Fix a catastrophic backtracking bug in JavaLexer (#1594)

* JavaLexer: Demonstrate a catastrophic backtracking bug

* JavaLexer: Fix a catastrophic backtracking bug

Closes #1586

1 files changed, 24 insertions, 1 deletions

diff --git a/tests/test_java.py b/tests/test_java.py
index 3baec0ad..f7b16bd7 100644
--- a/tests/test_java.py
+++ b/tests/test_java.py
@@ -7,9 +7,11 @@
     :license: BSD, see LICENSE for details.
 """
 
+import time
+
 import pytest
 
-from pygments.token import Text, Name, Punctuation, Keyword, Number
+from pygments.token import Keyword, Name, Number, Punctuation, String, Text
 from pygments.lexers import JavaLexer
 
 
@@ -76,3 +78,24 @@ def test_numeric_literals(lexer):
         (Text, '\n')
     ]
     assert list(lexer.get_tokens(fragment)) == tokens
+
+
+@pytest.mark.parametrize(
+    'text',
+    (
+        '""', '"abc"', '"ひらがな"', '"123"',
+        '"\\\\"', '"\\t"' '"\\""',
+    ),
+)
+def test_string_literals_positive_match(lexer, text):
+    """Test positive matches for string literals."""
+    tokens = list(lexer.get_tokens_unprocessed(text))
+    assert all([token is String for _, token, _ in tokens])
+    assert ''.join([value for _, _, value in tokens]) == text
+
+
+def test_string_literals_backtracking(lexer):
+    """Test catastrophic backtracking for string literals."""
+    start_time = time.time()
+    list(lexer.get_tokens_unprocessed('"' + '\\' * 100))
+    assert time.time() - start_time < 1, 'possible backtracking bug'