Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/llvm/examples/OCaml-Kaleidoscope/Chapter2/toplevel.ml

@@ -0,0 +1,34 @@
+(*===----------------------------------------------------------------------===
+ * Top-Level parsing and JIT Driver
+ *===----------------------------------------------------------------------===*)
+
+(* top ::= definition | external | expression | ';' *)
+let rec main_loop stream =
+  match Stream.peek stream with
+  | None -> ()
+
+  (* ignore top-level semicolons. *)
+  | Some (Token.Kwd ';') ->
+      Stream.junk stream;
+      main_loop stream
+
+  | Some token ->
+      begin
+        try match token with
+        | Token.Def ->
+            ignore(Parser.parse_definition stream);
+            print_endline "parsed a function definition.";
+        | Token.Extern ->
+            ignore(Parser.parse_extern stream);
+            print_endline "parsed an extern.";
+        | _ ->
+            (* Evaluate a top-level expression into an anonymous function. *)
+            ignore(Parser.parse_toplevel stream);
+            print_endline "parsed a top-level expr";
+        with Stream.Error s ->
+          (* Skip token for error recovery. *)
+          Stream.junk stream;
+          print_endline s;
+      end;
+      print_string "ready> "; flush stdout;
+      main_loop stream