🖊️ Add support for empty strings in level 12 and up #4494

grammars/level12-Additions.lark

@@ -13,7 +13,7 @@ sleep: _SLEEP (NUMBER | list_access | var_access | expression)?
 // all literal strings have to be quoted now, so arithmetic operators don't need to be excluded anymore
 text_with_spaces_without_single_quotes: /(?:[^\n،,' ]| (?!else|başka|अन्यथा|否则|ellers|anders|sinon|sino|وإلا))+/ -> text
 text_with_spaces_without_double_quotes: /(?:[^\n،," ]| (?!else|başka|अन्यथा|否则|ellers|anders|sinon|sino|وإلا))+/ -> text
-text_in_quotes: _SINGLE_QUOTE text_with_spaces_without_single_quotes _SINGLE_QUOTE | _DOUBLE_QUOTE text_with_spaces_without_double_quotes _DOUBLE_QUOTE
+text_in_quotes: _SINGLE_QUOTE text_with_spaces_without_single_quotes? _SINGLE_QUOTE | _DOUBLE_QUOTE text_with_spaces_without_double_quotes? _DOUBLE_QUOTE
 
 // FUNCTIONS ======================================== =============================
 command:+= call | error_nested_define | return

hedy.py

@@ -812,7 +812,8 @@ def text(self, tree):
         return self.to_typed_tree(tree, type_)
 
     def text_in_quotes(self, tree):
-        return self.to_typed_tree(tree.children[0], HedyType.string)
+        t = tree.children[0] if tree.children else tree
+        return self.to_typed_tree(t, HedyType.string)
 
     def var_access(self, tree):
         return self.to_typed_tree(tree, HedyType.string)
@@ -2458,7 +2459,7 @@ def NEGATIVE_NUMBER(self, meta, args):
 
     def text_in_quotes(self, meta, args):
         # We need to re-add the quotes, so that the Python code becomes name = 'Jan' or "Jan's"
-        text = args[0]
+        text = args[0] if args else ''
         if "'" in text:
             return f'"{text}"'
         return f"'{text}'"

tests/test_level/test_level_12.py

@@ -1070,6 +1070,13 @@ def test_assign_string(self, q):
 
         self.multi_level_tester(code=code, unused_allowed=True, expected=expected, max_level=17)
 
+    @parameterized.expand(HedyTester.quotes)
+    def test_assign_empty_string(self, q):
+        code = f"name = {q}{q}"
+        expected = "name = ''"
+
+        self.multi_level_tester(code=code, unused_allowed=True, expected=expected)
+
     def test_assign_text_with_inner_double_quote(self):
         code = """a is 'It says "Hedy"'"""
         expected = """a = 'It says "Hedy"'"""