allow nullable start symbol

microsoft · Jun 25, 2024 · 8dda7a4 · 8dda7a4
1 parent 1e9b008
commit 8dda7a4
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/controllers/llguidance_ctrl/src/earley/grammar.rs b/controllers/llguidance_ctrl/src/earley/grammar.rs
@@ -349,7 +349,7 @@ impl Grammar {
         let mut outp = Grammar::new();
 
         let start_data = self.sym_data(self.start());
-        if start_data.is_terminal() {
+        if start_data.is_terminal() || start_data.rules.iter().any(|r| r.rhs.is_empty()) {
             let new_start = outp.fresh_symbol("_start_repl");
             outp.add_rule(new_start, vec![SymIdx(1)]).unwrap();
         }