Support escaping internal backticks

2 files changed, 10 insertions, 1 deletions

diff --git a/pygments/lexers/r.py b/pygments/lexers/r.py
index b03e4798..64cf8bf1 100644
--- a/pygments/lexers/r.py
+++ b/pygments/lexers/r.py
@@ -80,7 +80,7 @@ class SLexer(RegexLexer):
     mimetypes = ['text/S-plus', 'text/S', 'text/x-r-source', 'text/x-r',
                  'text/x-R', 'text/x-r-history', 'text/x-r-profile']
 
-    valid_name = r'`[^`]+`|(?:(?:[a-zA-z]|[_.][^0-9])[\w_.]*)'
+    valid_name = r'(?:`[^`\\]*(?:\\.[^`\\]*)*`)|(?:(?:[a-zA-z]|[_.][^0-9])[\w_.]*)'
     tokens = {
         'comments': [
             (r'#.*$', Comment.Single),
diff --git a/tests/test_r.py b/tests/test_r.py
index a6464480..d0e9090b 100644
--- a/tests/test_r.py
+++ b/tests/test_r.py
@@ -48,6 +48,15 @@ class RTest(unittest.TestCase):
         ]
         self.assertEqual(tokens, list(self.lexer.get_tokens(fragment)))
 
+    def testName3(self):
+        # Internal backticks can be escaped
+        fragment = u'`.1 \` blah`'
+        tokens = [
+            (Name, u'`.1 \` blah`'),
+            (Token.Text, u'\n'),
+        ]
+        self.assertEqual(tokens, list(self.lexer.get_tokens(fragment)))
+
     def testCustomOperator(self):
         fragment = u'7 % and % 8'
         tokens = [