Script Refactoring, ParseGet reads record fields

Src/AST/Myc.Ast.Compiler.TypeChecker.pas

@@ -687,30 +687,77 @@ var
     newBase, newIndex: IAstNode;
     baseType, elemType: IStaticType;
     isOpt: Boolean;
+    idx: Integer;
+    key: IKeyword;
 begin
     I := Node.AsIndexer;
     newBase := Accept(I.Base);
     newIndex := Accept(I.Index);
-    baseType := PrepareBaseType(newBase, isOpt);
 
+    // Unwrap optional types to check the underlying structure
+    baseType := PrepareBaseType(newBase, isOpt);
     elemType := TTypes.Unknown;
-    if baseType.Kind = stSeries then
-        elemType := baseType.AsSeries.ElementType
-    else if baseType.Kind = stRecordSeries then
-        elemType := TTypes.CreateRecord(baseType.AsRecord.Definition)
-    else if baseType.Kind = stTuple then
-    begin
-        // Tuple Indexing (requires constant index for strong typing!)
-        if (newIndex.Kind = akConstant) and (newIndex.AsConstant.Value.Kind = vkScalar) then
+
+    case baseType.Kind of
+        // Case 1: Accessing Tuples (Heterogeneous fixed-size lists)
+        // Static typing requires the index to be a constant integer to determine the specific element type.
+        stTuple:
         begin
-            var idx := newIndex.AsConstant.Value.AsScalar.Value.AsInt64;
-            var tpl := baseType.AsTuple;
-            if (idx >= 0) and (idx < tpl.Count) then
-                elemType := tpl.Elements[Integer(idx)];
+            if (newIndex.Kind = akConstant) and (newIndex.AsConstant.Value.Kind = vkScalar) then
+            begin
+                var intIdx := newIndex.AsConstant.Value.AsScalar.Value.AsInt64;
+                var tpl := baseType.AsTuple;
+                if (intIdx >= 0) and (intIdx < tpl.Count) then
+                    elemType := tpl.Elements[Integer(intIdx)];
+            end;
+        end;
+
+        // Case 2: Accessing Records or Record Series (Field Access)
+        // Static typing requires the index to be a Keyword literal.
+        stRecord, stRecordSeries:
+        begin
+            if newIndex.Kind = akKeyword then
+            begin
+                key := newIndex.AsKeyword.Value;
+                var def := baseType.AsRecord.Definition;
+
+                idx := def.IndexOf(key);
+                if idx >= 0 then
+                begin
+                    var fieldType := TTypes.FromScalarKind(def[idx]);
+
+                    // If we access a field on a Stream/Series of Records, the result is a Series of that field (Column).
+                    // If we access a field on a single Record, the result is the scalar value.
+                    if baseType.Kind = stRecordSeries then
+                        elemType := TTypes.CreateSeries(fieldType)
+                    else
+                        elemType := fieldType;
+                end
+                else if Assigned(FLog) then
+                    FLog.AddError(Format('Field ":%s" not found in record definition.', [key.Name]), Node);
+            end
+            else if Assigned(FLog) then
+                FLog.AddError('Record access requires a constant keyword literal (e.g. :close).', Node);
+        end;
+
+        // Case 3: Accessing Series via Integer Index (Row Access)
+        // Returns the scalar element at the specific position.
+        stSeries:
+        begin
+            elemType := baseType.AsSeries.ElementType;
+        end;
+
+        // Case 4: Vector / Matrix (Homogeneous)
+        // Accessing a Vector returns the ElementType.
+        stVector:
+        begin
+            elemType := baseType.AsVector.ElementType;
         end;
     end;
 
+    // Propagate nullability if the base object was optional
     elemType := ApplyOptionality(elemType, isOpt);
+
     Result := TAst.Indexer(Node.Identity, newBase, newIndex, elemType);
 end;