bpo-40529: rlcompleter with case insensitive

Incorporated review comments @ Lib/rlcompleter.py
Added documentation @ Doc/library/rlcompleter.rst
Added unit testcase test_case_insentive_matches() @ Lib/test/test_rlcompleter.py

* skip news

Doc/library/rlcompleter.rst

@@ -5,6 +5,7 @@
    :synopsis: Python identifier completion, suitable for the GNU readline library.
 
 .. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
+.. sectionauthor:: Madhusudhan Kasula <kasula.madhusudhan@gmail.com>
 
 **Source code:** :source:`Lib/rlcompleter.py`
 
@@ -59,3 +60,19 @@ Completer objects have the following method:
    :func:`dir` function.  Any exception raised during the evaluation of the
    expression is caught, silenced and :const:`None` is returned.
 
+
+.. _case-sensitivity:
+
+Case Sensitivity
+-----------------
+
+You can change the Completer's default case sensitive selection to case insensitive using the following method:
+
+
+.. function:: rlcompleter.set_case_insensitive(option)
+
+   Return the *None*.
+
+   If called with *True*, it will set rlcompleter for case insensitive completions.
+
+   If called with *False*, it will set to default case sensitive completions.

Lib/rlcompleter.py

@@ -110,12 +110,13 @@ class Completer:
         defined in self.namespace that match.
 
         """
+        import re
         import keyword
         matches = []
         seen = {"__builtins__"}
         n = len(text)
         for word in keyword.kwlist:
-            if word[:n] == text:
+            if re.match(text, word[:n], flags=_re_ignorecase_flags):
                 seen.add(word)
                 if word in {'finally', 'try'}:
                     word = word + ':'
@@ -126,7 +127,8 @@ class Completer:
                 matches.append(word)
         for nspace in [self.namespace, builtins.__dict__]:
             for word, val in nspace.items():
-                if word[:n] == text and word not in seen:
+                if (re.match(text, word[:n], flags=_re_ignorecase_flags) and
+                    word not in seen):
                     seen.add(word)
                     matches.append(self._callable_postfix(val, word))
         return matches
@@ -193,7 +195,7 @@ _re_ignorecase_flags = 0
 def set_case_insensitive(option):
     import re
     global _re_ignorecase_flags
-    _re_ignorecase_flags = option and re.IGNORECASE or 0
+    _re_ignorecase_flags = re.IGNORECASE if option else 0
 
 def get_class_members(klass):
     ret = dir(klass)

Lib/test/test_rlcompleter.py

@@ -137,5 +137,31 @@ class TestRlcompleter(unittest.TestCase):
         self.assertEqual(completer.complete('Ellipsis', 0), 'Ellipsis(')
         self.assertIsNone(completer.complete('Ellipsis', 1))
 
+    def test_case_insentive_matches(self):
+        # add an additional attr for testing
+        CompleteMe.SpAm = 2
+        # enable the case insensitive option
+        rlcompleter.set_case_insensitive(True)
+        # test globals
+        self.assertEqual(self.completer.global_matches('completem'),
+                         ['CompleteMe('])
+        # test attr
+        self.assertNotEqual(self.completer.attr_matches('CompleteMe.spa'),
+                         ['CompleteMe.spam', 'CompleteMe.SpAm'])
+        # disable the case insensitive option
+        rlcompleter.set_case_insensitive(False)
+        # test globals
+        self.assertNotEqual(self.completer.global_matches('completem'),
+                            ['CompleteMe('])
+        self.assertEqual(self.completer.global_matches('CompleteM'),
+                         ['CompleteMe('])
+        # test attr
+        self.assertNotEqual(self.completer.attr_matches('CompleteMe.spa'),
+                            ['CompleteMe.spam', 'CompleteMe.SpAm'])
+        self.assertEqual(self.completer.attr_matches('CompleteMe.sp'),
+                         ['CompleteMe.spam'])
+        # delete the additional attr
+        del(CompleteMe.SpAm)
+
 if __name__ == '__main__':
     unittest.main()