Issue #10272: Upgrade Java Grammar from ANTLR2 to ANTLR4

src/main/java/com/puppycrawl/tools/checkstyle/CheckstyleParserErrorStrategy.java

@@ -0,0 +1,41 @@
+////////////////////////////////////////////////////////////////////////////////
+// checkstyle: Checks Java source code for adherence to a set of rules.
+// Copyright (C) 2001-2021 the original author or authors.
+//
+// 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;
+
+import org.antlr.v4.runtime.BailErrorStrategy;
+import org.antlr.v4.runtime.InputMismatchException;
+import org.antlr.v4.runtime.Parser;
+import org.antlr.v4.runtime.Token;
+
+/**
+ * Extending BailErrorStrategy allows us to report errors while
+ * cancelling the parsing operation. If input is not syntactically
+ * correct, we do not need to use antlr's recovery strategy, which
+ * can add significant overhead.
+ *
+ */
+public class CheckstyleParserErrorStrategy extends BailErrorStrategy {
+
+    @Override
+    public Token recoverInline(Parser recognizer) {
+        reportError(recognizer, new InputMismatchException(recognizer));
+        return super.recoverInline(recognizer);
+    }
+}