Refactoring for immutable nodes

Src/AST/Myc.Ast.Scope.pas

@@ -112,6 +112,7 @@ type
             TScopeItem = record
                 Value: TDataValue;
                 IsBoxed: Boolean;
+                function GetContent: TDataValue;
             end;
 
     private
@@ -606,7 +607,6 @@ end;
 
 procedure TScopeDescriptor.PopulateFromScope(Scope: TExecutionScope);
 var
-    val: TDataValue;
     i: Integer;
 begin
     // Recreate descriptor by iterating all defined symbols in the runtime scope.
@@ -627,11 +627,16 @@ begin
         // FSlotTypes[slotIndex] remains TTypes.Unknown.
 
         // Check if the symbol is also a macro and add it to the macro table.
-        val := Scope.ValuesArray[slotIndex].Value;
-        if (val.Kind = vkInterface) and (val.AsIntf<IAstNode> is TMacroDefinitionNode) then
+
+        var val := Scope.ValuesArray[slotIndex].GetContent;
+        if val.Kind = vkInterface then
         begin
-            if not FMacros.ContainsKey(name) then
-                FMacros.Add(name, val.AsIntf<IMacroDefinitionNode>);
+            var node := val.AsIntf<IAstNode>;
+            if (node <> nil) and (node.Kind = akMacroDefinition) then
+            begin
+                if not FMacros.ContainsKey(name) then
+                    FMacros.Add(name, node.AsMacroDefinition);
+            end;
         end;
     end;
 end;
@@ -652,4 +657,11 @@ begin
     Result := TExecutionScope.Create(Parent, Descriptor, CapturedUpvalues);
 end;
 
+function TExecutionScope.TScopeItem.GetContent: TDataValue;
+begin
+    Result := Value;
+    if IsBoxed then
+        Result := Result.AsIntf<IValueCell>.Value;
+end;
+
 end.