add check value of position in while cycle after increment

Author: rayokota

src/jsonata/tokenizer.py

@@ -137,7 +137,10 @@ def scan_regex(self) -> re.Pattern:
                 if pattern == "":
                     raise jexception.JException("S0301", self.position)
                 self.position += 1
-                current_char = self.path[self.position]
+                if self.position < self.length:
+                    current_char = self.path[self.position]
+                else:
+                    current_char = None
                 # flags
                 start = self.position
                 while current_char == 'i' or current_char == 'm':

tests/string_test.py

@@ -42,6 +42,16 @@ def test_regex(self):
         assert (jsonata.Jsonata("($matcher := $eval('/^' & 'foo' & '/i'); $.$spread()[$.$keys() ~> $matcher])")
                 .evaluate({"foo": 1, "bar": 2}) == {"foo": 1})
 
+    def test_regex_literal(self):
+        expr = jsonata.Jsonata("/^test.*$/")
+        result = expr.evaluate(None)
+        assert result.pattern == "^test.*$"
+
+    def test_eval_regex(self):
+        expr = jsonata.Jsonata("$eval('/^test.*$/')")
+        result = expr.evaluate(None)
+        assert result.pattern == "^test.*$"
+
     #
     # Additional $split tests
     #