added block comments

lib/lexer.ml

@@ -128,6 +128,17 @@ module State = struct
     let tt = lexeme |> Hashtbl.find_opt keywords |> Option.value ~default:(Identifier lexeme) in
     append_token code_pos tt state
 
+  let rec parse_block_commend (state : state) : state =
+    (* "- 2" since we already consumed the "/*" *)
+    let pos = { line = state.line; col = state.col - 2 } in
+    let found, state = advance_until '*' state in
+    if not found then append_error pos "Unterminated block commend" state
+    else if peek state = Some '/' then
+      let state = snd @@ advance state in
+      let lexeme = get_lexeme state (state.start_pos + 2) (state.cur_pos - 2) in
+      append_token pos (Comment lexeme) state
+    else parse_block_commend state
+
   let rec tokenize_rec (state : state) : state =
     let pos = { line = state.line; col = state.col } in
     let append_token = append_token pos in
@@ -166,15 +177,16 @@ module State = struct
             fun state ->
               let b, state = advance_if '=' state in
               append_token (if b then GreaterEqual else Greater) state
-        | '/' ->
+        | '/' -> (
             fun state ->
-              let found, state = advance_if '/' state in
-              if not found then append_token Slash state
-              else
-                let start_pos = state.cur_pos in
-                let _, state = advance_until '\n' state in
-                let lexeme = String.trim @@ get_lexeme state start_pos state.cur_pos in
-                append_token (Comment lexeme) state
+              match peek state with
+              | Some '/' ->
+                  let start_pos = state.cur_pos in
+                  let _, state = advance_until '\n' state in
+                  let lexeme = String.trim @@ get_lexeme state start_pos state.cur_pos in
+                  append_token (Comment lexeme) state
+              | Some '*' -> parse_block_commend (snd @@ advance state)
+              | _ -> append_token Slash state)
         | '"' ->
             fun state ->
               let found, state = advance_until '"' state in