Style improvements to errors

lark/lexer.py

@@ -171,7 +171,7 @@ class _Lex:
 
                 break
             else:
-                allowed = [v for m, tfi in lexer.mres for v in tfi.values()]
+                allowed = {v for m, tfi in lexer.mres for v in tfi.values()}
                 raise UnexpectedCharacters(stream, line_ctr.char_pos, line_ctr.line, line_ctr.column, allowed=allowed, state=self.state)
 
 

lark/parsers/xearley.py

@@ -111,7 +111,7 @@ class Parser(BaseParser):
             del delayed_matches[i+1]    # No longer needed, so unburden memory
 
             if not next_set and not delayed_matches and not next_to_scan:
-                raise UnexpectedCharacters(stream, i, text_line, text_column, {item.expect for item in to_scan}, set(to_scan))
+                raise UnexpectedCharacters(stream, i, text_line, text_column, {item.expect.name for item in to_scan}, set(to_scan))
 
             return next_to_scan