add antlr

lib/antlr4/include/RuleContextWithAltNum.h

@@ -0,0 +1,32 @@
+/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+
+#pragma once
+
+#include "ParserRuleContext.h"
+
+namespace antlr4 {
+
+  /// A handy class for use with
+  ///
+  ///  options {contextSuperClass=org.antlr.v4.runtime.RuleContextWithAltNum;}
+  ///
+  ///  that provides a backing field / impl for the outer alternative number
+  ///  matched for an internal parse tree node.
+  ///
+  ///  I'm only putting into Java runtime as I'm certain I'm the only one that
+  ///  will really every use this.
+  class ANTLR4CPP_PUBLIC RuleContextWithAltNum : public ParserRuleContext {
+  public:
+    size_t altNum = 0;
+
+    RuleContextWithAltNum();
+    RuleContextWithAltNum(ParserRuleContext *parent, int invokingStateNumber);
+
+    virtual size_t getAltNumber() const override;
+    virtual void setAltNumber(size_t altNum) override;
+  };
+
+} // namespace antlr4