encoding: Refactoring EncodingBuffer

Breaks: nfd:commit:c0273e3505ac2ccf843401be77a513d8eb663127
Breaks: ChronoSync:commit:e042f83a1df184a8e7a90ef00034d11026891cd1

Change-Id: I8275c6276c5ecfa280f87f584189907521febf5f
Refs: #2494, #2490
diff --git a/src/encoding/encoding-buffer-fwd.hpp b/src/encoding/encoding-buffer-fwd.hpp
new file mode 100644
index 0000000..359864f
--- /dev/null
+++ b/src/encoding/encoding-buffer-fwd.hpp
@@ -0,0 +1,58 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2015 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx 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 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx 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 copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_ENCODING_ENCODING_BUFFER_FWD_HPP
+#define NDN_ENCODING_ENCODING_BUFFER_FWD_HPP
+
+namespace ndn {
+namespace encoding {
+
+typedef bool Tag;
+
+/**
+ * @brief Tag for EncodingImpl to indicate that Encoder is requested
+ * Implementation of the tag may change to class. Use of true directly
+ * as a template parameter is discouraged.
+ */
+static const Tag EncoderTag = true;
+
+/**
+ * @brief Tag for EncodingImpl to indicate that Estimator is requested
+ * Implementation of the tag may change to class. Use of false directly
+ * as a template parameter is discouraged.
+ */
+static const Tag EstimatorTag = false;
+
+template<Tag TAG>
+class EncodingImpl;
+
+typedef EncodingImpl<EncoderTag> EncodingBuffer;
+typedef EncodingImpl<EstimatorTag> EncodingEstimator;
+
+} // namespace encoding
+
+using encoding::EncodingImpl;
+using encoding::EncodingBuffer;
+using encoding::EncodingEstimator;
+
+} // namespace ndn
+
+#endif // NDN_ENCODING_ENCODING_BUFFER_FWD_HPP