table: move PIT iterator to a separate file

This commit only moves code around and renames variables.
There's no functional change.

refs #3164

Change-Id: Icb6b249cc0c07fcfe42f7a6d6987de31285566e7
diff --git a/daemon/table/pit-iterator.cpp b/daemon/table/pit-iterator.cpp
new file mode 100644
index 0000000..0cdb395
--- /dev/null
+++ b/daemon/table/pit-iterator.cpp
@@ -0,0 +1,72 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2016,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "pit-iterator.hpp"
+
+#include <boost/concept/assert.hpp>
+#include <boost/concept_check.hpp>
+#include <type_traits>
+
+namespace nfd {
+namespace pit {
+
+BOOST_CONCEPT_ASSERT((boost::ForwardIterator<Iterator>));
+static_assert(std::is_default_constructible<Iterator>::value,
+              "Iterator must be default-constructible");
+
+Iterator::Iterator()
+  : m_iPitEntry(0)
+{
+}
+
+Iterator::Iterator(const NameTree::const_iterator& ntIt)
+  : m_ntIt(ntIt)
+  , m_iPitEntry(0)
+{
+}
+
+Iterator&
+Iterator::operator++()
+{
+  ++m_iPitEntry;
+  if (m_iPitEntry < m_ntIt->getPitEntries().size()) {
+    return *this;
+  }
+
+  ++m_ntIt;
+  m_iPitEntry = 0;
+  return *this;
+}
+
+Iterator
+Iterator::operator++(int)
+{
+  Iterator copy = *this;
+  this->operator++();
+  return copy;
+}
+
+} // namespace pit
+} // namespace nfd