fix: Propagate debug flag on loading grammar from cache

The debug flag is already saved in the cached file, but is not
resumed on loading the dumped file. To solve that,
 - add argument `debug` to parser_fronteds.WithLexer.deserialize
 - add argument `debug` lalr_parser.LALR_Parser.deserialize
 - propagate the value of the `debug` option on resuming a cached
   grammar, in lark.Lark._load

lark/lark.py

@@ -374,7 +374,8 @@ class Lark(Serialize):
             self._callbacks,
             self.options.postlex,
             self.options.transformer,
-            re_module
+            re_module,
+            self.options.debug
         )
         self.terminals = self.parser.lexer_conf.tokens
         self._terminals_dict = {t.name: t for t in self.terminals}

lark/parser_frontends.py

@@ -82,11 +82,13 @@ class WithLexer(_ParserFrontend):
         self.postlex = lexer_conf.postlex
 
     @classmethod
-    def deserialize(cls, data, memo, callbacks, postlex, transformer, re_module):
+    def deserialize(cls, data, memo, callbacks, postlex, transformer, re_module,
+                    debug):
         inst = super(WithLexer, cls).deserialize(data, memo)
 
         inst.postlex = postlex
-        inst.parser = LALR_Parser.deserialize(inst.parser, memo, callbacks)
+        inst.parser = LALR_Parser.deserialize(inst.parser, memo, callbacks,
+                                              debug)
 
         terminals = [item for item in memo.values() if isinstance(item, TerminalDef)]
         inst.lexer_conf.callbacks = _get_lexer_callbacks(transformer, terminals)

lark/parsers/lalr_parser.py

@@ -23,10 +23,10 @@ class LALR_Parser(object):
         self.parser = _Parser(analysis.parse_table, callbacks, debug)
 
     @classmethod
-    def deserialize(cls, data, memo, callbacks):
+    def deserialize(cls, data, memo, callbacks, debug=False):
         inst = cls.__new__(cls)
         inst._parse_table = IntParseTable.deserialize(data, memo)
-        inst.parser = _Parser(inst._parse_table, callbacks)
+        inst.parser = _Parser(inst._parse_table, callbacks, debug)
         return inst
 
     def serialize(self, memo):

tests/test_cache.py

@@ -86,6 +86,12 @@ class TestCache(TestCase):
             parser = Lark(g, parser='lalr', lexer=CustomLexer, cache=True)
             assert len(mock_fs.files) == 1
             assert parser.parse('a') == Tree('start', [])
+
+            # Test options persistence
+            mock_fs.files = {}
+            Lark(g, parser="lalr", debug=True, cache=True)
+            parser = Lark(g, parser="lalr", debug=True, cache=True)
+            assert parser.options.options['debug']
         finally:
             lark_module.FS = fs