ERR(s: String) extends Token // special error token

type TokenFun = String => Token

type LexRules = List[(Rexp, TokenFun)]

val While_lexing_rules: LexRules = 

  List((KEYWORD, (s) => T_KWD(s)),

       (ID, (s) => T_ID(s)),

       (COMMENT, (s) => T_COMMENT),

       (OP, (s) => T_OP(s)),

       (NUM, (s) => T_NUM(s)),

       (SEMI, (s) => T_SEMI),

       (COMMA, (s) => T_COMMA),

       (LPAREN, (s) => T_LPAREN),

       (RPAREN, (s) => T_RPAREN),

       (WHITESPACE, (s) => T_WHITESPACE))

// calculates derivatives until all of them are zeroable

@tailrec

def munch(s: List[Char], 

          pos: Int, 

          rs: LexRules, 

          last: Option[(Int, TokenFun)]): Option[(Int, TokenFun)] = {

  rs match {

  case Nil => last

  case rs if (s.length <= pos) => last

  case rs => {

    val ders = rs.map({case (r, tf) => (der(s(pos), r), tf)})

    val rs_nzero = ders.filterNot({case (r, _) => zeroable(r)})

    val rs_nulls = ders.filter({case (r, _) => nullable(r)})

    val new_last = if (rs_nulls != Nil) Some((pos, rs_nulls.head._2)) else last

    munch(s, 1 + pos, rs_nzero, new_last)

  }

}}

// iterates the munching function and returns a Token list

def tokenize(s: String, rs: LexRules) : List[Token] = munch(s.toList, 0, rs, None) match {

  case None if (s == "") => Nil

  case None => List(T_ERR(s"Lexing error: $s"))

  case Some((n, tf)) => {

    val (head, tail) = s.splitAt(n + 1)

    tf(head)::tokenize(tail, rs)

  }

}

def tokenizer(s:String) : List[Token] = 

  tokenize(s, While_lexing_rules).filter {

    case T_ERR(s) => { println(s); sys.exit(-1) }

    case T_WHITESPACE => false

    case T_COMMENT => false

    case _ => true

  } 

// Parser - Abstract syntax trees

abstract class Exp

abstract class BExp 

abstract class Decl

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 Sequ(e1: Exp, e2: Exp) extends Exp

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

// calculating the maximal needed stack size

def max_stack_exp(e: Exp): Int = e match {

  case Call(_, args) => args.map(max_stack_exp).sum

  case If(a, e1, e2) => max_stack_bexp(a) + (List(max_stack_exp(e1), max_stack_exp(e2)).max)

  case Write(e) => max_stack_exp(e) + 1

  case Var(_) => 1

  case Num(_) => 1

  case Aop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)

  case Sequ(e1, e2) => List(max_stack_exp(e1), max_stack_exp(e2)).max

}

def max_stack_bexp(e: BExp): Int = e match {

  case Bop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)

}

// Parser combinators

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

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

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

    for ((head, tail) <- parse(ts); if (tail.isEmpty)) yield head

  def parse_single(ts: I) : T = parse_all(ts).toList match {

    case List(t) => t

    case _ => { println ("Parse Error") ; sys.exit(-1) }

  }

}

class SeqParser[I <% Seq[_], T, S](p: => Parser[I, T], q: => Parser[I, S]) extends Parser[I, (T, S)] {

  def parse(sb: I) = 

    for ((head1, tail1) <- p.parse(sb); 

         (head2, tail2) <- q.parse(tail1)) yield ((head1, head2), tail2)

}

class AltParser[I <% Seq[_], T](p: => Parser[I, T], q: => Parser[I, T]) extends Parser[I, T] {

  def parse(sb: I) = p.parse(sb) ++ q.parse(sb)   

}

class FunParser[I <% Seq[_], T, S](p: => Parser[I, T], f: T => S) extends Parser[I, S] {

  def parse(sb: I) = 

    for ((head, tail) <- p.parse(sb)) yield (f(head), tail)

}

case class TokParser(tok: Token) extends Parser[List[Token], Token] {

  def parse(ts: List[Token]) = ts match {

    case t::ts if (t == tok) => Set((t, ts)) 

    case _ => Set ()

  }

}

implicit def token2tparser(t: Token) = TokParser(t)

case object NumParser extends Parser[List[Token], Int] {

  def parse(ts: List[Token]) = ts match {

    case T_NUM(s)::ts => Set((s.toInt, ts)) 

    case _ => Set ()

  }

}

case object IdParser extends Parser[List[Token], String] {

  def parse(ts: List[Token]) = ts match {

    case T_ID(s)::ts => Set((s, ts)) 

    case _ => Set ()

  }

}

implicit def ParserOps[I<% Seq[_], T](p: Parser[I, T]) = new {

  def || (q : => Parser[I, T]) = new AltParser[I, T](p, q)

  def ==>[S] (f: => T => S) = new FunParser[I, T, S](p, f)

  def ~[S] (q : => Parser[I, S]) = new SeqParser[I, T, S](p, q)

}

implicit def TokOps(t: Token) = new {

  def || (q : => Parser[List[Token], Token]) = new AltParser[List[Token], Token](t, q)

  def ==>[S] (f: => Token => S) = new FunParser[List[Token], Token, S](t, f)

  def ~[S](q : => Parser[List[Token], S]) = new SeqParser[List[Token], Token, S](t, q)

}

def ListParser[I <% Seq[_], T, S](p: => Parser[I, T], q: => Parser[I, S]): Parser[I, List[T]] = {

  (p ~ q ~ ListParser(p, q)) ==> { case ((x, y), z) => x :: z : List[T] } ||

  (p ==> ((s) => List(s)))

}

// expressions

lazy val Exp: Parser[List[Token], Exp] = 

  (T_KWD("if") ~ BExp ~ T_KWD("then") ~ Exp ~ T_KWD("else") ~ Exp) ==>

    { case (((((x, y), z), u), v), w) => If(y, u, w): Exp } ||

  (M ~ T_SEMI ~ Exp) ==> { case ((x, y), z) => Sequ(x, z): Exp } || M

lazy val M: Parser[List[Token], Exp] =

  (T_KWD("write") ~ L) ==> { case (x, y) => Write(y): Exp } || L

lazy val L: Parser[List[Token], Exp] = 

  (T ~ T_OP("+") ~ Exp) ==> { case ((x, y), z) => Aop("+", x, z): Exp } ||

  (T ~ T_OP("-") ~ Exp) ==> { case ((x, y), z) => Aop("-", x, z): Exp } || T  

lazy val T: Parser[List[Token], Exp] = 

  (F ~ T_OP("*") ~ T) ==> { case ((x, y), z) => Aop("*", x, z): Exp } || 

  (F ~ T_OP("/") ~ T) ==> { case ((x, y), z) => Aop("/", x, z): Exp } || 

  (F ~ T_OP("%") ~ T) ==> { case ((x, y), z) => Aop("%", x, z): Exp } || F

lazy val F: Parser[List[Token], Exp] = 

  (IdParser ~ T_LPAREN ~ ListParser(Exp, T_COMMA) ~ T_RPAREN) ==> 

    { case (((x, y), z), w) => Call(x, z): Exp } ||

  (T_LPAREN ~ Exp ~ T_RPAREN) ==> { case ((x, y), z) => y: Exp } || 

  IdParser ==> { case x => Var(x): Exp } || 

  NumParser ==> { case x => Num(x): Exp }

// boolean expressions

lazy val BExp: Parser[List[Token], BExp] = 

  (Exp ~ T_OP("==") ~ Exp) ==> { case ((x, y), z) => Bop("==", x, z): BExp } || 

  (Exp ~ T_OP("!=") ~ Exp) ==> { case ((x, y), z) => Bop("!=", x, z): BExp } || 

  (Exp ~ T_OP("<") ~ Exp) ==> { case ((x, y), z) => Bop("<", x, z): BExp } || 

  (Exp ~ T_OP(">") ~ Exp) ==> { case ((x, y), z) => Bop("<", z, x): BExp } || 

  (Exp ~ T_OP("<=") ~ Exp) ==> { case ((x, y), z) => Bop("<=", x, z): BExp } || 

  (Exp ~ T_OP("=>") ~ Exp) ==> { case ((x, y), z) => Bop("<=", z, x): BExp }  

lazy val Defn: Parser[List[Token], Decl] =

   (T_KWD("def") ~ IdParser ~ T_LPAREN ~ ListParser(IdParser, T_COMMA) ~ T_RPAREN ~ T_OP("=") ~ Exp) ==>

     { case ((((((x, y), z), w), u), v), r) => Def(y, w, r): Decl }

lazy val Prog: Parser[List[Token], List[Decl]] =

  (Defn ~ T_SEMI ~ Prog) ==> { case ((x, y), z) => x :: z : List[Decl] } ||

  (Exp ==> ((s) => List(Main(s)) : List[Decl]))

// compiler - built-in functions 

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

//

val library = """

.class public XXX.XXX

.super java/lang/Object

.method public <init>()V

        aload_0

        invokenonvirtual java/lang/Object/<init>()V

        return

.end method

.method public static write(I)V 

        .limit locals 5 

        .limit stack 5 

        iload 0 

        getstatic java/lang/System/out Ljava/io/PrintStream; 

        swap 

        invokevirtual java/io/PrintStream/println(I)V 

        return 

.end method

"""

// for generating new labels

var counter = -1

def Fresh(x: String) = {

  counter += 1

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

}

type Mem = Map[String, Int]

type Instrs = List[String]

def compile_expT(a: Exp, env : Mem, name: String) : Instrs = a match {

  case Num(i) => List("ldc " + i.toString + "\n")

  case Var(s) => List("iload " + env(s).toString + "\n")

  case Aop("+", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("iadd\n")

  case Aop("-", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("isub\n")

  case Aop("*", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("imul\n")

  case Aop("/", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("idiv\n")

  case Aop("%", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("irem\n")

  case If(b, a1, a2) => {

    val if_else = Fresh("If_else")

    val if_end = Fresh("If_end")

    compile_bexpT(b, env, if_else) ++

    compile_expT(a1, env, name) ++

    List("goto " + if_end + "\n") ++

    List("\n" + if_else + ":\n\n") ++

    compile_expT(a2, env, name) ++

    List("\n" + if_end + ":\n\n")

  }

  case Call(n, args) => if (name == n) { 

    val stores = args.zipWithIndex.map { case (x, y) => "istore " + y.toString + "\n" } 

    args.flatMap(a => compile_expT(a, env, "")) ++

    stores.reverse ++ 

    List ("goto " + n + "_Start\n") 

  } else {

    val is = "I" * args.length

    args.flatMap(a => compile_expT(a, env, "")) ++

    List ("invokestatic XXX/XXX/" + n + "(" + is + ")I\n")

  }

  case Sequ(a1, a2) => {

    compile_expT(a1, env, "") ++ List("pop\n") ++ compile_expT(a2, env, name)

  }

  case Write(a1) => {

    compile_expT(a1, env, "") ++

    List("dup\n",

         "invokestatic XXX/XXX/write(I)V\n")

  }

}

def compile_bexpT(b: BExp, env : Mem, jmp: String) : Instrs = b match {

  case Bop("==", a1, a2) => 

    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("if_icmpne " + jmp + "\n")

  case Bop("!=", a1, a2) => 

    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("if_icmpeq " + jmp + "\n")

  case Bop("<", a1, a2) => 

    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("if_icmpge " + jmp + "\n")

  case Bop("<=", a1, a2) => 

    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ List("if_icmpgt " + jmp + "\n")

}

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

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

    val env = args.zipWithIndex.toMap

    val is = "I" * args.length

    List(".method public static " + name + "(" + is + ")I \n",

         ".limit locals " + args.length.toString + "\n",

         ".limit stack " + (1 + max_stack_exp(a)).toString + "\n",

         name + "_Start:\n") ++   

    compile_expT(a, env, name) ++

    List("ireturn\n",

         ".end method \n\n")

  }

  case Main(a) => {

    List(".method public static main([Ljava/lang/String;)V\n",

         ".limit locals 200\n",

         ".limit stack 200\n") ++

    compile_expT(a, Map(), "") ++

    List("invokestatic XXX/XXX/write(I)V\n",

         "return\n",

         ".end method\n")

  }

}

def compile(class_name: String, input: String) : String = {

  val tks = tokenizer(input)

  //println(Prog.parse(tks))

  val ast = Prog.parse_single(tks)

  val instructions = ast.flatMap(compile_decl).mkString

  (library + instructions).replaceAllLiterally("XXX", class_name)

}

def compile_file(file_name: String) = {

  val class_name = file_name.split('.')(0)

  val output = compile(class_name, fromFile(file_name))

  val fw = new java.io.FileWriter(class_name + ".j") 

  fw.write(output) 

  fw.close()

}

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 compile_run(file_name: String) : Unit = {

  val class_name = file_name.split('.')(0)

  compile_file(file_name)

  val test = ("java -jar jvm/jasmin-2.4/jasmin.jar " + class_name + ".j").!!

  println("Time: " + time_needed(2, ("java " + class_name + "/" + class_name).!))

}

//examples

compile_run("defs.rec")

//compile_run("fact.rec")

// a problem with the parser 

val text = "(((((1)))))"

val tokens = tokenizer(text)

println(tokens)

val ast = Prog.parse_single(tokens)

println(ast)

Exp.parse_single(tokens)

val text = "((((1))))"

val tokens = tokenizer(text)

println(tokens)

Exp.parse(tokens)