Fixed parsing errors for Unicode escape sequences. Thanks to Dinesh Bolkensteyn

for patch #3412812.

src/checkstyle/com/puppycrawl/tools/checkstyle/grammars/java.g

@@ -1671,7 +1671,7 @@ CHAR_LITERAL
 
 // string literals
 STRING_LITERAL
-	:	'"' (ESC|~('"'|'\\'))* '"'
+    :   '"' ( ESC | ~'"' )* '"'
 	;
 
 
@@ -1686,39 +1686,54 @@ STRING_LITERAL
 protected
 ESC
 	:	'\\'
-		(	'n'
-		|	'r'
-		|	't'
-		|	'b'
-		|	'f'
-		|	'"'
-		|	'\''
-		|	'\\'
-		|	('u')+ HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT
-		|	('0'..'3')
-			(
-				options {
-					warnWhenFollowAmbig = false;
-				}
-			:	('0'..'7')
-				(
-					options {
-						warnWhenFollowAmbig = false;
-					}
-				:	'0'..'7'
-				)?
-			)?
-		|	('4'..'7')
-			(
-				options {
-					warnWhenFollowAmbig = false;
-				}
-			:	('0'..'9')
-			)?
+		(
+			('u')+
+			(options { generateAmbigWarnings=false; }
+			:	'0' '0' '5' ('c'|'C')
+				(options { generateAmbigWarnings=false; }
+				:	'\\' ('u')+ '0' '0' '5' ('c'|'C')
+				|	STD_ESC
+				)
+			|	HEX_DIGIT HEX_DIGIT HEX_DIGIT HEX_DIGIT
+			)
+		|
+			STD_ESC
 		)
 	;
 
 
+protected
+STD_ESC
+	:	'n'
+	|	'r'
+	|	't'
+	|	'b'
+	|	'f'
+	|	'"'
+	|	'\''
+	|	'\\'
+	|	('0'..'3')
+		(
+			options {
+				warnWhenFollowAmbig = false;
+			}
+		:	('0'..'7')
+			(
+				options {
+					warnWhenFollowAmbig = false;
+				}
+			:	'0'..'7'
+			)?
+		)?
+	|	('4'..'7')
+		(
+			options {
+				warnWhenFollowAmbig = false;
+			}
+		:	('0'..'9')
+		)?
+	;
+
 // hexadecimal digit (again, note it's protected!)
 protected
 HEX_DIGIT

src/testinputs/com/puppycrawl/tools/checkstyle/grammars/UnicodeEscape.java

@@ -0,0 +1,32 @@
+package com.puppycrawl.tools.checkstyle.grammars;
+
+/**
+ * Input for unicode escapes.
+ */
+public class UnicodeEscape
+{
+    char a = '\u005cr';
+    char b = '\u005cn';
+    char c = '\u005ct';
+    char d = '\uuuu005cn';
+    char e = '\u005c\u005c';
+    char f = '\u005c'';
+    char g = '"';
+    String h = "\u005c"";
+    String i = "'";
+    char j = '\"';
+    String k = "\'";
+    char l = '\u005C'';
+    char m = '\uABCD';
+    char n = '\u00AB';
+    char o = '\u005B';
+    char p = '\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu005cr'; // Tests the lookahead
+    char q = '\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu005D';
+    
+    char wtf1 = '\u005c\u005c'; // This is a legal backslash
+    String wtf2 = "\\u005c";    // = "\u005c", with a single backslash, and != a backslash!
+                                // There is an ambiguity in the grammar, the interpretation is done as "\\" + "u005c"
+    //char wtf3 = '\\u005c';    // This is therefore, illegal
+
+    //char z = '\u005cu005c'; /* This is illegal */
+}

src/tests/com/puppycrawl/tools/checkstyle/grammars/UnicodeEscapeTest.java

@@ -0,0 +1,43 @@
+////////////////////////////////////////////////////////////////////////////////
+// checkstyle: Checks Java source code for adherence to a set of rules.
+// Copyright (C) 2001-2011  Oliver Burn
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+////////////////////////////////////////////////////////////////////////////////
+package com.puppycrawl.tools.checkstyle.grammars;
+
+import com.puppycrawl.tools.checkstyle.BaseCheckTestSupport;
+import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
+import com.puppycrawl.tools.checkstyle.checks.naming.MemberNameCheck;
+
+import org.junit.Test;
+
+/**
+ * Tests that extended unicode escapes can be parsed.
+ * @author Dinesh Bolkensteyn (SonarSource)
+ */
+public class UnicodeEscapeTest
+    extends BaseCheckTestSupport
+{
+    @Test
+    public void testCanParse()
+        throws Exception
+    {
+        final DefaultConfiguration checkConfig =
+            createCheckConfig(MemberNameCheck.class);
+        final String[] expected = {};
+        verify(checkConfig, getPath("grammars/UnicodeEscape.java"), expected);
+    }
+}

src/xdocs/releasenotes.xml

@@ -39,6 +39,10 @@
           treats setxYz() as a setter for xYz, and setXYz() as a setter for
           XYz property to comply JavaBeans specification (bug #3370946).
         </li>
+        <li>
+          Fixed parsing errors for Unicode escape sequences. Thanks to
+          Dinesh Bolkensteyn for patch #3412812.
+        </li>
       </ul>
       <p>Notes:</p>
       <ul>