[ITMO] T08 Svetlana Antoshkina

src/Expr.lama

@@ -100,15 +100,103 @@ fun evalList (c, exprs) {
   esac
 }
 
-fun eval (c@[s, w], expr) {
-  failure ("evalExpr not implemented\n")
+fun evalDecls(c, exprs) {
+  fun evalDecl(c@[s, w], e) {
+    case e of
+        Var(x) -> let s = s.addNames(x) in [s, w]
+      | Fun(name, args, body) -> let s = s.addFunction(name, args, body) in [s, w]
+    esac
+  }
+
+  foldl(evalDecl, c, exprs)
+}
+
+fun evalArgs(s, args) {
+  fun evalArg(s, [name, value]) {
+    s.addName(name, value) 
+  }
+
+  foldl(evalArg, s, args)
+}
+
+fun eval (c@[st, w], expr) {
+  case expr of
+      Assn (expr1, expr2) -> 
+        let [c@[st, w], {ref, v}] = evalList(c, {expr1, expr2}) in 
+        case ref of 
+            Ref (x) -> [[st <- [x, v], w], v]
+          | ElemRef (arr, idx) -> arr[idx] := v; [c, v]
+        esac
+    | Seq (expr1, expr2) -> let [c1, v] = eval(c, expr1) in eval(c1, expr2)
+    | Skip -> [c, Void]
+    | If (cond, expr1, expr2) -> let [c, v] = eval(c, cond) in if v then eval(c, expr1) else eval(c, expr2) fi
+    | While (cond, body) -> 
+        let [c1, n] = eval(c, cond) in 
+        if n != 0
+        then
+          let [c2, _] = eval(c1, body) in
+          eval(c2, While(cond, body))
+        else
+          [c1, 0]
+        fi
+    | DoWhile (cond, body) -> evalList(c, {body, While (cond, body)})
+    | Var (x) -> [c, lookup(st, x)]
+    | Ref (x) -> [c, Ref (x)]
+    | Const (n) -> [c, n]
+    | Binop (op, expr1, expr2) -> 
+        let [c, {l, r}] = evalList(c, {expr1, expr2}) in 
+        [c, evalOp(op, l, r)]
+    | Ignore (expr1) -> let [c, v] = eval(c, expr1) in [c, Void]
+    | Scope (decl, stmt) -> 
+        let st = st.enterScope in
+        let c@[st, w] = evalDecls([st, w], decl) in
+        let [[st, w], x] = eval(c, stmt) in
+        [[st.leaveScope, w], x]
+    | Call (name, args) -> 
+        let Fun (argNames, body) = st.lookup(name) in
+        let [c@[st, w], vs] = c.evalList(args) in
+        let stIn = st.enterFunction in
+        let stIn = evalArgs(stIn, zip(argNames, vs)) in
+        let [[stIn, w], v] = eval([stIn, w], body) in
+        [[st.leaveFunction(stIn.getGlobal), w], v]
+    | Builtin (x, exprs) ->
+        let [c@[st, w], vals] = evalList (c, exprs) in
+        let [v, w] = evalBuiltin (x, vals, w) in
+        [[st, w], v]
+    | String (v) -> [c, v]
+    | Array (exprs) -> let [c, vals] = evalList (c, exprs) in [c, listArray (vals)]
+    | Elem (ea, ei) ->
+        let [c, arr] = eval (c, ea) in
+        let [c, idx] = eval (c, ei) in
+        let arr =
+          case arr of
+            Sexp (_, arr) -> arr
+          | arr -> arr
+          esac
+        in
+        [c, arr[idx]] 
+    | ElemRef (ea, ei) -> 
+        let [c, arr] = eval (c, ea) in
+        let [c, idx] = eval (c, ei) in
+        let arr =
+          case arr of
+            Sexp (_, arr) -> arr
+          | arr -> arr
+          esac
+        in
+        [c, ElemRef (arr, idx)] 
+    | Sexp (tag, exprs) ->
+        let [c, args] = evalList (c, exprs) in
+        [c, Sexp (tag, listArray (args))]
+    esac
 }
 
 -- Evaluates a program with a given input and returns an output
 public fun evalExpr (input, expr) {
-  case eval ([emptyState ().enterScope.addName ("read",   Fun ({}, External))
-                                      .addName ("write",  Fun ({"a"}, External))
-                                      .addName ("length", Fun ({"a"}, External)), createWorld (input)], expr) of
+  case eval ([emptyState ().enterScope--.addName ("read",   Fun ({}, External))
+                                      --.addName ("write",  Fun ({"a"}, External))
+                                      --.addName ("length", Fun ({"a"}, External))
+              , createWorld (input)], expr) of
     [c, _] -> c.snd.getOutput
   esac
 }

src/Parser.lama

@@ -57,6 +57,12 @@ fun binop (op) {
   ]
 }
 
+--var elseStmt = memo $ eta syntax (
+--  kElif e=exp kThen s1=exp s2=elseStmt {fun (a) {If(e(Val), s1(a), s2(a))}} |
+--  kElse s2=exp kFi {fun (a) {s2(a)}} |
+--  kFi {fun (a) {assertVoid(a, Skip, loc)}}
+--);
+
 -- Helper parser: parses a (possible empty) list of items separated by ","
 fun list0 (item) {
   list0By (item, s(","))
@@ -104,6 +110,16 @@ fun distributeScope (expr, exprConstructor) {
   | _                   -> exprConstructor (expr)
   esac
 }
+
+fun isBuiltin(name) {
+  case name of
+    "write" -> true
+  | "read" -> true
+  | "length" -> true
+  | "stringval" -> true
+  | _ -> false
+  esac
+}
 
 var primary    = memo $ eta syntax (
                                       -- S-expression
@@ -123,18 +139,41 @@ var primary    = memo $ eta syntax (
                                       -- decimal constant
                                       loc=pos x=decimal                                              {fun (a) {assertValue (a, Const (stringInt (x)), loc)}}     |
 
-                                      -- identifier
-                                      loc=pos x=lident args=inbr[s("("), list0(syntax(e=exp {e(Val)})), s(")")]? {fun (a) {
-                                                                                                                    case args of
-                                                                                                                      None -> case a of
-                                                                                                                                Ref  -> Ref (x)
-                                                                                                                              | Void -> Ignore (Var (x))
-                                                                                                                              | _    -> Var (x)
-                                                                                                                              esac
-                                                                                                                    | Some (args) -> assertValue (a, Call (x, args), loc)
-                                                                                                                    esac
-                                                                                                                 }} |
-                                      $(failure ("the rest of primary parsing in not implemented\n"))),
+      -- identifier
+      loc=pos x=lident args=inbr[s("("), list0(syntax(e=exp {e(Val)})), s(")")]? {
+        fun (a) {
+          case args of
+            None -> case a of
+                      Ref  -> Ref (x)
+                    | Void -> Ignore (Var (x))
+                    | _    -> Var (x)
+                    esac
+          | Some (args) -> assertValue (a,
+                                        if isBuiltin(x)
+                                        then Builtin (x, args)
+                                        else Call (x, args)
+                                        fi, 
+                                        loc)
+          esac
+        }
+      } |
+      inbr[s("("), scopeExpr, s(")")] |
+      kSkip {fun (a) {assertVoid(a, Skip, loc)}} |
+      loc=pos kIf e=scopeExpr kThen s1=scopeExpr s2=elseStmt {fun (a) {If(e(Val), s1(a), s2(a))}} |
+      loc=pos kThen {fun (a) {assertVoid(a, Skip, loc)}} |
+      loc=pos kWhile e=scopeExpr kDo s=scopeExpr kOd {fun (a) {assertVoid(a, While (e(Val), s(Void)), loc)}} |
+      loc=pos kDo s=scopeExpr kWhile e=scopeExpr kOd {fun (a) {
+        distributeScope(s(Void), fun(s) {assertVoid(a, DoWhile(e(Val), s), loc)})
+      }} |
+      loc=pos kFor s1=scopeExpr s[","] e=scopeExpr s[","] s2=scopeExpr kDo s=scopeExpr kOd {fun (a) {
+        distributeScope(s1(Void), fun (s1) {assertVoid(a, Seq(s1, While (e(Val), Seq(s(Void), s2(Void)))), loc)})
+      }}
+    ),
+    elseStmt = memo $ eta syntax (
+      kElif e=scopeExpr kThen s1=scopeExpr s2=elseStmt {fun (a) {If(e(Val), s1(a), s2(a))}} |
+      kElse s2=scopeExpr kFi {fun (a) {s2(a)}} |
+      kFi {fun (a) {assertVoid(a, Skip, loc)}}
+    ),
       basic      = memo $ eta (expr ({[Right, {[s (":="),
                                                 fun (l, loc, r) {
                                                   fun (a) {assertValue (a, Assn (l (Ref), r (Val)), loc)}
@@ -170,14 +209,14 @@ var primary    = memo $ eta syntax (
                                                                          | _        -> Skip
                                                                          esac)
                                                                       }}),
-      definition = memo $ eta syntax (kVar ds=list[syntax (lident (s["="] e=basic {e (Val)})?)] s[";"] {Var (ds)} |
-                                      kFun name=lident
-                                           args=inbr[s("("), list0 (lident), s(")")]
-                                           body=inbr[s("{"), scopeExpr, s("}")] {
-                                           Fun (name, args, body (Weak))
-                                      }
-                                     ),                                    
-      exp        = memo $ eta syntax (basic | s1=basic s[";"] s2=exp {fun (a) {Seq (s1 (Void), s2 (a))}});
+    definition = memo $ eta syntax (kVar ds=list[syntax (lident (s["="] e=basic {e (Val)})?)] s[";"] {Var (ds)} |
+                                    kFun name=lident
+                                          args=inbr[s("("), list0 (lident), s(")")]
+                                          body=inbr[s("{"), scopeExpr, s("}")] {
+                                          Fun (name, args, body (Weak))
+                                    }
+                                    ),   
+    exp      = memo $ eta syntax (basic | s1=basic s[";"] s2=exp {fun (a) {Seq (s1 (Void), s2 (a))}});
 
 -- Public top-level parser
 public parse = syntax (s=scopeExpr {s (Void)});