Simplify some code with Boost.Operators

Change-Id: Ic873bcbaf6be00d5c35601cfc8090df534d815ee
diff --git a/daemon/table/fib.cpp b/daemon/table/fib.cpp
index f30b976..87e180a 100644
--- a/daemon/table/fib.cpp
+++ b/daemon/table/fib.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -27,12 +27,8 @@
 #include "pit-entry.hpp"
 #include "measurements-entry.hpp"
 
-#include <ndn-cxx/util/concepts.hpp>
-
 namespace nfd::fib {
 
-NDN_CXX_ASSERT_FORWARD_ITERATOR(Fib::const_iterator);
-
 const unique_ptr<Entry> Fib::s_emptyEntry = make_unique<Entry>(Name());
 
 static inline bool
diff --git a/daemon/table/name-tree-iterator.cpp b/daemon/table/name-tree-iterator.cpp
index 24c1422..b085bb7 100644
--- a/daemon/table/name-tree-iterator.cpp
+++ b/daemon/table/name-tree-iterator.cpp
@@ -27,14 +27,8 @@
 #include "name-tree.hpp"
 #include "common/logger.hpp"
 
-#include <boost/range/concepts.hpp>
-#include <ndn-cxx/util/concepts.hpp>
-
 namespace nfd::name_tree {
 
-NDN_CXX_ASSERT_FORWARD_ITERATOR(Iterator);
-BOOST_CONCEPT_ASSERT((boost::ForwardRangeConcept<Range>));
-
 NFD_LOG_INIT(NameTreeIterator);
 
 Iterator::Iterator() = default;
@@ -56,14 +50,6 @@
   return *this;
 }
 
-Iterator
-Iterator::operator++(int)
-{
-  Iterator copy = *this;
-  this->operator++();
-  return copy;
-}
-
 std::ostream&
 operator<<(std::ostream& os, const Iterator& i)
 {
diff --git a/daemon/table/name-tree-iterator.hpp b/daemon/table/name-tree-iterator.hpp
index fef3e6e..2399826 100644
--- a/daemon/table/name-tree-iterator.hpp
+++ b/daemon/table/name-tree-iterator.hpp
@@ -28,6 +28,7 @@
 
 #include "name-tree-hashtable.hpp"
 
+#include <boost/operators.hpp>
 #include <boost/range/iterator_range_core.hpp>
 
 namespace nfd::name_tree {
@@ -74,15 +75,9 @@
 /**
  * \brief NameTree iterator.
  */
-class Iterator
+class Iterator : public boost::forward_iterator_helper<Iterator, const Entry>
 {
 public:
-  using iterator_category = std::forward_iterator_tag;
-  using value_type        = const Entry;
-  using difference_type   = std::ptrdiff_t;
-  using pointer           = value_type*;
-  using reference         = value_type&;
-
   Iterator();
 
   Iterator(shared_ptr<EnumerationImpl> impl, const Entry* ref);
@@ -94,31 +89,15 @@
     return *m_entry;
   }
 
-  const Entry*
-  operator->() const noexcept
-  {
-    BOOST_ASSERT(m_impl != nullptr);
-    return m_entry;
-  }
-
   Iterator&
   operator++();
 
-  Iterator
-  operator++(int);
-
   friend bool
   operator==(const Iterator& lhs, const Iterator& rhs) noexcept
   {
     return lhs.m_entry == rhs.m_entry;
   }
 
-  friend bool
-  operator!=(const Iterator& lhs, const Iterator& rhs) noexcept
-  {
-    return !(lhs == rhs);
-  }
-
 private:
   /** \brief Enumeration implementation; nullptr for end iterator.
    */
diff --git a/daemon/table/pit-iterator.cpp b/daemon/table/pit-iterator.cpp
index f0d0c8a..f3680f8 100644
--- a/daemon/table/pit-iterator.cpp
+++ b/daemon/table/pit-iterator.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -25,18 +25,8 @@
 
 #include "pit-iterator.hpp"
 
-#include <ndn-cxx/util/concepts.hpp>
-
 namespace nfd::pit {
 
-NDN_CXX_ASSERT_FORWARD_ITERATOR(Iterator);
-
-Iterator::Iterator(const NameTree::const_iterator& ntIt, size_t iPitEntry)
-  : m_ntIt(ntIt)
-  , m_iPitEntry(iPitEntry)
-{
-}
-
 Iterator&
 Iterator::operator++()
 {
@@ -48,16 +38,7 @@
     m_iPitEntry = 0;
     BOOST_ASSERT(m_ntIt == NameTree::const_iterator() || m_ntIt->hasPitEntries());
   }
-
   return *this;
 }
 
-Iterator
-Iterator::operator++(int)
-{
-  Iterator copy = *this;
-  this->operator++();
-  return copy;
-}
-
 } // namespace nfd::pit
diff --git a/daemon/table/pit-iterator.hpp b/daemon/table/pit-iterator.hpp
index bfe0e8e..e1647ff 100644
--- a/daemon/table/pit-iterator.hpp
+++ b/daemon/table/pit-iterator.hpp
@@ -34,42 +34,32 @@
 /**
  * \brief PIT iterator.
  */
-class Iterator
+class Iterator : public boost::forward_iterator_helper<Iterator, const Entry>
 {
 public:
-  using iterator_category = std::forward_iterator_tag;
-  using value_type        = const Entry;
-  using difference_type   = std::ptrdiff_t;
-  using pointer           = value_type*;
-  using reference         = value_type&;
-
-  /** \brief Constructor.
-   *  \param ntIt a name tree iterator that visits name tree entries with one or more PIT entries
-   *  \param iPitEntry make this iterator to dereference to the i-th PIT entry in name tree entry
+  /**
+   * \brief Constructor.
+   * \param ntIt a name tree iterator that visits name tree entries with one or more PIT entries
+   * \param iPitEntry make this iterator to dereference to the i-th PIT entry in name tree entry
    */
   explicit
-  Iterator(const NameTree::const_iterator& ntIt = {}, size_t iPitEntry = 0);
-
-  const Entry&
-  operator*() const
+  Iterator(const NameTree::const_iterator& ntIt = {}, size_t iPitEntry = 0)
+    : m_ntIt(ntIt)
+    , m_iPitEntry(iPitEntry)
   {
-    return *this->operator->();
   }
 
-  const shared_ptr<Entry>&
-  operator->() const
+  const Entry&
+  operator*() const noexcept
   {
     BOOST_ASSERT(m_ntIt != NameTree::const_iterator());
     BOOST_ASSERT(m_iPitEntry < m_ntIt->getPitEntries().size());
-    return m_ntIt->getPitEntries()[m_iPitEntry];
+    return *m_ntIt->getPitEntries()[m_iPitEntry];
   }
 
   Iterator&
   operator++();
 
-  Iterator
-  operator++(int);
-
   friend bool
   operator==(const Iterator& lhs, const Iterator& rhs) noexcept
   {
@@ -77,12 +67,6 @@
            lhs.m_iPitEntry == rhs.m_iPitEntry;
   }
 
-  friend bool
-  operator!=(const Iterator& lhs, const Iterator& rhs) noexcept
-  {
-    return !(lhs == rhs);
-  }
-
 private:
   NameTree::const_iterator m_ntIt; ///< current name tree entry
   size_t m_iPitEntry; ///< current PIT entry within m_ntIt->getPitEntries()
diff --git a/daemon/table/strategy-choice.cpp b/daemon/table/strategy-choice.cpp
index cefb245..c7b7a1a 100644
--- a/daemon/table/strategy-choice.cpp
+++ b/daemon/table/strategy-choice.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -30,12 +30,8 @@
 #include "common/logger.hpp"
 #include "fw/strategy.hpp"
 
-#include <ndn-cxx/util/concepts.hpp>
-
 namespace nfd::strategy_choice {
 
-NDN_CXX_ASSERT_FORWARD_ITERATOR(StrategyChoice::const_iterator);
-
 NFD_LOG_INIT(StrategyChoice);
 
 using fw::Strategy;