Compiler exceptions

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

@@ -8,13 +8,16 @@ uses
     System.Generics.Collections,
     Myc.Data.Scalar,
     Myc.Data.Value,
-    Myc.Ast.Nodes,
+    Myc.Ast.Nodes, // Provides EAstException
     Myc.Ast.Visitor,
     Myc.Ast.Scope,
     Myc.Ast.Types,
     Myc.Ast;
 
 type
+    // Exception specific to AST lowering/rewriting errors
+    ELoweringException = class(EAstException);
+
     IAstLowerer = interface(IAstVisitor)
         function Execute(const RootNode: IAstNode): IAstNode;
     end;
@@ -27,6 +30,8 @@ type
         FBinaryOperators: TDictionary<string, TScalar.TBinaryOp>;
         FUnaryOperators: TDictionary<string, TScalar.TUnaryOp>;
     protected
+    // Implement Visit methods here when specific lowering logic is added
+    // (e.g. converting operator function calls to specific node types if added in future)
     public
         constructor Create;
         destructor Destroy; override;
@@ -47,7 +52,7 @@ constructor TAstLowerer.Create;
 begin
     inherited Create;
 
-    // Operator folding maps
+    // Operator folding maps (Reserved for future static optimization)
     FBinaryOperators := TDictionary<string, TScalar.TBinaryOp>.Create;
 
     FBinaryOperators.Add('+', TScalar.TBinaryOp.Add);
@@ -76,12 +81,20 @@ end;
 class function TAstLowerer.Lower(const RootNode: IAstNode): IAstNode;
 begin
     var lowerer := TAstLowerer.Create as IAstLowerer;
-    Result := lowerer.Execute(RootNode);
+    try
+        Result := lowerer.Execute(RootNode);
+    except
+        on E: Exception do
+            raise ELoweringException.Create('Internal Error during AST Lowering: ' + E.Message);
+    end;
 end;
 
 function TAstLowerer.Execute(const RootNode: IAstNode): IAstNode;
 begin
-    Result := Accept(RootNode); // Use IAstNode-returning Accept
+    if not Assigned(RootNode) then
+        exit(nil);
+
+    Result := Accept(RootNode);
     if not Assigned(Result) then
         Result := TAst.Block([]);
 end;