Fixed a bug in string evaluation

examples/reconstruct_json.py

@@ -46,7 +46,7 @@ def test_lalr():
 
     new_json = Reconstructor(json_parser).reconstruct(tree)
     print (new_json)
-    print (json.loads(new_json) == json.loads(test_json)) 
+    print (json.loads(new_json) == json.loads(test_json))
 
 test_scanless()
 test_lalr()

lark/load_grammar.py

@@ -290,7 +290,8 @@ class ExtractAnonTokens(InlineTransformer):
 def _literal_to_pattern(literal):
     v = literal.value
     assert v[0] == v[-1] and v[0] in '"/'
-    s = literal_eval("u'''%s'''" % v[1:-1])
+    x = v[1:-1].replace("'", r"\'")
+    s = literal_eval("u'''%s'''" % x)
     return { 'STRING': PatternStr,
              'REGEXP': PatternRE }[literal.type](s)
 

tests/test_parser.py

@@ -407,6 +407,15 @@ def _make_parser_test(LEXER, PARSER):
                       """)
             x = g.parse(r'\a')
 
+        def test_special_chars(self):
+            g = _Lark(r"""start: "\n"
+                      """)
+            x = g.parse('\n')
+
+            g = _Lark(r"""start: /\n/
+                      """)
+            x = g.parse('\n')
+
 
         def test_backslash2(self):
             g = _Lark(r"""start: "\"" "-"