security: Add transformation sink/source

Change-Id: I2698f79f639c2bd7c3ce2e00f48be634dc4c983d
Refs: #3009
diff --git a/src/security/transform/transform-base.cpp b/src/security/transform/transform-base.cpp
new file mode 100644
index 0000000..85df6b9
--- /dev/null
+++ b/src/security/transform/transform-base.cpp
@@ -0,0 +1,110 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2016 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.
+ */
+
+#include "transform-base.hpp"
+
+namespace ndn {
+namespace security {
+namespace transform {
+
+Error::Error(size_t index, const std::string& what)
+  : std::runtime_error("Error in module " + std::to_string(index) + ": " + what)
+  , m_index(index)
+{
+}
+
+Downstream::Downstream()
+  : m_isEnd(false)
+{
+}
+
+size_t
+Downstream::write(const uint8_t* buf, size_t size)
+{
+  if (m_isEnd)
+    BOOST_THROW_EXCEPTION(Error(getIndex(), "Module is closed, no more input"));
+
+  size_t nBytesWritten = doWrite(buf, size);
+  BOOST_ASSERT(nBytesWritten <= size);
+  return nBytesWritten;
+}
+
+void
+Downstream::end()
+{
+  if (m_isEnd)
+    return;
+
+  m_isEnd = true;
+  return doEnd();
+}
+
+Upstream::Upstream()
+  : m_next(nullptr)
+{
+}
+
+void
+Upstream::appendChain(unique_ptr<Downstream> tail)
+{
+  if (m_next == nullptr) {
+    m_next = std::move(tail);
+  }
+  else {
+    BOOST_ASSERT(dynamic_cast<Transform*>(m_next.get()) != nullptr);
+    static_cast<Transform*>(m_next.get())->appendChain(std::move(tail));
+  }
+}
+
+Source::Source()
+  : m_nModules(1) // source per se is counted as one module
+{
+}
+
+void
+Source::pump()
+{
+  doPump();
+}
+
+Source&
+Source::operator>>(unique_ptr<Transform> transform)
+{
+  transform->setIndex(m_nModules);
+  m_nModules++;
+  this->appendChain(std::move(transform));
+
+  return *this;
+}
+
+void
+Source::operator>>(unique_ptr<Sink> sink)
+{
+  sink->setIndex(m_nModules);
+  m_nModules++;
+  this->appendChain(std::move(sink));
+
+  this->pump();
+}
+
+} // namespace transform
+} // namespace security
+} // namespace ndn