src/main/java/me/topchetoeu/jscript/common/Instruction.java

@@ -352,8 +352,8 @@ public class Instruction {
     public static Instruction loadThis() {
         return new Instruction(Type.LOAD_THIS);
     }
-    public static Instruction loadArgs() {
+    public static Instruction loadArgs(boolean real) {
-        return new Instruction(Type.LOAD_ARGS);
+        return new Instruction(Type.LOAD_ARGS, real);
     }
     public static Instruction loadRestArgs(int offset) {
         return new Instruction(Type.LOAD_REST_ARGS, offset);

src/main/java/me/topchetoeu/jscript/compilation/FunctionArrowNode.java

@@ -54,17 +54,21 @@ public class FunctionArrowNode extends FunctionNode {
 
         if (!src.is(i + n, "=>")) return ParseRes.failed();
         n += 2;
+        n += Parsing.skipEmpty(src, i + n);
 
-        ParseRes<Node> body = ParseRes.first(src, i + n,
+        if (src.is(i + n, "{")) {
-            (s, j) -> JavaScript.parseExpression(s, j, 2),
+            var body = CompoundNode.parse(src, i + n);
-            CompoundNode::parse
+            if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected a compount statement after '=>'");
-        );
+            n += body.n;
-        if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected an expression or a compount statement after '=>'");
-        n += body.n;
 
-        return ParseRes.res(new FunctionArrowNode(
+            return ParseRes.res(new FunctionArrowNode(loc, src.loc(i + n - 1), params, body.result), n);
-            loc, src.loc(i + n - 1),
+        }
-            params, body.result
+        else {
-        ), n);
+            var body = JavaScript.parseExpression(src, i + n, 2);
+            if (!body.isSuccess()) return body.chainError(src.loc(i + n), "Expected a compount statement after '=>'");
+            n += body.n;
+
+            return ParseRes.res(new FunctionArrowNode(loc, src.loc(i + n - 1), params, body.result), n);
+        }
     }
 }

src/main/java/me/topchetoeu/jscript/compilation/FunctionNode.java

@@ -31,12 +31,12 @@ public abstract class FunctionNode extends Node {
             .remove(LabelContext.CONTINUE_CTX);
 
         return new CompileResult(env, scope, params.params.size(), target -> {
-            if (hasArgs || params.params.size() > 0) target.add(Instruction.loadArgs());
+            if (hasArgs || params.params.size() > 0) target.add(Instruction.loadArgs(true));
 
-            if (hasArgs) {
+            // if (hasArgs) {
-                var argsVar = scope.defineStrict(new Variable("arguments", true), loc());
+            //     var argsVar = scope.defineStrict(new Variable("arguments", true), loc());
-                target.add(_i -> Instruction.storeVar(argsVar.index(), params.params.size() > 0));
+            //     target.add(_i -> Instruction.storeVar(argsVar.index(), params.params.size() > 0));
-            }
+            // }
 
             if (params.params.size() > 0) {
                 if (params.params.size() > 1) target.add(Instruction.dup(params.params.size() - 1));

src/main/java/me/topchetoeu/jscript/compilation/JavaScript.java

@@ -24,6 +24,7 @@ import me.topchetoeu.jscript.compilation.control.ThrowNode;
 import me.topchetoeu.jscript.compilation.control.TryNode;
 import me.topchetoeu.jscript.compilation.control.WhileNode;
 import me.topchetoeu.jscript.compilation.scope.FunctionScope;
+import me.topchetoeu.jscript.compilation.values.ArgumentsNode;
 import me.topchetoeu.jscript.compilation.values.ArrayNode;
 import me.topchetoeu.jscript.compilation.values.ObjectNode;
 import me.topchetoeu.jscript.compilation.values.RegexNode;
@@ -60,7 +61,7 @@ public final class JavaScript {
         "finally", "for", "do", "while", "switch", "case", "default", "new",
         "function", "var", "return", "throw", "typeof", "delete", "break",
         "continue", "debugger", "implements", "interface", "package", "private",
-        "protected", "public", "static"
+        "protected", "public", "static", "arguments"
     );
 
     public static ParseRes<? extends Node> parseParens(Source src, int i) {
@@ -115,7 +116,7 @@ public final class JavaScript {
         if (id.result.equals("false")) return ParseRes.res(new BoolNode(loc, false), n);
         if (id.result.equals("null")) return ParseRes.res(new NullNode(loc), n);
         if (id.result.equals("this")) return ParseRes.res(new ThisNode(loc), n);
-        // if (id.result.equals("arguments")) return ParseRes.res(new ArgumentsNode(loc), n);
+        if (id.result.equals("arguments")) return ParseRes.res(new ArgumentsNode(loc), n);
 
         return ParseRes.failed();
     }

src/main/java/me/topchetoeu/jscript/compilation/values/ArgumentsNode.java

@@ -0,0 +1,17 @@
+package me.topchetoeu.jscript.compilation.values;
+
+import me.topchetoeu.jscript.common.Instruction;
+import me.topchetoeu.jscript.common.parsing.Location;
+import me.topchetoeu.jscript.compilation.CompileResult;
+import me.topchetoeu.jscript.compilation.Node;
+
+
+public class ArgumentsNode extends Node {
+    @Override public void compile(CompileResult target, boolean pollute) {
+        if (pollute) target.add(Instruction.loadArgs(false));
+    }
+
+    public ArgumentsNode(Location loc) {
+        super(loc);
+    }
+}

src/main/java/me/topchetoeu/jscript/compilation/values/operations/CallNode.java

@@ -13,6 +13,7 @@ import me.topchetoeu.jscript.common.parsing.Source;
 import me.topchetoeu.jscript.compilation.CompileResult;
 import me.topchetoeu.jscript.compilation.JavaScript;
 import me.topchetoeu.jscript.compilation.Node;
+import me.topchetoeu.jscript.compilation.values.ArgumentsNode;
 import me.topchetoeu.jscript.compilation.values.ArrayNode;
 import me.topchetoeu.jscript.compilation.values.ObjectNode;
 import me.topchetoeu.jscript.compilation.values.ThisNode;
@@ -55,6 +56,9 @@ public class CallNode extends Node {
         else if (func instanceof ThisNode) {
             res = "this";
         }
+        else if (func instanceof ArgumentsNode) {
+            res = "arguments";
+        }
         else if (func instanceof ArrayNode) {
             var els = new ArrayList<String>();
 

src/main/java/me/topchetoeu/jscript/runtime/Frame.java

@@ -101,8 +101,9 @@ public final class Frame {
      */
     public final Value[][] captures;
     public final List<Value[]> locals = new ArrayList<>();
-    public final Value self;
     public final Value argsVal;
+    public Value self;
+    public Value fakeArgs;
     public final Value[] args;
     public final boolean isNew;
     public final Stack<TryCtx> tryStack = new Stack<>();

src/main/java/me/topchetoeu/jscript/runtime/InstructionRunner.java

@@ -185,7 +185,10 @@ public class InstructionRunner {
         var func = new CodeFunction(env, name, frame.function.body.children[id], captures);
         if (!callable) func.enableCall = false;
         if (!constructible) func.enableNew = false;
-        if (captureThis) func.self = frame.self;
+        if (captureThis) {
+            func.self = frame.self;
+            func.argsVal = frame.argsVal;
+        }
         frame.push(func);
 
         frame.codePtr++;
@@ -472,7 +475,8 @@ public class InstructionRunner {
     }
 
     private static Value execLoadArgs(Environment env, Instruction instr, Frame frame) {
-        frame.push(frame.argsVal);
+        if ((boolean)instr.get(0) || frame.fakeArgs == null) frame.push(frame.argsVal);
+        else frame.push(frame.fakeArgs);
         frame.codePtr++;
         return null;
     }

src/main/java/me/topchetoeu/jscript/runtime/values/functions/CodeFunction.java

@@ -9,6 +9,7 @@ public final class CodeFunction extends FunctionValue {
     public final FunctionBody body;
     public final Value[][] captures;
     public Value self;
+    public Value argsVal;
     public Environment env;
 
     private Value onCall(Frame frame) {
@@ -26,8 +27,11 @@ public final class CodeFunction extends FunctionValue {
     }
 
     @Override public Value onCall(Environment env, boolean isNew, String name, Value thisArg, Value ...args) {
-        if (self != null) return onCall(new Frame(env, isNew, self, args, this));
+        var frame = new Frame(env, isNew, thisArg, args, this);
-        else return onCall(new Frame(env, isNew, thisArg, args, this));
+        if (argsVal != null) frame.fakeArgs = argsVal;
+        if (self != null) frame.self = self;
+
+        return onCall(frame);
     }
 
     public CodeFunction(Environment env, String name, FunctionBody body, Value[][] captures) {