Fixed #30 : Add variable support in BNF concept definition

Fixed #31 : Add regex support in BNF Concept
Fixed #33 : Do not memorize object during restore

tests/non_reg/test_sheerka_non_reg.py

@@ -1237,6 +1237,18 @@ as:
         assert len(l) > 0
         sheerka.save_execution_context = False
 
+    def test_i_can_define_a_regex_concept_and_parse_it(self):
+        sheerka, context = self.init_test().unpack()
+
+        res = sheerka.evaluate_user_input("def concept binary from bnf r'[01]+'")
+        assert len(res) == 1
+        assert res[0].status
+
+        res = sheerka.evaluate_user_input("01001")
+        assert len(res) == 1
+        assert res[0].status
+        assert sheerka.isinstance(res[0].body, "binary")
+
 
 class TestSheerkaNonRegFile(TestUsingFileBasedSheerka):
     def test_i_can_def_several_concepts(self):