Replace iterator_facade and iterator_adaptor with std iterators

Borrows the 'proxy reference' technique used in the boost templates

include/yaml-cpp/node/detail/iterator.h

@@ -10,7 +10,7 @@
 #include "yaml-cpp/dll.h"
 #include "yaml-cpp/node/ptr.h"
 #include "yaml-cpp/node/detail/node_iterator.h"
-#include <boost/iterator/iterator_adaptor.hpp>
+#include <iterator>
 
 namespace YAML {
 namespace detail {
@@ -18,13 +18,21 @@ struct iterator_value;
 
 template <typename V>
 class iterator_base
-    : public boost::iterator_adaptor<iterator_base<V>, node_iterator, V,
-                                     std::forward_iterator_tag, V> {
+    : public std::iterator<std::forward_iterator_tag, V, ptrdiff_t, V*, V> {
+
  private:
   template <typename>
   friend class iterator_base;
   struct enabler {};
-  typedef typename iterator_base::base_type base_type;
+  typedef node_iterator base_type;
+
+  struct proxy {
+    explicit proxy(const V& x) : m_ref(x) {}
+    V* operator->() { return std::addressof(m_ref); }
+    operator V*() { return std::addressof(m_ref); }
+
+    V m_ref;
+  };
 
  public:
   typedef typename iterator_base::value_type value_type;
@@ -32,22 +40,28 @@ class iterator_base
  public:
   iterator_base() {}
   explicit iterator_base(base_type rhs, shared_memory_holder pMemory)
-      : iterator_base::iterator_adaptor_(rhs), m_pMemory(pMemory) {}
+      : m_iterator(rhs), m_pMemory(pMemory) {}
 
   template <class W>
   iterator_base(const iterator_base<W>& rhs,
                 typename std::enable_if<std::is_convertible<W*, V*>::value,
                                           enabler>::type = enabler())
-      : iterator_base::iterator_adaptor_(rhs.base()),
-        m_pMemory(rhs.m_pMemory) {}
+      : m_iterator(rhs.m_iterator), m_pMemory(rhs.m_pMemory) {}
 
- private:
-  friend class boost::iterator_core_access;
+  iterator_base<V>& operator++() { ++m_iterator; return *this; }
 
-  void increment() { this->base_reference() = std::next(this->base()); }
+  template <typename W>
+  bool operator==(const iterator_base<W>& rhs) {
+    return m_iterator == rhs.m_iterator;
+  }
 
-  value_type dereference() const {
-    const typename base_type::value_type& v = *this->base();
+  template <typename W>
+  bool operator!=(const iterator_base<W>& rhs) {
+    return m_iterator != rhs.m_iterator;
+  }
+
+  value_type operator*() const {
+    const typename base_type::value_type& v = *m_iterator;
     if (v.pNode)
       return value_type(Node(*v, m_pMemory));
     if (v.first && v.second)
@@ -55,7 +69,12 @@ class iterator_base
     return value_type();
   }
 
+  value_type* operator->() const {
+    return proxy(**this);
+  }
+
  private:
+  base_type m_iterator;
   shared_memory_holder m_pMemory;
 };
 }

include/yaml-cpp/node/detail/node_iterator.h

@@ -9,7 +9,8 @@
 
 #include "yaml-cpp/dll.h"
 #include "yaml-cpp/node/ptr.h"
-#include <boost/iterator/iterator_facade.hpp>
+#include <iterator>
+#include <memory>
 #include <map>
 #include <utility>
 #include <vector>
@@ -51,12 +52,20 @@ struct node_iterator_type<const V> {
 
 template <typename V>
 class node_iterator_base
-    : public boost::iterator_facade<
-          node_iterator_base<V>, node_iterator_value<V>,
-          std::forward_iterator_tag, node_iterator_value<V> > {
+    : public std::iterator<
+          std::forward_iterator_tag, node_iterator_value<V>,
+          ptrdiff_t, node_iterator_value<V>*, node_iterator_value<V> > {
  private:
   struct enabler {};
 
+  struct proxy {
+    explicit proxy(const node_iterator_value<V>& x) : m_ref(x) {}
+    node_iterator_value<V>* operator->() { return std::addressof(m_ref); }
+    operator node_iterator_value<V>*() { return std::addressof(m_ref); }
+
+    node_iterator_value<V> m_ref;
+  };
+
  public:
   typedef typename node_iterator_type<V>::seq SeqIter;
   typedef typename node_iterator_type<V>::map MapIter;
@@ -86,13 +95,11 @@ class node_iterator_base
         m_mapIt(rhs.m_mapIt),
         m_mapEnd(rhs.m_mapEnd) {}
 
- private:
-  friend class boost::iterator_core_access;
   template <typename>
   friend class node_iterator_base;
 
   template <typename W>
-  bool equal(const node_iterator_base<W>& rhs) const {
+  bool operator==(const node_iterator_base<W>& rhs) const {
     if (m_type != rhs.m_type)
       return false;
 
@@ -107,7 +114,12 @@ class node_iterator_base
     return true;
   }
 
-  void increment() {
+  template <typename W>
+  bool operator!=(const node_iterator_base<W>& rhs) const {
+    return !(*this==rhs);
+  }
+
+  node_iterator_base<V>& operator++() {
     switch (m_type) {
       case iterator_type::None:
         break;
@@ -119,9 +131,10 @@ class node_iterator_base
         m_mapIt = increment_until_defined(m_mapIt);
         break;
     }
+    return *this;
   }
 
-  value_type dereference() const {
+  value_type operator*() const {
     switch (m_type) {
       case iterator_type::None:
         return value_type();
@@ -133,6 +146,10 @@ class node_iterator_base
     return value_type();
   }
 
+  value_type* operator->() const {
+    return proxy(**this);
+  }
+
   MapIter increment_until_defined(MapIter it) {
     while (it != m_mapEnd && !is_defined(it))
       ++it;