add antlr

lib/antlr4/include/ANTLRFileStream.h

@@ -0,0 +1,27 @@
+/* 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 "ANTLRInputStream.h"
+
+namespace antlr4 {
+
+  /// This is an ANTLRInputStream that is loaded from a file all at once
+  /// when you construct the object (or call load()).
+  // TODO: this class needs testing.
+  class ANTLR4CPP_PUBLIC ANTLRFileStream : public ANTLRInputStream {
+  protected:
+    std::string _fileName; // UTF-8 encoded file name.
+
+  public:
+    // Assumes a file name encoded in UTF-8 and file content in the same encoding (with or w/o BOM).
+    ANTLRFileStream(const std::string &fileName);
+
+    virtual void loadFromFile(const std::string &fileName);
+    virtual std::string getSourceName() const override;
+  };
+
+} // namespace antlr4