From 6e06e4f89e4090ec63fa76489049580c59e7bba2 Mon Sep 17 00:00:00 2001
From: Dave Abrahams <dave@boostpro.com>
Date: Wed, 19 Nov 2003 20:16:52 +0000
Subject: [PATCH] Refactored minimum_category

[SVN r20865]
---
 .../iterator/detail/minimum_category.hpp      | 90 +++++++++++++++++++
 .../boost/iterator/iterator_categories.hpp    | 80 +----------------
 include/boost/iterator/zip_iterator.hpp       |  2 +
 3 files changed, 93 insertions(+), 79 deletions(-)
 create mode 100755 include/boost/iterator/detail/minimum_category.hpp

diff --git a/include/boost/iterator/detail/minimum_category.hpp b/include/boost/iterator/detail/minimum_category.hpp
new file mode 100755
index 0000000..bb323f1
--- /dev/null
+++ b/include/boost/iterator/detail/minimum_category.hpp
@@ -0,0 +1,90 @@
+// Copyright David Abrahams 2003. Use, modification and distribution is
+// subject to the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef MINIMUM_CATEGORY_DWA20031119_HPP
+# define MINIMUM_CATEGORY_DWA20031119_HPP
+
+# include <boost/type_traits/is_convertible.hpp>
+# include <boost/type_traits/is_same.hpp>
+
+# include <boost/mpl/aux_/lambda_support.hpp>
+
+namespace boost { namespace detail { 
+//
+// Returns the minimum category type or error_type
+// if T1 and T2 are unrelated.
+//
+// For compilers not supporting is_convertible this only
+// works with the new boost return and traversal category
+// types. The exact boost _types_ are required. No derived types
+// will work. 
+//
+//
+template <bool GreaterEqual, bool LessEqual>
+struct minimum_category_impl;
+
+template <class T1, class T2>
+struct error_not_related_by_convertibility;
+  
+template <>
+struct minimum_category_impl<true,false>
+{
+    template <class T1, class T2> struct apply
+    {
+        typedef T2 type;
+    };
+};
+
+template <>
+struct minimum_category_impl<false,true>
+{
+    template <class T1, class T2> struct apply
+    {
+        typedef T1 type;
+    };
+};
+
+template <>
+struct minimum_category_impl<true,true>
+{
+    template <class T1, class T2> struct apply
+    {
+        BOOST_STATIC_ASSERT((is_same<T1,T2>::value));
+        typedef T1 type;
+    };
+};
+
+template <>
+struct minimum_category_impl<false,false>
+{
+    template <class T1, class T2> struct apply
+    : error_not_related_by_convertibility<T1,T2>
+    {
+    };
+};
+
+template <class T1, class T2>
+struct minimum_category
+{
+    typedef minimum_category_impl< 
+        ::boost::is_convertible<T1,T2>::value
+      , ::boost::is_convertible<T2,T1>::value
+    > outer;
+      
+    typedef typename outer::template apply<T1,T2> inner;
+    typedef typename inner::type type;
+      
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(2,minimum_category,(T1,T2))
+        };
+    
+# if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
+template <>
+struct minimum_category<int,int>
+{
+    typedef int type;
+};
+# endif
+
+}} // namespace boost::detail
+
+#endif // MINIMUM_CATEGORY_DWA20031119_HPP
diff --git a/include/boost/iterator/iterator_categories.hpp b/include/boost/iterator/iterator_categories.hpp
index cf5ac39..5da1956 100644
--- a/include/boost/iterator/iterator_categories.hpp
+++ b/include/boost/iterator/iterator_categories.hpp
@@ -17,10 +17,8 @@
 # include <boost/mpl/identity.hpp>
 # include <boost/mpl/placeholders.hpp>
 # include <boost/mpl/aux_/lambda_support.hpp>
-# include <boost/mpl/aux_/msvc_eti_base.hpp>
 
 # include <boost/type_traits/is_convertible.hpp>
-# include <boost/type_traits/is_same.hpp>
 
 # include <boost/static_assert.hpp>
 
@@ -44,83 +42,7 @@ struct random_access_traversal_tag
   : bidirectional_traversal_tag {};
 
 namespace detail
-{
-
-  //
-  // Returns the minimum category type or error_type
-  // if T1 and T2 are unrelated.
-  //
-  // For compilers not supporting is_convertible this only
-  // works with the new boost return and traversal category
-  // types. The exact boost _types_ are required. No derived types
-  // will work. 
-  //
-  //
-  template <bool GreaterEqual, bool LessEqual>
-  struct minimum_category_impl;
-
-  template <class T1, class T2>
-  struct error_not_related_by_convertibility;
-  
-  template <>
-  struct minimum_category_impl<true,false>
-  {
-      template <class T1, class T2> struct apply
-      {
-          typedef T2 type;
-      };
-  };
-
-  template <>
-  struct minimum_category_impl<false,true>
-  {
-      template <class T1, class T2> struct apply
-      {
-          typedef T1 type;
-      };
-  };
-
-  template <>
-  struct minimum_category_impl<true,true>
-  {
-      template <class T1, class T2> struct apply
-      {
-          BOOST_STATIC_ASSERT((is_same<T1,T2>::value));
-          typedef T1 type;
-      };
-  };
-
-  template <>
-  struct minimum_category_impl<false,false>
-  {
-      template <class T1, class T2> struct apply
-        : error_not_related_by_convertibility<T1,T2>
-      {
-      };
-  };
-
-  template <class T1, class T2>
-  struct minimum_category
-  {
-      typedef minimum_category_impl< 
-          ::boost::is_convertible<T1,T2>::value
-        , ::boost::is_convertible<T2,T1>::value
-      > outer;
-      
-      typedef typename outer::template apply<T1,T2> inner;
-      typedef inner::type type;
-      
-      BOOST_MPL_AUX_LAMBDA_SUPPORT(2,minimum_category,(T1,T2))
-  };
-    
-# if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
-  template <>
-  struct minimum_category<int,int>
-  {
-      typedef int type;
-  };
-# endif
-  
+{  
   //
   // Convert a "strictly old-style" iterator category to a traversal
   // tag.  This is broken out into a separate metafunction to reduce
diff --git a/include/boost/iterator/zip_iterator.hpp b/include/boost/iterator/zip_iterator.hpp
index 8d60894..5b52683 100755
--- a/include/boost/iterator/zip_iterator.hpp
+++ b/include/boost/iterator/zip_iterator.hpp
@@ -28,6 +28,8 @@
 #include <boost/iterator/iterator_categories.hpp>
 #include <boost/detail/iterator.hpp>
 
+#include <boost/iterator/detail/minimum_category.hpp>
+
 #include <boost/tuple/tuple.hpp>
 
 #if BOOST_WORKAROUND(__GNUC__, == 2) || BOOST_WORKAROUND(__MWERKS__, <= 0x2407)