From eb06c122d1ea9d2e63fd9a7ae44b44b6f6f0bfd4 Mon Sep 17 00:00:00 2001
From: Jeremy Siek <jeremy.siek@gmail.com>
Date: Sun, 18 Mar 2001 18:37:49 +0000
Subject: [PATCH] rigged new iterator_traits for backward compatibility

[SVN r9577]
---
 development/boost/iterator_concepts.hpp     | 169 +++++---------------
 development/boost/iterator_traits.hpp       | 123 +++++++++++---
 development/libs/iterator/concept_tests.cpp |  66 +++++++-
 3 files changed, 205 insertions(+), 153 deletions(-)

diff --git a/development/boost/iterator_concepts.hpp b/development/boost/iterator_concepts.hpp
index acea6e3..a3ddc8b 100644
--- a/development/boost/iterator_concepts.hpp
+++ b/development/boost/iterator_concepts.hpp
@@ -3,6 +3,8 @@
 
 #include <boost/concept_check.hpp>
 #include <boost/iterator_traits.hpp>
+#include <boost/type_traits/conversion_traits.hpp>
+#include <boost/static_assert.hpp>
 
 namespace boost_concepts {
   // Used a different namespace here (instead of "boost") so that the
@@ -11,6 +13,7 @@ namespace boost_concepts {
 
 
   //===========================================================================
+  // Iterator Access Concepts
 
   template <typename Iterator>
   class ReadableIteratorConcept {
@@ -23,11 +26,12 @@ namespace boost_concepts {
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
       boost::function_requires< boost::EqualityComparableConcept<Iterator> >();
-      boost::function_requires< boost::DefaultConstructibleConcept<Iterator> >();
-      
       boost::function_requires< 
-        boost::ConvertibleConcept<return_category, boost::readable_iterator_tag> >();
-
+        boost::DefaultConstructibleConcept<Iterator> >();
+      
+      BOOST_STATIC_ASSERT((boost::is_convertible<return_category*,
+                           boost::readable_iterator_tag*>::value));
+                          
       reference r = *i; // or perhaps read(x)
       value_type v(r);
       boost::ignore_unused_variable_warning(v);
@@ -44,10 +48,11 @@ namespace boost_concepts {
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
       boost::function_requires< boost::EqualityComparableConcept<Iterator> >();
-      boost::function_requires< boost::DefaultConstructibleConcept<Iterator> >();
-      
       boost::function_requires< 
-        boost::ConvertibleConcept<return_category, boost::writable_iterator_tag> >();
+        boost::DefaultConstructibleConcept<Iterator> >();
+      
+      BOOST_STATIC_ASSERT((boost::is_convertible<return_category*,
+                           boost::writable_iterator_tag*>::value));
 
       *i = v; // an alternative could be something like write(x, v)
     }
@@ -65,12 +70,12 @@ namespace boost_concepts {
 
     void constraints() {
       boost::function_requires< ReadableIteratorConcept<Iterator> >();
-      
-      boost::function_requires< 
-        boost::ConvertibleConcept<return_category, 
-          boost::constant_lvalue_iterator_tag> >();
 
-      typedef typename boost::require_same<reference, const value_type&>::type req;
+      BOOST_STATIC_ASSERT((boost::is_convertible<return_category*, 
+                           boost::constant_lvalue_iterator_tag*>::value));
+
+      BOOST_STATIC_ASSERT((boost::is_same<reference, 
+                           const value_type&>::value));
 
       reference v = *i;
       boost::ignore_unused_variable_warning(v);
@@ -88,13 +93,13 @@ namespace boost_concepts {
 
     void constraints() {
       boost::function_requires< ReadableIteratorConcept<Iterator> >();
-      boost::function_requires< WritableIteratorConcept<Iterator, value_type> >();
-      
       boost::function_requires< 
-        boost::ConvertibleConcept<return_category, 
-          boost::constant_lvalue_iterator_tag> >();
+        WritableIteratorConcept<Iterator, value_type> >();
+      
+      BOOST_STATIC_ASSERT((boost::is_convertible<return_category*, 
+                           boost::mutable_lvalue_iterator_tag*>::value));
 
-      typedef typename boost::require_same<reference, value_type&>::type req;
+      BOOST_STATIC_ASSERT((boost::is_same<reference, value_type&>::value));
 
       reference v = *i;
       boost::ignore_unused_variable_warning(v);
@@ -103,24 +108,25 @@ namespace boost_concepts {
   };
   
   //===========================================================================
+  // Iterator Traversal Concepts
 
   template <typename Iterator>
   class SinglePassIteratorConcept {
   public:
-    typedef typename boost::iterator_traits<Iterator>::motion_category 
-      motion_category;
+    typedef typename boost::iterator_traits<Iterator>::traversal_category 
+      traversal_category;
     typedef typename boost::iterator_traits<Iterator>::difference_type
       difference_type;
 
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
       boost::function_requires< boost::EqualityComparableConcept<Iterator> >();
-      boost::function_requires< boost::DefaultConstructibleConcept<Iterator> >();
-
       boost::function_requires< 
-        boost::ConvertibleConcept<motion_category, 
-          boost::single_pass_iterator_tag> >();
-      
+        boost::DefaultConstructibleConcept<Iterator> >();
+
+      BOOST_STATIC_ASSERT((boost::is_convertible<traversal_category*, 
+                           boost::single_pass_iterator_tag*>::value));
+
       // difference_type must be a signed integral type
 
       ++i;
@@ -133,30 +139,28 @@ namespace boost_concepts {
   template <typename Iterator>
   class ForwardIteratorConcept {
   public:
-    typedef typename boost::iterator_traits<Iterator>::motion_category 
-      motion_category;
+    typedef typename boost::iterator_traits<Iterator>::traversal_category 
+      traversal_category;
 
     void constraints() {
       boost::function_requires< SinglePassIteratorConcept<Iterator> >();
 
-      boost::function_requires< 
-        boost::ConvertibleConcept<motion_category, 
-          boost::forward_iterator_tag> >();
+      BOOST_STATIC_ASSERT((boost::is_convertible<traversal_category*, 
+                           boost::forward_iterator_tag*>::value));
     }
   };
   
   template <typename Iterator>
   class BidirectionalIteratorConcept {
   public:
-    typedef typename boost::iterator_traits<Iterator>::motion_category 
-      motion_category;
+    typedef typename boost::iterator_traits<Iterator>::traversal_category 
+      traversal_category;
 
     void constraints() {
       boost::function_requires< ForwardIteratorConcept<Iterator> >();
       
-      boost::function_requires< 
-        boost::ConvertibleConcept<motion_category, 
-          boost::bidirectional_iterator_tag> >();
+      BOOST_STATIC_ASSERT((boost::is_convertible<traversal_category*, 
+                           boost::bidirectional_iterator_tag*>::value));
 
       --i;
       (void)i--;
@@ -167,18 +171,17 @@ namespace boost_concepts {
   template <typename Iterator>
   class RandomAccessIteratorConcept {
   public:
-    typedef typename boost::iterator_traits<Iterator>::motion_category 
-      motion_category;
+    typedef typename boost::iterator_traits<Iterator>::traversal_category 
+      traversal_category;
     typedef typename boost::iterator_traits<Iterator>::difference_type
       difference_type;
 
     void constraints() {
       boost::function_requires< BidirectionalIteratorConcept<Iterator> >();
 
-      boost::function_requires< 
-        boost::ConvertibleConcept<motion_category, 
-          boost::random_access_iterator_tag> >();
-
+      BOOST_STATIC_ASSERT((boost::is_convertible<traversal_category*, 
+                           boost::random_access_iterator_tag*>::value));
+      
       i += n;
       i = i + n;
       i = n + i;
@@ -190,92 +193,6 @@ namespace boost_concepts {
     Iterator i, j;
   };
 
-  //===========================================================================
-
-  template <typename Iterator>
-  class ReadableRandomAccessIteratorConcept {
-  public:
-    typedef typename boost::iterator_traits<Iterator>::value_type value_type;
-    typedef typename boost::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::iterator_traits<Iterator>::difference_type
-      difference_type;
-
-    void constraints() {
-      boost::function_requires< RandomAccessIteratorConcept<Iterator> >();
-      boost::function_requires< ReadableIteratorConcept<Iterator> >();
-      
-      reference r = i[n];
-      value_type v(r);
-      boost::ignore_unused_variable_warning(v);
-    }
-    difference_type n;
-    Iterator i;
-  };
-
-  template <typename Iterator>
-  class WritableRandomAccessIteratorConcept {
-  public:
-    typedef typename boost::iterator_traits<Iterator>::value_type value_type;
-    typedef typename boost::iterator_traits<Iterator>::difference_type
-      difference_type;
-
-    void constraints() {
-      boost::function_requires< RandomAccessIteratorConcept<Iterator> >();
-      boost::function_requires< WritableIteratorConcept<Iterator, value_type> >();
-
-      i[n] = v;
-      boost::ignore_unused_variable_warning(v);
-    }
-    difference_type n;
-    value_type v;
-    Iterator i;
-  };
-
-  template <typename Iterator>
-  class ConstantLvalueRandomAccessIteratorConcept {
-  public:
-    typedef typename boost::iterator_traits<Iterator>::value_type value_type;
-    typedef typename boost::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::iterator_traits<Iterator>::difference_type
-      difference_type;
-
-    void constraints() {
-      boost::function_requires< RandomAccessIteratorConcept<Iterator> >();
-      boost::function_requires< ReadableIteratorConcept<Iterator> >();
-
-      typedef typename boost::require_same<reference, const value_type&>::type req;
-
-      reference v = i[n];
-      boost::ignore_unused_variable_warning(v);
-    }
-    difference_type n;
-    value_type v;
-    Iterator i;
-  };
-  
-  template <typename Iterator>
-  class MutableLvalueRandomAccessIteratorConcept {
-  public:
-    typedef typename boost::iterator_traits<Iterator>::value_type value_type;
-    typedef typename boost::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::iterator_traits<Iterator>::difference_type
-      difference_type;
-
-    void constraints() {
-      boost::function_requires< RandomAccessIteratorConcept<Iterator> >();
-      boost::function_requires< WritableIteratorConcept<Iterator, value_type> >();
-      boost::function_requires< ReadableIteratorConcept<Iterator> >();
-
-      typedef typename boost::require_same<reference, value_type&>::type req;
-
-      reference v = i[n];
-      boost::ignore_unused_variable_warning(v);
-    }
-    difference_type n;
-    value_type v;
-    Iterator i;
-  };
-  
 } // namespace boost_concepts
 
 
diff --git a/development/boost/iterator_traits.hpp b/development/boost/iterator_traits.hpp
index 585f194..6f5d9b2 100644
--- a/development/boost/iterator_traits.hpp
+++ b/development/boost/iterator_traits.hpp
@@ -2,21 +2,14 @@
 #define BOOST_ITERATOR_TRAITS_HPP
 
 #include <boost/config.hpp>
-#include <boost/type_traits.hpp>
+#include <boost/type_traits/conversion_traits.hpp>
+#include <boost/type_traits/cv_traits.hpp>
+#include <boost/pending/ct_if.hpp>
+#include <boost/detail/iterator.hpp>
 
 namespace boost {
-  
-  template <typename Iterator>
-  struct iterator_traits {
-    typedef typename Iterator::value_type value_type;
-    typedef typename Iterator::reference reference;
-    typedef typename Iterator::pointer pointer;
-    typedef typename Iterator::difference_type difference_type;
-    typedef typename Iterator::return_category return_category;
-    typedef typename Iterator::motion_category motion_category;
-  };
 
-  // Motion Categories
+  // Traversal Categories
   struct single_pass_iterator_tag { };
   struct forward_iterator_tag : public single_pass_iterator_tag { };
   struct bidirectional_iterator_tag : public forward_iterator_tag { };
@@ -28,29 +21,113 @@ namespace boost {
   struct mutable_lvalue_iterator_tag : virtual public writable_iterator_tag,
     virtual public readable_iterator_tag { };
   struct constant_lvalue_iterator_tag : public readable_iterator_tag { };
-  
-#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
+
+  struct error_iterator_tag { };
+
+  // Inherit from iterator_base if your iterator defines its own
+  // return_category and traversal_category. Otherwise, the "old style"
+  // iterator category will be mapped to the return_category and
+  // traversal_category.
+  struct new_iterator_base { };
 
   namespace detail {
-    template <bool IsConst>
-    struct pointer_return_category {
-      typedef constant_lvalue_iterator_tag type;
+
+    struct iter_traits_from_nested_types {
+      template <typename Iterator> struct bind {
+        typedef typename Iterator::value_type value_type;
+        typedef typename Iterator::reference reference;
+        typedef typename Iterator::pointer pointer;
+        typedef typename Iterator::difference_type difference_type;
+        typedef typename Iterator::return_category return_category;
+        typedef typename Iterator::traversal_category traversal_category;
+      };
     };
-    template <>
-    struct pointer_return_category<false> {
-      typedef mutable_lvalue_iterator_tag type;
+
+    template <typename ValueType>
+    struct choose_lvalue_return {
+      typedef typename ct_if<is_const<ValueType>::value,
+			     boost::constant_lvalue_iterator_tag,
+			     boost::mutable_lvalue_iterator_tag>::type type;
     };
+    
+    
+    template <typename Category, typename ValueType>
+    struct iter_category_to_return {
+      typedef typename ct_if<
+        is_convertible<Category*, std::forward_iterator_tag*>::value,
+        typename choose_lvalue_return<ValueType>::type,
+        typename ct_if<
+          is_convertible<Category*, std::input_iterator_tag*>::value,
+          boost::readable_iterator_tag,
+          typename ct_if<
+            is_convertible<Category*, std::output_iterator_tag*>::value,
+            boost::writable_iterator_tag,
+            boost::error_iterator_tag
+          >::type
+       >::type
+      >::type type;
+    };
+
+    template <typename Category>
+    struct iter_category_to_traversal {
+      typedef typename ct_if<
+        is_convertible<Category*, std::random_access_iterator_tag*>::value,
+        boost::random_access_iterator_tag,
+        typename ct_if<
+          is_convertible<Category*, std::bidirectional_iterator_tag*>::value,
+          boost::bidirectional_iterator_tag,
+          typename ct_if<
+            is_convertible<Category*, std::forward_iterator_tag*>::value,
+            boost::forward_iterator_tag,
+            boost::single_pass_iterator_tag>::type
+          >::type
+        >::type type;
+    };
+
+    struct iter_traits_from_old_traits {
+      template <typename Iterator> class bind {
+        typedef boost::detail::iterator_traits<Iterator> OldTraits;
+        typedef typename OldTraits::iterator_category Cat;
+      public:
+        typedef typename OldTraits::value_type value_type;
+        typedef typename OldTraits::reference reference;
+        typedef typename OldTraits::pointer pointer;
+        typedef typename OldTraits::difference_type difference_type;
+        typedef iter_category_to_return<Cat,value_type>::type return_category;
+        typedef iter_category_to_traversal<Cat>::type traversal_category;
+      };      
+    };
+
+    template <typename Iterator>
+    class choose_iter_traits {
+      typedef typename ct_if<is_convertible<Iterator*,
+                                            new_iterator_base*>::value,
+                             iter_traits_from_nested_types,
+                             iter_traits_from_old_traits>::type Choice;
+    public:
+      typedef typename Choice:: template bind<Iterator> type;
+    };
+    
   } // namespace detail
+  
+  template <typename Iterator>
+  class iterator_traits
+    : public detail::choose_iter_traits<Iterator>::type { };
+
+#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
 
   template <typename T>
-  struct iterator_traits<T*> {
+  struct iterator_traits<T*>
+  {
     typedef T value_type;
     typedef T& reference;
     typedef T* pointer;
     typedef std::ptrdiff_t difference_type;
-    typedef typename detail::pointer_return_category<is_const<T>::value>::type
+    typedef typename ct_if<is_const<T>::value,
+			   boost::constant_lvalue_iterator_tag,
+			   boost::mutable_lvalue_iterator_tag>::type
       return_category;
-    typedef random_access_iterator_tag motion_category;
+    typedef boost::random_access_iterator_tag traversal_category;
   };
 
 #endif
diff --git a/development/libs/iterator/concept_tests.cpp b/development/libs/iterator/concept_tests.cpp
index 9ef2ed9..032e889 100644
--- a/development/libs/iterator/concept_tests.cpp
+++ b/development/libs/iterator/concept_tests.cpp
@@ -1,13 +1,71 @@
 #include <boost/iterator_concepts.hpp>
+#include <boost/operators.hpp>
+
+struct new_iterator
+  : public boost::iterator<std::random_access_iterator_tag, int>,
+    public boost::new_iterator_base
+{
+  typedef boost::random_access_iterator_tag traversal_category;
+  typedef boost::mutable_lvalue_iterator_tag return_category;
+
+  int& operator*() const { return *m_x; }
+  new_iterator& operator++() { return *this; }
+  new_iterator operator++(int) { return *this; }
+  new_iterator& operator--() { return *this; }
+  new_iterator operator--(int) { return *this; }
+  new_iterator& operator+=(std::ptrdiff_t) { return *this; }
+  new_iterator operator+(std::ptrdiff_t) { return *this; }
+  new_iterator& operator-=(std::ptrdiff_t) { return *this; }
+  std::ptrdiff_t operator-(const new_iterator&) const { return 0; }
+  new_iterator operator-(std::ptrdiff_t) const { return *this; }
+  bool operator==(const new_iterator&) const { return false; }
+  bool operator!=(const new_iterator&) const { return false; }
+  bool operator<(const new_iterator&) const { return false; }
+  int* m_x;
+};
+new_iterator operator+(std::ptrdiff_t, new_iterator x) { return x; }
+
+struct old_iterator
+  : public boost::iterator<std::random_access_iterator_tag, int>
+{
+  int& operator*() const { return *m_x; }
+  old_iterator& operator++() { return *this; }
+  old_iterator operator++(int) { return *this; }
+  old_iterator& operator--() { return *this; }
+  old_iterator operator--(int) { return *this; }
+  old_iterator& operator+=(std::ptrdiff_t) { return *this; }
+  old_iterator operator+(std::ptrdiff_t) { return *this; }
+  old_iterator& operator-=(std::ptrdiff_t) { return *this; }
+  old_iterator operator-(std::ptrdiff_t) const { return *this; }
+  std::ptrdiff_t operator-(const old_iterator&) const { return 0; }
+  bool operator==(const old_iterator&) const { return false; }
+  bool operator!=(const old_iterator&) const { return false; }
+  bool operator<(const old_iterator&) const { return false; }
+  int* m_x;
+};
+old_iterator operator+(std::ptrdiff_t, old_iterator x) { return x; }
 
 int
 main()
 {
-  boost::function_requires< 
-    boost_concepts::MutableLvalueRandomAccessIteratorConcept<int*> >();
+  boost::function_requires<
+    boost_concepts::MutableLvalueIteratorConcept<int*> >();
+  boost::function_requires<
+    boost_concepts::RandomAccessIteratorConcept<int*> >();
 
-  boost::function_requires< 
-    boost_concepts::ConstantLvalueRandomAccessIteratorConcept<const int*> >();
+  boost::function_requires<
+    boost_concepts::ConstantLvalueIteratorConcept<const int*> >();
+  boost::function_requires<
+    boost_concepts::RandomAccessIteratorConcept<const int*> >();
 
+  boost::function_requires<
+    boost_concepts::MutableLvalueIteratorConcept<new_iterator> >();
+  boost::function_requires<
+    boost_concepts::RandomAccessIteratorConcept<new_iterator> >();
+
+  boost::function_requires<
+    boost_concepts::MutableLvalueIteratorConcept<old_iterator> >();
+  boost::function_requires<
+    boost_concepts::RandomAccessIteratorConcept<old_iterator> >();
   return 0;
 }