Small fixes

lark/utils.py

@@ -176,20 +176,20 @@ Py36 = (sys.version_info[:2] >= (3, 6))
 import sre_parse
 import sre_constants
 categ_pattern = re.compile(r'\\p{[A-Za-z_]+}')
-def get_regexp_width(regexp):
+def get_regexp_width(expr):
     if regex:
         # Since `sre_parse` cannot deal with Unicode categories of the form `\p{Mn}`, we replace these with
         # a simple letter, which makes no difference as we are only trying to get the possible lengths of the regex
         # match here below.
-        regexp_final = re.sub(categ_pattern, 'A', regexp)
+        regexp_final = re.sub(categ_pattern, 'A', expr)
     else:
-        if re.search(categ_pattern, regexp):
-            raise ImportError('`regex` module must be installed in order to use Unicode categories.', regexp)
-        regexp_final = regexp
+        if re.search(categ_pattern, expr):
+            raise ImportError('`regex` module must be installed in order to use Unicode categories.', expr)
+        regexp_final = expr
     try:
         return [int(x) for x in sre_parse.parse(regexp_final).getwidth()]
     except sre_constants.error:
-        raise ValueError(regexp)
+        raise ValueError(expr)
 
 ###}
 

tests/test_parser.py

@@ -1,10 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import
 
-try:
-    import regex as re
-except ImportError:
-    import re
+import re
 import unittest
 import logging
 import os
@@ -23,6 +20,11 @@ from io import (
 
 logging.basicConfig(level=logging.INFO)
 
+try:
+    import regex
+except ImportError:
+    regex = None
+
 from lark.lark import Lark
 from lark.exceptions import GrammarError, ParseError, UnexpectedToken, UnexpectedInput, UnexpectedCharacters
 from lark.tree import Tree
@@ -1787,7 +1789,7 @@ def _make_parser_test(LEXER, PARSER):
                 self.assertEqual(a.line, 1)
                 self.assertEqual(b.line, 2)
 
-        @unittest.skipIf(sys.version_info[0] == 2, 'Unicode and Python 2 do not place nicely together.')
+        @unittest.skipIf(not regex or sys.version_info[0] == 2, 'Unicode and Python 2 do not place nicely together.')
         def test_unicode_class(self):
             "Tests that character classes from the `regex` module work correctly."
             g = _Lark(r"""?start: NAME
@@ -1797,7 +1799,7 @@ def _make_parser_test(LEXER, PARSER):
 
             self.assertEqual(g.parse('வணக்கம்'), 'வணக்கம்')
 
-        @unittest.skipIf(sys.version_info[0] == 2, 'Unicode and Python 2 do not place nicely together.')
+        @unittest.skipIf(not regex or sys.version_info[0] == 2, 'Unicode and Python 2 do not place nicely together.')
         def test_unicode_word(self):
             "Tests that a persistent bug in the `re` module works when `regex` is enabled."
             g = _Lark(r"""?start: NAME