windows: clarify that regex globbing with backslashes unavailable on windows. Add test to verify it on non-windows.

tests/test_builtins.py

@@ -1,6 +1,7 @@
 """Tests the xonsh lexer."""
 from __future__ import unicode_literals, print_function
 import os
+import re
 
 import nose
 from nose.tools import assert_equal, assert_true, assert_not_in
@@ -8,6 +9,7 @@ from nose.tools import assert_equal, assert_true, assert_not_in
 from xonsh import built_ins 
 from xonsh.built_ins import Env, reglob, regexpath, helper, superhelper, \
     ensure_list_of_strs
+from xonsh.tools import ON_WINDOWS
 
 def test_env_normal():
     env = Env(VAR='wakka')
@@ -42,6 +44,15 @@ def test_reglob_tests():
     for f in testfiles:
         assert_true(f.startswith('test_'))
 
+if not ON_WINDOWS:
+    def test_repath_backslash():
+        home = os.path.expanduser('~')
+        exp = os.listdir(home)
+        exp = {p for p in exp if re.match(r'\w\w.*', p)}
+        exp = {os.path.join(home, p) for p in exp}
+        obs = set(regexpath(r'~/\w\w.*'))
+        assert_equal(exp, obs)
+        
 def test_repath_home_itself():
     exp = os.path.expanduser('~')
     obs = regexpath('~')

xonsh/built_ins.py

@@ -17,7 +17,7 @@ from collections import Sequence, MutableMapping, Iterable, namedtuple, \
     MutableSequence, MutableSet
 
 from xonsh.tools import string_types, redirect_stdout, redirect_stderr
-from xonsh.tools import suggest_commands, XonshError, ON_POSIX
+from xonsh.tools import suggest_commands, XonshError, ON_POSIX, ON_WINDOWS
 from xonsh.inspectors import Inspector
 from xonsh.environ import default_env
 from xonsh.aliases import DEFAULT_ALIASES, bash_aliases
@@ -273,7 +273,12 @@ def reglob(path, parts=None, i=None):
             base = ''
         elif len(parts) > 1:
             i += 1
-    regex = re.compile(os.path.join(base, parts[i]).replace('\\', '\\\\'))
+    regex = os.path.join(base, parts[i])
+    if ON_WINDOWS:
+        # currently unable to access regex backslash sequences
+        # on Windows due to paths using \.
+        regex = regex.replace('\\', '\\\\')
+    regex = re.compile(regex)
     files = os.listdir(subdir)
     files.sort()
     paths = []