util: Exposing IndentedStream class as part of public API
Change-Id: I2162a1c3e463f76e4192baf2eb618afd73082781
Refs: #2238
diff --git a/src/util/indented-stream.hpp b/src/util/indented-stream.hpp
new file mode 100644
index 0000000..0ab76a2
--- /dev/null
+++ b/src/util/indented-stream.hpp
@@ -0,0 +1,82 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 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_UTIL_INDENTED_STREAM_HPP
+#define NDN_UTIL_INDENTED_STREAM_HPP
+
+#include <ostream>
+#include <sstream>
+#include <string>
+
+namespace ndn {
+namespace util {
+
+/**
+ * @brief Output to stream with specified indent or prefix
+ *
+ * For example, the following code:
+ *
+ * std::cout << "Hello" << std::endl;
+ * IndentedStream os1(std::cout, " [prefix] ");
+ * os1 << "," << "\n";
+ * {
+ * IndentedStream os2(os1, " [another prefix] ");
+ * os2 << "World!" << "\n";
+ * }
+ * // either os1 needs to go out of scope or call os1.flush()
+ *
+ * Will produce the following output:
+ *
+ * Hello
+ * [prefix] ,
+ * [prefix] [another prefix] World!
+ *
+ * Based on http://stackoverflow.com/a/2212940/2150331
+ */
+class IndentedStream : public std::ostream
+{
+public:
+ IndentedStream(std::ostream& os, const std::string& indent);
+
+ ~IndentedStream();
+
+private:
+ // Write a stream buffer that prefixes each line
+ class StreamBuf : public std::stringbuf
+ {
+ public:
+ StreamBuf(std::ostream& os, const std::string& indent);
+
+ virtual int
+ sync();
+
+ private:
+ std::ostream& m_output;
+ std::string m_indent;
+ };
+
+ StreamBuf m_buffer;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_INDENTED_STREAM_HPP