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VladNitu

ObjectVlad

VladNitu
Apr 2nd, 2023
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  1. import Library._
  2. import Parser._
  3. import Untyped._
  4.  
  5. case class NotImplementedException(s: String) extends RuntimeException(s)
  6.         case class DesugarOpInvalidExcep(s: String) extends DesugarException(s)
  7.         case class InterpOpInvalidExcep(s: String) extends InterpException(s)
  8.  
  9.         object Desugar {
  10.  
  11.         val ZCombinator =
  12.         """
  13.  (lambda (f)
  14.    ((lambda (y)
  15.       (y y))
  16.     (lambda (z)
  17.       (f (lambda (x)
  18.            ((z z) x))))))
  19.  """
  20.  
  21.  
  22.         def desugarList (l: List[ExprExt]): ExprC = l match {
  23.         case h :: t => ConsC(desugar(h), desugarList(t))
  24.         case _ => NilC()
  25.         }
  26.  
  27.         /** Binds all the values before processing the `body`, so that all the names are in scope */
  28.         def solveLetBinds(binds: List[LetBindExt], body: ExprExt): ExprC = binds match {
  29.         case LetBindExt(name, value) :: t => SeqC(SetC(name, desugar(value)), solveLetBinds(t, body))
  30.         case Nil => desugar(body)  // No more bindings to declare
  31.         }
  32.  
  33.         def desugarMethods(methods: List[MethodExt]): ExprC = methods match {
  34.         case Nil => UndefinedC()
  35.         case meth :: t => IfC(EqStrC(IdC("msg"), StringC(meth.name)), FdC("self" :: meth.args, desugar(meth.body)), desugarMethods(t))
  36.         }
  37.  
  38.         def desugarMethodsDelegate(methods: List[MethodExt]): ExprC = methods match {
  39.         case Nil => AppC(IdC("method"), List(IdC("msg")))
  40.         case meth :: t => IfC(EqStrC(IdC("msg"), StringC(meth.name)), FdC("self" :: meth.args, desugar(meth.body)), desugarMethodsDelegate(t))
  41.         }
  42.        
  43.         // OBJECTS
  44.  
  45.         def solveLetBindsObjects(binds: List[FieldExt], body: ExprC): ExprC = binds match {
  46.         case FieldExt(name, value) :: t => SeqC(SetC(name, desugar(value)), solveLetBindsObjects(t, body))
  47.         case Nil => body  // No more bindings to declare
  48.         }
  49.  
  50.         def desugarDoSeq (l: List[ExprExt]): ExprC = l match {
  51.         case h :: Nil => desugar(h)
  52.         case h :: t :: Nil => SeqC(desugar(h), desugar(t))
  53.         case h :: t => SeqC(desugar(h), desugarDoSeq(t))
  54.         }
  55.  
  56.         def desugar(e: ExprExt): ExprC = e match {
  57.  
  58.         case NilExt() => NilC()
  59.         case TrueExt() => TrueC()
  60.         case FalseExt() => FalseC()
  61.         case NumExt(x) => NumC(x)
  62.         case BinOpExt(sym, l, r) => sym match {
  63.         case "+" => PlusC(desugar(l), desugar(r))
  64.         case "*" => MultC(desugar(l), desugar(r))
  65.         case "-" => PlusC(desugar(l), MultC(NumC(-1), desugar(r)))
  66.  
  67.         case "and" => IfC(desugar(l), desugar(r), FalseC())
  68.         case "or" => IfC(desugar(l), TrueC(), desugar(r))
  69.  
  70.         case "num=" => EqNumC(desugar(l), desugar(r))
  71.         case "num<" => LtC(desugar(l), desugar(r))
  72.         case "num>" => LtC(MultC(NumC(-1), desugar(l)), MultC(NumC(-1), desugar(r))) // In interp, evaluate `l` first while also use `LtC` => Multiply eq. by (-1) on both sides
  73.         case "cons" => ConsC(desugar(l), desugar(r))
  74.  
  75.         case "setbox" => SetboxC(desugar(l), desugar(r))
  76.         case "seq" => SeqC(desugar(l), desugar(r))
  77.  
  78.         // NEW
  79.         case "str=" => EqStrC(desugar(l), desugar(r))
  80.         case "str++" => ConcStrC(desugar(l), desugar(r))
  81.  
  82.  
  83.         case _ => throw new DesugarOpInvalidExcep(s"Cannot desugarize this binary operator: $sym")
  84.         }
  85.  
  86.         case UnOpExt(sym, l) => sym match {
  87.         case "-" => MultC(NumC(-1), desugar(l))
  88.         case "not" => IfC(desugar(l), FalseC(), TrueC())
  89.         case "head" => HeadC(desugar(l))
  90.         case "tail" => TailC(desugar(l))
  91.         case "is-nil" => IsNilC(desugar(l))
  92.         case "is-list" => IsListC(desugar(l))
  93.  
  94.         // Newly added unOps: `box`, `unbox`
  95.         case "box" => BoxC(desugar(l))
  96.         case "unbox" => UnboxC(desugar(l))
  97.  
  98.         case _ => throw new DesugarOpInvalidExcep("Cannot desugarize this unary operator: " + sym);
  99.         }
  100.         case ListExt(l) => l match { // Alternative: ConsC(desugar(h), desugar(ListExt(t))) // !!: generative recursion;
  101.         case h :: t => desugarList(l)
  102.         case _ => NilC()
  103.         }
  104.  
  105.         case IfExt(c, t, e) => IfC(desugar(c), desugar(t), desugar(e))
  106.  
  107.         case AppExt(f, args) => AppC(desugar(f), args.map(arg => desugar(arg)))
  108.  
  109.         case IdExt(c) => IdC(c)
  110.  
  111.         case FdExt(params, body) => FdC(params, desugar(body))
  112.  
  113.         case LetExt(binds, body) => AppC(
  114.         FdC(binds.map(bind => bind.name), desugar(body)),
  115.         binds.map(bind => desugar(bind.value))
  116.         )
  117.         case SetExt(id, e) => SetC(id, desugar(e))
  118.  
  119.         // Make use of Z_Combinator from Lecture Notes (!);
  120.         // Desugar RecLamExt as a AppC(ZComb, FdC(List(name), FdC(List(param)), body)) <=> Application of ZComb function that takes as a parameter the body of actual function
  121.         case RecLamExt(name, param, body) => AppC (
  122.         desugar(parse(ZCombinator)),
  123.         List(FdC(List(name), FdC(List(param), desugar(body))))
  124.         )
  125.  
  126.         // Newly added: `LetRecExt`, which makes use of `LetBindExt`
  127.         // Desugar `let-rec` into `AppC`; ALTERNATIVE - desugar `let-rec` into `let`, but this would imply generative recursion
  128.         // 2 pass algorithm:
  129.         // 1. Scan bindings; Create bindings for all names in `let-rec` w/ `UninitializedC`
  130.         // 2. Rescan when evaluating (in interp) and update the bindings' values accordingly
  131.         case LetRecExt(binds, body) => AppC(
  132.         FdC(binds.map(bind => bind.name), solveLetBinds(binds, body)),
  133.         binds.map(bind => UninitializedC()) // Allow `indirect recursion`
  134.         )
  135.  
  136.         // NEW
  137.         case StringExt(str) => StringC(str)
  138.  
  139.         case ObjectExt(fields: List[FieldExt], methods: List[MethodExt]) => {
  140.  
  141.         if (fields.size == 0) throw new DesugarOpInvalidExcep("Objects must have at least one filed")
  142.  
  143.         val body = FdC(List("msg"), desugarMethods(methods))
  144.  
  145.         AppC ( // LetRecExt desugar
  146.         FdC(fields.map(bind => bind.name), solveLetBindsObjects(fields, body)),
  147.         fields.map(bind => UninitializedC())
  148.         )
  149.         }
  150.  
  151.  
  152.         case ObjectDelExt(del: ExprExt, fields: List[FieldExt], methods: List[MethodExt]) => {
  153.         // IDEA: Parametrize all methods by `self`
  154.  
  155.         val delegate = desugar(del)
  156.  
  157.         val body = FdC(List("msg"), desugarMethodsDelegate(methods))
  158.  
  159.         AppC ( // LetRecExt desugar
  160.         FdC("method" :: fields.map(bind => bind.name), solveLetBindsObjects(fields, body)),
  161.         delegate :: fields.map(bind => UninitializedC())
  162.         )
  163.  
  164.         }
  165.  
  166.  
  167.         case MsgExt(recvr: ExprExt, msg: String, args: List[ExprExt]) => {
  168.         val initBody = AppC(AppC(IdC("self"), List(StringC(msg))), IdC("self") :: args.map(desugar))
  169.         AppC(FdC(List("self"), initBody), List(desugar(recvr)))
  170.         }
  171.  
  172.         case DoSeqExt(expr: List[ExprExt]) => {
  173.         // Parser ensures the following cond:
  174.         //  if (expr.size < 1) throw new DesugarOpInvalidExcep("do-seq expressions should always have at least one subexpression")
  175.         if (expr.size == 1)
  176.         desugar(expr(0))
  177.         else
  178.         desugarDoSeq(expr)
  179.         }
  180.  
  181.  
  182.         }
  183.         }
  184.  
  185.         object Interp {
  186.         type Store = List[Cell]
  187.         type PointerEnvironment = List[Pointer]
  188.  
  189.         // Do not remove this method. We use this for grading.
  190.         def interp(e: ExprC): Value = interp(e, Nil, Nil)._1
  191.  
  192.         // Helper methods from assignment "Manipulating Stores"
  193.  
  194.         def lookup(name: String, nv: PointerEnvironment): Int = nv match {
  195.         case Nil => throw new InterpOpInvalidExcep("Identifier not found")
  196.         case Pointer(_name, location) :: t if _name == name => location
  197.         case h :: t => lookup(name, t)
  198.         }
  199.  
  200.         def update(loc: Int, st: Store, v: Value): Store = st match {
  201.         case Nil => throw new InterpOpInvalidExcep("Cell location not found")
  202.         case Cell(location, value) :: t if location == loc => Cell(loc, v) :: t
  203.         case h :: t => h :: update(loc, t, v)
  204.         }
  205.  
  206.         def fetch(loc: Int, st: Store): Value = st match {
  207.         case Nil => throw new InterpOpInvalidExcep("Cell location not found")
  208.         case Cell(location, value) :: t if location == loc => value
  209.         case h :: t => fetch(loc, t)
  210.         }
  211.  
  212.         def newLoc(store: Store): Int = store.length
  213.  
  214.         def extendStore(c: Cell, st: Store): Store = c :: st
  215.  
  216.         def interpArgs(args: List[ExprC], nv: PointerEnvironment, st1: Store): (List[Value], Store) = args match {
  217.         case Nil => (Nil, st1) // base case -> Empty list in current environment; later on prepend to List[Value]s
  218.         case arg :: t => {
  219.         val (v, st2): (Value, Store) = interp(arg, nv, st1)
  220.         val (values, st3) = interpArgs(t, nv, st2)
  221.         (v :: values, st3)
  222.         }
  223.         }
  224.  
  225.         def extendEnvStore(params: List[String], interpretedArgs: List[Value], nv: PointerEnvironment, st1: Store): (PointerEnvironment, Store)
  226.         =  (params, interpretedArgs) match { // REMEMBER: params.length == interpretedArgs.length
  227.         case (Nil, Nil) => (nv, st1)
  228.         case (param :: t_params, arg :: t_args) => {
  229.         val newLocation = newLoc(st1)
  230.         val newPointer: Pointer = Pointer(param, newLocation)
  231.         val extendedNv: PointerEnvironment = newPointer :: nv
  232.         val extendedStore: Store = extendStore(Cell(newLocation, arg), st1)// Extend store by prepending new values to previous Store
  233.         extendEnvStore(t_params, t_args, extendedNv, extendedStore)
  234.         }
  235.         }
  236.  
  237.         def interp(e: ExprC, nv: PointerEnvironment, st1: Store): (Value, Store) = e match {
  238.  
  239.         case NilC() => (NilV(), st1)
  240.         case TrueC() => (BoolV(true), st1)
  241.         case FalseC() => (BoolV(false), st1)
  242.         case NumC(x) => (NumV(x), st1)
  243.  
  244.         case PlusC(l, r) => {
  245.  
  246.         val (v1, st2) = interp(l, nv, st1)
  247.         val (v2, st3) = interp(r, nv, st2)
  248.  
  249.         (v1, v2) match {
  250.         case (NumV(a), NumV(b)) => (NumV(a + b), st3)
  251.         case _ => throw new InterpOpInvalidExcep("These operations are only defined for numbers")
  252.         }
  253.         }
  254.  
  255.         case MultC(l, r) => {
  256.  
  257.         val (v1, st2) = interp(l, nv, st1)
  258.         val (v2, st3) = interp(r, nv, st2)
  259.  
  260.         (v1, v2) match {
  261.         case (NumV(a), NumV(b)) => (NumV(a * b), st3)
  262.         case _ => throw new InterpOpInvalidExcep("These operations are only defined for numbers")
  263.         }
  264.         }
  265.  
  266.         case EqNumC(l, r) => {
  267.  
  268.         val (v1, st2) = interp(l, nv, st1)
  269.         val (v2, st3) = interp(r, nv, st2)
  270.  
  271.         (v1, v2) match {
  272.         case (NumV(a), NumV(b)) => if (a == b) (BoolV(true), st3) else (BoolV(false), st3)
  273.         case _ => throw new InterpOpInvalidExcep("These operations are only defined for numbers")
  274.         }
  275.         }
  276.  
  277.         case LtC(l, r) => {
  278.  
  279.         val (v1, st2) = interp(l, nv, st1)
  280.         val (v2, st3) = interp(r, nv, st2)
  281.  
  282.         (v1, v2) match {
  283.         case (NumV(a), NumV(b)) => if (a < b) (BoolV(true), st3) else (BoolV(false), st3)
  284.         case _ => throw new InterpOpInvalidExcep("These operations are only defined for numbers")
  285.         }
  286.         }
  287.  
  288.  
  289.         case ConsC(l, r) => {
  290.         val (v1, st2) = interp(l, nv, st1)
  291.         val (v2, st3) = interp(r, nv, st2)
  292.  
  293.         (ConsV(v1, v2), st3)
  294.         }
  295.  
  296.  
  297.         case HeadC(e) => interp(e, nv, st1) match {
  298.         case (ConsV(h, _), st2) => (h, st2)
  299.         case _ => throw new InterpOpInvalidExcep("HEAD not allowed")
  300.         }
  301.  
  302.         case TailC(e) => interp(e, nv, st1) match {
  303.         case (ConsV(_, t), st2) => (t, st2)
  304.         case _ => throw new InterpOpInvalidExcep("TAIL not allowed")
  305.         }
  306.  
  307.         case IsNilC(e) => interp(e, nv, st1) match {
  308.         case (NilV(), st2) => (BoolV(true), st2)
  309.         case (ConsV(_, _), st2) => (BoolV(false), st2)
  310.         case _ => throw new InterpOpInvalidExcep("isNil not allowed")
  311.         }
  312.  
  313.         case IsListC(e) => {
  314.         val (v1, st2) = interp(e, nv, st1)
  315.         v1 match {
  316.         case NilV() | ConsV(_, _) => (BoolV(true), st2)
  317.         case _ => (BoolV(false), st2)
  318.         }
  319.         }
  320.  
  321.         case IfC(e, e1, e2) => interp(e, nv, st1) match {
  322.         case (BoolV(true), st2) => interp(e1, nv, st2)
  323.         case (BoolV(false), st2) => interp(e2, nv, st2)
  324.         case _ => throw new InterpOpInvalidExcep(s"IF not allowed as $e does not evaluate to Boolean")
  325.         }
  326.  
  327.         case UninitializedC() => (UninitializedV(), st1)
  328.  
  329.         case AppC(f, args) => interp(f, nv, st1) match {
  330.         case (PointerClosV(f@FdC(params, body), env), st2) => {
  331.         //Alternative - val (interpretedArgs, st3) = interpArgsAlt(args, nv, st2, Nil)
  332.         val (interpretedArgs, st3) = interpArgs(args, nv, st2)
  333.         val (envNew, stNew): (PointerEnvironment, Store) = extendEnvStore(params, interpretedArgs, env, st3)
  334.         interp(body, envNew, stNew)
  335.         }
  336.         //case FdC(params, body) if (params.size != args.size) => throw new InterpOpInvalidExcep("Error thrown in case AppC/ClosV - Number of `params` and `args` do not match")
  337.         case _ => throw new InterpOpInvalidExcep("Error thrown in case AppC/ClosV - `f` IS NOT a function definition")
  338.         }
  339.  
  340.         case IdC(s) =>  (fetch(lookup(s, nv), st1), st1)
  341.  
  342.         case fdc@FdC(params, body) => (PointerClosV(fdc, nv), st1)
  343.  
  344.         case BoxC(v) => {
  345.         val (v1, st2) = interp(v, nv, st1)
  346.         val newLocation = newLoc(st2)
  347.         (BoxV(newLocation), extendStore(Cell(newLocation, v1), st2))
  348.         }
  349.  
  350.         case UnboxC(b) => {
  351.         val (b1, st2) = interp(b, nv, st1)
  352.         b1 match {
  353.         case BoxV(loc) => (fetch(loc, st2), st2)
  354.         case _ => throw new InterpOpInvalidExcep(s"Cannot unbox $b1, as it is not a box")
  355.         }
  356.         }
  357.  
  358.         case SetboxC(b, c) => { // REMEMBER - left->right evaluation order
  359.  
  360.         val (b1, st2) = interp(b, nv, st1)
  361.         val (b2, st3) = interp(c, nv, st2)
  362.  
  363.         b1 match {
  364.         case BoxV(loc) => (b2, update(loc, st3, b2))
  365.         case _ => throw new InterpOpInvalidExcep(s"Cannot Setbox $b1, as it is not a box")
  366.         }
  367.  
  368.         }
  369.  
  370.         case SetC(v, b) => interp(b, nv, st1) match{
  371.         case (v1, st2) => (v1, update(lookup(v, nv), st2, v1))
  372.         case _ => throw new InterpOpInvalidExcep("SetC not allowed.")
  373.         }
  374.  
  375.         case SeqC(b1, b2) => {
  376.         val st2 = interp(b1, nv, st1)._2
  377.         interp(b2, nv, st2)
  378.         }
  379.  
  380.         // NEW
  381.         case EqStrC(l, r) => {
  382.         val (v1, st2) = interp(l, nv, st1)
  383.         val (v2, st3) = interp(r, nv, st2)
  384.         (v1, v2) match {
  385.         case (StringV(s1), StringV(s2)) => if (s1 == s2) (BoolV(true), st3) else (BoolV(false), st3)
  386.         case _ => throw new InterpOpInvalidExcep("EqStringC not allowed.")
  387.         }
  388.         }
  389.         case ConcStrC(l, r) => {
  390.         val (v1, st2) = interp(l, nv, st1)
  391.         val (v2, st3) = interp(r, nv, st2)
  392.  
  393.         (v1, v2) match {
  394.         case (StringV(s1), StringV(s2)) => (StringV(s1 + s2), st3)
  395.         case _ => throw new InterpOpInvalidExcep("EqStringC not allowed.")
  396.         }
  397.  
  398.         }
  399.         case StringC(str) => (StringV(str), st1)
  400.         }
  401.         }
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