Issue #7548: Fixed parsing of line magic.

* Bash rules apply after %sx, %sc and %system
* Plain text rules after any othe magic.

IPython/nbconvert/utils/lexers.py

@@ -49,9 +49,9 b' from IPython.testing.skipdoctest import skip_doctest'
 line_re = re.compile('.*?\n')
 
 ipython_tokens = [
-  (r'(\%+)(\w+)\s+(\.*)(\n)', bygroups(Operator, Keyword,
+  (r'(%)(sx|sc|system)(.*)(\n)', bygroups(Operator, Keyword,
                                        using(BashLexer), Text)),
-  (r'(\%+)(\w+)\b', bygroups(Operator, Keyword)),
+  (r'(%)(\w+)(.*\n)', bygroups(Operator, Keyword, Text)),
   (r'^(!)(.+)(\n)', bygroups(Operator, using(BashLexer), Text)),
   (r'^(.+)(=)(\s*)(!)(.+)(\n)', bygroups(
       # With the limited syntax allowed on the l.h.s. of a shell capture,

IPython/nbconvert/utils/tests/test_lexers.py

@@ -42,6 +42,7 b' class TestLexers(TestsBase):'
             (Token.Text, ' '),
         ] + tokens
         self.assertEqual(tokens_2, list(self.lexer.get_tokens(fragment_2)))
+
         fragment_2 = 'x, = ' + fragment
         tokens_2 = [
             (Token.Name, 'x'),
@@ -51,3 +52,28 b' class TestLexers(TestsBase):'
             (Token.Text, ' '),
         ] + tokens
         self.assertEqual(tokens_2, list(self.lexer.get_tokens(fragment_2)))
+
+        fragment_2 = 'x, = %sx ' + fragment[1:]
+        tokens_2 = [
+            (Token.Name, 'x'),
+            (Token.Punctuation, ','),
+            (Token.Text, ' '),
+            (Token.Operator, '='),
+            (Token.Text, ' '),
+            (Token.Operator, '%'),
+            (Token.Keyword, 'sx'),
+            (Token.Text, ' '),
+        ] + tokens[1:]
+        self.assertEqual(tokens_2, list(self.lexer.get_tokens(fragment_2)))
+
+        fragment_2 = 'f = %R function () {}\n'
+        tokens_2 = [
+            (Token.Name, 'f'),
+            (Token.Text, ' '),
+            (Token.Operator, '='),
+            (Token.Text, ' '),
+            (Token.Operator, '%'),
+            (Token.Keyword, 'R'),
+            (Token.Text, ' function () {}\n'),
+        ]
+        self.assertEqual(tokens_2, list(self.lexer.get_tokens(fragment_2)))